Volume 6, No. 1, 2014
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JOURNAL OF ENGINEERING & PROCESSING
MANAGEMENT
An Internation Journal
Supported by
Ministry of Science and Technology of Republic of Srpska and
Academy of Science and Arts of Republic of Srpska
Journal of Engineering & Processing Management|
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Volume 6, No. 1, 2014
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Name of Journal/Naziv časopisa:
Journal of Engineering & Processing Management
Editors/Urednici:
Prof. Miladin Gligorić, co-editor
Prof. Mitar Perušić, co-editor
Technical Editor/Tehnički urednik:
Aleksandar Došić
Editorial board/UreĎivački odbor:
Prof. Miladin Gligorić, University of East Sarajevo, Faculty of Technology Zvornik, RS, B&H
Prof. Mitar Perušić, University of East Sarajevo, Faculty of Technology Zvornik, RS, B&H
Prof. Miomir Pavlović, University of East Sarajevo, Faculty of Technology Zvornik, RS, B&H
Prof. Milovan Jotanović, University of East Sarajevo, Faculty of Technology Zvornik, RS, B&H
Prof. Andrzej Kowal, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Krakow,
Poland,
Prof. Vladimir Srdić, Universty of Novi Sad, Faculty of Technology, Serbia
Prof. Zdravko Krivokapić, University of Podgorica, Faculty of Mechanical Engineering, Montenegro
Prof. Ţeljko Grbavĉić, University of Belgrade, Faculty of Technology and Metallurgy, Serbia
Prof. Svetomir Hadţi Jordanov, University ―St. Kiril and Metodij‖ Skopje, Faculty of Technology and
Metallurgy, Macedonia
Prof. Ivan Krastev, Institute of Physical Chemistry, Bulgarian Academy of Sciences, Bulgaria
Prof. Regina Fuchs-Godec, University of Maribor, Faculty of Chemistry and Chemical Engineering, Slovenia
Prof. Ivan Esih, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Croatia.
Publisher/Izdavač:
University of East Sarajevo, Faculty of Technology Zvornik, Republic of Srpska, Bosnia & Herzegovina
For publisher/ Za izdavača:
Prof. Miladin Gligorić
Number of copies/Tiraž:
500
Journal of Engineering & Processing Management
Karakaj bb, 75 400 Zvornik
Republic of Srpska, Bosnia & Herzegovina
+ 387(56) 261 072 + 387(56) 260 190 [email protected] www.journalepm.org
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Predgovor
Poštovani,
cilj časopisa je prezentacija i diskusija rezultata koji su neposredno vezani za teorijske,
inženjerske i menadžerske aspekte, kako u hemijskoj i procesnoj industriji, prehrambenoj industriji,
tako i u metalurgiji, građevinarstvu i industriji, kao i tema iz oblasti zaštite životne sredine. Ovom
prilikom pozivamo autore sa univerziteta, istraživačkih centara i industrije da uzmu učešće u
narednim brojevima ovog časopisa.
Uređivački odbor
Preface
Dear,
The main objective of the Journal is presentation and discussion of the results that are
directly linked to theoretical managing and engineering aspects in chemical and processing
industry, food industry as well as in metallurgy, construction and industrial finishing, also including
themes related to environment and environmental protection. The authors from universities,
research centres and industry are invited to submit papers and take part in future numbers of this
publication.
Editorial board
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Volume 6, No. 1, 2014
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CONTENTS
1.
SYNTHESIS 4-NITRO-4-BIPHENYL BY CROSS-COUPLING REACTION
Lj.Vasiljević, I. Ćirić, D. Grujić
7
2.
EFFECT OF LIGHT ON THE AGING, CORROSION, AND
DEGRADATION OF MATERIALS, IN RELATION TO THE ENHANCED
REMOVAL OF ORGANIC POLLUTANTS
I. Juranić
15
3.
DEVELOPMENT AND OPTIMIZATION OF CARVEDILOL
FORMULATION USING EXPERIMENTAL DESIGN
P. Sibinović, V. Marinković, R. Palić, I. Savić, I. Savić-Gajić, D. Milenović,
R. Janković
TREATMENT OF GROUND WATER CONTAMINATED OIL
DERIVATIVES
V. Šćekić, R. Cvejić, S. Smiljić
49
INFLUENCE OF 4A ZEOLITE SYNTHESIS PROCESS PARAMETERS ON
WATER SORPTION CAPACITY
M. Janković, A. Tanasijević, R. Filipović, M. Perušić
PREDICTING THE BALLISTIC STRENGTH OF ULTRA HIGH
MOLECULAR WEIGHT POLYETHYLENE/FIBER COMPOSITES BY
IMPLEMENTING FULL FACTORIALEXPERIMENTAL DESIGN
D. Dimeski, V. Srebrenkoska
79
7.
DEFINING REGULATING PARAMETERS
OF SODIUM DITHIONYTE Na2S2O4
M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
99
8.
RESEARCH OF CHARACTERISTICS OF PROCESS NEUTRALIZATION
OF ACID WASTEWATER BY LIME SLUDGE
S. Begić, V. Mićić, Z. Petrović, S. Tuzlak
4.
5.
6.
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91
109
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Lj.Vasiljević, I. Ćirić, D. Grujić
DOI: 10.7251/JEPMSR1406007V
UDK: 547.622:66.095
Naučni rad
SINTEZA 4-NITRO-4-METILDIFENILA CROSS-COUPLING REAKCIJOM
Ljubica Vasiljević1, Ivan Ćirić2, Dragana Grujić3
[email protected]
1
Univerzitet u Istočnom Sarajevu, Tehnološki fakultet, 75400 Zvornik, Republika Srpska, BiH
2
Visoka tehnološka škola strukovnih studija, 15000 Šabac, Srbija
3
Univerzitet u Banjoj Luci, Tehnološki fakultet, 78000 Banja Luka, Republika Srpska, BiH
Izvod
Difenili čine važnu klasu organskih jedinjenja. Značajni su u oblasti prirodnih proizvoda,
polimera i savremenih medicinskih materijala. U ovom radu je odabran sintetski put crosscoupling (Suzuki-eve) reakcije polazeći od benzena preko jodonijum soli do 4-nitro-4´-metildifenila.
Dobijeni intermedijeri kao i konačni proizvod sinteza su potvrđeni određivanjem temperature
topljenja, kao i IC-spektroskopijom. Krajnji proizvod je potvrđen i NMR-spektroskopijom.Ovaj
sintetski put dobijanja difenila, koji može biti ključni intermedijer u mnogim sintezama, ima niz
prednosti u odnosu na ranije definisane sintetske puteve, zbog tolerantnosti u odnosu na širok krug
funkcionalnih grupa, regio i stereo selektivnost i specifičnost. Osim toga, neorganski proizvodi u
sintezi nisu toksični kao do sada korišteni teški metali (Hg(II), Tl(III), Pb(IV)) i lako se odvajaju.
Postignuti su i visoki prinosi proizvoda reakcije.
Ključne riječi: difenili, 4-nitro-4´-metildifenil, cross-coupling reakcija (Suzuki).
UVOD
Najpogodniji naĉin dobijanja supstituisanih biarila je „unakrsno-kuplovanje―(crosscouplingreaction, Suzuki) – reakcija katalizovana plemenitim metalima [1-4]. Jako dobra metoda za
stvaranje CC veze izmeĊu bor-organskih jedinjenja i organskih halogenida (trifluoracetatima) ili
jodonijumovim solima je reakcija unakrsno-kuplovanje katalizovano paladijumom [2,3]. U ovom
tipu reakcija najrasprostranjenijajedinjenja, u svojstvu bor-organskih jedinjenja, su borne kiseline.
Reakcije unakrsnog kuplovanja poseduju niz prednosti u odnosu na sliĉne metode.
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Najvaţnije prednosti pomenute metode su neosetljivost na prisustvo vode, tolerantnost u odnosu na
širok krug funkcionalnih grupa, regio-specifiĉnost i stereo-specifiĉnost [5-7]. Osim toga, neorganski
proizvodi reakcije nisu toksiĉni i lako se odvajaju od reakcionih komponenata.
Reakcija unakrsnog-kuplovanja vrši se korišćenjem baza, od kojih se naĉešće primenjuju: Na2CO3,
NaOH, NaOEt, t-BuOK. Što su substrati sterno usloţnjeniji, time jaĉe baze daju veći prinos [1,2].
Reakcija unakrsnog-kuplovanja moţe biti vršena na sobnoj temperaturi, ali se ona odvija vrlo sporo
u tom sluĉaju, pa se zbog toga reakciona smeša obiĉno zagreva na 60110 C, naroĉito ako se
koriste sterno oteţani supstrati (ili supstrati sa sternom smetnjom).
Katalizator koji se koristi je u obliku PdCl2 (0,1 moldm3 rastvor), ĉini ovu metodu sinteze veoma
specifiĉnom jer je primena ovog katalizatora, osloboĊenog od fosfonijumovih liganada, što
opravdava napred iznešene prednosti sintetskog puta [2,6].
U reakciji unakrsnog-kuplovanja moguće je korišćenje substrata kako sa elektrondonornim, tako i sa
elektronakceptornim grupama.
Jedinjenja polivalentnog joda mogu se podeliti u nekoliko grupa. U prvu spadaju jedinjenja,
kombinovana s jednim ugljeniĉnim ligandom (RIX2), RIX4). Ona se koriste za selektivnu oksidaciju
razliĉitih organskih supstrata. Druga grupa jedinjenja polivalentnog joda ukljuĉuje jodonijumove
soli R2I*X, koje sadrţe dva ugljeniĉna liganda. Jodonijumove soli ne ispoljavaju oksidaciona
svojstva, i koriste se za transformaciju jednog ugljeniĉnog liganda u nukleofilni supstrat[6,7].
Interesovanje prema jedinjenjima joda(III) izazvano je sliĉnim osobinama jedinjenja joda(III) i
Hg(II), Tl(III), Pb(IV), ali odsustvom toksiĉnosti, pristutne kod teških metala, koja je odigrala
presudnu ulogu u razvoju ovog interesovanja [6].
U ovom radu predmet jeunakrsno-kuplovanjepara-tolilborne kiseline i 4-nitro-difeniljodonijumbromida katalizovano solima dvovalentnog paladijuma.[8,9]
EKSPERIMENTALNI DIO
Temperature toplenja su odreĊene u otvorenoj kapilari, standardnim laboratorijskim postupkom. IC
spektri su snimljeni na Perkin Elmer Spectrum u KBr fazi. NMR spektri su snimljeni na BRUKER
250ARX sectrometer (300MHz) koristeći TMS kao internacionalni standard.4-nitro-4´-metildifenil
je sintetizovan preko niza sledećih intermedijera:4-nitrojodobenzen, 4-nitro(dihlorojodo)benzen, 4nitrojodozobenzen, 4-nitro-difeniljodonijum-bromid i na kraju 4-nitro-4-metildifenil.
Reakcioni put se odvijao prema sledećoj reakcionoj šemi:
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Slika 1. Reakciona shema dobijanja 4-nitro-4-metildifenila iz benzena
1. 4-nitrojedobenzen
U trogrli balon, snabdeven mehaniĉkom mešalicom, povratnim hladnjakom i kapalicom, stavlja se
8,9 cm3 (0,1 mol, 7,8 g) benzena, 12,7 g (0,05 mol) usitnjenog praha joda, 6 cm3 ugljen-tetrahlorida
i 20 cm3glacijalne sirćene kiseline. Zatim se toj smeši pri zagrevanju (110 C) u silikonskom
kupatilu dodaje u toku 1 ĉasa u kapima smeša, koja se sastoji od 11,7 cm3 azotne kiseline (d = 1,14
kg/m3) i 34,5 cm3 sumporne kiseline (d = 1,84kg/m3). Mešanje smeše traje 1 ĉas, posle ĉega se
reakciona smeša razblaţuje s vodom. Izdvojeni ţuti talog se odfiltrira, ispira sa rastvorom natrijumsulfata i suši na vazduhu. Prekristalizacija se vrši iz benzena.
TToplj. = 170 C. Prinos iznosi 8,82 g (0,0354 mol) (35%). Literaturna vrednost TToplj. = 171 C.
2. 4-nitro(dihlorojodo)benzen
U balonu se rastvara 8,82 g (0,0354 mol) para-nitrojodbenzena u 200 cm3 hloroforma. Balon se
ohladi ledom i pri mešanju se propušta gasoviti hlor (14,5 g KMnO4, 61 cm3 HCl ( = 36%) u toku
1 ĉasa. Izdvojeni ţuto-zeleni talog se odfiltrira, ispira sa hloroformom i suši na vazduhu. T Toplj. =
174 C (uz razlaganje). Prinos 9,57 g (0,030 mol) (84%).Literaturna vrednost TToplj. = 175176 C
(uz razlaganje) [10].
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3. 4-nitrojodozobenzen
U poseban avan, hlaĊen u kadi sa ledom, stavi se 9,57 g (0,030 mol) 4-nitro-(dihlorjodo)benzena,
8,7 g bezvodnog natrijum-karbonata (0,082 mol) i 20 g usitnjenog leda. Smesa se utrljava, sve dok
se led ne rastopi, nakon ĉega se dodaje 25 cm3 5 moldm3 rastvor NaOH i ostavi preko noći.
Obrazovana oranţ supstanca se odfiltrira, ispira vodom, hloroformom i suši na vazduhu.
TToplj = 70 C (uz razlaganje). Prinos 6,97 g (0,0263 mol) (88%).Literaturna vrednost TToplj = 78 C
(uz razlaganje) [8].
4.
4-nitro-difeniljodonijum-bromid
U 37 cm3 koncentrovane sumporne kiseline i 4,4 cm3 benzena pri temperaturi od 30 C pri mešanju
se dodaje 6,97 g (0,0263 mol) praha 4-nitrojodozobenzena u toku 20 minuta. Reakciona smeša se
zadrţava 1 ĉas. Nakon toga isĉezava oksidaciona sposobnost (proba sa KI). Zatim se sadrţaj balona
izliva u 250 g leda, odfiltrira talog, rastvor se dva puta tretira aktivnim ugljem i obradi sa rastvorom
od 4,87 g natrijum-bromida u 24,5 cm3 vode. Talog se ispira vodom, etrom, suši na vazduhu.
TToplj. = 150 C. Prinos 4,27 g (0,0105 mol) (10%).Literarna vrednost: TToplj. = 149 C [14].
5.
4-nitro-4-metildifenil
Suvoj smeši paratoliborne kiseline (0,14 g, 0,0011 mol), kalijum-karbonata (0,28 g, 0,0022 mol), 4nitro-difeniljodinijum-bromida (0,38 g, 0,001 mol) u atmosferi argona dodaje se pri mešanju vodeni
rastvor paladijum-hlorida (2 cm3,  (PdCl2) = 1%) i postepeno zagreva od sobne temperature do 80
C do isĉezavanja tolilborne kiseline (6 ĉasova). Zatim se smeša ekstrahuje etrom (2x20 cm3), suši
nad natrijum-sulfatom, odfiltrira i predestiluje etar.
TToplj. = 140 C. Prinos 0,15 g (0,0007 mol) (75%).Literarna vrednost: TToplj. = 140 C[6].
REZULTATI I DISKUSIJA
U organskoj hemiji je vaţna ne samo sinteza nekog jedinjenja, nego i dokaz njegove strukture. Osim
u literatiri opisanih konstanti – temperatura topljenja i kljuĉanja, indeksa prelamanja (za teĉnosti),
kao metoda odreĊivanja strukturnih formula (ili prisustva odreĊenih funkcionalnih grupa) javljaju se
i IC-spektroskopija i spektroskopija nuklearne magnetne rezonance (NMR). U daljem tekstu su dati
IC spektri svih dobijenih jedinjenja, a takoĊe i NMR spektar krajnjeg proizvoda.
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Tabela 1. IC spektri svih dobijenih jedinjenja
Jedinjenje
Trake apsorpcije, cm1
Grupa
4-nitrojodbenzen
830860
13301350
15001530
840860
13401360
15101530
840860
13401360
15201530
840860
1,4-disupstitucija
4-nitro(dihlorjodo)benzen
4-nitrojodozobenzen
4-nitrodifeniljodonijum-bromid
4-nitro-4-metildifenil
Nitro-grupa
1,4-disupstitucija
Nitro-grupa
1,4-disupstitucija
Nitro-grupa
1,4-disupstitucija
13401360
15001530
13401360
15101530
Nitro-grupa
Nitro-grupa
Tabela 2.Reakcioni prinosi sa temperaturama topljenja svih dobijenih jedinjenja
Jedinjenje
4-nitrojodbenzen
4-nitro(dihlorjodo)benzen
4-nitrojodozobenzen
4-nitrodifeniljodonijumbromid
4-nitro-4-metildifenil
Prinos
Temperatura topljenja
tt exp.[°C]
tt liter.[°C]
170
171
174
175
70
78*
m[g]
8,82
9,57
6,97
[%]
35
84
88
4,27
10
150
149
0,15
75
140
140
podaci nagovještavaju na onečišćenja uzorka
*
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Slika 2. 1H-NMR-spektar 4-nitro-4-metildifenila
Podaci 1H-NMR-spektra 4-nitro-4-metildifenila (rastvarač CDCl3, TMS)
H-NMR-spektra 4-nitro-4-metildifenila(CDCl3, 300MHz): δ: 8,27-8,24 (d, 2H), 7,71-7,68(d, 2H) 7,52-7,49
1
(d, 2H) 7,26-7,23 (d, 2H), 2,39 (s, 3H).
ZAKLJUČAK

Odabrani sintetski put cross-coupling reakcije, sproveden prema zadatoj reakcionoj šemi
(slika 1), dao je oĉekivani proizvod 4-nitro-4-metildifenil.

Intermedijerni proizvodi, jodonijum soli su potvrĊeni sa IC spektroskopijom (tabela 1).

Vrednosti apsorpcionih maksimuma(cm-1), dati u tabeli 1 potvrĊuju da su dobijene
jodonijum soli kao prekursori u ovoj cross-coupling reakciji kao odabranom sintetskom putu.

Reakcioni prinosi koji su se kretali od 10 do 88% (tabela 2), mogu posluţiti za analizu
opravdanosti ovog sintetskog puta.

Temperature topljenja dobijene eksperimentalno se jako dobro slaţu sa literaturnim
podacima za temperature topljenja sintetisanih intermedijera i 4-nitro-4-metildifenila, što
potvrĊuje da smo u ovim hemijskim reakcijama dobili oĉekivane proizvode reakcije (tabela
2).
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Ove vrijednosti nailaze na odstupanje samo u sluĉaju sinteze4-nitojodozobenzena
temperatura topljenja ukazala na ĉinjenicu da je uzorak bio oneĉišćen.

gdje
H-NMR-spektra 4-nitro-4-metildifenila (CDCl3, 300MHz): δ: 8,27-8,24 (d, 2H), 7,71-7,68
(d, 2H) 7,52-7,49 (d, 2H) 7,26-7,23 (d, 2H), 2,39 (s, 3H) sa pouzdanošću nam potvrĊuje da
se radi o proizvodu koji je bio predmet sintetskog cross-coupling puta.
1
LITERATURA
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
Suzuki, ―Organoborates in new synthetic reactions,‖ Acc. Chem. Res. 15, (1982), 178-184.
Corma, H. Garcia and A. Leyva, ―Bifunctional palladium-basic zeolites as catalyst for Suzuki
reaction,‖ App. Catal. A General 236, (2002), 179-185.
J. Tsuji, Transition Metal Reagents and Catalysts, Innovations in Organic Synthesis, J. Willey,
(2000).
M. Moreno-Manas, M. Perez and R. Pleixats, ―Palladium-Catalysed Suzuki-Type Self
Coupling of Arylboronic Acids. A mechanistic Study,‖ J. Org. Chem. 61, (1996), 2346-2351.
G. T. W. Solomons, Organic Chemistry, J. Willey, (2000).
S. Kotha, K. Lahiri and D. Kashinath, ―Recent applications of the Suzuki-Miyaura crosscoupling reaction in organic synthesis‖, Tetrahedron, 58, (2002), 9633-9695.
M. Dams, L. Drijkoningen, B. Pauwels, G.V. Tendeloo, D.E. DeVas and P.A. Jacobs, ―PdZeolites as Heterogeneous Catalysts in Heck Chemistry,‖ J. Catal. 209, (2002), 225-236.
Chen, T.; Liu, X.-G.; Shi, M. Tetrahedron 2007, 63, 4874. (b) Liu, L.; Wang, F.; Shi, M.
Organometallics 2009, 28, 4416. (c) Liu, L.; Wang, F.; Shi, M. Eur. J. Inorg. Chem. (2009),
1723.
[9] Song, H.; Gu, L.-N.; Zi, G. J. Organomet. Chem. 694 (2009), 1493.
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DOI: 10.7251/JEPMSR1406007V
UDK: 547.622:66.095
Scientific paper
SYNTHESIS 4-NITRO-4-BIPHENYL BY CROSS-COUPLING REACTION
Ljubica Vasiljević1, Ivan Ćirić2, Dragana Grujić3
[email protected]
1
3
University of East Sarajevo, Faculty of Technology, 75400 Zvornik, Republic of Srpska, B&H
2
Higher Eduacation School for Applied Studies of Technology, 15000 Sabac, Serbia
University of Banja Luka, Faculty of Technology, 78000 Banja Luka, Republic of Srpska, B&H
Abstract
Biphenylsarean important class of organic compounds. Theyare importantin the field of
natural products, polymersand the contemporary medical materials. Synthetic route cross-coupling
(Suzukis) reaction, starting from benzenevia the iodoniumsaltto 4-nitro-4'-metilbiphenyl is chosen in
this study. The resulting intermediates and final product of the synthesis was confirmed by
determination of the melting point and infrared spectroscopy. The final product was confirmed by
NMR spectroscopy. This synthetic pathway to obtain biphenyls, which may be a key intermediate in
many syntheses, there area number of advantages over the previously-defined synthetic routes due
to the tolerance in respect of a wide range of functional groups, regio and stereoselectivity and
specificity. In addition, theinorganic productsin the synthesis of non-toxic so farbeen used as heavy
metals (Hg (II), Tl(III), Pb(IV)) and can be easily separated. High yields of the reaction products
are obtained.
Keywords: biphenyls,4-nitro-4'-metilbiphenyl,cross-coupling reaction (Suzuki).
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I. Juranić
DOI: 10.7251/JEPMEN1406015J
UDK: 544.526:504.5
Review
EFFECT OF LIGHT ON THE AGING, CORROSION, AND DEGRADATION
OF MATERIALS, IN RELATION TO THE ENHANCED REMOVAL OF
ORGANIC POLLUTANTS
Ivan Juranić
[email protected]
University of Belgrade, Institute for Chemistry, Technology and Metallurgy, Center for Chemistry,
11001 Belgrade, Serbia
Abstract
A review on advanced photochemical processes influencing properties of materials is
presented. Particular emphasis is given on photolytic processes for the removal of pollutants.
Separately are presented methods for the removal of biological pollution.
Major concern is paid to the methods for removal of persistent chemical pollutants. Two major
groups of processes are known: homogenous and heterogeneous photocatalytic methods. The
heterogeneous photocatalysis is usually done with semiconductor nanoparticles, capable to absorb
light. In semiconductor the absorption of light quanta is connected with the promotion of electron(s)
from valence to conduction band, leaving a positively charged hole(s) in CB. Electrons and holes
can react with adsorbed molecules including water molecules. In this way the reactive intermediates
are produced, which upon the sequence of reactions end with complete mineralization of
ingredients.
The scaling-up of heterogeneous photocatalytic process is closely connected with efficacy of them.
As a matter of fact, many factors are involved in kinetics of photocatalysis: concentration of
pollutants; concentration of catalyst; temperature; radiant flux; quantum yield; dopants; etc. The
interrelations among various parameters are mostly nonlinear, and construction of the photoreactor
is very demanding task. In last 30 years a lot of study was done, and general conclusion is that TiO2
(mostly anatase) is most efficient photocatalyst, but there is a lot of work needed on improvement of
such processes.
Keywords: photocatalysis, semiconductor photocatalysts, enhanced degradation of
pollutants, doped photocatalysts.
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INTRODUCTION
Aging, corrosion and degradation of materials have common relation to effect of light. On
the other hand, there are specific aspects of these changes which deserve their own elaboration. In
this review, the issues of aging and corrosion will be briefly mentioned, and major subject will be
removal of air- and water pollutants.
AGING
Aging is common feature of all materials, and there is a well defined distinction between physical
and chemical aging [1]. The physical aging is easily monitored and predicted taking into account
physical stress and temperature [2]. Generally, this aspect of aging is rather slow. Chemical aging is
more complex and more efficient. It could be caused by chemical agents, but also by illumination
and ionizing radiation, and similar ‗physical‘ actions.
Particular concern is needed in the conservation of art and other collections because ―Collections
items damaged by light cannot be repaired or fixed by conservators. Light damage is permanent,
irreversible, and cumulative, meaning that each exposure to light poses some damage that eventually
causes significant change in the item including weakening, embrittlement, yellowing, darkening,
color shift, and other issues depending upon the nature of the item exposed to light‖ [3, 4].
The importance of light for the changes of materials is well-known for a long time. It is a part of
every accelerated aging test. For example, of dental materials [5, 6], polyvinyl acetate paints [7],
acrylic paints [8, 9], of PVC/CaCO3 composites [10], of chalcogenide glasses [11] (this is closely
related to heterogeneous photocatalysis), of secondary organic aerosol material [12], of multicrystalline silicon materials [13], and many other.
At this point we shall not offer a detailed account of light-assisted aging, but it will be explained
along the general discussion of light-assisted degradation and removal of pollutants in air and water.
CORROSION
Corrosion is specific aspect of aging and degradation of metals [14].
The corrosion behavior of carbon steel was largely studied [15, 16]. Weight loss measurements were
carried out in the three conditions, sunlight, shadow and dark conditions using the same solution. In
polarization tests, an increase in the anodic current density and the corrosion rate of carbon steel
appeared under UV light.
Since iron oxides exhibit a semiconductor-like behavior, the current density increases by the
migration of photoelectrons and production of holes at the interface. EIS tests confirmed that in the
presence of UV light the charge transfer resistance of the system decreases significantly, which is in
agreement with polarization data.
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The immersion test indicated that the sunlight increased the weight loss of the specimens within
seven days. This is explained by the promotion of corrosion and rust formation due to the active
oxygen generated by photoelectrochemical reactions under UV light.
The photo-corrosion is induced by an accumulation of photo-excited holes at the oxide surface,
probably because the accumulation may increase the interfacial potential difference at the oxide
surface and weaken the M-O bond of the oxide. The effect is due to photo-enhanced
electromigration of charged defects like oxygen vacancies and interstitial Fe in the oxide film.
POLLUTANTS IN AIR AND WATER
Major types of pollutants, can be recognized as biological (bacteria and viruses) and
chemical (natural or anthropogenic).
Bacterial pollutants - generally, pathogens are very common in the environment, and it is a subject
of permanent concern of health and sanitary professionals. Air pollution by bacterial pollutants is
serious only in closed space without proper ventilation and/or cleaning.
Because water is a natural medium for many microorganisms, biologically polluted water is more
serious problem. Waterborne microbial species are known to be inactivated by solar disinfection, as
given in Table 1 [17].
It was shown that pathogens listed in Table 1 are readily inactivated by exposure to sunlight in
simple PET bottles.
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Table 1. Several most common pathogen microorganisms and their susceptibility to light
Microbe Species
Bacteria
Disease
Reduction with SODIS method (6h, 40 °C)
Indicator for water
quality & enteritis
Cholera
Typhus
Dysentery
Dysentery
Diarrhoea
99.999%
Disease
Reduction with SODIS method (6h, 40 °C)
Rotavirus
Diarrhoea, dysentery
90%
Polio virus
Polio
99.9 - 99.99%
Hepatitis virus
Hepatitis
Reports from users
Disease
Reduction with SODIS method (6h, 40 °C)
Giardia species
Cryptosporidium spe.
Giardiasis
Cryptosporidiasis
Amoeba species
Amibiasis
Cysts rendered inactive
Cysts rendered inactive after > 10h
exposure
Not rendered inactive.
Water temperature must be above 50 °C
for at least 1h to render inactive!
Escherichia coli
Vibrio cholera
Salmonella species
Shigella flexneri
Campylobacter jejuni
Yersinia enterocolitica
99.999%
99.999%
99.999%
99.999%
99.999%
Virus
Parasites
An additional list of microbial pathogens described in papers listed at SODIS site [18, 35].
Enterococcus sp.
Mycobacterium avium
Mycobacterium intracellulare
Pseudomonas aeruginosa
Salmonella typhimurium
Shigella dysenteriae type 1
Streptococcus faecalis
Staphylococcus epidermidis
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Using advanced photolytic methods the removal of persistent microorganisms can be achieved [19].
Not only in water, but also on solid surfaces [20].
Chemical pollutants are equally versatile. Volatile organic compounds (VOC) are present in
atmosphere stemming both from natural and anthropogenic sources. Importance of monitoring the
status of VOC in atmosphere is well illustrated by World Meteorology Organization (WMO) in their
―Statement Of Guidance For Atmospheric Chemistry‖ [21]. The photochemical transformations of
VOCs are under extensive basic research for decades now [22-24].
The biggest source of chemical pollution is waste from chemical industry. Particularly, the organic
raw industry waste [25, 26] may be a problem, because it is often hard to control its spreading. It is
particularly true with gaseous pollutants [27] like formaldehyde [25, 28], (HCHO), automobile
exhaust [29], liquid, gasoline [30, 31], benzene [32, 33]. Most of it can be readily removed using
various standard methods. Crude, refractory organic compounds [34] (called persistent and/or
recalcitrant) present the opposite problem and can be efficiently removed using only advanced
photocatalytic methods [35]. It could be stated that the general approach for the removal of
recalcitrant pollutants is their transformation to more reactive derivatives [36].
Pharmaceutical waste is another problem which is rarely seriously treated. Because of specific effect
of waste drugs it‘s important to completely remove them from water and soil [37]. On the other
hand, it is equally important to monitor the effect of light on the drugs [38]. Similar status have
pesticides [39] (and agrochemicals in general) [40].
Surfactants, and textile dyes (including their precursors) [41] are very common pollutants and their
removal and monitoring of their degradation products attracted a lot of interest. As specific
examples, one can point to the photoactive pollutants capable of producing harmful intermediates:
photodegradation of 4-nitrophenol [42], chlorophenols [43, 44], and many others.
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THE REMOVAL OF POLLUTANTS
Generally, most desirable methodology for the removal of pollutants is regular biological
activity of specific organisms. In practice, it is hard to obtain efficient action of natural processes.
The major reason is that high concentration of pollutants drastically inhibits the growth of biological
material.
Research results are showing that particulate and dissolved natural organic material (NOM) in
marine and surface waters, interstitial waters in sediments and soil solutions are influencing the
(chemo)dynamics of inorganic and organic contaminants [45]. Among NOM components, the most
interest attracted humic acids [46]. Humic substances (HS) are the largest constituent of soil organic
matter (∼60%) and are considered to be a key component of the terrestrial ecosystem, being
responsible for many complex chemical reactions in soil [47]. They are very stable in natural
medium because of their intimate interactions with soil mineral phases and are chemically too
complex to be used by micro organisms. As far as soil is concerned, one of the most striking
characteristics of HS is their ability to interact with metal ions, oxides, hydroxides, mineral and
organic compounds [48], including toxic pollutants [49-51], to form water-soluble and waterinsoluble complexes.
Formation of such complexes contributes to a reduction of toxicity through the passivation of
harmful ingredients. Moreover, HS can interact with xenobiotic organic molecules such as
pesticides [48, 52-54].
Very promising is the use of adapted microorganisms. Major problem is that much polluted (e.g.
saline) waters are not fit for microorganisms [55]. Nevertheless, it can be a very cost-effective
method for removal of pollutants.
Combination of various biological methods for the removal of pollutants is used for constructed
wetlands. Constructed wetlands (wetland treatment systems) are wetlands designed to improve
water quality. They use the same processes that occur in natural wetlands but have the flexibility of
being constructed. As in natural wetlands, vegetation, soil, and hydrology are the major components.
Different soil types and plant species are in use. Regarding hydrology, surface flow and subsurface
flow constructed wetlands are the main types [56]. Subsurface flow constructed wetlands are further
subdivided into horizontal or vertical flow.
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Many constructed wetlands deal with domestic wastewater where BOD and COD (Biochemical and
Chemical Oxygen Demand, respectively) are used as a sum parameter for organic matter. In general,
the removal efficiency for organic contaminants is high.
ADVANCED METHODS FOR REMOVAL OF ORGANIC POLLUTANTS
Advanced oxidation comprises a range of similar but different chemical processes (AOP)
aimed at tackling pollution in water, air and soil. Several directions are identified on advanced
oxidation for water/wastewater treatment [57]. Water treatment by means of AOPs constitutes a core
theme of research covering areas such as:
- industrial effluent treatment including, amongst others, distillery, agrochemical, craftbleaching, pulp and paper, textile dye house, oilfield and metal-plating wastes;
-
hazardous effluent treatment including hospital and slaughterhouse wastes;
-
removal of pathogens and persistent, endocrine disrupting pharmaceutical residues from
municipal wastewater treatment plant (WWTP) effluents (i.e. after secondary treatment);
AOPs can provide effective technological solutions for water treatment. Such solutions are vital for
supporting and enhancing the competitiveness of different industrial sectors, including the water
technology sector, in the global market. The main goals of academic, research and industrial
communities through the development and implementation of environmental applications of AOPs
will be:
- new concepts, processes and technologies in wastewater treatment with potential benefits
for the stable quality of effluents, energy and operational cost savings and the protection
of the environment;
-
new sets of advanced standards for wastewater treatment;
-
new methodologies for the definition of wastewater treatment needs and framework
conditions;
-
new know-how for contributing to enhancement of the European water industry
competitiveness.
A specific feature of all advanced photolytic processes for treating of pollutants in air, soil and water
is their ability for the microbial inactivation [20, 58]. General idea of AOPs is in the first place the
use of reactive intermediates for the destruction of pollutants [26, 59, 60].
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The major reactive species are OH radicals, singlet oxygen and ozone. The water photolysis is an
obvious source for OH radicals.
Generally, photolytic methods [60, 61] can be divided on direct [59] and heterogeneous
photocatalysis. Direct photolysis methods [62-64] usually involve use of photosensitizers,
addition/generation of O3 [66], and/or H2O2 [66]. More adequate term will be homogeneous
photocatalysis. These methods are well described in classical works on photochemistry.
Direct irradiation with 206 nm UV of triphenyltin chloride (TPTCl), rhodamine B (RhB), and
dimethyl phthalate (DMP) [68], proved that UV can directly decompose them without any oxidants
or catalysts. It is reasonable to foresee that 206 nm UV would probably be suitable for the removal
of most of organic pollutants in wastewater, which will provide alternative way to photo-degrade
organic compounds in solution. However, intermediate products showed that only a part of targets
can finally be mineralized into CO2 under 206 nm UV irradiation.
Direct photolysis was applied for the removal of chlorophenols at various pH and using various light
sources [43, 67]. The effect of wavelength and pH on the direct photolysis of 2-chlorophenol (2CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) in aqueous solution was studied by
UV XeBr (282 nm) and KrCl (222 nm) excilamps. The highest pseudo-first order rate constants and
quantum yields were found for molecular form of 4-CP (at pH 2 and 5.7) and anionic forms of 2-CP
and 2,4-DCP (at pH 11) when irradiated by XeBr excilamp. The maximum removal efficiency of
molecular 2-CP and 2,4-DCP with the lowest UV dose of absorbed energy was observed using KrCl
excilamp. On the contrary, the XeBr excilamp needed the lowest dose (~2 J·cm-2) for complete
degradation of molecular 4-CP and anionic 2-CP.
Some concerns are raised about the influence of UV irradiation on the quality of drinking water. A
study was made [69] that showed that UV irradiation change the properties of DOM (dissolved
organic matter), and increases the chlorine demand, but does not stimulate biological regrowth and
biofilm formation in water distribution system.
Working at optimized experimental conditions (pH of 2, and H2O2 : EDTA molar ratio of 10), using
a microwave-activated photochemical reactor and monitoring the EDTA degradation by total
organic carbon analysis, mineralization ratios higher than 90% were observed at reaction times of 6
min [70].
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It was found [28] that both background DOC (Dissolved Organic Carbon) and alkalinity have an
inhibitory effect on the reaction rate of metaldehyde and therefore on EEos∗ especially for UV/TiO2
where the alkalinity is a major issue and a chemical or physical process needs to be used to break the
TiO2 aggregates. Although more photons are absorbed by TiO2 than by H2O2, the UV/H2O2 process
remains more effective in term of quantum yield and energy consumption. The highest energy UV
irradiation is affordable with so-called vacuum ultra violet (VUV) mercury lamps. A study of
degradation of anatoxin-A [63] in aqueous solution showed that work with 172 nm lamp needs more
than six time greater illumination in comparison with photolysis in the presence of moderate amount
of H2O2. The optimization of reactor design, TiO2 particles properties, and of the efficiency of light
sources, will reduce the energy consumption and enhance use of AOPs as the drinking water
treatment processes.
The photo-Fenton process [30, 31, 43, 60, 71] is one of the more widely studied AOPs. In the
classical mechanism, hydroxyl radicals are generated by the cycle of oxidation and reduction
reactions (outlined in eqs. 1 and 2) that requires the presence of ferrous ions (Fe2+), hydrogen
peroxide H2O2 and UV irradiation [72, 73]. In the first step, ferrous ions are oxidized by H2O2
(Fenton reaction), generating hydroxyl radicals (eq. 1). In the second step, the ferric ions (Fe3+) are
reduced photochemically to the initial oxidation state (Fe2+), producing an additional hydroxyl
radical, which reacts again via Eq. 1 as long as H2O2 is available.
Fe2+ + H2O2 → Fe3+ + OH- + OH(1)
Fe3+ + H2O
Fe2+ + H+ + OH(2)
∗ The electrical energy consumption currently represents the main part of the overall operating cost
of AOPs and its evaluation is essential in order to evaluate the economic viability of a process. A
figure of merit named electrical energy per order (EEo) has been introduced (Bolton, J.R., Bircher,
K.G., Tumas, W., Tolman, C.A., Pure and Applied Chemistry 2001, 73, 627-637), which is defined
as the electrical energy (in kWh) required to degrade a given volume of a pollutant, typically 1 m3,
by one order of magnitude, and is expressed in kWh m−3.
Being a homogeneous AOP system, the photo-Fenton process presents no limitations of mass
transfer, favoring the kinetics of degradation relative to heterogeneous systems such as TiO2/UV. In
some cases, the concentration of iron used in the photo-Fenton system may exceed the limit
established by environmental legislation and may require removal of the ferric and/or ferrous ions at
the end of the process.
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An important barrier to industrial applications of AOP is the elevated cost of installing, operating,
and maintaining artificial sources of UV radiation such as ionizers or lamps. Experiments on the
degradation of raw gasoline in aqueous media demonstrated the feasibility of conducting the photoFenton process with medium-pressure mercury vapor lamps as the irradiation source. This suggested
the possibility of using solar irradiation as the source of photons in this process. The experiments
carried out in a falling film type solar reactor and three concentration variables were analyzed, i.e.,
iron (Fe2+) from 0.5 to 1.0 mM, total added hydrogen peroxide (H2O2) from 100 to 200 mmol/L, and
sodium chloride (NaCl) from 200 to 2000 ppm.
As a matter of fact, an ecologically effective water treatment technique using electrochemically
generated hydroxyl radicals [74], i.e. electro-Fenton process, was described as a good alternative to
photo-Fenton reaction. It is worth mentioning the Fenton-like reactions as alternative, too, since it is
not necessary to remove the ferric and/or ferrous ions at the end of the process and allow operation
over a wide pH range [See Ref. 112].
Heterogeneous photocatalysis
Heterogeneous photocatalysis can be described as the acceleration of photoreaction in the presence
of a solid catalyst. In the contexts of history and research, interest in heterogeneous photocatalysis
can be traced back to many decades when Fujishima and Honda discovered in 1972 the
photochemical splitting of water into hydrogen and oxygen in the presence of TiO2 [75]. From this
time, extensive research, much of it published, has been carried out to produce hydrogen from water
in oxidation-reduction reactions using a variety of semiconductor catalyst materials.
In recent years (about two decades) heterogeneous photocatalysis arises as a major promising
approach for efficient removal of pollutants [11, 35, 76-81]. In recent literature there are more than
2000 publications on the subject.
Semiconductors naturally emerged as photocatalysts, because of their specific energy gap between
filled (valence) and empty (conducting) electron levels. Semiconductors have energy gap of few eV
(∆E in Fig. 1. Usually it is denoted as Eg – ‗energy gap‘). The smaller the gap, the absorption is
more in the visible part of spectrum. On the other hand, very small energy gap makes the material
more reactive and susceptible to environmental conditions.
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Orbitals
Energy
N=1
N=2
N=10
N2000 N»2000
LUMO
∆E
∆E
∆E
∆E
HOMO
Atom
Molecule
Cluster
Q-size
particles
Semiconductor
Figure 1. Change in the electronic structure of a semiconductor as the
number N of singly occupied orbitals present, increases from unity to
clusters of more than 2000
Several metal chalkogenides (oxides, sulfides and selenides) are viable photocatalysts: TiO2, ZnO
[82-85], CuO [86], CdS [87], CuSe [88], ZnSe [88], WO3 [89], etc. But, in almost all practical
applications, the catalyst used was non-porous titania (mainly anatase). Titania was sometimes
modified either by iron doping or by deposition of a metal (Pt, Rh, or Ni).
-2
E vs. NHE
-1
H· /H2
0
2.4 eV
1
3.0 eV
3.2 eV
O2/H2O
3.2 eV
2.7 eV
2.2 eV
2
CdS
3
TiO2 (rutile)
TiO2 (anatase)
SrTiO3
WO3
Fe2O3
Figure 2. Valence and conductance band positions for various
semiconductors and useful, relevant redox couples at pH≈0. In order to
photoreduce a chemical species, the conductance band of the semiconductor
must be more negative than the reduction potential of the chemical species;
to photo-oxidize a chemical species, the potential of the valence band of the
semiconductor must be more positive than the oxidation potential of the
chemical species.
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Inertness to chemical environment and long-term photostability has made TiO2 an important
material in many practical applications, and in commercial products ranging from drugs to foods,
cosmetics to catalysts, paints to pharmaceuticals, and sunscreens to solar cells in which TiO2 is used
as a desiccant, brightener, or reactive mediator.
*
The U.S. Food and Drug Administration permits up to 1% TiO2 as an inactive ingredient in food products.
While there are no known health effects associated with the use of TiO2, a recent study found that 3-6 year
old children are the most affected group of people that consume TiO2 particles from food products. Many
new properties of TiO2 have been explored. It should be stated that regulatory framework for the use of TiO2
in food products are yet to be firmly established in many countries, especially developing nations. The
catalyst itself is unchanged during the process and no consumable chemicals are required. This results in
considerable savings and simpler operation of the equipment involved.
Titanium dioxide is generally recognized as a most interesting photocatalyst [28, 60, 76, 90-93],
which has a number of favorable properties: chemical inertness, does not change under prolonged
irradiation, biologically neutral for almost all organisms. On the other hand, it has a number of
unfavorable properties, too: a) Of the two important polymorphs of TiO2, anatase begins to absorb
UV light around 387 nm (band gap energy, Ebg ∼3.2 eV), whereas the absorption onset of rutile
occurs around 413 nm (Ebg ∼3.0 eV) increasing sharply to shorter wavelengths. It means that TiO2
absorbs a relatively small fraction (cca. 3-5%) of the solar radiation reaching the Earth‘s surface. b)
The most important issue regards the notion that once photogenerated, e− and h+, tend to recombine
more efficiently and rapidly, relative to otherwise slow redox chemistry at the TiO2 surface (see
Table 2).
The science that underlies heterogeneous photocatalysis has shown that the lowest energy level of
the bottom of the conduction band (CB) of TiO2 is a measure of the reduction potential of the
photogenerated electrons, whereas the higher energy level of the valence band (VB) is a measure of
the oxidation potential of photogenerated holes. pH-Dependent flat band potentials, Vfb, of the CB
and VB bands of this metal oxide determine the energy of electrons and holes at the interface.
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Accordingly, reductive and oxidative processes of couples with redox potentials more positive and
more negative than the Vfb of CB and VB, respectively, can be driven by surface trapped electrons
(e−) and holes (h+) that are poised to engage in various processes, the most important of which are
photoreductions and photooxidations.
Corollary, the obvious strategy for the improvement of the performance of heterogeneous
photocatalytic system is to lower the band-gap, to enable the absorption of the larger fraction of
visible light. It can be achieved by doping of TiO2 with various materials.
Figure 3. Doping of TiO2 with p-block elements
Very good results were obtained by doping titania with p-block elements: N [94], C, S [95], B, F
[96], as seen on Fig. 3. Although visible light absorption can be easily introduced by doping,
absorption does not always result in satisfactory visible light photocatalytic activity, which is
usually found to be not as good as that of pure TiO2 under UV irradiation. As a matter of fact,
several problems can be associated to single TiO2 doping. High doping levels can hardly be attained
because of the high formation energy, due to the unmatchable ionic charge and/or radius between
the doped ions and host ones.
Absorption in the visible region remains rather limited, relative to the band-band absorption of pure
TiO2 in the UV region. Moreover, the recombination rate of the charge carriers is found to increase
in doped samples, because of dopant-derived localized states in the band gap and bulk defects such
as oxygen vacancies, acting as recombination centers. These also limit the mobility of the
photogenerated carriers in the bulk, which hinders the migration of the carriers to the chemical
species adsorbed on the photocatalyst surface. Also importantly, the introduction of electronic states
above the valence band decreases the oxidation power under visible light irradiation.
The general working principle of photocatalysis is fairly well known and is the same in water and
air. The process is initiated by activating the catalyst with light of sufficient energy, commonly this
is ultraviolet (UV) light.
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When this happens, an electron is excited from the filled valence band to the empty conduction
band, leaving behind a hole in the valence band (Fig. 3). An electron-hole (e−–h+) pair is thus
generated (reaction (3)), which can recombine again (either in bulk or on the surface, see Fig. 4) or
which can migrate toward the catalyst surface and initiate redox reactions to reduce or oxidize the
pollutants [78].
volume
recombination
hν
 
A
A
R
D+

D
surface
recombination
Figure 3. Fate of electrons and holes within a spherical particle
of titania in the presence of acceptor (A) and donor (D)
molecules
There are two distinct species present: a hole and an electron. The following reactions represent a
couple of the possible reactions of e− and h+ on the surface, giving rise to reactive species
TiO2 + hν
TiO2(h+ + e−)
TiO2(h+) + −OH(ads) → TiO2 + OH•(ads)
(3)
(4)
TiO2(e−) + O2(ads) → TiO2 + O2(ads)•−
(5)
The hole can react on the surface with adsorbed water or surface hydroxyl groups in order to form
hydroxyl radicals (reaction (4)). These radicals are postulated to be very important for the oxidation
processes because of their high activity. There exists a widespread agreement on the major role in
TiO2 photocatalysis of these hydroxyl radicals generated by adsorbed water species on the TiO2
surface. Despite this consensus, several studies have questioned whether this mechanism is indeed
reasonable to all TiO2 photocatalytic oxidation reactions [97].
Apart from reactions with the positive hole, the electron can also initiate some reactions. It can, for
instance, react with adsorbed oxygen to form the superoxide radical anion (reaction (5)).
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It was concluded that free hydroxyl radicals can only be generated by the electroreduction of oxygen
with photogenerated conduction band electrons because the photo-oxidation of nonadsorbed water
molecules (or surface OH groups) with valence band holes is both thermodynamically and
kinetically unfavorable. The detailed mechanism for the photocatalytic oxidation reactions thus
remains a controversial issue.
The feasibility of these reactions depends on the redox potential of TiO2. As can be seen in Fig. 5,
the redox potential of the conduction band of TiO2 is more negative than that of the O2/O2•− redox
couple. This means that oxygen can be reduced to superoxide radical anions (reaction (5)). The
redox potential of several other species can be found in Fig. 5, where they are compared to the redox
potential of TiO2.
-0.52
-0.45
e
e
-1
Ti3+-OH
0
+0.28
+1
H2/H2O (-0.413)
O2/O2·- (-0.28)
O2/H2O2 (+0.28)
Fe(CN)64-/3- (+0.36)
O2/H2O (+0.83)
H2O2/H2O (+1.35)
+2
+2.53
h
h
O3/H2O (+2.07)
·
OH/H2O (+2.27)
+3
(pH = 7)
Figure 4. Schematic diagram showing the potentials for various redox
processes occurring on the TiO2 surface at pH 7
Other strategy for the improvement of photocatalytic efficiency is to change the surface of TiO 2
particles to increase the rate of oxidation/reduction of adsorbed substrate(s).
An important aspect of semiconductor photochemistry, in macrocrystalline and microcrystalline
material, is the retardation of the electron-hole recombination process through charge carrier
trapping [76]. As indicated earlier, in the preparation of semiconductor colloids, ideal crystal lattices
are not produced in many cases, the colloid material can be so disorganized as to appear amorphous
to X-ray diffraction. Thus most semiconductor colloid materials will have surface and bulk
irregularities, i.e. defects, and these can act as electron-hole recombination centers or traps. The
presence of such traps can alter significantly the photochemistry associated with the semiconductor
colloid.
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Table 2. Primary processes and associated characteristic time domains in the TiO2-sensitized
photomineralization of organic pollutants [126]
Primary process
Characteristic time
Charge carrier generation
TiO2 + hν → h+ + efs ( very fast)
Charge carrier trapping
h+ + >TiIVOH → { >TiIVOH·+ }
10 ns (fast)
IV
III
e + >Ti OH ← → { > Ti OH }
100 ps (shallow trap; dynamic
equilibrium)
e- + > TiIV → >TiIII
10 ns (deep trap)
Charge carrier recombination
e- + { >TiIVOH·+ } → >TilVOH
100 ns (slow)
+
III
IV
h + >Ti OH → >Ti OH
10 ns (fast)
Interfacial charge transfer
{ >TiIVOH·+ } + organic pollutant → >TiIVOH + oxidized pollutant
100 ns (slow)
{ >TiIIIOH } + O2 → >TiIVOH + O·ms ( very slow)
Electron-hole recombination on most semiconductor materials is usually very fast [98], e.g. typically
less than 10 ns for TiO2 (see Table 2). However, if a hole scavenger is added to a semiconductor
colloid, it is possible to remove some of the photogenerated holes and effectively trap the
photogenerated electrons for a sufficient time to allow their transient absorption spectrum to be
recorded. It was shown [99] that the specific-adsorbed anions such as F−, PO43−, and SO42− are able
to act as hole-scavenging agents. Similarly, if an electron scavenger is added, the transient
absorption spectrum of trapped photogenerated holes can be determined. In a series of simple flash
photolysis experiments conducted on TiO2 colloids, were recorded the absorption spectra of trapped
photogenerated electrons (using PVA/Polyvinylalcohol or thiocyanate as the hole scavenging agent)
and of trapped photogenerated holes (using Pt or methyl viologen as the electron scavenging agent),
which life-time is in microseconds.
The use of electron and hole scavengers in photochemical studies involving semiconductor colloids
is widespread and often assumed rather than clearly stated. The most commonly used electron
scavenger is dissolved oxygen, and the most commonly used hole scavenger is the PVA added to the
colloid dispersion for steric stabilization or an added alcohol, such as isopropanol.
The study was done [100] which has shown that the recombination rate is in direct relation with
light intensity. Fewer charge carriers - fewer recombinations. Because the charge carrier
deactivation on the surface of particles is essential for the efficacy of the photocatalysis process, it is
favorable to eliminate, as much as possible, the volume recombination of electrons and holes.
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An interesting way is described by production of nano-flower structures which have extremely high
surface to volume ratio [88].
There are reports [101] on the photodegradation of several dyes under exposure to visible light in
the presence of TiO2 nanoparticles. The visible-light irradiation mechanism (eqs 6-11) is clearly
different from the UV-irradiation pathway described previously; the dye, not the semiconductor
TiO2, is excited by visible light:
dye + hν → dye*
(6)
·+
dye* + TiO2 → dye + TiO2(e)
(7)
TiO2(e) + O2 → TiO2 + O2·(8)
·+
O2 + e + 2 H → H2O2
(9)
H2O2 + e → ·OH + OH(10)
dye·+ + O2 (or O2·- or ·OH) → peroxide or hydroxyl intermediates
→ → degraded or mineralized products
(11)
The excited dye injects an electron to the conduction band of TiO2, whence it is scavenged by
preadsorbed oxygen, O2, to form active oxygen radicals similar to those in UV irradiation processes.
These active radicals drive the photodegradation or mineralization. The TiO2 plays a significant role
of an electron carrier, leading to separation of injected electrons and cationic dye radicals.
VERSATILE APPLICATIONS OF HETEROGENEOUS PHOTOCATALYSIS
Because of complex (photo)chemistry behind the heterogeneous photocatalytic processes,
the search for the improved efficiency of these processes is mostly driven by researchers intuition,
and every promising idea has to be tested experimentally for its validity. Here are several examples
of these searches.
Photocatalyzed degradation of polymers in aqueous semiconductor suspensions [102] revealed that
the photodegradation of water-insoluble polymeric films or particulates in TiO2 aqueous dispersions
is not very efficient. The blending of TiO2 with PVC makes it more susceptible to the effect of light,
but improvement is not much impressive.
Very efficient removal of chlorinated aromatics pollutants was achieved with photocatalytic
membrane reactor [103]. The combination of dynamic membrane (CaCO3) with photocatalysts (FeZnIn2S4) is proved to be practicable for removal of halogenated compounds in water. This hybrid
system can give rise of continuous photocatalysis, stirring, and separation of photocatalysts, in a
single device. When the TiO2 is used as photocatalyst, the performance is just 3-5 % lower than with
Fe-ZnIn2S4.
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Cu(II)-TiO2
CO2
Degradation products
··· acetaldehyde
··· water
CB +0.04
Cu2+/Cu+
H2O2
eVisible light
O2
Imogolite
Imogolite
VB +3.04
·OH
·OH
·OH
h+
h+
CO2
Degradation products
CO2
Degradation products
Figure 5. Possible photodegradation mechanisms of acetaldehyde under
visible light irradiation; with Cu(II)-grafted TiO2–imogolite composite as
photocatalyst
Imogolite* with a nanotubular structure was synthesized hydrothermally and used to prepare
imogolite–TiO2 and imogolite–Cu(II)-grafted TiO2 composites. The photocatalytic degradation of
acetaldehyde by these composites was investigated [86]. Nanotubular imogolite had a high specific
surface area (245 m2/g), with a strong surface affinity for water molecules. Under UV irradiation,
photodegradation of acetaldehyde by the imogolite– TiO2 composite was greater than that of TiO2,
indicating that imogolite plays an important role in adsorbing the acetaldehyde. The optimum
mixtures of the TiO2 as the photocatalyst, and imogolite as the adsorbent, lie between the
compositions TiO2:2-imo and TiO2:3-imo. However, the photoactivity is also dependent on the
relative humidity. With increasing relative humidity, the photodegradation activity decreases, but
the photodegradation activity of the Cu(II)-grafted TiO2–imogolite composite of composition CuTiO2:3-imo was less affected by the relative humidity, and this composite also exhibited higher
photoactivity under visible light irradiation than Cu(II)-grafted TiO2 (Cu- TiO2). The imogolitecontaining composite has been suggested to be a very effective visible-light-driven photocatalyst
and could be used to completely decompose or remove VOCs.
Nano-crystalline TiO2 electrodes prepared by the electrophoretic immobilization of Degussa P25 on
tin oxide glass showed [104] high efficiencies for the degradation of formic acid in one- and twocompartment photo-electrochemical cells (PEC). The application of +1.0 V to the TiO2 electrode
resulted in a marked increase in the rate of degradation of the formic acid when the concentration of
dissolved O2 was low.
*Imogolite is an aluminosilicate with a single-walled nanotubular structure consisting of a layer of aluminum(III)
hydroxide (gibbsite), with isolated silicate groups bound on the inner wall.
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There was not a marked increase in the rate in O2 saturated solutions compared to the open circuit
(OC) electrode. Similar results were obtained with nanocrystalline films of TiO2 prepared on
borosilicate and ITO (indium doped tin oxide) coated borosilicate glass, using a stirred tank reactor
[105]. Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under
UVA and UVB irradiation shoved that the rate of formic acid oxidation under UVB irradiation was
30% greater as compared to UVA irradiation.
In a two-compartment PEC formic acid was photocatalytically degraded at the anode while Cu2+
was reduced to Cu0 at the cathode when the illuminated TiO2 anode was short-circuited to the
copper mesh cathode. The initial IPCE (incident photon to current efficiency) for this system was
9.5%. This technology is worth testing whether it would work with ‗real‘ industrial effluents and
solar illumination.
Recently, a very marked improvement in doping of TiO2 is achieved [106]. Usually, high doping
will generate pronounced structure distortion that degrades the electron-hole separation. However,
the substitutional replacement of surface bridging O‘s (by surface bombardment with N atoms from
adequate source) can retain the structure perfection even at the 9.4% doping level. The obtained
samples combine beneficial effects of both extraordinary electronic structure at high doping level
and superior charge separation efficiency with structure perfection.
The high activity of surface modified TiO2 samples implies the importance of surface chargetrapping sites as compared to the bulk sites [107]. The surface N doping increases the photoactivity
dramatically, but it does not show noticeable change of optical absorption. This is because only a
small portion of the surface has been modified, which is not detectable by the UV-vis spectrometer.
In the N-TiO2 surface layer, the photogenerated electron can be captured by the π-conjugated
structure of N via a percolation mechanism. Hence, the N sites act as the electron acceptors in the
TiO2, effectively suppressing the charge recombination and leaving more holes at Ti sites to form
reactive species that promote the degradation of dyes/pollutants.
The results imply a conclusion that the photocatalytic activity is wavelength dependent. To interpret
this, a schematic drawing of the energy diagram is shown in Figure 6.
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Figure 6. Schematic drawing of energy levels and the proposed processes of
electron excitation in the N-TiO2 samples
For the sample under UV irradiation, all the excitations of (1)−(4) will be facilitated, whereas only
(2)−(4) are possible under visible light. The visible light activities for (2)−(4) are ~2.85 times lower
than that under UV light. Therefore, the wavelength dependence of the external reaction efficiency
(η) was found to be η(vis)/η(UV) = 0.35, which is in good agreement with the value of 0.3 for the
charge separation efficiency ratio, Φ(vis)/Φ(UV) [108]. This implies that nearly all free charges
generated by visible light excitation contribute to the photocatalytic reactions. The wavelength
dependence of external reaction efficiency is reasonable because the final states of the electrons
induced by visible light (Ti 3d ← N 2p transition) are different from that induced by UV excitation
(Ti 3d ← O 2p and Ti 3d ← N 2p transition). Therefore, different redox potentials are generated by
photons with different energies. The efficiency of this photocatalyst is twice that of the other doped
TiO2 [109], [110], probably due to the fact that modification is confined at the surface. Moreover, on
the basis of XPS measurement and DFT calculations, broad states are formed at the VBM (valence
band maximum), which benefits enhancing the lifetime of the photoexcited carriers [111]. The
formation of broad states makes the diffusion of electrons easier inside the lattice, which retards the
corresponding recombination.
A photoreaction generally takes place in water environment, and photogenerated electron−hole pairs
can react with H2O to form reactive oxygen species (ROS). Typically, the photogenerated electron
combine with adsorbed oxygen to form superoxide anion (O2.-), and the holes react with
OH− to form hydroxyl radicals, (OH•). Subsequently, a chain reaction is activated to decompose the
pollutants into small molecules. The majority of electron-hole pairs is trapped at bulk trapping sites
and recombine there with release of heat.
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Therefore, to have higher activity, not only the materials should absorb more photons, but also the
amount of surface trapped electron-hole pairs should increase, competing with their recombination
in the bulk. Surface nitridation can improve the photoactivity under visible light irradiation.
However, the ability that the electron-hole pairs generated at N sites to migrate to the surface is also
important. To achieve the best modified results, only the top ∼10 nm of the surface needs to be
engineered. Results suggest that the carrier diffusion dynamics may exhibit different behavior under
UV and visible light irradiation.
As interesting alternative to TiO2 photocatalyst, it was found [112] that tungsten oxide (WO3) with a
band gap sufficiently narrow for visible light absorption (i.e., 2.6 eV) has the proper energy level of
valence band (i.e., +3.1 VNHE) for oxidation of absorbed water or hydroxide ions, into •OH,
providing the potential capability for visible-light-induced water treatment and disinfection.
However, the conduction band (CB) potential (i.e., +0.4 VNHE) of WO3 is not negative enough to
reduce molecular oxygen as an electron acceptor ubiquitously present in aqueous environmental
media. As a result, the photocatalytic reactions on pure WO3 are limited due to the rapid
recombination of electron-hole pairs.
The strategies to enable WO3 to harness visible light for pollutant oxidation by facilitating charge
separation include
(1) application of electron acceptors alternative to O2 (e.g., Cu(II), S2O82−),
(2) loading of co-catalyst (e.g., CuO, Pt), and
(3) coupling of semiconductors with different band-gap structures.
For example, Cu(II) ions function as electron scavengers to retard the recombination of charge
carriers, resulting in a two to three orders of magnitude improvement in the WO3 photocatalytic
surface mineralization of methanol.
The combination with Fenton-like reagent drastically accelerated WO3-mediated photocatalytic
oxidation under initially neutral pH conditions that favor the precipitation of Fe(III)-oxyhydroxides
[89]. Although significant photo-reduction of Fe(III) to Fe(II) took place on WO3 irrespective of pH
conditions, the inability of Fe(III) as an electron scavenger to facilitate charge separation at neutral
pH was confirmed, and is based on the negligible oxidative degradation in the WO3/Fe(III) system.
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On the other hand, the photo-generation of Fe(II) led to more rapid H2O2 decomposition in the
WO3/Fe(III)/H2O2 system (relative to the WO3/H2O2 system), implying the possible involvement of
the Fenton reaction in the enhanced photocatalytic degradation. The photolytic experiments with
various probe compounds (benzoic acid, coumarin, and methanol) showed that the
WO3/Fe(III)/H2O2 system was more photoactive for the production of both •OH and Fe(IV) than the
WO3/H2O2 system. The efficacy for hydroxylation of benzoic acid and coumarin (as •OH probe)
correlated well to the rate of photocatalytic 4-CP oxidation as initial pH of the aqueous suspensions
of WO3/Fe(III)/H2O2 increases, indicating that Fe(II)-mediated conversion of H2O2 to •OH is
responsible for the improved photocatalytic activity of the ternary system for organic oxidation. In
addition to the iron-catalyzed decomposition of H2O2 to produce •OH at circum-neutral pH,
significant oxidative degradation under visible light irradiation was achieved in the
WO3/Fe(III)/H2O2 system.
The WO3-modified TiO2 nanotubes proved to be photocatalytically highly efficient [112] using solar
light. Depending on the WO3 content, either negative or positive effects were observed. It was
proposed that the negative influence could result from the appearance of charge recombination
centers, and by contrast, that the positive influence could be explained by a limitation of the
photogenerated charge recombination induced by the modification. The formation of a W xTi1−xO2
solid solution, leading to the emergence of intermediate energy levels depending on the tungsten
content, was proposed. The TiNT-WO3 4% composite material was found as the most effective
photocatalyst for the degradation of organosulfur compounds such as diethyl sulfide.
Combination of photocatalytic methods with other AOPs is studied too. Effect of ultrasonication is
very complex [122]. Ultrasound enhances the production of HO· and other free radicals, but, on the
other hand, the light is scattered by cavitation bubbles attenuating the light flux.
Many pollutants like insecticides, pesticides, detergents as well as several chemical warfare agents
(CWA) are organophosphorous compounds. The removal of dimethyl methylphosphonate (DMMP)
and trimethyl phosphate (TMP) was obtained using the modified titania catalyst [123]. Deposition of
Pt and Pd particles over TiO2 Degussa P25 by mild chemical reduction allowed obtaining very
active photocatalyst with activity much higher comparing to pure P25 and modified or unmodified
Hombifine. The highest activity was observed at Pt content 1 wt.%, whereas almost same activity
was at Pt and Pd content of 0.1%. Sulfuric acid additions further increased the activity at low Pt
content but decreased it at high Pt content. Platinized photocatalyst demonstrated the same shape of
reaction rate versus DMMP concentration dependence, with increased reaction rate constant that
was attributed to a better charge separation. Photocatalytic oxidation of DMMP in 3 L recirculating
batch reactor was studied with supported and suspended photocatalyst. The highest reaction rate was
obtained with air bubbling and supported catalyst at the highest recirculation rate.
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It was demonstrated that the increase in stirring rate or recirculation rate does not improve DMMP
mass transfer. Instead, it improves the reaction rate via the increase of the dissolved oxygen
concentration. The recirculating reactor demonstrated the same kinetic dependences as obtained in a
beaker. The supported photocatalyst was stable in multiple uses whereas suspended photocatalyst
was not.
The reverse processes, i.e. photocatalytic reduction which can enhance sequestration of CO2, are
subject of very intense studies [124]. Investigation is primarily directed to facilitating activation of
two of the most thermodynamically stable molecules, CO2 and H2O. Conversions achieved so far
are extremely small, <1%, occurring at a very slow rate, and catalysts tend to become deactivated
very quickly. The CO2 photoreduction process is highly complex, involving multi-electron transfer,
and is non-selective, leading to a range of C1 - C3 compounds whose reaction pathways have not yet
been fully established.
Another line of intensive research is the production of H2 [125]. Despite a relatively low efficiency
of the photocatalytic (TiO2) hydrogen production system, for a capacity of 32.48 m3/hr, the
hydrogen production cost is around 3.00 US$, which is attractively low and acceptable, compared to
the other water purification systems such as activated carbon or UV/O3. There is a good chance to
make the photocatalytic systems a better alternative way of hydrogen production.
ANALYSIS OF PARAMETERS FOR BUILDING OF LARGE SCALE EQUIPMENT FOR REMOVAL OF
POLLUTANTS FROM WATER AND AIR
Potential of heterogeneous photocatalytic processes was recognized more than 30 years ago,
but its implementation for large-scale removal of pollutants from water was very slow [80]. At the
start, two major problems were recognized. How to provide uniform light distribution inside the
reactor through the absorbing and scattering liquid to the catalyst, and how to provide the high
surface areas for catalyst coating per unit of reactor volume. On this line were done the analyses of
several other parameters influencing the yield and kinetics of photocatalysis [77, 113]:
Mass of catalyst
Either in static, or in slurry, or in dynamic flow photoreactors, the initial rates of reaction were
found to be directly proportional to the mass m of catalyst. This indicates a true heterogeneous
catalytic regime. However, above a certain value of m, the reaction rate levels off, and become
independent of m. This limit depends on the geometry and on the working conditions of the
photoreactor. It was found equal to 1.3 mg TiO2 per square centimeter of a cross-section of a fixed
bed, and to 2.5 mg TiO2 per cubic centimeter of suspension.
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These limits correspond to the maximum amount of TiO2 in which all the particles - i.e. all the
surface exposed - are totally illuminated. For higher quantities of catalyst, a screening effect by
excess particles occurs, which masks part of the photosensitive surface. For applications, this
optimum mass of catalyst has to be chosen in order (i) to avoid an unnecessary excess of catalyst
and (ii) to ensure a total absorption of efficient photons.
One major barrier to the development of a photocatalytic reactor is that the reaction rate is usually
slow compared to conventional chemical reaction rates, due to low concentration levels of the
pollutants. Other crucial hurdle is the need to provide large amounts of active catalyst inside the
reactor. Even though the effective surface area of the porous catalyst coating may be high, there can
only be a thin coating (about 1 μm thick) applied to a surface. Larger thickness of catalyst layer
washes away during experiments due to poor adhesion. Thus, the amount of active catalyst in the
reactor is limited and, even if individual degradation processes can be made relatively efficient, the
overall conversion efficiency will still be low. This problem severely restricts the processing
capacity of the reactor and the time required to achieve high conversions is measured in hours, if not
days.
Wavelength
The variations of the reaction rate as a function of the wavelength follows the UV-visible absorption
spectrum of the catalyst, with a threshold corresponding to its band gap energy. For TiO2 with E 
3.02 eV, this requires:   400 nm. One must be aware of possibility of light absorption by
reactants, too.
Initial concentration
The kinetics, generally, follows a Langmuir-Hinshelwood mechanism with the rate r varying
proportionally with the coverage as:
r = k(KC/(1 +KC))
For diluted solutions (C < 10-3 M), KC becomes << 1 and the reaction is first order, whereas for
concentrations > cca. 510-3 M, (KC>> 1), the reaction rate is at maximum and is of the zeroth
order. Similar Langmuir-Hinshelwood expressions including partial pressures P instead of C have
been found for gaseous reactants. In some cases, such as in alcohol dehydrogenation, the rate
follows a square root variation:
r = k[ K½C½/ (1 + K½C½) ]
This indicates that the active species react in the dissociated adsorbed state. In other cases, such as in
the photocatalytic degradation and mineralization of chlorobenzoic acids, a zero kinetic order was
found, even at low concentrations. This is due to a strong chemisorption on titania with the
saturation of the hydroxylic adsorption sites. For a maximum yield, reactions should be performed
with initial concentrations equal to, or higher than, the threshold of the plateau.
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Temperature
Because of the photonic activation, the photocatalytic systems do not require heating. The true
activation energy is nil, in agreement with an experimental activation energy Ea very small (a few
kJ/mol). Photocatalysis is generally operating at room temperature. At low temperature (<0 °C), the
activation energy Ea increases and tends to become equal to the heat of desorption of the reaction
product. This is exemplified by the case of hydrogen in alcohol dehydrogenation or alkanedeuterium isotopic exchange, carried out on bifunctional Pt/TiO2 photocatalysts [114, 115]. This
means that at these low temperatures, the rate-limiting step becomes desorption of the H2 (or HD)
from the metallic part of the catalyst.
By contrast, at 'high' temperatures (θ  70 °C) for various types of photocatalytic reactions (as those
that use mirror-focused solar light), the activity decreases and the apparent activation energy
becomes negative [116]. This indicates that the adsorption of the reactant becomes the rate limiting
step.
As a consequence, the optimum temperature is generally comprised between 20 and 80 °C. This
explains why solar devices which use light concentrators require coolers. This absence of heating is
attractive for photocatalytic reactions carried out in aqueous media and in particular for
environmental purposes (photocatalytic water purification). There is no need to waste energy in
heating water which possesses a high heat capacity. Photocatalysis has been presented as
competitive with incineration for VOC treatment in air [117].
Radiant flux
The light power invested is determined by measuring the radiant flux. The total light power emitted
corresponds to cca. 20% of the electrical power consumed. It has been shown, for all types of
photocatalytic reactions, that the rate of reaction r is proportional to the radiant flux, . This
confirms the photo-induced nature of the activation of the catalytic process, with the participation of
photo-induced electrical charges (electrons and holes) to the reaction mechanism. However, above a
certain value estimated to be cca. 250 W/m2, the reaction rate r becomes proportional to 1/2. It can
be demonstrated that the rate of electron-hole formation becomes greater than the photocatalytic
rate, which favors the electron-hole recombination:
e- + p+ → N + E
(N: neutral center; E: energy (light hv'  hv , or heat).
The optimal light power utilization corresponds to the domain where r is proportional to.
The problem of photon energy absorption has to be considered regardless of reaction kinetics
mechanisms. The high degree of interaction among the transport processes, reaction kinetics, and
light absorption leads to a strong coupling of physico-chemical phenomena - a major obstacle in the
development of photocatalytic reactors [81].
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The illumination factor is of utmost importance since the amount of catalyst that can be activated
determines the water treatment capacity of the reactor. The volume of photocatalytic reactor,
assuming a well-mixed reactor, can be expressed as
where Q is the volumetric flow rate (m3/s), Cin is the inlet pollutant concentration (mol/m3), X is the
fractional conversion desired, η is the effectiveness factor (the ratio of actual rate to observed rate), κ
is illuminated catalyst surface area in contact with reaction liquid inside the reactor volume (m2/m3)
and
is the average mass destruction rate (mol/m2/s). Hence, smallest reactor volume will be
obtained when κ and
are as large as possible for specified values of Q, Cin, and X.
is a
reaction specific parameter as it expresses the performance of catalyst for the breakdown of a
specific model component, while κ is a reactor specific parameter representing the amount of
catalyst inside a reactor that is sufficiently illuminated so that it is active, and is in contact with the
reaction liquid. An increase in
can be accomplished by modifying the physical nature of the
catalyst in terms of its structure and morphology, or by the addition of additional oxidizing agents.
Improving the degradation rates would lead to the need of reduced amount of catalyst to be
illuminated, and, therefore, a smaller reactor volume. The parameter κ, illuminated specific surface
area, helps to compare design efficiency of different photocatalytic reactors as it defines the efficacy
to install as much active catalyst per unit volume of reaction liquid in the reactor.
Quantum yield
By definition, it is equal to the ratio of the reaction rate in molecules per second (or in mol per s) to
the efficient photonic flux in photons per second (or in Einstein per second (an Einstein is a mol of
photons)). This is a kinetic definition, which is directly related to the instantaneous efficiency of a
photocatalytic system. Its maximum value is equal to 1. It may vary on a wide range according (i) to
the nature of the catalyst; (ii) to the experimental conditions used and (iii) especially to the nature of
the reaction considered. We have found values comprised between 10-4 and 0.7. The knowledge of
this parameter is fundamental. It enables one (i) to compare the activity of different catalysts for the
same reaction, (ii) to estimate the relative feasibility of different reactions, and (iii) to calculate the
energetic yield of the process and the corresponding cost.
Quantum yield highly depends on electron-hole recombination in bulk. If the path to surface is
shorter, the efficacy of chemical transformation of adsorbed molecule is improved. Producing the
catalyst with mesoporous structure and suspended on reticulated support, having high surface to
volume ratio, proved to be very effective [118, 119].
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Modifications of the catalyst by noble metal deposit and ion-doping
As generally observed, the maximum quantum yields are always obtained with titania. In addition,
anatase is the most active allotropic form among the various ones available, either natural (rutile and
brookite) or artificial (TiO2-B, TiO2-H). In photocatalytic reactions involving hydrogen, either as a
reactant (deuterium-alkane isotopic exchange) or as a product (alcohol dehydrogenation), the system
requires the presence of a metal acting as a co-catalyst necessary (i) to dissociate the reactant (D2)
and (ii) to recombine H and D into dihydrogen (or HD). Additionally, the metal (i) attracts electrons,
by photoinduced metal-support interaction (PMSI), (ii) decreases the electron-hole recombination
and (iii) maintains the turn-over number constant [120].
Another modification was aimed at extending the photosensitivity of titania to the visible region to
efficient harvest cheaper and more abundant solar photons. This was done by ion doping, either ntype (Nb5+, Sb5+, Mo6+, Ta5+) or p-type (Ga3+, Cr3+, Al3+). Unfortunately, ion doping was found to
strongly inhibit the reaction and decrease the quantum yield. This was explained by the fact that
both pentavalent donor impurities and trivalent acceptor impurities behave as electron-hole
recombination centers. However, this drawback could be turned into advantage by using ion doping
as a means of passivating TiO2-based pigments in paintings and plastics against weathering [121].
Acknowledgment
Author acknowledges the financial support of the Ministry of Education, Science and Technological
Development of the Republic of Serbia (Grant 172035).
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
Struik, L.C.E. Polymer Engineering and Science, 17(3), (1997) 165-173.
Bystritskaya, E.V., Pomerantsev, E.V., Rodionova, O.Ye. Chemometrics and Intelligent
Laboratory Systems 1999, 46, 175-178.
Care (Preservation, Library of Congress), Lighting of Library Materials – Collections.
http://www.loc.gov/preservation/care/light.html . Accessed 31.5.2013 on 18:04:55
Harrison, C., Aging Paintings: Some Causes and Effects. http://www.previewart.com/Conservators/03-11/conservation03-11.html . Accessed 31.5.2013 on 18:30:43
Pires-de-Souza, F-de-C.P., Casemiro, L.A., Garcia, L-da-F.R., Cruvinel, D.R. The Journal of
Prosthetic Dentistry 2009, 101(1), 14-18.
Nasim, I., Neelakantan, P., Sujeer, R., Subbarao, C.V. Journal of Dentistry 2010, 38s, e137e142.
Journal of Engineering & Processing Management|
41
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[7]
Wei, S., Pintus, V., Schreiner, M. Journal of Analytical and Applied Pyrolysis 2012, 97, 158-
163, http://dx.doi.org/10.1016/j.jaap.2012.05.004
[8] Pintus, V., Wei, S., Schreiner, M. Anal Bioanal Chem 2012, 402, 1567-1584. DOI
10.1007/s00216-011-5369-5
[9] Pintus, V., Schreiner, M. Anal Bioanal Chem 2011, 399, 2961-2976. DOI 10.1007/s00216010-4357-5
[10] Liu, H., Dong, L., Xie, H., Wan, L., Liu, Z., Xiong C. J. Appl. Polym. Sci. 2013, 127, 27492756. DOI: 10.1002/app.37595
[11] Kozdras, A., Golovchak, R., Shpotyuk, O., Szymura, S., Saiter, A., Saiter, J-M. J. Mater. Res.
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
2011, 26(18), 2420-2427. DOI: 10.1557/jmr.2011.264
Sareen, N., Moussa, S.G., McNeill, V.F. J. Phys. Chem. A 2013, 117, 2987-2996.
dx.doi.org/10.1021/jp309413j
Damiani, B., Nakayashiki, K., Kim, D.S., Yelundur, V., Ostapenko, S., Tarasov, I., Rohatgi,
A. Proceedings of 3rd World Conference on Photovoltaic Cell conversion, 18 May 2013,
Osaka, Japan, ISBM: 4-9901816-0-3. Vol. 1, pp. 927-930.
St. Germain, D. Wire Rope News & Sling Technology June 2010, 1-2.
Riazi, H. R., Danaee, I., Peykari, M. Met. Mater. Int. 2013, 19(2), 217-224. doi:
10.1007/s12540-013-2014-1
Bastidas, J.M., Scantlebury, J.D. Corrosion Science 1986, 26(5), 341-347.
SODIS Water Project. Available online:
http://www.sodis.ch/methode/forschung/mikrobio/index_EN (accessed on 22 June 2013).
http://www.sodis.ch/methode/forschung/publikationen/index_EN#microbiology (accessed on
22 June 2013).
Arslan-Alaton, I., Olmez-Hanci, T. In Advances in Treating Textile Effluent. Pp. 73-90.
Edited by Peter J. Hauser, ISBN 978-953-307-704-8, Publisher: InTech, DOI: 10.5772/20435
Matafonova, G., Batoev, V. Chemosphere 2012, 89 637-647.
http://dx.doi.org/10.1016/j.chemosphere.2012.06.012
Barrie, L., WMO, and approved by ET-EGOS-1, December 2005)
http://www.wmo.int/pages/prog/www/OSY/SOG/SoG-Atm-chemistry.doc;
accessed
on
15.July, 2013.
Tadić, J., Juranić, I., Moortgat, G.K. Molecules 2001, 6, 287-299.
Tadić, J., Juranić, I., Moortgat, G.K. Journal of Photochemistry and Photobiology A:
Chemistry 2001, 143, 169-179.
Tadić, J., Juranić, I., Moortgat, G.K. J. Chem. Soc., Perkin Trans. 2 2002, 135-140.
Richards, J.R., Goshaw, D.G. Patent No: US006770174B1, 2004.
Santiago-Morales, J., Gómez, M.J., Herrera, S., Fernández-Alba, A.R., García-Calvo, E.,
Rosal R. Water Res. 2012, 46, 4435-4447.
Journal of Engineering & Processing Management|
42
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[27] Disdier, J., Pichat, P., Mas D. J. Air & Waste Manage. Assoc. 2005, 55, 88-96. ISSN 1047[28]
[29]
[30]
[31]
3289
Autin, O., Hart, J., Jarvis, P., MacAdam, J., Parsons, S.A., Jefferson, B. Applied Catalysis B:
Environmental 2013, 138-139, 268-275.
Sugihara, S., Hatanaka, K. Water 2009, 1, 92-99.
Tiburtius, E.R.L., Peralta-Zamora, P, Emmel, A. Journal of Hazardous Materials 2005, 126(13), 86-90, doi:10.1016/j.jhazmat.2005.06.003
Moraes, J.E.F., Silva, D.N., Quina, F.H., Chiavone-Filho, O., Nascimento, C.A.O. Environ.
Sci. Technol. 2004, 38, 3746-3751.
[32] Tsuji, M., Kawahara, T., Kamo, N., Miyano, M. Bull. Chem. Soc. Jpn. 2010, 83(5), 582-591.
DOI: 10.1246/bcsj.20090335
[33] Getoff, N. Res. Chem. Intermed. 2001, 27(4,5), 343-358.
[34] Caliman, A.F., Teodosiu, C., Balasanian, I. Environmental Engineering and Management
Journal 2002, 1(2), 187-196.
[35] Ibhadon, A.O., Fitzpatrick, P. Catalysts 2013, 3, 189-218; doi:10.3390/catal3010189
[36] McLarnon, C.R., Granite, E.J., Pennline, H.W. Fuel Processing Technology 2005, 87, 85-89.
[37] Me´ndez-Arriaga, F., Otsu, T., Oyama, T., Gimenez, J., Esplugas, S., Hidaka, H., Serpone, N.
[38]
[39]
[40]
[41]
[42]
[43]
[44]
[45]
[46]
[47]
Water Research 2011, 45, 2782-2794. DOI: 10.1016/j.watres.2011.02.030
Pilaniya, K., Chandrawanshi, H.K., Pilaniya, U., Manchandani, P., Jain, P., Singh, N. Journal
of Advanced Pharmaceutical Technology & Research 2010, 1(3), 302-310.
DOI:10.4103/0110-5558.72422
Aaron, J.J., Oturan M.A. Turk. J. Chem. 2001, 25, 509-520.
Ahmed, S., Rasul, M.G., Brown, R., Hashib, M.A. Journal of Environmental Management
2011, 92, 311-330. doi:10.1016/j.jenvman.2010.08.028
Venhuis, S.H., Mehrvar, M. International Journal of Photoenergy 2004, 6, 115-125.
Marci, G., Palmisano, L., Sclafani, A., Venezia, A.M., Campostrini, R., Carfuran, G., Martin,
C., Rives, V., Solana, G. J . Chem. Soc. Faraday Trans. 1996, 92(5), 819-829.
Pera-Titus, M., Garcia-Molina, V., Baños, M.A., Giménez, J., Esplugas, S. Applied Catalysis
B: Environmental 2004, 47, 219-256.
Ho, T-F.L., Bolton, J.R. Wat. Res. 1998, 32(2), 489-497.
Kordel, W., Dassenakis, M., Lintelmann, J., Padberg, S. Pure & Appl. Chem. 1997, 69(7),
1571-1600.
Trevisan, S., Francioso, O., Quaggiotti, S., Nardi, S. Plant Signaling & Behavior 2010, 5(6),
635-643.
Stevenson, F.J., Organic forms of soil nitrogen. In: John Wiley, ed. Humic Chemistry:
Genesis, Composition, Reaction, New York, 1994, pp. 59-95.
Journal of Engineering & Processing Management|
43
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[48] Albers, C.N., Banta, G.T., Hansen, P.E., Jacobsen, O.S. Environ Sci Technol 2008, 1, 8687[49]
[50]
[51]
[52]
[53]
8691.
Cattani, I., Zhang, H., Beone, G.M., Del Re, A.A., Boccelli, R., Trevisan, M. J. Environ. Qual.
2009, 6, 493-501.
Luo, W., Gu, B. Environ. Sci. Technol. 2009, 43, 152-156.
Wang, S., Mulligan, C.N. Chemosphere 2009, 74, 274-279.
Vermeer, A.W.P., Interactions between humic acid and hematite and their effects on metal
ion speciation, Wageningen University, The Netherlands. (PhD thesis) 1996.
Martin-Neto, L., Traghetta, D.G., Vaz, C.M., Crestana, S., Sposito, G. J. Environ. Qual. 2001,
30, 520-525.
[54] Celano, G., Smejkalová, D., Spaccini, R., Piccolo, A. J. Agric. Food. Chem. 2008, 27, 73607366.
[55] Lefebvre, O., Moletta, R. Water Research 2006, 40, 3671-3682.
doi:
10.1016/j.watres.2006.08.027
[56] Haberl, R., Grego, G., Langergraber, G., Kadlec, R.H., Cicalini, A-R., Dias, S.M., Novais,
J.M., Aubert, S., Gerth, A., Thomas, H., Hebner, A. JSS - J. Soils & Sediments 2003, 3(2),
109-124. DOI: http://dx.doi.org/10.1065/jss2003.03.70
[57] Comninellis, C., Kapalka, A., Malato, S., Parsons, S.A., Poulios, I., Mantzavinos D. J. Chem.
Technol. Biotechnol. 2008, 83, 769-776. DOI: 10.1002/jctb.1873
[58] Dunlop, P.S.M., Byrne, J.A., Manga, N., Eggins, B.R. Journal of Photochemistry and
Photobiology A: Chemistry 2002, 148, 355-363.
[59] Ehhalt, D.H. The Science of the Total Environment 1994, 143, 1-15.
[60] Legrini, O., Oliveros, E., Braun, A.M. Chem. Rev. 1993, 93, 671-698.
[61] Oliveira, A.S., Saggioro, E.M., Pavesi, T., Moreira, J.C., Ferreira, L.F.V. In: Molecular
Photochemistry - Various Aspects. Edited by Dr. Satyen Saha, ISBN 978-953-51-0446-9,
Publisher InTech, Published online 30, March, 2012, Published in print edition March, 2012.
[62] Kramer, J.B., Canonica, S., Hoigne, J., Kaschig, J. Environ. Sci. Technol. 1996, 30, 22272234.
[63] Afzal, A., Oppenlander, T., Bolton, J.R., El-Din, M.G. Water Research 2010, 44, 278-286.
doi:10.1016/j.watres.2009.09.021
[64] Chen, J., Advanced Oxidation Technologies. Photocatalytic Treatment of Wastewater, PhD
Thesis, Wageningen University 1997. ISBN 90-5485-762-5.
[65] Penkett, S.A., Law, K.S., Cox, T., Kasibhatla, P. In Atmospheric Chemistry in a Changing
World, G.P. Brasseur, R.G. Prinn, A.A.P. Pszenny (eds.), Springer-Verlag, Berlin, 2003.
[66] Hofman-Caris, C.H.M., Harmsen, D.J.H., Beerendonk, E.F. In M.M. Nederlof, Colofon,
Advanced oxidation processes, Techneau, 2010, Deliverable number D 2.4.1.2b.
Journal of Engineering & Processing Management|
44
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[67] Matafonova, G., Philippova, N., Batoev V. Engineering Letters 2011, 19(1), EL_19_1_04.
[68]
[69]
[70]
[71]
[72]
Advance online publication: 10. February 2011.
Ye, Z.L., Cao, C.Q., He, J.C., Zhang, R.X., Hou, H.Q. Chinese Chemical Letters 2009, 20,
706-710. doi:10.1016/j.cclet.2008.12.033
Choi, Z., Choi, Y-J. Water Research 2010, 44, 115-122. doi:10.1016/j.watres.2009.09.011
Kunz, A., Peralta-Zamora, P., Duran N. Advances in Environmental Research 2002, 7, 197202.
Tokumura, M., Ohta, A., Znad, H.T., Kawase Y. Water Research 2006, 40, 3775 -3784.
Chong, M.N., Jin, B., Chow, C.W.K., Saint C. Water Research 2010, 44, 2997-3027.
[73] Lau, I.W.C., Wang, P., Chiu, S.S.T., Fang, H.H.P. Journal of Environmental Sciences 2002,
14(3), 388-392.
[74] Oturan, M.A. Journal of Applied Electrochemistry 2000, 30, 475-482.
[75] Fujishima, A., Honda K. Nature 1972, 238, 37-38. doi:10.1038/238037a0
[76] Mills, A., Le Hunte, S. Journal of Photochemistry and Photobiology A: Chemistry 1997, 108,
1-35.
[77] Herrmann, J-M. Catalysis Today 1995, 24, 157-164.
[78] Herrmann, J-M. Catalysis Today 1999, 53, 115-129.
[79] Khatae, A.R., Kasiri, M.B., Alidokht, L. Environmental Technology 2011, 32(15), 16691684. http://dx.doi.org/10.1080/09593330.2011.597432 .
[80] Mukherjee, P.S., Ray, A.K. Chem. Eng. Technol. 1999, 22(3), 253-260.
[81] Ray, A.K. Chemical Engineering Science 1999, 54, 3113-3125.
[82] Garcıa-Lopez, E., Marci, G., Serpone, N., Hidaka, H. J. Phys. Chem. C 2007, 111, 1802518032.
[83] Lv, Y., Pan, C., Ma, X., Zong, R., Bai, X., Zhu, Y. Applied Catalysis B: Environmental 2013,
138-139, 26-32. http://dx.doi.org/10.1016/j.apcatb.2013.02.011
[84] Zhou, M., Gao, X., Hu, Y., Chen, J., Hu, X. Applied Catalysis B: Environmental 2013, 138139, 1-8. http://dx.doi.org/10.1016/j.apcatb.2013.02.029
[85] Wanga, Y., Meng, X., Yu, X., Zhang, M., Yang J. Applied Catalysis B: Environmental 2013,
138-139, 326-332. http://dx.doi.org/10.1016/j.apcatb.2013.03.002
[86] Katsumata, K-I., Hou, X., Sakai, M., Nakajima, A., Fujishima, A., Matsushita, N.,
MacKenzie, K.J.D., Okada, K. Applied Catalysis B: Environmental 2013, 138-139, 243-252.
http://dx.doi.org/10.1016/j.apcatb.2013.03.004
[87] Li, C., Ahmed, T., Ma, M., Edvinsson, T., Zhu J. Applied Catalysis B: Environmental 2013,
138-139, 175-183. http://dx.doi.org/10.1016/j.apcatb.2013.02.042
[88] Shi, W., Shi, J., Yu, S., Liu, P. Applied Catalysis B: Environmental 2013, 138-139, 184-190.
http://dx.doi.org/10.1016/j.apcatb.2013.02.031
Journal of Engineering & Processing Management|
45
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[89] Lee, H., Choi, J., Lee, S., Yun, S-T., Lee, C., Lee, J. Applied Catalysis B: Environmental
[90]
[91]
[92]
[93]
2013, 138-139, 311-317. http://dx.doi.org/10.1016/j.apcatb.2013.03.006
Matthews, R.W. Pure &Appl. Chem. 1992, 64(9), 1285-1290.
Jiang, Y., Amal, A. Applied Catalysis B: Environmental 2013, 138-139, 260-267.
http://dx.doi.org/10.1016/j.apcatb.2013.02.026
Radoiĉić, M.B., Janković, I.A., Despotović, V.N., Šojić, D.V., Savić, T.D., Šaponjić, Y.V.,
Abramović, B.F., Ĉomor M.I. Applied Catalysis B: Environmental 2013, 138-139, 122-127.
http://dx.doi.org/10.1016/j.apcatb.2013.02.032
Linsebigler, A.L., Lu, G., Yates, J.T.Jr. Chem. Rev. 1995, 95, 735-758.
[94] Viswanathan, B., Krishanmurthy, K. R. Hindawi Publishing Corporation, International
Journal of Photoenergy 2012, Article ID 269654, 10 pages. doi:10.1155/2012/269654
[95] Emeline, A.V., Kuznetsov, V.N., Rybchuk, V.K., Serpone, N. International Journal of
Photoenergy, Volume 2008, Article ID 258394, 19 pages. doi:10.1155/2008/258394
[96] Dozzi, M.V., Selli, E. Journal of Photochemistry and Photobiology C: Photochemistry
Reviews 2013, 14, 13-28, http://dx.doi.org/10.1016/j.jphotochemrev.2012.09.002
[97] Hauchecorne, B., Lenaerts, S. Journal of Photochemistry and Photobiology C:Photochemistry
Reviews 2013, 14, 72-85. http://dx.doi.org/10.1016/j.jphotochemrev.2012.09.003
[98] Rothenberger, G., Moser, J., Gratzel, M., Serpone, N., Sharma, D.K. J. Am. Chem. Soc. 1985,
107, 8054-8059.
[99] Sheng, H., Li, Q., Ma, W., Ji, H., Chen, C., Zhao, J. Applied Catalysis B: Environmental
2013, 138-139, 212-218. http://dx.doi.org/10.1016/j.apcatb.2013.03.001
[100] Bickley, R.I., Hogg, L.T. Res. Chem. Intermed. 2007, 33(3-5), 333-349.
[101] Wu, T., Lin, T., Zhao, J., Hidaka, H., Serpone, N. Environ. Sci. Technol. 1999, 33, 13791387. And references cited therein.
[102] Horikoshi, S., Serpone, N., Hisamatsu, Y., Hidaka, H. Environ. Sci. Technol. 1998, 32, 40104016.
[103] Gao, B., Liu, L., Liu, J., Yang, F. Applied Catalysis B: Environmental 2013, 138-139, 62-69.
http://dx.doi.org/10.1016/j.apcatb.2013.02.023
[104] Byrne, J.A., Davidson, A., Dunlop, P.S.M., Eggins, B.R. Journal of Photochemistry and
Photobiology A: Chemistry 2002, 148, 365-374.
[105] McMurray, T.A., Byrne, J.A., Dunlop, P.S.M., McAdams, E.T. Journal of Applied
Electrochemistry 2005, 35, 723-731. DOI 10.1007/s10800-005-1397-1
[106] Tao J., Yang M., Chai J. W., Pan J. S., Feng Y. P., Wang S. J. J. Phys. Chem. C 2014, 118,
994−1000. DOI: dx.doi.org/10.1021/jp408798f
[107] Kong, M.; Li, Y.; Chen, X.; Tian, T.; Fang, P.; Zheng, F.; Zhao, X. J. Am. Chem. Soc. 2011,
133, 16414−16417.
Journal of Engineering & Processing Management|
46
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[108] Katoh, R.; Furube, A.; Yamanaka, K.-i.; Morikawa, T. J. Phys. Chem. Lett. 2010, 1,
3261−3265.
[109] Asahi, R.; Morikawa, T.; Ohwaki, T.; Aoki, K.; Taga, Y. Science 2001, 293, 269−271.
[110] Irie, H.; Watanabe, Y.; Hashimoto, K. J. Phys. Chem. B 2003, 107, 5483−5486.
[111] Ma, X.; Wu, Y.; Lu, Y.; Xu, J.; Wang, Y.; Zhu, Y. J. Phys. Chem. C 2011, 115, 16963-16969.
[112] Grandcolas, M., Cottineau, T., Louvet, A., Keller, N., Keller, V. Applied Catalysis B:
Environmental 2013, 138-139, 128-140. http://dx.doi.org/10.1016/j.apcatb.2013.02.041
[113] Imoberdorf, G.E., Irazoqui, H.A., Alfano, O.M., Cassano, A.E. Chemical Engineering
Science 2007, 62, 793-804. doi: 10.1016/j.ces.2006.10.004
[114] Pichat, P., Herrmann, J.M., Disdier, J., Courbon, H., Mozzanega, M.N. Nouv. J. Chim. 1981,
5, 627-35.
[115] Courbon, H., Herrmann, J.M., Pichat, P. J. Catal. 1985, 95, 539.
[116] Pichat, P., Herrmann, J.M., in J.M. Serpone, J.M. and Pelizzetti, E. (Editors), Photocatalysis,
Fundamentals and Applications, Wiley, New York, 1989, p. 217.
[117] Miller, R. and Fox, R. in Ollis, D.F. and A1-Ekabi, H. (Editors), Photocatalytic Purification
and Treatment of Water and Air, Elsevier, Amsterdam, 1993, p. 573.
[118] Ochuma, I.J., Osibo, O.O., Fishwick, R.P., Pollington, S., Wagland, A., Wood, J.,
Winterbottom, J.M. Catalysis Today 2007, 128, 100-107. doi: 10.1016/j.cattod.2007.05.015
[119] Mao, M., Wang, J., He, J., Yan, Z.In Chemical Templates to Biotemplates. New and Future
Developments in Catalysis, Steven L. Suib, Amsterdam, 2013, pp 443-469.
http://dx.doi.org/10.1016/B978-0-444-53872-7.00020-0
[120] Herrmann, J.M. in Strong Metal-Support Interactions, Tauster, S.J., Baker, R.T.K. and
Dumesic, J.A. (Editors), ACS series, Vol. 298, 1986, p. 200.
[121] Völz, H.G., Kaempf, G., Fitzky, H.G., Klaeren, A., ACS Symp. Ser. 1981, 151, p. 163.
[122] Son, Y., Lim, M., Khim, J., Ashokkumar, M. Ind. Eng. Chem. Res. 2012, 51, 232-239.
dx.doi.org/10.1021/ie202401z
[123] Kozlova, E.A., Vorontsov, A.V. Applied Catalysis B: Environmental 2006, 63, 114-123.
doi:10.1016/j.apcatb.2005.09.020
[124] Jeyalakshmi, V., Rajalakshmi, K., Mahalakshmy, R., Krishnamurthy, K. R., Viswanathan, B.
Res. Chem. Intermed. 2013, 39, 2565-2602. DOI 10.1007/s11164-012-0783-7
[125] Oralli, E., Dincer, I., Naterer, G.F. International Journal of Hydrogen Energy 2011, 36, 94469452. doi: 10.1016/j.ijhydene.2010.12.136
[126] Hoffmann M.R., Martin S.T., Choi W., Bahnemann D.W. Chem. Rev. 1995, 95, 69-96.
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P. Sibinovic, V. Marinkovic, R. Palic, I. Savic, I. Savic-Gajic, D. Milenovic, R. Jankovic
DOI: 10.7251/JEPMEN1406049S
UDK: 615.011:615.453.6:615.22
Scientific paper
DEVELOPMENT AND OPTIMIZATION OF CARVEDILOL
FORMULATION USING EXPERIMENTAL DESIGN
Predrag Sibinovic1, Valentina Marinkovic1, Radosav Palic2, Ivan Savic3, Ivana Savic-Gajic3,
Dragan Milenovic1, Rada Jankovic1
[email protected]
1
2
Pharmaceutical and Chemical Industry Zdravlje-Actavis, 16000 Leskovac, Serbia
University of Nis, Faculty of Science and Mathematics, Department of Chemistry,
18000 Nis, Serbia
3
University of Nis, Faculty of Technology, 16000 Leskovac, Serbia
Abstract
The aim of this paper was to develop and optimize the carvedilol tablets formulation using
the full factorial design. The content of binder (PVP K30), content of disintegrant (crospovidone)
and main compression force were used as the independent variables. Tablets were prepared by wet
granulation. The percentage of released carvedilol from prepared formulation after 10 minutes was
defined as the response. It has been found that formulation with the low content of binding agents
(4.8%), high content of disintegrant (4.5%) and compression force of 50 N has the best profile of
drug. The optimal formulation was defined based on implementation of pharmaceuticaltechnological tests (testing strength, friability, disintegrating, contents of drug substance, drug
release profiles). The stability of the optimal formulation with carvedilol was estimated using the
aging tests.
Keywords: carvedilol, formulation, experimental design, dissolution profile.
INTRODUCTION
Carvedilol is a non selective adrenergic blocking agent (Fig.1), i.e. a lipid soluble compound, which
is practically insoluble in water and poorly absorbed from the gastrointestinal tract [1]. The slow
absorption of carvedilol can be attributed to its poor water solubility [2, 3].
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P. Sibinovic, V. Marinkovic, R. Palic, I. Savic, I. Savic-Gajic, D. Milenovic, R. Jankovic
Figure 1. Chemical structure of carvedilol
Norepinephrine has the abilities to stimulate the nerves that control the heart muscles by binding to
the β1- and β2-adrenergic receptors, i.e. to bind to the α1-adrenergic receptors on blood vessels,
causing them to constrict and raise blood pressure. In these case, carvedilol has an important role to
block binding to the β1- and β2-adrenergic receptors [4], which both slows the heart rhythm and
reduces the force of the heart's pumping. This pharmaceutical active substance blocks the α 1adrenergic receptors [5], which lower blood pressure. Relative to other beta blockers, carvedilol has
minimal inverse agonist activity [6]. This suggests that carvedilol has a reduced negative
chronotropic and inotropic effect in compared with other beta blockers. However, to date this
theoretical benefit has not been established in clinical trials, and the current version of the
ACC/AHA guidelines on congestive heart failure management does not give preference to
carvedilol over other beta-blockers. It is a racemic mixture in which non-cardioselective βadrenergic receptor blocking activity is present in the S(-) enantiomer and selective 1-adrenergic
receptor blocking activity is present in both R(+) and S(-) enantiomers at equal potency. At higher
concentrations it blocks the entry of Ca2+ into the vascular smooth muscle.
Experimental design is a well-known approach that commonly used in the development and
optimization of the drug formulations [7-9]. This method enables that the desired formulation be
achieved as fast as possible. Using this approach it is possible to analyze the influence of
formulation factors on the selected response. Given that the types and quantities of excipients impact
the release of the pharmaceutically active substance from the formulation, the aim of this study was
the development and optimization of the composition of carvedilol formulation in the solid dosage
form. The full factorial design with three variables at two levels was used to formulate the tablets
with suitable physical and chemical properties.
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P. Sibinovic, V. Marinkovic, R. Palic, I. Savic, I. Savic-Gajic, D. Milenovic, R. Jankovic
MATERIALS AND METHODS
Materials. Karvileks tablets (Zdravlje-Actavis, Leskovac, Serbia) were used for the examinations.
One tablet contains 12.5 mg of carvedilol and other ingredients. The average mass of the tablet is
120 mg. Dilatrend tablets were obtained as a gift sample from F. Hoffmann-La Roche, Switzerland.
Polyvinylpyrrolidone K30 (PVP K30) was purchased from BASF, Germany and crospovidone was
purchased from ISP Chemical, USA. All other chemicals were of analytical grade.
Experimental design. The pharmaceutical formulations were commonly developed using the
traditional optimization technique so-called one-variable-at-a-time. This approach requires the
higher consumption of time, employers, chemicals and energy in compared with methodology of
experimental design. Also, it may be difficult to find the optimal formulation since the effect
between the process variables are not estimated. Because of these reasons, it is important to use the
established statistical tools, such as factorial design for optimization of the content of
pharmaceutical formulations [10-12].
The number of experiments required for these studies is dependent on the number of independent
variables. The response/s is/are measured for each trial and then either simple linear (Y = b0 + b1X1 +
b2X2 + b3X3) or interactive (Y = b0 + b1X1 + b2X2 + b3X3 + b12X1X2 + b13X1X3...) or quadratic (Y = b0 +
b1X1 +b2X2 + b3X3 + b12X1X2 + b13X1X3... + b11X12), where Y is the response, b0 the intercept, b1 the
main coefficients, bxy the interaction coefficients. Model is fitted by carrying out multiple regression
analysis and F-statistics to identify statistically significant terms.
The reduced equation, an equation containing only statistically significant terms, then used for
drawing response surface plots to visualize the impact of changing variables at a glance. The
optimum point may be identified from the plot and replicate trials may be run to verify the
prediction of optimum response. For simplicity, it was decided to perform a three variable study at
two experimental levels to achieve the set objectives efficiently. Design-Expert software (version
7.1.6, Stat-Ease Inc., USA) was used for experimental design and statistical evaluation of the data.
Development of tablets. The composition of the different formulations of Karvileks uncovered
tablets (Zdravlje-Actavis, Leskovac, Serbia) is shown in Table 1.
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Table 1. Composition of uncovered tablets of Karvileks
Ingredients
F1
F2
F3
F4
F5
F6
F7
F8
Karvedilol
12.5
12.5
12.5
12.5
12.5
12.5
12.5
12.5
PVP K-30
6.00
6.25
6.00
6.25
6.00
6.25
6.00
6.25
Crospovidone
3.75
3.75
5.63
5.63
3.75
3.75
5.63
5.63
Lactose
94.75 94.50 92.88 92.63 94.75 94.50 92.88 92.63
(mg per tablet)
Magnesium
stearate
Silicium dioxide
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.4
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
The matrix tablets were prepared by wet granulation method using PVP K30:water (2:1) as a binder
solvent, lactose as a diluent, and mixture of silicium-dioxide and magnesium stearate as the glidant
and lubricant, respectively. Crospovidone was used as a disintegrant. The quantity of lactose which
is used as an excipience was changed in order to achieve standard specified mass of tablets.
The ingredients were weighed accurately and passed through a 0.8 mm sieve to get uniform size
particles and then they were mixed geometrically for 5 to 10 min. Granulation was done with a
solution of PVP K30 in sufficient water. The granules (40 mesh) were dried in conventional hot air
oven at 40 °C. Drying of the granules was stopped when the sample taken from the oven reached a
loss on drying (LOD) value of 1-3%, as measured by a moisture balance at 105 °C. The dried
granules were passed through a 1.0 mm, homogenized with crospovidone, silicium-dioxide and
magnesium stearate and then compressed on a single punch tablet machine (Erweka EK 0,
Germany). The tablets were round and flat with an average diameter of 7.0 ± 0.1 mm and a
thickness of 2.6 ± 0.2 mm.
Characterization of tablets. The prepared tablets were evaluated for mass uniformity (20 tablets)
[13]. Hardness (10 tablets) and thickness (10 tablets) was measured by an Erweka Multicheck tester
(Germany), and friability was determined (10 tablets) using an Erweka Friability tester TDR 100
(Germany). Disintegration test was performed using Disintegration test apparatus by placing each
tablet in each basket with the disc Erweka ZT301 (Germany). The process was carried out using
water maintained at 37 °C.
The drug content in each formulation was determined by HPLC-UV (Agilent 1100 Series, USA),
using a Lichrosorb Si60 column (250×4,6 mm, 7µm) at 20 C, an injection volume of 20 μL and
was detected at 280 nm.
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The flow rate was adjusted at 2 ml/min, and the mobile phase was a mixture of 0.005 mol/l
CH3COONa in methanol, 1,4 dioxan and acetic acid (88:10:2, v/v). The pH was adjusted to 4.0 with
acetic acid. 20 tablets were powdered and average mass of one tablet was dissolved in mobile phase.
The solutions were filtered through a 0.45 μm membrane filter, before analysis.
In vitro drug release studies. The in vitro drug release studies were conducted using the USP 28
type II (10) (paddle) dissolution apparatus (Erweka). 1000 ml of citrate buffer (pH 4.5) was used as
medium. The study was conducted at 37 ± 0.5 °C and at paddle rotation of 75 rpm. Samples of 5 ml
were collected at predetermined time intervals and replaced with fresh citrate buffer. The samples
were filtered and diluted and the drug content in the samples was estimated at 285 nm using an
Agilent 8453 UV–VIS spectrophotometer. Cumulative percentage drug release was calculated using
an equation obtained from a standard curve. Mathematical models, zero-order, first-order and
Korsmayer-Peppas were applied to analyze the release mechanism and pattern [14].
Similarity factor (f2) analysis. In vitro release profile of carvedilol from selected Karvileks tablet
formulations and the marketed sustained release tablets were performed under similar conditions.
The similarity factor between the two formulations was determined using the data obtained from the
drug release study. The data was analyzed by the equation 1:


f 2  50  log 

1
 1
N

1
 R
i
 Ti 
2


 100



(1)
where are N - number of time points, Ri and Ti - dissolution of reference and test products at time
"i". If f2 is greater than 50 it is considered that two formulations share similar drug release behaviors.
Stability studies. Optimized formulation tablets were packed in suitable primary packaging and
then kept at 45 C and 75% relative humidity (RH) for 6 months in order to perform the accelerated
stability test. At the end of 3 months, the tablet properties including hardness, friability and
disintegration time as well as drug content and dissolution were evaluated.
RESULTS AND DISCUSSION
Interpretation of the effects
The estimated effects are usually graphically or/and statistically interpreted, to determine their
significance. In our opinion, combining a graphical with a statistical evaluation can be
recommended. Graphical methods consist in drawing normal probability or half-normal probability
plots. They can be constructed manually by the analyst or obtained by use of statistical software.
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Both graphs plot the (absolute) factor effects as a function of values derived from a normal
distribution. The non-significant effects are found on a straight line through zero line where as the
significant effects deviate from this line. Half normal probability plot is shown in Figure 2.
Figure 2. Half-normal probability plots for the seven effects on the response carvedilol dissolved
Building the model
After executing the experiments and determining the responses, the polynomial or factorial models
describing the relationships between the responses and the considered factors can be built. Models
usually includes an intercept, the main effect terms, the interaction terms, and quadratic terms.
Occasionally, not all terms are included in the model and/or the non-significant terms are excluded,
for instance, using the backward elimination regression procedure. Interactive statistical first-order
complete model was generated to evaluate carvedilol disolved after 10 min. Final equation was
given in terms of coded factors:
Carvedilol dissolved Q10  77.20  4.78 X 1  3.12 X 2  7.02 X 3  1.57 X 1 X 2  3.16 X 2 X 3  1.94 X 1 X 2 X 3
The main effects (X1, X2 and X3) represent the average result of changing one factor at a time from
its low to high value. The interactions (X1X2, X2X3 and X1X2X3) show how the carvedilol disolved
value changes when two or more factors are simultaneosly changed.
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The carvedilol disolved values for the eight formulations show a wide variation, i.e. the response
ranges from a minimum of 59.24 to a maximum of 93.20% in 10 min. The data clearly indicates that
the carvedilol disolved is strongly dependant of the factors.
It may be concluded that the low levels of X1 (binder concentration) and X3 (main compression
force) and high level of X2 (desintegrant concetration) appear to favour the preparation of carvedilol
tablets with desired dissolution after 10 min.
Evaluation of the model
After building the model, it can be interpreted graphically and/or statistically. Graphically, the
model can be visualized by drawing 2D contour plots or 3D response-surface plots. A 2D contour
plot shows the isoresponse lines as a function of the levels of two factors, while a 3D responsesurface plot represents the response, on a third dimension, as a function of the levels of two factors.
Graphical representation of the model built for the response carvedilol dissolved at hardness of 50
and 70 N as: (a) 2D contour plot, and (b) 3D response-surface plot are shown in Figures 3 and 4.
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Figure 3. Graphical representation of the model built for the response carvedilol dissolved after 10 min at
hardness 50 N as: (a) 2D contour plot, and (b) 3D response-surface plot
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Figure 4. Graphical representation of the model built for the response carvedilol dissolved after 10 min at
hardness 70 N as: (a) 2D contour plot, and (b) 3D response-surface plot
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The ANOVA results of regression analysis for the simple model are depicted in Table 2. The
obtained results showed that the main compression force (X3) was the most significant carvedilol
release factor: the lower hardness of tablets give better dissolution profile. Factor binding
concentration PVP K30 (X1) has less influence on dissolution profile of carvedilol, while factor
disintegrant concentration crospovidone (X2) had no significant influence in this study.
Table 2. ANOVA test of the experimental design results
factor
df
sum of squares
mean square
Model
6
784.74
130.79
X1
1
182.60
182.60
X2
1
78.00
78.00
X3
1
394.24
394.24
X1 X2
1
19.66
19.66
X2 X3
1
80.14
80.14
X1 X2X3
1
30.11
30.11
Residual
1
0.48
0.48
Determination of the optimal formulation
In an optimization context, the model is most frequently used to predict the optimum. Often the
optimum is selected from the graphical representation of the model. The overlay plot provided by
the Design expert software showed an acceptable region that met the requirement of the response
(Fig. 5).
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Figure 5. The overlay plot for carvedilol dissolved after 10 min at hardness of 50 N (a),
and at hardness of 70N (b)
Evaluation of tablets
The uncovered tablets of Karvileks were prepared by wet granulation technique using lactose and
PVP K30. The silica-dioxide, magnesium stearate and crospovidone were used in the phase of
homogenization. The results of the physico-chemical characterization are shown in Table 3.
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Тable 3. Physico-chemical characterization of Karvileks tablets
Uniformity of
Hardness
Friability
Disintegration
Drug content
weight (mg)
(N)
(%)
time (min)
(mg)
F1
122.0
50
0.1
3.8
12.71
F2
120.3
50
0.13
4.5
12.48
F3
121.9
50
0.07
3.5
12.53
F4
121.4
50
0.1
3.8
12.58
F5
120.9
70
0.05
7.5
12.68
F6
120.8
70
0.08
9.5
12.39
F7
120.7
70
0.07
7.0
12.42
F8
120.9
70
0.03
8.1
12.55
Formulation
The weight of the tablet varied between 120.3 mg to 122.0 mg for different formulations with low
standard deviation values, indicating uniformity of weight. The variation in weight was within the
range of ±7.5% complying with pharmacopoeial specifications. The hardness for different
formulations was found to be between 50 to 70 N indicating satisfactory mechanical strength. The
friability was below 1% for all the formulations, which is an indication of good mechanical
resistance of the tablet.
The drug content varied between 12.39 to 12.71 mg in different formulations with low coefficient of
variation (C.V.< 1.0%), indicating content uniformity in the prepared batches. The disintegration
time was found to be in the range of 3.7 to 12.5 min for all the formulations.
In vitro dissolution studies
The pharmacokinetic parameters of carvedilol were used to calculate a theoretical drug release
profile for an eight dosage form [15]. The percent of carvedilol dissolved was determined by UVVIS spectrophotometric method at 285 nm, after 10, 20, 30 i 60 min. The in-vitro drug release
profiles of carvedilol for all the formulations and the marketed product are shown in Figure 6.
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% of carvediolo dissolved
120
exp 1
100
exp 2
exp 3
80
exp 4
60
exp 5
exp 6
40
exp 7
20
exp 8
Dilatrernd
0
0
20
40
60
80
time / min
Figure 6. Dissolution properties of carvedilol
The experimental design 23 was applied with following independent variables: binder concentration
PVP K30 (X1), disintegrant concentration crospovidone (X2), resistance to crushing (X3), while
percent of carvedilol dissolved (Y1) after 10 min was used as dependent variable (Table 4).
Table 4. Experimental design table
Exp. X0 X1 X2 X3
X1
X2
Binder
Disintegrant
concentration
concentration
(%)
(%)
X3
Y1
Hardness
% of carvedilol
(N)
dissolved
1
+
-
-
-
4.8
3.0
50
92.30
2
+
+
-
-
5.0
3.0
50
76.22
3
+
-
+
-
4.8
4.5
50
85.20
4
+
+
+
-
5.0
4.5
50
83.15
5
+
-
-
+
4.8
3.0
70
68.54
6
+
+
-
+
5.0
3.0
70
59.24
7
+
-
+
+
4.8
4.5
70
81.86
8
+
+
+
+
5.0
4.5
70
71.07
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Drug release profiles of formulations F1-F4, (resistance to crushing of 50 N), showed a release of
92.30, 76.22, 85.20 and 83.15% in 10 min, respectively (Table 5).
Table 5. Drug release profiles of formulations F1-F8 and Dilatrend tablets
t,
Dilatrend
exp. 1
exp. 2
exp. 3
exp. 4
exp. 5
exp. 6
exp. 7
exp. 8
0
0
0
0
0
0
0
0
0
0
10
92.30
76.22
85.20
83.15
68.54
59.24
81.86
71.07
89.78
20
96.61
86.65
91.92
91.57
93.49
71.27
95.64
89.93
93.04
30
99.29
94.66
98.54
96.17
97.28
81.54
100.30
94.77
96.90
60
104.73
97.76
100.94
103.65
103.24
87.21
104.88
99.04
103.20
min
tablets
It is expected that the developed formulation should have the following theoretical drug release
profile over 80% after 10 min [16]. Formulations F1, F3 and F4 met the needed theoretical drug
release profile and from these reason, it was considered the suitable formulations among all the four
formulations of this series.
Drug release profiles of formulations F5-F8 (resistance to crushing of 70 N) are shown in Table 5.
The percentage of drug released from formulations F5-F8 was 76.12, 58.42, 86.64 and 79.70%,
respectively, in 10 min. However, formulations F5, F6 and F8 failed to meet the required theoretical
drug release profile. Formulation F7 met the desired theoretical drug release profile. Therefore, it
was considered the best formulation among all the four formulations of this series.
However, formulation F3 met the theoretical drug release profile. Also, taking into consideration
results for friability, desintegration and drug content, this formulation complied with all specified
physical and chemical properties. Therefore, formulation F3 was considered the most suitable
formulation among all the eight formulations.
Drug release kinetics
The data obtained from in vitro dissolution studies were fitted in different models zero order, first
order and Korsemeyer‘s equation (Table 6). In order to confirm the exact mechanism of drug release
from these tablets, the data were fitted in accordance with Korsemeyer‘s equation [17]. Regression
analysis was performed and regression values r2 were 0.888 to 0.998 for different formulations.
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Table 6. Kinetics of in vitro carvedilol release from Karvileks tablets
Formulation
Zero order
First order
k0
k1
(mg/min)
r2
1/min
Korsemeyer
model
r2
n
r2
F1
0.235
0.957
0.119
0.968
0.079
0.998
F2
0.387
0.756
0.046
0.935
0.145
0.917
F3
0.289
0.779
0.115
0.928
0.098
0.950
F4
0.379
0.910
0.074
0.998
0.122
0.998
F5
0.457
0.717
0.108
0.986
0.168
0.888
F6
0.525
0.804
0.023
0.903
0.228
0.941
F7
0.326
0.819
0.112
1.000
0.103
0.968
F8
0.341
0.784
0.060
0.997
0.121
0.954
Similarity factor analysis between the formulation F3 of Karvileks and marketed product for the
drug release showed the f2 factor of 76.75, which is greater than 50. This value indicate that the
release of the drug from the prepared tablets is similar to the marketed tablet.
Stability studies
Physical properties of the optimized formulation (F3) after keeping it in accelerated stability
conditions (45 °C and 75% RH) are illustrated in Table 7. Hardness of tablets was in the range of
48.93 – 51.32 N, which was considered as acceptable for tablet formulations. After exposure to the
stability testing conditions for three months, despite the fact that the disintegration time and
friability of tablets were in the ranges of 3.50 – 4.10 min and 0.07 – 0.14%, respectively, the tablets
were still within the limits defined for these variables. Drug content of tablets was ranged from
100.10 to 99.20% at the end of stability studies.
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Table 7. Physicochemical characteristics of the optimized formulation (F3)
after accelerated stability studies (45 °C and 75% RH)
Dependant variable
Time (months)
0
3
6
Hardness (N)
48.93 ± 3.17
51.04 ± 4.39
51.32 ± 3.41
Disintegration time (min)
3.50 ± 0.20
4.00 ± 0.10
4.10 ± 0.20
0.07
0.12
0.14
Drug content (%)
100.10 ± 1.76
99.80 ± 1.23
99.20 ± 1.65
Q10
85.20 ± 2.84
84.90 ± 1.98
83.02 ± 2.76
Q60
100.94 ± 0.57
97.62 ± 2.43
99.89 ± 1.54
Friability (%)
The results of dissolution studies for tablets after stability experiments are represented in Table 7. It
was shown that the data were very close to the freshly prepared tablets and more than 80% of
carvedilol got dissolved from all tablets in the first 10 min of the test (Q10). As mentioned above, the
disintegration time of tablets exposed to the stability testing conditions was increased compared to
fresh tablets. The slight decrease of the drug dissolved from the tablets in the first 10 min could be
attributed to the finding. In conclusion, the optimized formulation F3 could be considered stable
even after 6 months of being kept under accelerated stability conditions.
CONCLUSION
This study demonstrates the use of factorial design for the development and optimization of
carvedilol tablet formulation. This statistical technique allows scientists to examine more than one
independent variable at a time. The desirable goals can be obtained by systematic formulation
approach in shortest possible time. Obtained results showed that the most significant factor for
dissolution profile of carvedilol from Karvileks tablets (Zdravlje-Actavis, Serbia) was the main
compression forse. Considering the individual response evaluation, the most suitable carvedilol
tablet formulation should present in its component PVP K30 - low level, disintegrant - high level,
and main compression force-low level.
Acknowledgments. The financial support was provided from the Ministry of Education, Science
and Technological Development of the Republic of Serbia under the project TRp-34012.
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REFERENCES
[1]
A. A. Othman, D. M. Tenero, D. A. Boyle, N. D. Eddington, M. J. Fossler, AAPS J., 9(2007)
pp.E208–E218.
[2]
Y. Zhang, Z. Zhi, X. Li, J. Gao, Y. Song, Int. J. Pharm., 454(2013) pp.403-411.
[3]
K. Yuvaraja, J. Khanam, J. Pharmaceut. Biomed., 96(2014) pp.10-20.
[4]
P. C. Stafylas, P. A. Sarafidis, Vasc. Health Risk Manag., 4(2008) pp.23–30.
[5]
A. A. Othman, D. M. Tenero, D. A. Boyle, AAPS J., 9(2007) pp.E208–E218.
[6]
B. T. Vanderhoff, H. M. Ruppel, P. B. Amsterdam, Am. Fam. Physician. 58(1998) pp.16271634.
[7]
I. M. Savic, K. Nikolic, G. Nikolic, I. Savic, D. Agbaba, M. Cakic, Drug Dev. Ind. Pharm.,
39(2013) pp.1084-1090.
[8]
M. Cakic, Z. Mitic, G. Nikolic, I. Savic, I. M. Savic, Expert Opin. Drug Dis., 8(2013)
pp.1253-1263.
[9]
I. M. Savic, G. S. Nikolic, I. M. Savic, K. Nikolic, D. Agbaba, Acta Pol. Pharm., 69(2012)
pp.739-749.
[10]
I. S. Ahmed, R. N. Shamma, R. A. Shoukri, Pharm. Dev. Technol., 18(2013) pp.935-943.
[11]
A. K. Katharya, R. Chaudhary, R. Sharma, Y. Singh, U. V. S. Teotia, Development, 5(2013)
pp.700-710.
[12]
S. S. Mane, M. S. Kamble, O. R. Mane, V. G. Borwandkar, P. P. Aute, P. D. Chaudhari, A.
V. Bhosale, Indo Am.J. Pharm. Res., 3(2013) pp.4585-4593.
[13]
European Pharmacopoeia 6th ed., Strasbourg, France, 2008.
[14]
R. Korsmeyer, R. Gurny, E. Doelker, P. Buri, N. Peppas, Int. J. Pharm., 15(1983) pp.25-35.
[15]
G. S. Banker, N. R. Anderson, In the Theory and Practice of Industrial Pharmacy, L.
Lachmann, H. A. Liberman, J. L. Kaing, Eds. Varghese Publishing House, Bombay, 1987,
pp.297-299.
[16]
Z. Djuric, Ј. Parojcic, Practical exercises of biopharmaci, Nijansa, Zemun, Serbia, 2004.
[17]
C. S. L. Chiao, J. R. Robinson, Sustained-release drug delivery systems, in remington: The
Science and Practice of Pharmacy, 19th ed., Lippincott, Williams and Wilkins,
Philadelphia, 2000, Vol. 2, pp.1660–1675.
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P. Sibinovic, V. Marinkovic, R. Palic, I. Savic, I. Savic-Gajic, D. Milenovic, R. Jankovic
DOI: 10.7251/JEPMEN1406049S
UDK: 615.011:615.453.6:615.22
Naučni rad
RAZVOJ I OPTIMIZACIJA FORMULACIJE KARVEDILOLA PRIMENOM
EKSPERIMENTALNOG DIZAJNA
Predrag Sibinovic1, Valentina Marinkovic1, Radosav Palic2, Ivan Savic3, Ivana Savic-Gajic3,
Dragan Milenovic1, Rada Jankovic1
[email protected]
1
Farmaceutska i hemijska industrija Zdravlje-Actavis, 16000 Leskovac, Srbija
2
Univerzitet u Nišu, Prirodno matematički fakultet, Departman za hemiju,
18000 Niš, Srbija
3
Univerzitet u Nišu, Tehnološki fakultet, 16000 Leskovac, Srbija
Izvod
Primenom metodologije punog faktorijalnog dizajna u radu je izvršen razvoj i optimizacija
formulacije tableta na bazi karvedilola. Sadrţaj vezivnog sredstva i sredstva za raspadanje, odnosno
sila komprimovanja tokom izvoĊenja eksperimenta definisane su kao nezavisno promenljive
veliĉine. Procenat oslodoĊenog karvedilola iz pripremljenih formulacija nakon 10 min izabran je
kao zavisno promenljiva veliĉina. Na osnovu dobijenih rezultata utvrĊeno je da formulacija sa
niskim sadrţajem sredstva za vezivanje (4,8%), visokim sadrţajem sredstva za raspadanje (4,5%) i
silom komprimovanja od 50 N ima najbolji profil oslobaĊanja lekovite supstance. MeĊutim,
optimalna formulacija sa najboljim fiziĉkim svojstvima odabrana je nakon sprovoĊenja
farmaceutsko-tehnoloških testova (ispitivanje ĉvrstine, friabilnosti, raspadljivosti, sadrţaja lekovite
supstance, profila oslobaĊanja lekovite supstance). Primenom testova starenja odreĊena je stabilnost
optimalne formulacije karvedilola.
Ključne reči: karvedilol, formulacija, eksperimentalni dizajn, profil rastvaranja.
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V. Šćekić, R. Cvejić, S. Smiljić
DOI: 10.7251/JEPMSR1406067S
UDK: 628.112:665.6
Stručni rad
TRETMAN PODZEMNIH VODA ZAGAĐENIH DERIVATIMA NAFTE
Velimir Šćekić, Radoje Cvejić, Sava Smiljić
[email protected]
Univerzitet UNION Beograd, Fakultet za strateški i operativni menadžment,
11 070 Beograd, Srbija
Izvod
Tretman podzemnih voda predstavlja najvaţniji segment iz delokruga zaštite prirodnih
resursa, jer bez biloški i bakteriološki ispravne vode nema ţivota na planeti. Sprovodi se kroz
sagledavanje svih negativnih elemenata u vodi, utvrĊivanje procenata njihove toksiĉnosti i
pronalaţenje najadekvatnijih metoda za njihovo uklanjanje. Cilj je praćenje, unapreĊenje kvaliteta
voda i zaštita ţivotne sredine, uopšte posmatrano.
Ključne reči: nafta, derivati nafte, podzemne vode, naftne mrlje, remedijacija.
UVOD
ZagaĊenje podzemnih voda i zemljišta uopšte, a pre svega ugljovodonicima iz naftnih
derivata ima višestruko negativan uticaj na ţivotnu sredinu. Ti polutanti u ţivotnu sredinu mogu da
dospeju iz razliĉitih razloga, npr. kao rezultat akcidenata tokom transporta, prilikom odlaganja
otpada, ili iz industrijskih postrojenja. Sudbina naftnih ugljovodonika u ţivotnoj sredini zavisi od
razliĉitih faktora pri ĉemu nije uvek lako proceniti stepen zagaĊenja obzirom da su koncentracije
ugljovodonika specifiĉne za odreĊene sredine.
ZagaĊenje voda naftom predstavlja poseban problem zbog perzistencije i mogućnosti
zagaĊenja izvorišta vode za piće, bilo da se radi o podzemnim ili površinskim resursima, usled kojih
moţe doći ĉak i do humanitarnih katastrofa. Inaĉe, vaţno je napomenuti da su zagaĊenje i zaštita
podzemnih voda predmet sporadiĉne paţnje još od vremena Stare Grĉke i Rima.
Angaţovanje nauke vezano je za period industrijske revolucije, kada se po meri razvoja
industrije odvija intenzivna i nekontrolisana eksploatacija svih prirodnih resursa. Zbog porasta
koliĉine industrijskog i komunalnog otpada, odlaganog prvenstveno u reĉne tokove, posebno brzo se
odvija proces zagaĊivanja vodnih resursa, a time ponajviše podzemnih vodnih resursa.
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Npr., samo jedna baterija ili ulje iz motornog vozila, baĉeni na zemljište ili 1 litar izlivene
nafte dovoljni su da trajno zatruju izvor pijaće vode.
Sirova nafta, kao veoma kompleksna smeša, sastoji se od nekoliko hiljada jedinjenja, od
lakih gasova (kao što je metan) do teških asfaltnih supstanci. Većina komponenata nafte je toksiĉna
za ĉoveka i ţivi svet. Zbog potencijalne opasnosti za ţivotnu sredinu od zagaĊenja kompleksnim
hemijskim materijama, kao što su naftni ugljovodonici, razvijene su razliĉite remedijacione tehnike
za vodu, sediment i zemljište pomoću kojih se nad njima vrše razliĉiti tretmani sa ciljem umanjenja
opasnosti za zagaĊenje ĉovekove okoline. Do skoro je to za RS bila misaona imenica, dok se danas i
kod nas mnoge od tih tehnika redovno sprovode u cilju što veće i efikasnije zaštite voda i njihovih
izvorišta.
Generalno posmatrano prirodni resursi, pre svih zemljište i vode na planeti Zemlji su
zanemareni. Od postanka, do danas, iz dana u dan zagaĊenja svih vrsta su se samo povećavala. I
niko o tome nije vodio raĉuna. Sve do skorije prošlosti na zagaĊenja ţivotne sredine se svet
oglušavao. Industrija je radila šta i kako je htela, a stanovništvo na planeti je mislilo da pije ispravnu
vodu. A onda je svetom kao munja projurila vest da će kroz sto godina najvredniji resurs na planeti
biti ĉista pijaća voda. Ne nafta, ne prirodni gas, ne zlato.
MeĊutim, u poslednjoj deceniji, ponajviše u SAD – u, a sve više i meĊu ĉlanicama EU se
vodi raĉuna o ţivotnoj sredini, pre svega oĉuvanju zemljišta i izvorišta voda. I RS je krenula tim
putem, u poslednji ĉas. Stoga i jeste cilj ovog rada da se pojasni naĉin zagaĊenja voda uopšte i
sagleda tretman podzemnih voda zagaĊenih derivatima nafte pri obavljanju tehnoloških procesa.
NAFTA I NJENI DERIVATI
Nafta, ili još popularnije crno zlato, vodi poreklo od organskog biljnog i ţivotinjskog
uginulog istaloţenog materijala koji se najpre razlagao dejstvom aerobnih, a potom anaerobnih
bakterija. Danas preovladava savremeno mišljenje da je nafta nastala od masnih i voštanih supstanci
razliĉitih sitnih ţivotinjskih i biljnih morskih organizama - planktona. Pod povoljnim uslovima, koji
su vladali u dalekim geološkim dobima, ţivele su i razmnoţavale se u toplim morskim zalivima
velike koliĉine tih organizama, koje su se uginuvši taloţile na morsko dno i transformisale u nove
oblike. Prvi korak dogodio se još pre 300 - 400 miliona godina. Tada su se ti ostaci poĉeli taloţiti na
dno okeana i vremenom ih je pokrio pesak i mulj. Zatim, pre 50 - 100 miliona godina ti ostaci su
već bili prekriveni velikim slojem peska i mulja koji je stvarao ogromne pritiske i visoke
temperature. Pod tim uslovima, usled prirodnih biorazgradivih procesa, nastali su sirova nafta i
prirodni plin, bez kojih se danas ţivot na planeti ne moţe ni zamisliti.
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Ovako transformisana materija u oblik sirove nafte je zatim dospevala u sve dublje slojeve
zemljine kore, gde se pod dejstvom visokog pritiska, temperature, hemijski i fiziĉki menjala uz
katalitiĉko dejstvo prisutnih mineralnih supstanci vode, vodonik-sulfida, sumpora i drugih primesa.
Migracijom kroz porozne i propustljive stene, nafta je dospevala do nepropustnih slojeva
sedimentnih stena u kojima se skupljala vekovima.
.Po hemijskom sastavu nafta predstavlja smešu velikog broja ugljovodonika (ĉak -98%), a
ostatak ĉine manje koliĉine jedinjenja kiseonika (2%), sumpora (0.15-6%) i azota (0.005-4%),
asfaltno smolaste materije, mineralne materije, kao i tragovi metala. Najzastupljenije klase
ugljovodonika su: parafini, nafteni i aromatiĉni ugljovodonici.
Preradom sirove nafte procesima frakcione destilacije, katalitiĉkog i termiĉkog krekovanja ili
reforminga, dobijaju se rafinerijski proizvodi koji imaju razliĉite fiziĉko-hemijske osobine. Oni se
nazivaju derivati nafte i predstavljaju nusprodukte koji nastaju prilikom prerade izvorne sirove nafte.
Osnovni derivati nafte su: benzin, rafinerijski gas, plin, ulje za loţenje, motorna ulja, parafini,
maziva, bitumeni, avio gorivo itd. Naftini derivati mogu sadrţati i toksiĉne sastojke poput PAH-ova,
PCB-a kao i neke metale (posebno olovo), stoga je veoma vaţna njihova pravilna proizvodnja,
transport i korišćenje radi oĉuvanja prirodne ravnoteţe ţivotne sredine.
Fiziĉko-hemijske osobine nafte kao što su gustina, viskoznost, taĉka paljenja, taĉka
kljuĉanja, rastvorljivost itd. znaĉajne su u pogledu predviĊanja kako će se nafta ponašati prilikom
akcidentnih sluĉajeva izlivanja u zemljište ili u vodenu sredinu, a time i odabira najefikasnijeg puta
sanacije ugroţene zone.
Nafta nema nikakvo drugo, osim toksiĉnog delovanja na ţivi svet. Neadekvatno
transportovanje ili korišćenje, kao i odlaganje otpada od nafte i naftnih derivata pri obavljanju
tehnoloških procesa moţe dovesti do akcidenata nesagledevih razmera po biodiverzitet uopšte.
Ugljovodonici iz nafte se lancem ishrane prenose na sve ostale organizme nezavisno od naĉina
njihovog dospevanja u ţivotnu sredinu. Posebno znaĉajni u pogledu toksiĉnosti su hlorovani,
aromatiĉni i policikliĉni aromatiĉni ugljovodonici.
U nafti se nalaze i policikliĉni aromatiĉni ugljovodonici (PAH). Oni se u prirodi javljaju u
obliku ĉaĊi, izduvnih gasova, uglja, katrana. To su produkti nepotpunog sagorevanja fosilnih goriva
i organske materije i ispoljavaju toksiĉne, mutagene i kancerogene efekte [4] .
NAFTNO ZAGAĐENJE PODZEMNIH VODA
Proces izlivanja nafte otpoĉinje izlivanjem na površinu zemljišta, usled kojeg dolazi do
narušavanja njegove strukture, zatvaranja pora i slepljivanja ĉestica zemlje. Time se menja reţim
kretanja i koliĉine kiseonika što izaziva izumiranje aerobnih organizama koji svojim uticajem
razaraju pedološki sloj [6]. Nafta koja se izlila na površinu zemlje migrira.
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Naime, izlivena nafta se kreće naniţe kroz nezasićeno zemljište pod uticajem gravitacije i
boĉno pod uticajem kapilarnih sila. Nakon dostizanja nivoa podzemne vode nafta se kreće u tri faze:
- kao gasna faza iznad zagaĊene vode,
- kao ĉista faza i
- kao faza rastvorenih ugljovodonika.
Nestanak nafte, kao zagaĊivaĉa sa površine zemljišta odvija se kroz sledeće procese:
- hemijsku degradaciju (hidrolizom i fotolizom),
- isparavanjem sa površine zemlje,
-
resorpcijom u biljke i ulaskom u lanac ishrane,
biodegradacijom pod uticajem mikroorganizama i
poniranjem u podzemne vode.
Kada se zbog nepaţnje, akcidentne situacije, zastarelog tehnološkog procesa ili
neminovnosti same tehnologije nafta pojavi u vodi dolazi do pojave razliĉitih procesa na ĉiji
intenzitet utiĉu fiziĉko-hemijske karakteristike same nafte tj. njenih derivata, klimatski uslovi itd.
Jedan od najprisutnijih oblika nalaţenja nafte kao zagaĊujuće supstance u vodi jeste naftna mrlja.
Ona narušava razmenu toplote, vlage i gasova izmeĊu atmosfere i hidrosfere. Mrlja spreĉava i
prodor sunĉevih zraka u vodu. Ona najbrţe i najlakše moţe uništiti ekosistem voda na planeti i
dovesti do ekološke katastrofe nesagledivih razmera.
Eksperimentalno je utvrĊeno da je proseĉna debljina naftnog sloja oko 0.15 cm. Nafta i njeni
derivati se u vodi izlaţu biogenom razlaganju i oksidativnoj hemijskoj degradaciji. Pri tome nastaju
naftenske kiseline, fenoli i karbonilna jedinjenja koja se, budući da su polarna dobro rastvaraju u
vodi. Upravo zbog toga se sastav u vodi rastvorenih derivata nafte vremenom menja. Nakon
izlivanja nafte na vodenu površinu tokom vremena dolazi do povećanja njene gustine, što rezultuje
taloţenjem. Inaĉe, nafta moţe potonuti, ako je predhodno bila adsorbovana teškim ĉesticama peska
ili mulja [3]. Na proces sorpcije utiĉu mineraloški sastav tla, temperatura, pH i organske materije što
je vezano za veliĉinu i strukturu ovih ĉestica. Koncentracija organskih zagaĊujućih materija u
sedimentu je u dinamiĉkoj ravnoteţi sa koncentracijom u vodenom rastvoru iznad sedimenta. Glavni
procesi koji doprinose razlaganju nafte u vodi ili na vodenim površinama su: isparavanje,
rastvaranje, emulgovanje, disperzija, taloţenje, oksidacija i mikrobiološka degradacija.
Akcidentne situacije
Akcidentne situacije predstavljaju momente u kojima dolazi do iznenadnih toksiĉnih
dejstava na vodne tokove, koji nastaju ljudskom nepaţnjom i koji izazivaju trovanje biljnog i
ţivotiljskog sveta, pa time direktno ugroţavaju zdravlje i ţivot ljudi.
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U tim momentima neophode su hitne odn. blagovremene intervencije od strane drţave,
nadleţnih republiĉkih i gradskih inspekcijskih organa pre svega na lokalizaciji akcidenta, a potom i
spreĉavanju njegovog daljeg širenja i na kraju na sanaciji istog. Kaznena politika RS na osnovu
najnovojih zakonskih i podzakonskih akata iz oblasti zaštite ţivotne sredine je više nego rigidna po
uzroĉnike ovakvih katastrofa.
Poznatije akcidentne situacije koje su dovele do ugroţavanja ekosistema nadzemnih, a time i
podzemnih voda usled izlivanja nafte i naftnih derivata prilikom obavljanja procesa eksploatacije u
poslednjih 100 godina u svetu su: godine 1967. brodolom tankera Torrey Canyon prouzrokovao je
akcident usled kojeg se izlilo 117 000 tona nafte u blizini Velike Britanije i Francuske. Zatim izliv s
tankera Amoco Cadiz 1978. godine kada se izlilo 230 000 tona nafte u blizini Aljaske. 1979. god. u
Meksiĉkom zalivu dogodio se izliv iz naftnih platformi. Tamna mrlja bila je velika 200 km, i
prozrokovala je ekološku katastrofu nezapamćenih razmera. Nafta je uništila sve pred sobom, sl. 1.
Slika 1. Posledice izlivanja nafte u Meksičkom zalivu
U martu mesecu 1989. godine tanker Exxon Valdez nasukao se na ostrvo Princa Vilijama (Aljaska).
Tom prilikom je u more iscurelo 35 000 tona sirove nafte koja se ubrzo raširila na veće podruĉje
zbog jakih struja i neblagovremene intervencije. Uginulo je oko 4000 morskih vidri, nekoliko stotina
hiljada morskih ptica, a uništeno je i nekad bogato ribolovno podruĉje. Posledice te katastrofe
prisutne su još i danas. Naftna kompanija Exxon potrošila je ukupno 8 milijardi ameriĉkih dolara za
ĉišćenje. Godine 1993. tanker Baraer udario je u severnu obalu Škotske.
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Dogodila se ekološka katastrofa nesagledivih srazmera, kojom prilikom se izlilo 84 000 tona nafte.
U delu Balkanskog poluostrva akcidenti su se najĉešće dogaĊali na ostrvu Krku u Hrvatskoj gde se
nalazi najveći terminal za istovar sirove nafte i njenih derivata kojim se snabdevaju rafinerije sve do
MaĊarske. U RS trenutno ima nekoliko detektovanih crnih ekoloških taĉaka usled akcidenata
uzrokovanih nepravilnim postupanjem sa naftom. To su Veliki baĉki kanal, koji je zvaniĉno
najzagaĊeniji vodotok u Evropi, a regije oko Bora i Panĉeva spadaju meĊu najugroţenije na Starom
kontinentu, jer, to su jedini transportni pravci za dopremanje nafte do industrije i malih potrošaĉa.
Vaţno je napomenuti da ni posle 11 godina nisu sanirane posledice bombardovanja Rafinerije Novi
Sad. Prilikom razaranja 1999. iz Rafinerije je iscurilo više od 70.000 tona sirove nafte, što je
proporcionalno duplo veća katastrofa nego na Aljasci. Bombe su tada izazvale sagorevanje sirove
nafte, a toksiĉne, kancerogene supstance dospele su u vazduh, zemlju i podzemne vode. Razaranje
objekata, opreme i rezervoara izazvalo je izlivanje i oticanje dela nafte i derivata u Dunav, a pri
nepotpunom sagorevanju nastali produkti su se taloţili u okolnom zemljištu. Zbog potapanja
brodova i rušenja terminala deo naftnih derivata dospeo je u kanal Dunav-Tisa-Dunav koji ni do
danas nije oĉišćen [1].
METODE REMEDIJACIJE PODZEMNIH VODA
Metode remedijacije podzemnih voda podrazumevaju niz aktivnosti koje se preduzimaju sa
ciljem sanacije postojećeg zagaĊenja, koja mogu biti posledica ekscesnih izlivanja opasnih materija
ili dugotrajne loše prakse rukovanja opasnim materijama, odnosno opasnim otpadom, u cilju
sniţenja koncentracije zagaĊujućih materija do nivoa koji je zakonom predviĊen ili koji ne
predstavlja opasnost po ţivotnu sredinu i zdravlje ljudi. U zavisnosti od vrste i obima zagaĊenja, kao
i zagaĊenog medija primenjuju se razliĉite metode remedijacije kao što su remedijacija crpenjem i
tretmanom vode, bioremedijacija aplikacijom adekvatnih sojeva bakterija, itd. Aktivnosti na
remedijaciji se izvode kroz sledeće faze: [2]
- Modela disperzije zagaĊujuće materije u prirodnoj sredini,
- Laboratorijskih istraţivanja u cilju identifikacije vrste i obima zagaĊenja,
- Izrada pilot testova remedijacije,
- Terenski pilot testovi remedijacije,
- IzvoĊenje remedijacije uz kontrolna uzorkovanja i merenja.
Kada zakonskom regulativom nisu definisani ciljani parametri remedijacije, oni se definišu
izradom procene rizika na zdravlje ĉoveka i ţivotnu sredinu, u skladu sa svetskom praksom. Postoji
na raspolaganju niz metoda ĉišćenja u cilju realizacije remedijacije lokacija sa opasnim otpadom.
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Razlikuju se postupci in sity koji se izvode na samoj lokaciji i postupci koji se izvode na
mestu van lokacije.
Postupci koji se izvode na licu mesta ukljuĉuju mere koje ne menjaju lokaciju, kao što je
ograniĉavanje upotrebe, obezbeĊivanje površine, monitoring podruĉja i privremeno skladištenje
zagaĊenja koje se pojavilo.
Mere izvan lokacije ukljuĉuju uklanjanje i premeštanje deponije u celini. In sity mere mogu
se sastojati od mera sigurnosti sa ciljem da se preseku putevi zagaĊivanja (sniţenje nivoa podzemne
vode, inkapsulacija, imobilizacija) ili intenzivnije metode dekontaminacije. Metode dekontaminacije
ukljuĉuju fiziĉko-hemijske, biološke i termiĉke metode. In sity postupci se mogu takoĊe izvoditi na
samom mestu ili izvan njega.
Tehnologije koje se primenjuju za remedijaciju podzemnih voda u sluĉaju zagaĊenja
naftnim ugljovodonicima, mogu se svrstati u sledeće osnovne grupe:
- pasivna remedijacija,
- pasivni/reaktivni tretman u bunarima,
- air sparging (produvavanje vazduha),
- biosparging,
-
bioslurping,
UV-oksidacija i
tehnologija ispumpavanja i tretiranja podzemne vode (Maletić, 2006).
Pasivna remedijacija podrazumeva in sity tretman, koji koristi prirodne procese u cilju
zaustavljanja širenja kontaminacije, kao i redukcije koncentracije i koliĉine prisutnog specifiĉnog
zagaĊenja. Odvija se sama, ĉime odrţava ravnoteţu biodiverziteta i pomaţe nemarnom ĉoveĉanstvu
da saĉuva prirodu. Proces pasivne remedijacije moţe: redukovati masu zagaĊujućih materija (kroz
proces kao što je biodegradacija); redukovati koncentraciju (jednostavnim razblaţenjem ili
disperzijom); ili vezati zagaĊujuće materije za zemljište da bi se spreĉila migracija zagaĊenja
(adsorpcija). Ovde adsorpcija spreĉava migraciju kontaminacije na ona mesta gde bi mogla ugroziti
ljudsko zdravlje i ţivotnu sredinu.
Pasivni/reaktivni tretman u bunarima predstavlja in sity remedijacionu tehnologiju koja
se koristi u hitnim situacijama, a razvijena je i primenjuje se poslednjih nekoliko godina. Bunari za
tretman ispunjeni razliĉitim punjenjima (u zavisnosti od vrste prisutnog zagaĊenja), instaliraju se
tako da prate prirodno kretanje vode. Pri toku vode kroz bunar za tretman, zagaĊujuće materije se ili
zadrţavaju u bunaru (na primenjenom matriksu) ili se prevode u bezopasne supstance, koje zatim
izlaze iz bunara zajedno sa tretiranom vodom. Punjenje bunara zavisi od vrste prisutnih zagaĊujućih
materija, a najĉešće se primenjuju sledeće vrste punjenja:
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-
-
Sorpcione barijere – sadrţe punjenje koje fiziĉki uklanja zagaĊujuće materije iz
podzemne vode i zadrţava ih na površini barijere (npr. aktivni ugalj i zeoliti),
Precipitacione barijere – sadrţe punjenje koje reaguje sa zagaĊujućim materijama
rastvorenim u podzemnoj vodi, pri ĉemu se stvaraju nerastvorna jedinjenja koja se taloţe
(npr. kreĉnjak koji se koristi za podizanje pH i za imobilisanje metala iz podzemne
vode) i
Degradacione barijere – uzrokuju reakcije koje degradiraju zagaĊujuće materije
podzemne vode u bezopasne produkte (npr. bunari napunjeni sa granulama gvoţĊa
pomaţu da se degradiraju pojedina volatilna organska jedinjenja; bunari napunjeni
nutrijentima sa izvorom kiseonika stimulišu aktivnost mikroorganizama koji se nalaze u
podzemnoj vodi ĉime stimulišu degradaciju svih štetnih elemenata u vodi).
Najĉešće se koriste dva tipa bunara za tretman podzemne vode:
-
Propustljivi reaktivni bunari – najjednostavnija forma ovih bunara sastoji se od rova koji
je napunjen propustljivim materijalom, gde se zagaĊujuće materije uklanjaju razliĉitim
procesima transfera mase i
-
Sistem sa levcima i kapijama – koristi se kada je struja podzemne vode suviše velika ili
duboka da bi se kopala jama. Sistem se sastoji od bunara u obliku levka koji obezbeĊuje
prolazak vode kroz kapiju koja propušta kontaminiranu podzemnu vodu do reaktivne
ispune.
Tehnologija se uspešno koristi za tretman podzemne vode kontaminirane sa VOC, SVOC i
neorganskim jedinjenjima. Nedostatak ove tehnologije je u tome što bunari za pasivan tretman imaju
tendenciju smanjenja kapaciteta. Osim toga, velike i duboke struje vode se teţe tretiraju od plitkih i
malih struja.
Air sparging, odn. u prevodu sa engleskog produvavanje vazduha predstavlja in sity
tehnologiju koja se koristi već 15 godina za uklanjanje volatilnih organskih jedinjenja (eng. VOC,
volatile organic compound), kao i semivolatilnih organskih komponenti (eng. SVOC, semivolatile
organic compound ), rastvorenih u podzemnoj vodi, apsorbovanih i/ili zarobljenih u porama zemlje
u zoni saturisanoj vodom. Tehnologija podrazumeva injektovanje atmosferskog vazduha, pod
pritiskom u vodom saturisanu zonu zemlje, pri ĉemu dolazi do volatalizacije zagaĊujućih
komponenti iz vode i do njihove poboljšane biodegradacije usled povećane površinske koncentracije
kiseonika. Injektovani vazduh takoĊe, dovodi do formiranja kanala u saturisanoj zoni zemlje, kroz
koje zagaĊujuće materije nošene strujom vazduha dospevaju do nesaturisane zone.
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Na ovaj naĉin, komponente izdvojene iz zone zemlje saturisane vodom, lakše podleţu
biodegradaciji (veći sadrţaj dostupnog kiseonika), ili se pak, dalje uklanjaju primenom specijalnih
sistema.
Sumarno, tokom produvavanja vazduha kroz podzemnu vodu, odvijaju se tri mehanizma
uklanjanja volatilnih i semivolatilnih organskih zagaĊujućih komponenti: (1) in sity uklanjanje, (2)
volatalizacija zarobljenih i adsorbovanih komponenti u kapilarnim porama zemlje i (3) njihova
aerobna biodegradacija.
Ova tehnologija se moţe koristiti za širok opseg volatilnih i semivolatilnih kontaminanata
podzemne vode i zemljišta, ukljuĉujući benzin i druge komponente goriva i hlorovanih rastvaraĉa.
Efikasnost ove tehnologije u mnogome zavisi od karakteristika podzemne vode, ali i okolnog
zemljišta (naroĉito u saturisanoj zoni).
Biosparging podrazumeva injektovanje vazduha i nutrijenata u zemljište ispod nivoa vode
(u zonu saturisanu vodom), pri ĉemu se postiţe poboljšana biodegradacija kontaminanata sa
prirodno prisutnim mikroorganizmima. Ova tehnologija je primenljiva za uklanjanje produkata nafte
rastvorenih u podzemnoj vodi, ili adsorbovanih na zemljištu ispod nivoa vode. Ĉesto se koristi u
konjukciji sa ekstrakcijom vode na ĉvrstoj fazi (eng. SVE, soil vapor extraction), naroĉito ako su
prisutna volatilna organska jedinjenja. Biosparging tehnologija predstavlja modernu tehnologiju
preĉišćavanja, u okviru koje se na unapred definisan naĉin inkorporira taĉno definisana zapremina
vazduha radi postizanja što efikasnijeg mikrobiološkog potencijala zagaĊenog tela. Ova tehnologija
ima nekoliko prednosti: oprema je dostupna i laka za instaliranje, vreme tretmana je relativno kratko
6-24 meseca, efikasnost se povećava sa produvavanjem vazduha, ne zahteva uklanjanje tretmana, ili
skladištenje podzemne vode, mala brzina injektovanja redukuje potrebu za tretman gasova itd.
Nrdostaci: primenljiva je samo za lokacije gde se moţe primeniti air sparging i gde nema slobodne
faze ugljovodonika, zatim hemijski, fiziĉki i biološki procesi nisu dobro prouĉeni, a postoji i
potencijalna opasnost od migracije zagaĊujućih materija.
UV-oksidacija predstavlja kombinovani tretman zagaĊene vode. Podrazumeva korišćenje
UV zraka i razliĉitih oksidanata. Ona je jedna od najvaţnijih tehnika za remedijaciju podzemne vode
u hitnim sluĉajevima. U ovu svrhu, u konjukciji sa UV zraĉenjem, najĉešće se primenjuju oksidanti
kao što su: ozon i vodonik-peroksid. Sistem se sastoji od reaktora u kome su smeštene UV lampe, u
koji se uz dodatak oksidanta, uvodi kontaminirana podzemna voda sl.2.[5].
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Slika 2. UV-peroksid tretman podzemnih voda
Bioslurping je realitvno nova remedijaciona tehnologija koja kombinuje elemente vakumunapreĊenog ispumpavanja (za uklanjanje slobodnih produkata iz podzemne vode – kapljica ulja,
ĉvrstih ĉestica i sl.), bioprovetravanja (potpomaţe biodegradaciju organskog zagaĊenja) i aerobne
bioremedijacije ugljovodoniĉnih kontaminanata. Bioslurping sistem se sastoji od specijalno
dizajniranih bunara u koje se postavlja usisna cev, koja je sa jedne strane povezana sa vakuum
pumpom, a sa druge uronjena u nevodenu teĉnu fazu, odnosno u uljanu fazu. Bioslurping sistemi
sluţe uglavnom za uklanjanje plutajuće nevodene teĉne faze. Najvaţnije karakteristike bioslurping
tehnologija su: uklanjanje slobodnih produkata (što dovodi do ubrzavanja remedijacije); i povećanje
efikasnosti prirodne (pasivne) bioremedijacije. Tehnologija je meĊutim, neefektivna za
nepropustljiva zemljišta, npr. zemljišta u kojima preovlaĊuje glina.
ZAKLJUČAK
ZagaĊenje podzemnih voda i zemljišta uopšte, a pre svega ugljovodonicima iz naftnih
derivata prilikom obavljanja tehnoloških procesa ima višestruko negativan uticaj na ţivotnu sredinu.
Laiĉkom nepaţnjom ili namernom nebrigom dolazi do zagaĊenja zemljišta, voda, pa i ĉitavih
ekosistema ĉime se ugroţava opstanak flore i faune, samim tim i ljudi na planeti zemlji. I najĉešća
zagaĊenja zemljišta i vode dolaze upravo iz nafte i njenih derivata. Po pravilu, ona su uvek toksiĉna.
Stoga su nauĉnici decenijama izuĉavali mogućnosti smanjenja ukupnih negativnih efekata ovih
zagaĊenja iz koji su i nastale najrazliĉitije tehnike za remedijaciju, kojima se pokušava na brz,
efikasan i što jeftiniji naĉin smanjiti negativan efekat svih zagaĊenja proisteklih iz nafte.
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Ex-situ tretman podzemne vode (―ispumpaj i biološki tretiraj‖, (eng. pump-and-biotreat)
zagaĊene naftom i njenim derivatima u sklopu tehniĉke in-situ bioremedijacije zemljišta zagaĊenog
naftom i derivatima nafte predstavlja najlakšu i najzastupljeniju tehniku za preĉišćavanje voda koja
se u RS koristi.
LITERATURA
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Dalmacija B..i ostali:.„Naftno zagaĊenje podruĉja Ratno ostrvo, Mogućnosti prirodne
bioremedijacije―, Prirodno-matematiĉki fakultet, Novi Sad, 2004.str.24.
Dalmacija B., „Prouĉavanje primarnog i sekundarnog mikrobiološkog preĉišćavanja mešanih
rafinerijskih i komunalnih otpadnih voda, Doktorska disertacija―, Prirodno-matematiĉki
fakultet, Novi Sad, 1984.str.37.
Dorĉić I..: „Osnove ĉišćenja uljnih zagaĊenja, Kemija u industriji―, Zagreb, 1987.str.94.
Dragutin M..: „Mikroorganizmima protiv oneĉišćenja―, INA ĉasopis, Hrvatska, 2006.
(www.ina.hr)
.Maletić S.: „Pregled tehnologija za remedijaciju podzemnih voda, Kvalitet voda―, Departman
za hemiju, PMF, Novi Sad, 2006.str.118.
Marković, D. A.i ostali: „Fiziĉko hemijski osnovi zaštite ţivotne sredine, Izvori zagaĊivanja,
posledice i zaštita―, Univerzitet u Beogradu, Beograd, 1996.str.217.
www.biremediation.info
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V. Šćekić, R. Cvejić, S. Smiljić
DOI: 10.7251/JEPMSR1406067S
UDK: 628.112:665.6
Professional paper
TREATMENT OF GROUND WATER CONTAMINATED OIL
DERIVATIVES
Velimir Šćekić, Radoje Cvejić, Sava Smiljić
[email protected]
University UNION Belgrade, Faculty for Strategic and Operational Management,
11070 Belgrade, Serbia
Abstract
Treatment of groundwater is the most important part of the scope of protection of natural
resources, because no biological and bacteriological water there is no life on the planet.
Implemented through consideration of all the negative elements in the water, determine the
percentage of their toxicity and finding the most appropriate method for their removal. The aim is to
monitor, improve water quality and the environment in general observed.
Keywords: oil, petroleum.
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M. Janković, A. Tanasijević, R. Filipović, M. Perušić
DOI: 10.7251/JEPMSR1406079J
UDK: 661.183.6:66.081
Naučni rad
UTICAЈ PROCESNIH PARAMETARA NA KAPACITET SORPCIЈE
VODE 4A ZEOLITA
Mladen Janković2, AnĊelko Tanasijević1, Radislav Filipović2, Mitar Perušić1
[email protected]
1
Univerzitet u Istočnom Sarajevu, Tehnološki fakultet, 75400 Zvornik, Republika Srpska, BiH
2
Fabrika „Alumina“, 75400 Zvornik, Republika Srpska, BiH
Izvod
U radu јe ispitivan uticaј procesnih parametara na sorpcione karakteristike zeolita 4A.
Posmatrani procesni odnose se na uticaј temperature kristalizaciјe, uticaј vremena kristalizaciјe i
uticaј koncentraciјe Na2O. Paralelno sa ispitivanjem uticaјa ovih parametara na kapacitet sorpciјe
vode zeolita 4A, što јe bio primarni cilj, analiziran je njihov uticaј na kapacitet adsorpciјe
dibutilftalata (DBF) sintetisanih prahova kao i kristaličnost i prosječnu veličinu dobiјenih čestica
zeolita. Dobiјeni rezultati pokazuјu da kapacitet sorpciјe vode zeolita 4A raste sa porastom
temperature i vremena kristalizaciјe, a opada sa porastom koncentraciјe Na2O. Uticaј datih
parametara na adsorpciјu DBF, kao i na srednju veličinu čestica јe manje izražen. Kristaličnost
takođe pokazuјe značaјnu zavisnost od temperature.
Ključne riječi: parametri, sinteza, sorpciјa, zeolit, 4A.
1. UVOD
Zeoliti predstavljaјu grupu materiјala sa sve većom primenom u razliĉitim oblastima ljudskih
aktivnosti ukljuĉuјući i prije svega nekoliko veoma bitnih industriјskih procesa u koјima su poјedine
vrste zeolita postale gotovo nezamenljive. Razlog za tako veliki znaĉaј zeolita јeste njihova
karakteristiĉna kristalna struktura koјa im omogućava posjedovanje izuzetnih sorpcionih, a takoĊe i
јonoizmjenjivaĉkih i katalitiĉkih osobina. Od velikog broјa razliĉitih tipova zeolita, zeolit 4A se od
svoјe prve sinteze i uvoĊenja u industriјsku upotrebu '50-ih godina prošlog veka, do danas zadrţao
kao tip zeolita koјi se naјviše upotrebljava.
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Struktura zeolita, njegova svoјstva (veliĉina i oblik ĉestica, raspored veliĉina) kao i prethodno
navedene osobine u mnogome zavise od vrednosti procesnih parametara tokom sinteze zeolita, kao
što su temperatura dodavanja reakcionih komponenti, temperatura kristalizaciјe, vrijeme ukapavanja
i kristalizaciјe, koncentraciјa i odnos silikatne i aluminatne vrste u sistemu za sintezu, pH vrijednost
u sistemu idr. Zbog toga јe uticaј razliĉitih procesnih parametara na osobine, kako zeolita 4A tako i
drugih vrsta zeolita, ĉesto istraţivani dokumentovan u literaturi. Predmet rada upravo јe istraţivanje
uticaјa temperature kristalizaciјe, vremena kristalizaciјe i koncentraciјe natriјumaluminata (izraţene
preko koncentraciјe Na2O) na sorpcioni kapacitet zeolita 4A, izraţen preko kapaciteta sorpciјe vode
kao bitnog faktora za samu primjenu datog zeolita, te mogućnosti kontrole procesa i kvaliteta
dobiјenog proizvoda optimizacijom ovih parametara. Za širu analizu posmatran je i uticaј navedenih
parametara na sorpcione karakteristike, analiziran јe i njihov uticaј na sorpciјu dibutilftalata (DBF)
kao i kristaliĉnosti veliĉinu zrna 4A zeolita.
2. EKSPERIMENTALNI DIO
Eksperimentalni rad koncipiran je u dva dijela, prvi dio obuhvatao јe sinteze zeolita 4A pri
razliĉitim vrijednostima navedenih uslova u okviru ĉega јe ukupno izvedeno 9 sinteza. Sinteze su
izvoĊene u vodenom kupatilu pomoću koga јe odrţavana temperatura kristalizaciјe. Pri izvoĊenju
sinteza temperatura kristalizaciјe je mijenjana u intervalu od 78°C do 88°C, koncentraciјu Na2O u
rastvoru u intervalu od 71,92 do 90,52 g/l i vrijeme kristalizaciјe u intervalu od 120 do 240 minuta.
Drugi dio obuhvatao јe ispitivanje osobina uzoraka zeolita 4A dobiјenih u sintezama ukljuĉuјući i
ispitivanje kapaciteta sorpciјe vode uzoraka, kapaciteta adsorpciјe dibutilftalata (DBF), kristaliĉnosti
i srednje veliĉine ĉestica, te razmatranje njihovih vrednosti u funkciјi procesnih parametara
karakteristiĉnih za odgovaraјuću sintezu.
Od standardnih metoda, vršeno je odreĊivanje konstitucione vode, sadrţaja i slobodnog SiO2,
ukupnog sadrţaja i slobodnog Al2O3, JIK-a, zatim adsorpcije ulja i sorpcije vode. Metoda adsorpcije
ulja zasniva se na odreĊivanju adsorpciјe ulja na osnovu adsorpciјe dibutilftalata (DBF) na
ĉesticama zeolita. Kapacitet sorpciјe vode se u ovom sluĉaјu odreĊuјe metodom vakuuma na
temperaturi 20°C. Obzirom na cilj rada i uticaј osnovnih procesnih parametara sinteze zeolita 4A na
sorpcioni kapacitet zeolita izraţen kapacitetom sorpciјe vode (WSC,od engl. – Water Sorption
Capacity), a s druge strane da je kapacitet sorpciјe vode zeolita 4A јedna јe od naјznaĉaјniјih
osobina za njegovu komerciјalnu upotrebu, te јe i poznavanje njegove zavisnosti od poјedinih
uslova sinteze kljuĉno za dobiјanje proizvoda zadovoljavaјućih karakteristika. Iz ovog razloga,
izvedeni su i odgovarajući uslovi sinteze, odnosno procesni parametri ĉiјi јe uticaј ispitivan bili su:
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- temperatura kristalizaciјe (tkr.),
- koncentraciјa Na2O u filtratu (CNa2O),
- vrijeme kristalizaciјe (τkr.).
Za izvoĊenje sinteza korištene su sirovine:
- natriјumsilikat (vodenostaklo),
- natriјumaluminat,
- filtratzeolita.
Sve korištene polazne sirovine su taĉno definisanog sastava i koliĉina.
3. REZULTATI I DISKUSIJA
Prioritetno je ispitivan uticaј razliĉitih procesnih parametara kao što su temperatura, koncentraciјa
Na2O u rastvoru i vrijeme kristalizaciјe, na kapacitet sorpciјe vode kod zeolita 4A (WSC).
Analiziran je i uticaј posmatranih procesnih parametra i na druge osobine sintetisanih prahova, i to
srednji diјametar (dsr) i raspodela veliĉine ĉestica kao i kapacitet adsorpciјe ulja izraţen preko
kapaciteta adsorpciјe dibutiftalata (ADBF). Rezultati u skladu sa navednim prikazani su u tri dijela
zavisno od analiziranog parametra.
Uticaј temperature kristalizaciјe. Uticaј temperature na osobine sintetisanog praha ispitivan јe na
osnovu tri sinteze, svake pri razliĉitoј temperaturi a pri stabilnim (konstantnim) ostalim
parametrima.
Tabela1. Rezultati uticaјa temperature na osobine zeolita 4A
Broј
sinteze
1
2
3
tkr.
tkr.
[°C]
78
82
88
[min]
120
120
120
c
(Na2O)
[g/l]
71.6
72.22
71.92
WЅC
ADBF
dsr
[%]
25.07
26.78
26.85
[g/g]
0.70
0.80
0.80
[µm]
3.26
3.45
4.10
Na osnovu dobiјenih rezultata (Tab. 1), јasno se vidi da temperatura znaĉaјno utiĉe na osobine
sintetisanog praha kao što us sorpcioni kapaciteti veliĉina ĉestica a povezano sa veliĉinom ĉestica i
na adsorpciјu ulja.
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Slika1. Uticaј tempearature na kapacitet sorpciјe vode kod sintetisanih prahova 4A zeolita
Sa porastom temperature raste i sorpcioni kapacitet vode kod sintetisanog praha (Sl. 1), dok јe uticaј
temperature na veliĉinu ĉestica i adsorpciјu ulja. Dobiјeni rezultati ukazuјu da sa porastom
temperature raste i brzina rasta kristala kao i brzina kristalizaciјe. Kada јe u pitanju srednji diјametar
ĉestica rezlutati pokazuјu da on raste sa povećanjem temperature ali smatramo da se ovaј fenomen
mora јoš dodatno ispitati na većem broјu sinteza što će biti predmet daljih istraţivanja.
a)
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b)
Slika 3. Uticaј tempearature na kapacite tadsorpciјe ulja kod sintetisanih prahova 4A zeolita (a) i srednji
diјametar čestica kod sintetisanih prahova 4A zeolita (b)
Uticaј temperature na kristaliĉnost dobiјenih prahova prikazan јe na X-ray diјagramima sa slika4.,
gde se moţe vidjeti da јe kristaliĉnost praha sintetisanog na temperaturi 78°C oko 85,3% a praha
sintetisanog na temperaturi 88°C 116% u odnosu na posmatrani standard (koji ne predstavlja i
maksimalni iznos kristaliĉnosti). Ovi rezultati ukazuјu na ĉinjenicu da јe naniţoј temperaturi
potrebno duţe vrijeme kristalizaciјe.
Slika 4. Kristaličnost praha sintetisanog na temperaturi 78°C i 88°C
Uticaј koncentraciјe Na2O u rastvoru. Koncentraciјa Na2O u rastvoru se moţe prikazati na
nekoliko naĉina, u radu je prikazana preko koncentarciјe Na2O u filtartu (matiĉnom rastvoru) nakon
završetka sinteze obzirom da u principu, u toku sinteze izreaguјu skoro upotpunosti Al2O3 i SiO2 dok
Na2O ostaјe u suvišku.
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Tabela 2. Rezultati uticaјa koncentraciјe Na2O na osobine zeolita 4A
Broј
sinth.
3
4
5
6
tkr.
τkr.
[°C]
88
88
88
88
WЅC
[min]
c
(Na2O)
[g/l]
120
120
120
120
71.92
74.40
90.52
90.21
26.85
26.95
23.5
24.05
[%]
A
(DBF)
[g/g]
0.80
0.80
0.75
0.80
dsr
[µm]
4.1
3.95
3.9
3.85
JIK
[gCa
O/g]
158
150
174
172
Na bazi prikazanih rezultata (Tab. 2.) pri konstantnoј temperaturi i vremenu kristalizaciјe sa
povećanjem sadrţaјa Na2O u rastvoru smanjuјe se kapacitet sorpciјe vode zeolita 4A. TakoĊe se
moţe primijetiti i neznatno smanjenje srednjeg preĉnika sintetisanih ĉestica. U pogledu adsorpciјe
ulja niјe primijećen znaĉaјan uticaј. Pretpostavlja se da јe za uoĉeno smanjenje kapaciteta sorpciјe
vode 4A zeolita, razlog to što povećana koncentraciјa Na2O utiĉe na to da se prilikom procesa
kristalizaciјe stimuliše kristalizaciјa sodalitske forme, a takoĊe se uzrokuјe i promjena u obliku
kristala pri ĉemu se umјesto kubiĉne forme dobiјane što zaobljeniјa forma (Sl.5) na koјoј su јasno
vidljivi „ljuspasti sloјevi―. Pored toga, postoјi vjerovatnoća da u ovakvim uslovima moţe doći i do
poјave zeolita P (NaP) u tragovima koјi i u prisustvu od 1-1,5% moţe znaĉaјno smanjiti sorpcioni
kapacitet zeolita 4A, odnosno djeluјe kao inhibitor procesa sorpciјe vode.
Slika 5. SEM uzorka sintetisanog praha pri višoј koncentraciјi Na2O (sinteza 5, koncentraciјa Na2O 90,52
g/l) i nižoј koncentraciјi Na2O (sinteza3, koncentraciјa Na2O 71,92 g/l)
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Slika 6. Raspodela veličine čestica sintetisanog praha (sinteze 3 i 6, ▬ koncentraciјa Na2O 71,92 g/l, ▬
koncentraciјa Na2O 90,21 g/l)
Moţe se smatrati da јe smanjenje preĉnika ĉestica sa porastom koncentraciјe Na2O uzrokovano
povećanom rastvorljivošću nukleusa, ĉime se usporava proces kristalizaciјe i rasta ĉestica. Krive
raspodjele veliĉine ĉestica pokazuјu maseni udeo, R [%], ĉestica odreĊenog diјametra, D [μm], u
uzorcima zeolita dobiјenim iz odgovaraјućih sinteza.
Uticaј vremena kristalizaciјe. Uticaј vremena kristalizaciјe na osobine sintetisanih prahova
ispitavane su na dva naĉina. Kod prvog naĉina su svi drugi parametri odrţavani konstantnim a
menjano je vrijeme kristalizaciјe (sinteze 1 i 7), dok smo kod drugog naĉina vršili naknadno
dodavanje aluminatnog rastvora u suvišak vodenog stakla i ostavljali da se dovrši proces
kristalizaciјe (sinteze 8 i 9). TakoĊe je menjano i vrijeme kristalizaciјe nakon dodavanja korekcione
koliĉine natriјumaluminata. Dodatna koliĉina natriјumaluminata dodavana je nakon 120 min., a
kristalizaciјa јe traјala od 180- 240 minuta. Dobiјeni rezultati su prikazani u tebeli 3.
Tabela3. Rezultati sintetisanih prahova sa različitim vremenom kristalizaciјe
Broј
tkr.
τkr.
sinteze
[°C]
1
7
8
9
78
78
88
88
WЅC
[min]
c
(Na2O)filtr.
[g/l]
120
180
180
240
71.60
71.54
63.86
70.68
25.07
27.02
17.70
27.45
[%]
A
(DBF)
[g/g]
0.70
0.75
1.00
0.75
dsr
[µm]
3.26
3.90
6.41
7.45
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Kao što se iz prikazanih rezultata vidi, sa produţenjem vremena kristalizaciјe povećava se i
kapacitet sorpciјe vode (Sl.7) a takoĊe јe primećeno i neznatno povećanje srednjeg preĉnika ĉestica
sintetisanog praha. Kada јe u pitanju adsorpciјa ulja vidljivo јe da se na niţoј temperaturi (78°C) sa
povećanjem vremena kristalizaciјe povećava i adsorpciјa ulja, s tim što, kako niјe bilo znaĉaјniјe
promene u kristaliĉnosti, nivo povećanje adsorpciјe niјe znaĉaјno. Navišoј temperaturi (88°C) to
niјe sluĉaј, a pretpostavljamo da јe razlog tome što na višoј temperaturi pri kraćem vremenu sinteze
niјe bilo dovljno vremena za kristalzaciјu nakon dodavanja korekcione koliĉine natriјumaluminata,
te us u tom sluĉaјu nastalene kristalne forme sa povišenom adsorbciјom ulja. Ove pretpostavke nam
potvrĊuјu i rezultati X-ray difrakcione analize.
Slika 7. Difraktogram sintetisanih prahova u zdodavanje korekcion ekoličine natriјumaluminata ( ▬ nakon
180 min, ▬nakon 240 min), privremenu kristalizaciјe 120 min na 78°C( ▬ sinteza 1, ▬standard)
U toku vremena kristalizaciјe od 180 minuta (60 minuta nakon dodavanja korekcione koliĉine
natriјumaluminata) dobiјena јe kristaliĉnost 49.15% dok јe u toku vremena kristalizaciјe od 240
minuta (120 minuta nakon dodavanja korekcione koliĉine natriјumaluminata) dobiјena kristaliĉnost
90.47%.
Kada јe u pitanju kristaliĉnost sintetisanih prahova na niţim temperaturama (78°C) moţe se
zakljuĉiti da јe potrebno duţe vrijeme od 2 sata da bi se dobila zadovoljavaјuća kristaliĉnost. Nakon
120 minuta dobiјena јe kristaliĉnost 85,3% a sa produţenjem vremena kristalizaciјe na 180 minuta
dobiјena јe kristaliĉnost 86,06 %.
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Slika 8. Raspodela veličine čestica kod uzorka dobiјenog uz naknadno dodavanje natriјumaluminatnog
rastvora (sinteza 10)
Ovi rezultati nam pokazuјu da ni sa produţenjem vremena sa 120 na 180 minuta niјe došlo do
znaĉaјniјe promene kristaliĉnosti te da јe na niţim temperaturama potrebno znatno duţe vrijeme za
kristalizaciјu, 4-5 sati. Prikazana јe raspodjela veliĉine ĉestica sintetisanog praha (Sl. 8, sinteza 10)
gde se moţe vidjeti da usled naknadnog dodavanja aluminatnog rastvora dobiјa sebimodalna
raspodelu veliĉine ĉestica. Prilikom nastaјanja novih centara kristalizaciјe dolazi istovremeno do
formiranja novih ĉestica kao i do povezivanja postoјećih ĉestica u velike aglomerate za razliku od
sinteza kada јe vršeno dodavanje natriјum aluminatnog rastvora u јednoј fazi.
4. ZAKLJUČAK
Na osnovu izvedenih eksperimenata i dobiјenih rezultata moţemo izvesti sledeće zakljuĉke, da
kapacitet sorpciјe vode raste sa porastom temperature. TakoĊe јe uoĉen i porast kapaciteta
adsorpciјe dibutilftalata sa porastom temperature izmeĊu prve dve sinteze. Brzina rasta kristala kao I
brzina kristalizaciјe povećavaјu se sa porastom temperature kristalizaciјe. Usled toga, sa
temperaturom se povećava i srednja veliĉina ĉestica sintetisanog praha. Moţe se vidjeti da
kristaliĉnost dobiјenih prahova takoĊe se povećava sa porastom temperature. Naniţoј temperaturi
potrebno јe znatno duţe vrijeme kristalizaciјe za postizanje znaĉaјniјeg porasta kristaliĉnosti.
Kapacitet sorpciјe vode opada sa povećanjem sadrţaјa Na2O u rastvoru. Na bazi provedenih
ispitivanje niјe uoĉen znaĉaјan uticaј sadrţaјa Na2O u rastvoru na adsorpciјu dibutilftalata. Kapacitet
sorpciјe vode raste sa produţavanjem vremena kristalizaciјe. Srednja veliĉina ĉestica sintetisanih
prahova se neznatno smanjuјe sa porastom sadrţaјa Na2O u rastvoru, dok se s druge strane neznatno
povećava sa porastom vremena kristalizaciјe.
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LITERATURA
[1]
[2]
[3]
[4]
[5]
[6]
J.R. Ugal, K.H. Hassan, I.H.Ali, I.H., Preparation of Type 4A Zeolite from Iraqi Kaolin:
characterization and properties measurements, Journal of the Association of Arab
Universities for Basic and Applied Sciences, [online] Vol. 9 (2010) 1-8.
B. Subotić, J. Bronić, T. Antonić-Jelić, Nukleacija zeolita - fikcije i stvarnost, Institut "RuĊer
Bošković" - Zagreb, Prvi hrvatski zeolitni simpozij s meĊunarodnim sudjelovanjem, Split,
Hrvatska, 26-27. Septembar 2008.
R. Von Ballamoos, J.B. Higgins, M.M.J. Treacy (eds.), Butterworth-Heinemann, Boston, MA,
(1992) pp. 321-328.
A.Tanasijević, M.Perušić, R.Filipović, M.Radić, D.Kešelj, D.Lazić, Optimization of the
synthesis parameters of NaA zeolite, Contemporary Materials Book of Abstracts, ANURS,
(2013)pp.67.
S.P. Zhdanov, N.N. Feoktisova, L.M. Vtjurina, In: G. Ohlmann, H. Pfeifer, R. Fricke, et.al.,
Catalysis and Adsorption by Zeolites, Studies in Surface Science and Catalysis Vol. 65.,
Amsterdam: Elsevier, (1991) pp. 287-276.
S. Bosnar, J. Bronić, I. Krznarić, B. Subotić, Influence of the concentrations of aluminium and
silicon in the liquid phase on the growth kinetics of zeolite A and X microcrystals, Croatica
Chemica Acta 78, (2005) pp.1-8.
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M. Janković, A. Tanasijević, R. Filipović, M. Perušić
DOI: 10.7251/JEPMSR1406079J
UDK: 661.183.6:66.081
Scientific paper
INFLUENCE OF 4A ZEOLITESYNTHESIS PROCESS PARAMETERS ON
WATER SORPTION CAPACITY
Mladen Janković2, AnĊelko Tanasijević1, Radislav Filipović2, Mitar Perušić1
[email protected]
1
University of East Sarajevo, Faculty of Technology, 75400 Zvornik, Republic of Srpska, B&H
2
Factory „Alumina“, 75400 Zvornik, Republic of Srpska, B&H
Abstract
This paper studies the effect of process parameters on the sorption characteristics of zeolite
4A. The observed process are related to the influence of crystallization temperature, crystallization
time and influence concentrations of Na2O. In parallel with the examination of the impact of these
parameters on the capacity of water sorption of zeolite 4A, which was the primary goal, are
analyzedinfluence on the adsorption capacity of dibutyl phthalate (DBF) synthesized powders as
well as crystallinity and average size of the resulting particles of the zeolite. The results show that
the capacity of water sorptione zeolite 4A increases with temperature and crystallization time, and
decreased with increasing concentrations of Na2O. The influence of given parameters DBF
adsorption, and the mean particle size is less prominent. Crystallinity also shows a significant
dependence on temperature.
Кeywords: parameters, synthesis, sorption, zeolite, 4A.
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D. Dimeski, V. Srebrenkoska
DOI: 10.7251/JEPMEN1406091D
UDK: 677.1/.5
Scientific paper
PREDICTING THE BALLISTIC STRENGTH OF ULTRA HIGH
MOLECULAR WEIGHT POLYETHYLENE/FIBER COMPOSITES BY
IMPLEMENTING FULL FACTORIALEXPERIMENTAL DESIGN
Dimko Dimeski, Vineta Srebrenkoska
[email protected]
University “Goce Delčev“, Faculty of Technology, 2000 Štip, Macedonia
Abstract
The purpose of the study is to predict the ballistic strength of hard ultra-high molecular
weight polyethylene fiber/phenolicballistic composites by implementing the full factorial
experimental design. When designing ballistic composites two major factors are the most important:
the ballistic strength and the weight of the protection. The ultimate target is to achieve the required
ballistic strength with the lowest possible weight of the protection. The hard ballistic
UHMWPE/phenolic composites were made by the open mold high pressure, high-temperature
compression of prepreg made of plain woven UHMWPE fiber fabric and polyvinyl butyral modified
phenolic resin.The preparation of the composites was done in accordance to the 22 full
factorialexperimental design. The areal weight of composites was taken to be the first factor and the
second – fiber/resin ratio. The first factor low and high levels are chosen to be 2 kg/m2 and 9 kg/m2,
respectfully and for the second factor – 80/20 and 50/50, respectfully. The first-order linear model
to approximate the response i.e. the ballistic strength of the composites within the study domain (2 –
9) kg/m2 x (80/20 – 50/50) ratio was used. The influence of each individual factor on the response
function is established, as well as the interaction of the two factors. It was found out that the
estimated first-degree regression equation with interaction gives a very good approximation of the
experimental results of the ballistic strength of composites within the study domain.
Keywords: UHMWPE fiber, ballistic composites, factorial design, regression equation, V50.
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INTRODUCTION
Since the beginning of armed conflict, armor has played a significant role in the protection of
warriors. In present-day conflicts, armor has inarguably saved countless lives. Over the course of
history—and especially in modern times—the introduction of new materials and improvements in
the materials already used to construct armor have led to better protection and a reduction in the
weight of the armor. Body armor, for example, has progressed from the leather skins ofantiquity,
through the flak jackets of World War II to today‘s highly sophisticated designs that exploit ceramic
plates and polymeric fibers to protect a person against direct strikesfrom armor-piercing projectiles
and fragments of explosive devices. The advances in vehicle armor capabilities have similarly been
driven by new materials.Modern optimal protection needs to be achieved without compromising
practical constraints such as weight and cost reductions. One of the ―new ―materials which is widely
used in the last three decades is ultra high molecular weight polyethylene (UHMWPE) fiber.
UHMWPE fiberis a crystalline molecule that consists of long molecular chains that are highly
oriented and show strong intermolecular chain bonding. It is made from bulk UHMWPE by gel
spinning process. In normal polyethylene the molecules are not oriented and are easily torn apart. In
a gel spinning process the molecules are dissolved in a solvent and spun through a spinneret. In the
solution the molecules that form clusters in the solid state become disentangled and remain in that
state after the solution is cooled to give filaments. As the fiber is drawn, a very high level of
macromolecular orientation is attained resulting in a fiber with a very high tenacity and modulus
[1,2,3]
The resounding characteristic of UHMWPE fiber is its remarkable strength. This very strong fiber
has made its biggest impact in the ballistics defense where it‘s used in bulletproof vests and helmets.
It is stronger than fiberglass and almost ten times stronger than steel on a kilogram-for-kilogram
comparison. It is the one of the strongest man-made fibers.Itshigh elongation at break, high modulus
and high strength make it the idealreinforcement solution for reducing weight and for combating
increasing threats [4]. Very high strength of UHMWPEfibers is essential factor in the energy
absorbing mechanism needed to defeat dynamic ballistic impact or to mitigate blast. This makes the
fibers the material of choice for:
• Ballistic vests and helmets
• Blast panels that protect against landmines
• Engineered ballistics panels (either stand-alone or as part of a combined solution)
• Spall liners
By combining fibres with an appropriate resin matrix system – typically phenolic – essential
mechanical and physical properties can be engineered into the composite.
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Because of their high strength/weight ratio UHMWPE fibers are mainly used forballistic vestsor as
reinforcements for composites (helmets, panels)for personal protection[5,6].
Most military casualties which are due to high speed ballistic projectiles are not caused by bullets.
The main threat is from fragmenting devices. In combat, this means, in particular, grenades, mortars,
artillery shells, mines, and improvised explosive devices (IEDs) used by terrorists.
One strategy of experimentation that is used extensively in practice is the one-factor-at-a-time
(OFAT) approach. The OFAT method consists of selecting a starting or baseline set of levels, for
each factor, and then successively varying each factor over its range with the other factors held
constantat the baseline level. After all tests are performed, a series of graphs are usually constructed
showing how response variable is affected by varying each factor with all other factors held
constant. The major disadvantage of the OFAT strategy is that it fails to consider any possible
interaction between the factors. The correct approach to dealing with several factors is to conduct
factorial experiment. This is an experimental strategy in which factors are varied together, instead
one at a time, and enables the experimenter to investigate the individual effects of each factor and to
determine whether the factors interact.
2. EXPERIMENTAL PROCEDURE
Experimental composite plates were made by impregnation of UHMWPE fiber fabric with
thermosetting phenolic resin modified with polyvinylbutyral. Intrinsically brittle phenolic resin is
modified for flexibility which better contributes to kinetic energy absorption of the high-speed
impact and its dispersion in the adjacent layers. As reinforcement plain woven UHMWPE fiber
fabric with areal weight of 2958 g/m2was used. The fabric was surface modified for better
adhesion with phenolic resins. The composites i.e. laminates were produced by open-mold
compression at high pressure and temperature of 155 oC within 150 minutes for fully curing i.e.
cross-linking of the resin. No post-curing treatment was done.
During the impregnation several factors wereobserved(speed of impregnation, resin viscosity,
metering rolls gap in the impregnating machine) so that the required resin pick-up and its content in
the prepreg was achieved.
The areal weight of the composites was adjusted simply by adding more prepreg layers in the press
packet from the lowest to the highest area weight in accordance to the experimental design.
In the 22 full factorial experimental design (FFED) the areal weight of the composite is taken to be
the first factor, and the second factor - fiber/resin ratio. For the first factor the low and the high
levels are 2 kg/m2 and 9 kg/m2, respectfully, and for the second factor – resin content of 20% and 50
% (which corresponds to fiber/resin ratios of 20/80 and 50/50, respectfully).
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Within this relatively narrow areal weight region, which is of importance only for panels for
personal ballistic protection, the liner dependence of ballistic strength vs. areal weight was assumed.
That‘s why the first-degree model with interactions was used to predict the response i.e. the ballistic
strength of the composites within the study domain (2 – 9) kg/m2 x (20%– 50%) resin content.
The full factorial experimental designallows to make mathematical modeling of the investigated
process in a study domain in the vicinity of a chosen experimental point [7, 8]. To cover the whole
study domain, for the areal weight of the composites the experimental point 5,5 3,5 kg/m2,was
chosen, and for the resin content , the experimental point 35  15 % (which corresponds to
previously defined levels for fiber/resin ratios)
All test are done with a standard 1,1g chisel-nosed fragment simulating projectiles which are nondeformable, made of quenched and tempered steel with a flat rectangular tip. The ballistic limit
velocities, V50, arecalculated in accordance to the STANAG 2920 calculation method. V50 value
presents 50 % probability of penetration and is statistical test developed by the US military. In
accordance to the FFED procedure 4 (22) trails are needed, i.e. all possible combinations of the
variables are tested.
The coding of the variables is done in accordance to table 1.
Table 1. Coding convention of the variables
Areal weight,
kg/m2
Resin content,
%
Zero level, xi=0
5.5
35
Interval of variation
3.5
15
High level, xi=+1
9
50
Low level, xi =-1
2
20
Code
x1
x2
4. RESULTS AND DISCUSSION
The results of the test are presented in Table 2 together with the experimental matrix.
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Table 2. Experimental matrix with results
Trials
Areal
weight,
x1
Resin
UHMWPE
Interaction
content,
composite
x1x2
x2
V50, (m/s)
1
-1
-1
+1
268.9
2
+1
-1
-1
580.6
3
-1
+1
-1
248.0
4
+1
+1
+1
545.8
-1 Level
2 kg/m2
20%
-
-
+1 Level
9 kg/m2
50%
-
-
By implementing the 22 full factorial experimental designit was found out that response function
with coded variables, yk,was:
yk  410,825  152,375x1  13,925x2  3,475x1 x2
and in engineering variables, yn:
y n  191,1286  45,8524 x1  0,5643x2  0.0662 x1 x2
In the FFED the term x1x2is the interaction between factors which also has influenceon the response,
in our case V50 value.
Analyzing the regression equation it can be find out that the main positive contribution to the V50 is
given by the areal weight of the composites i.e. V50 is directly proportional to the areal weight. On
the other hand, the resin content of the composite has inversely proportional effect on ballistic
strength which means the higher the resin content the lower the ballistic strength. The interaction of
the two factors, with coefficient of -0,0662 has slightly negative effect on the ballistic strength
which is of secondary order compared to areal weight and resin content of the composites.
To validate the equation theoretically calculated results arecompared with experimental values for
composites with areal weight of 2, 3, 4, 5, 6, 7, 8, 9 kg/m2 and constant resin content of 35%.This
comparison can be done with any other value for the resin content as long as it is within the study
domain. The results are presented in Figure 1.
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Figure 1. Ballistic strength vs. areal weight of composites
As it can be seen from Figure 1 there is a very good match between calculated and the experimental
values. All calculated values are placed in a straight line which is in accordance with the assumed
model of the experiment and are in close proximity of the experimental data.
CONCLUSION
-
-
-
For a range of the areal weight and for a range of the resin content the experimental
measurements of the ballistic strength of composite laminates were carried out by
implementing the 22 full factorial experimental design. A correlation equation was
established for V50 as a function of the areal weight and the resin content of the composites.
A very good agreement was found between experimental and calculated values. It was
observed that if the study domain is precisely established the full factorial experimental
design can be employed in order to give good approximation of the response i.e. V50 value.
V50 is directly proportional to the areal weight of the composites and inversely proportional
to the resin content, the areal weight being more dominant factor than the resin content
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D. Dimeski, V. Srebrenkoska
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
D. E. Demco, C. Melian, J. Simmelink, V. M. Litvinov and M. Möller, ―Structure and
Dynamics of Drawn Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers by 1H,
13C and 129XE NMR,‖ Macromolecular Chemistry and Physics, 211(2010) pp. 26112623.
P. Smith and P. J. Lemstra, ―Ultrahigh Strength Polyethylene Filaments by Solution
Spinning/Drawing‖, Journal of Materials Science, Vol. 15, No. 2, 1980, pp. 505-514.
M. J. M. Jacobs, ―Creep of Gel-Spun Polyethylene Fibres,‖ Ph.D. Thesis, Eindhoven
University of Technology, Eindhoven, December 1999.
R. Marissen, L. Smit and C. Snijder, ―Dyneema Fibers inComposites, the Addition of Special
Mechanical Functionalities,‖Conference Proceedings, Advancing with Composites 2005,
Naples, October 2005.
J. G. H. Bouwmeester, R. Marissen and O. K. Bergsma,―Carbon/Dyneema® Intralaminar
Hybrids: New Strategyto Increase Impact Resistance or Decrease Mass of Carbon Fiber
Composites,‖ ICAS2008 Conference Anchorage,Alaska, September 2008.
I. M. Ward and P. J. Hine, ―The Science and Technologyof Hot Compaction,‖ Polymer, Vol.
45, No. 5, 2004, pp.1413-1427.
G.Box, D.Behnken, ―Some new two level designs for the study of quantitative variables.‖,
Technometrics 2, pp.455-475.
W. Hunter, S. Hunter, ―Statistics for Experimenters: Design, innovation and discovery‖, John
Wiley and Sons, 2005.
M. P. Vlasblom and J. L. J. van Dingenen, ―The Manufacture,Properties and Applications of
High Strength, High Modulus Polyethylene Fibers,‖ In: A. R. Bunsell,Ed., Handbook of
Tensile Properties of Textile and TechnicalFibres, Woodhead Publishing Ltd., Cambridge,
2009. doi:10.1533/9781845696801.2.437
P. M. Cunniff, ―Dimensionless Parameters for Optimizationof Textile-Based Body Armor
Systems‖, Proceedingsof 18th International Symposium on Ballistics, SanAntonio,
November 1999.
M. J. N. Jacobs and J. L. J. van Dingenen, ―Ballistic ProtectionMechanisms in Personal
Armour,‖ Journal ofMaterials Science, Vol. 36, No. 13, 2001, pp. 3137-3142.
M. J. N. Jacobs and J. L. J. van Dingenen, ―Ballistic ProtectionMechanisms in Personal
Armour,‖ Journal ofMaterials Science, Vol. 36, No. 13, 2001, pp. 3137-3142.
H. van der Werff, U. Heisserer and S. L. Phoenix, ―Modellingof Ballistic Impact on Fiber
Composites,‖ PersonalArmour Systems Symposium 2010, Quebec City, September 2010.
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[14] H. van der Werff and A. J. Pennings, ―Tensile Deformationof High Strength and
High Modulus Fibers,‖ Colloid& Polymer Science, Vol.269, No. 8. pp.747-763
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M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
DOI: 10.7251/JEPMSR1406099B
UDK: 546.224:546.33
Naučni rad
UTVRĐIVANJE REGULIRAJUĆIH FAKTORA
SINTEZE NATRIJUMDITIONITA – Na2S2O4
Mustafa Burgić1, Amir Fazlić1, Jasminka Sadadinović1, Mirela Burgić-Salihović2
[email protected]
1
Univerzitet u Tuzli, Tehnološki fakultet, 75000 Tuzla, BiH
2
SISECAM Soda Lukavac, 75300 Lukavac, BiH
Izvod
Ditioniti natrijuma i cinka (Na2S2O4 i ZnS2O4), poznati pod imenom hidrosulfiti, efikasna su
redukciona sredstva koja imaju široku primjenu u raznim granama industrije [1]. Najvažnija
primjena natrijumditionita je u tekstilnoj industriji, te kao pomoćno sredstvo kod bojenja, štampanja
i bijeljenja. U farmaceutskoj industriji koristi se pri sintezi nekih lijekova, u prehrambeboj industriji
za bijeljenje sirupa voća, jestivog ulja te masti i želatina.
Polazne sirovine za dobijanje ditionita su cinkov prah, SO2 gas i Na2CO3. Ditioniti, Me2S2O4,
MeS2O4 su soli ditiosumporaste kiseline H2S2O4. koja nije izolovana u slobodnom stanju, zbog svoje
velike nestabilnosti.
Ključne riječi: natrijumditionit,sinteza, regulirajući faktori, cinkov prah, natrijumkarbonat.
UVOD
Natrijumditionit javlja se kao bezvodna so Na2S2O4, [1], molekulske teţine 174, i u obliku dihidrata
Na2S2O4∙2H2O, molekulske teţine 210. Zagrijavanjem dihidrata do 520C u alkoholu on prelazi u
bezvodni natrijumditionit. Sa povećanjem temperature rastorljivost im se povećava, [2]. Ako je u
vodi prisutan natrijumhlorid ili natrijumhidroksid, rastvorljivost se naglo smanjuje.
Natrijumditionit se karakteriše svojom nepostojanošću koja se povećava prisustvom vlage. Ovo
razlaganje u odsustvu vazduha moţe se prikazati slijedećom jednaĉinom:
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M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
2 Na2S2O4 + H2O →Na2S2O3 + 2 NaHSO3
(1)
Brzina razlaganja u odsustvu vazduha zavisi od koncentracije, tako da se 10 % rastvor razloţi za 10
dana, a 3 % rastvor za 37 dana. Prisustvom kiseonika iz vazduha razlaganje se ubrzava i teĉe prema
jednaĉini:
Na2S2O4 + H2O + O2 →NaHSO3 + NaHSO4
(2)
Zavisnost brzine razlaganja u prisustvu vlage i kiseonika iz vazduha od koncentracije rastvora,
obrnuta je od prethodnog sluĉaja, tako da se 3% rastvor Na2SO4 razloţi za 1 dan, a 20 % rastvor za 2
dana [3].
U baznoj sredini reakcija se odvija prema jednaĉini:
2 Na2S2O4 + 2 NaOH→ Na2S2O3 + 2 Na2SO3 + H2O
(3)
Dok u prisustvu viška alkalija ditionit reaguje sa tiosulfatom prema jednaĉini:
Na2S2O4 + Na2S2O3 + 4 NaOH → 3 Na2SO3 + Na2S + 2 H2O
(4)
Primjena natrijumditionita zasnovana je na njegovoj velikoj redukcionoj sposobnosti, što se moţe
vidjeti iz oksido-redukcionog potencijala:
HS2 O4  H 2 O  2H 2 SO3  H   2e  ; E0 = 0,23 V
(5)
S 2 O42  4 OH   2 SO32  2 H 2 O  2e  ;
(6)
E0 = 1,4 V
On reducira bakarne i ţivine soli do metala.
Osnove postupaka sinteze natrijumditionita
Najznaĉajnije metode sinteze natrijumditionita koje su našle industrijsku primjenu su slijedeće.
- redukcija SO2 sa cink prahom
- redukcija NaHSO3 sa cink prahom
- redukcija NaHSO3 sa ntrijumamalgamom
- redikcija NaHSO3 sa mravljom kiselinom
- elektrohemijski postupak redukcije NaHSO3
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M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
Redukcija SO2 sa cink prahom
U praksi je najzastupljenija metoda sinteze redukcija SO2 gasa sa cink prahom [3]. U prvoj fazi
sumporasta kiselina reaguje sa cink prahom i pri tome se obrazuje cinkditionit prema jednaĉini:
Zn + 2 H2SO3 →ZnS2O4 + 2 H2O
(7)
Cinkditionit je nestabilno jedinjenje i on se u drugoj fazi prevodi u natrijumditionit pomoću
natrijumhidroksida ili natrijumkarbonata prema reakcijama:
ZnS2O4 + 2 NaOH →Na2S2O4 + Zn(OH)2
(8)
ZnS2O4 + Na2CO3 → Na2S2O4 + ZnCO3
(9)
Dobijeni natrijumditionit je u obliku dihidrata koje je nestabilno jedinjenje, te se zagrijavanjem na
560C prevodi u bezvodnu so koja se u suhom stanju moţe ĉuvati duţe vrijeme.
Nakon odvajanja taloga Zn(OH)2 ili ZnCO3, rastvor natrijumditionit dihidrata se uparava u vakuumu
ili se isoljava pomoću NaCl. Kristali dihidrata nakon odvajanja od matiĉnog rastvora zagrijavaju se
na 560C i pri tome nastaje bezvodna so (reakcija 10), koja se suši u vakumu na temperaturi 80 –
900C u vremenu od 2 sata.
Na2S2O4∙2 H2O →Na2S2O4 + 2 H2O
(10)
Kao sporedni proizvod nastaje ZnCO3 ili Zn(OH)2 koji se daljom obradom mogu prevesti u ZnO,
veoma traţen proizvod u industriji gume i emajla [4].
EKSPERIMENTALNI DIO
Laboratorijska sinteza natrijumditionita preko cinkditionita
Opis postupka sinteze
Sinteza natrijumditionita po izabranoj metodi redukcijom sumporaste kiseline sa cink prahom,
eksperimentalno je raĊena u cilju utvrĊivanje regulirajućih parametara procesa.
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Protok SO2 gasa praćen je pomoću mjernog ureĊaja. U staklenom reaktoru odvijaju se slijedeće
reakcije [5]:
SO2 + H2O→H2SO3
(11)
Zn + 2 H2SO3→ZnS2O4 + 2 H2O
(12)
Sinteza je provedena na temperaturi izmeĊu 35 i 450C, jer na višim temperaturama dolazi do
razlaganja cinkditionita. Potrebno je voditi raĉuna o doziranoj koliĉini SO2 gasa, jer stvaranje viška
slobodne sumporaste kiseline dovodi do razlaganja cinkditionita, koji je nestabilan u kiseloj sredini.
Kraj reakcije odreĊen je jedino praćenjem prelaza boje suspenzije iz tamno sive u svijetlo sivu boju.
Ako boja rastvora postane narandţasta, to je znak da smo uveli višak SO2 gasa, pa je potrebno
dodati cink-prah i nastaviti sa miješanjem u svrhu spreĉavanja razlaganja cinkditionita. Da bi rastvor
cinkditionita bio stabilan duţe vrijeme, dodaje se rastvor natrijumhidroksida do vrijednosti pH = 8, a
sadrţaj cinkditionita treba da bude 400 – 440 gr/l. Po završetku ove faze, cinkditionit se filtrira a
dobijeni rastvor cinkditionita se preraĊuje u slijedećoj operaciji dvogube izmjene [4].
Određivanje uticaja temperature na brzinu reakcije sinteze cinkditionita:
Pri sintezi cinkditionita koja se odvija prema reakciji[5], [6], [7]:
Zn + 2 H2SO3 = ZnS2O4 → ZnS2O4 + 2 H2O + 577,668 kJ/mol (13)
osloboĊena koliĉina topline od 577,688 kJ/mol odvodi se hlaĊenjem sa vodom. Temperatura na
kojoj se vodi reakcija je izmeĊu 35 i 450C. Da bi se definisao uticaj temperature na brzinu reakcije,
eksperimenti su raĊeni sa standardnim kvalitetom cink praha (tabela 1).
Tabela 1. Kvalitet cink praha
Red.
br.
1
2
3
4
Sadrţaj
%
Sadrţaj
%
Sadrţaj ukupnog cinka
Sadrţaj aktivnog cinka
Sadrţaj ZnO
Sadrţaj ZnO
99,36%
97,98
1,72
0,01
ĉestice veće od 90 µ
ĉestice izmeĊu 63 i 90µ
ĉestice manje od 63µ
3,2
12,2
84,6
Eksperimenti su raĊeni na slijedećim temperaturama: 35; 37,5; 40; i 450C. Za svaku temperaturu
raĊena su dva eksperimenta, a po završetku reakcije rastvor je analiziran na sadrţaj ZnS 2O4 i Zn u
g/l, te je mjerena specifiĉna gustina. Prilikom rada, trajno je odrţavana temperatura sa odstupanjem
od max ± 0,50C.
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Laboratorijska sinteza cinkditionita raĊena je sa sadrţajem cink-praha u suspenziji 20 –25 %. Odnos
cink-praha i vode 1:4 a baza je bila 150 g aktivnog cinka.
Prema analizi cink-praha koji je korišten za oglede izraĉunata je porebna koliĉina, jer se iz rezultata
analize moţe vidjeti da je sadrţaj aktivnog cink-praha razliĉit u zavisnosti od kvaliteta što se mora
imati u vidu.
Odgovarajući inputi pri izvoĊenju eksperimenta prezentirani su u tabeli 2.
Tabela 2. Količina uzoraka korištenih pri izvođenju eksperimenta
Ulaz
Sirovina
Izlaz
grama
mola
grama
mola
Cink prah
150,0
2,294
0,0
0,00
SO2 gas
293,6
4,588
0,0
0,00
Voda
600,0
33,350
600,0
33,350
ZnS2O4
0,0
0,000
443,6
2,294
Za svaki eksperiment uzeto je 150 grama aktivnog cink-praha i 600 grama vode. SO2 gas doziran je
postepeno do kraja reakcije koja se odreĊuje promjenom boje suspenzije.
Protok vode za hlaĊenje i broj okretaja mješalice bili su konstantni za sve eksperimente.
REZULTATI I DISKUSIJA
Dobijeni rezultati mjerenja i analize pokazani su u tabeli 3.
Tabela 3. Rezultati sinteze cinkditionita u funkciji temperature
Broj
Ogled
Temp.
susp.
0
C
Vrijeme
uvoĊenja
SO2,min
1
O–1
35,0
95
2
O–2
35,0
98
3
O–3
37,5
78
4
O–4
37,5
78
5
O–5
40,0
65
6
O–6
40,0
65
7
O–7
42,5
58
8
O–8
42,5
56
9
O–9
45,0
52
10
O – 10
45,0
54
Srednje
vrijeme
min
96,5
78
65,0
57,0
53,0
g/l
ZnS2O4
g/l
Zn
Sesifiĉna
gustina
638,9
222,6
1,474
638,5
215,7
1,469
634,1
214,2
1,462
638,5
215,7
1,467
640,0
216,2
1,462
636,7
215,1
1,449
638,2
215,6
1,453
644,4
217,7
1,459
-
-
1,458
658,0
222,6
1,462
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Dobijeni rezultati mogu se i grafiĉki prikazati gdje je na apscisi dato vrijeme, a na ordinati
temperatura na kojoj se provodi reakcija, slika 1.
Slika 1 Uticaj temperature na vrijeme reakcije
Iz rezultata ispitivanja moţe se vidjeti da je potrebno vrijeme za reakciju na 35 0C prosjeĉno 96,5
minuta, a na 450C to prosjeĉno vrijeme iznosi 53 minuta.
TakoĊe, moţe se vidjeti da je na 400C prosjeĉno vrijeme 65 minuta, znaĉi za 31,5 minuta kraće
vrijeme nego na 350C, a 12 minuta duţe vrijeme nego na temperaturi od 450C.
Pošto se na temperaturi većoj od 450C nastali cinkditionit brţe razlaţe (izvjesna koliĉina razlaţe se
već u toku reakcije nastajanja cinkditionita), to je za proces proizvodnje najpovoljnija temperatura
od 400C jer je, kako se vidi, na taj naĉin smanjeno vrijeme u odnosu na radnu temperaturu od 350C
skoro za trećinu u odnosu na potrebno rijeme kada je radna temperatura 350C.
U narednim ispitivanjima za utvrĊivanje drugih faktora raĊeno je samo pri temperaturi od 400C sa
maksimalnim odstupanjem od ± 0,50C.
Utvrđivanje uticaja kvaliteta cink praha na brzinu reakcije
U eksperimentu je korišeten cink prah slijedećeg kvaliteta (analiza je data u tabeli 4). Rrazlika je u
sadrţaju cinka i veliĉini ĉestica
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Eksperimentom je utvrĊena radna temperatura od 400C, uz konstantni broj okretaja mješalice i
konstantan protok vode za hlaĊenje reakcione mase. UraĊena su za svaku vrstu kvaliteta cink-praha
po 2 eksperimenta i pri tome je odreĊivan sadrţaj ZnS2O4 u g/l, Zn u g/l i mjerena specifiĉna
gustina.
Tabela 4. Analiza korištenja cink-praha za sintezu cinkditionita
Kvalitet
cink-praha
Ukupan
Zn
Aktivni
Zn
ZnO
H2O
Veliĉina
> 90μ
Veliĉina
63-90μ
Veliĉina
< 63µ
Standardni
99,36
97,98
1,72
0,01
3,2
12,2
84,6
Superfini
99,24
96,82
3,01
0,01
0,7
1,4
97,9
Ultrafini
99,36
96,49
3,57
0,02
1,9
0,4
97,7
Tabela 5. Uticaj kvaliteta cink-praha na brzinu reakcije
Vrijeme
Kvalitet
uvoĊenja
Br.
cink-praha SO2 gasa.
min
1
Standardni
65
2
Standardni
65
3
Superfini
68
4
Superfini
70
5
Ultrafini
76
6
Ultrafini
74
Prosjeĉno
vrijeme,
min
65
69
75
g/l
ZnS2O4
g/l
Zn
Specifiĉna
gustina
632,6
213,94
1,470
625,2
211,44
1,470
637,0
215,44
1,471
642,9
217,43
1,461
642,9
217,43
1,497
675,0
228,40
1,437
Temperatura je regulisana preko protoka SO2 gasa, jer je protok vode za hlaĊenje bio konstantan uz
konstantan broj okretaja mješalice. Rezultati su prikazani u tabeli 5.Na osnovu rezultata ispitivanja
prikazanih u tabeli 5. moţe se zakljuĉiti da se vrijeme uvoĊenja SO2 gasa povećava, idući od
standardnog kvaliteta cink-praha prema ultra finom kvalitetu. Pošto je temperatura reakcione mase
koja je regulisana protokom SO2 gasa bila konstantna 40 ± 0,50C, uz osiguranje konstantnog protoka
vode za hlaĊenje i broja okretaja mješalice, vidi se da je vrijeme reakcije povećano iako se veliĉina
ĉestica smanjuje sa kvalitetom cink-praha. Prema tome, imamo povećanje brzine reakcije. Sa ovim
povećanjem brzine reakcije, osloboĊena koliĉina toplote u jedinici vremena je veća. Kako je
naglašeno, protok vode za hlaĊenje bio je konstantan, pa prema tome jedini naĉin da se odrţi
utvrĊena temperatura je smanjenje protoka SO2 gasa. To je razlog zbog ĉrga je sa povećanjem
ĉestica od standardnog kvaliteta prema ultrafinom kvalitetu cink-praha, povećano vrijeme reakcije.
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M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
ZAKLJUČAK
Na osnovu provedenih istraţivanja sinteze natrijumditionita u funkcije temperature i kvaliteta cinkpraha utvrĊeni su optimalni uslovi. Radna temperatura je 400C, kvalitet cink praha standardan,
ukupno vrijeme reakcije 65 minuta, uz konstantan broj okretaja mješalice i konstantan protok vode
za hlaĊenje reakcione smjese.
Kako je rastvor cinkditionita nestabilan, sinteza natrijumditionita ja raĊena do kraja da se dobije
gotov proizvod koji je stabilan.
Ispitivanja prevoĊenja cink-ditionita u natrijumditionit bila su predmet naknadnog istraţivanja.
LITERATURA
[1]
[2]
Ulmans, Encyklopädie der Technischen Chemie, Bd. 15, 1964, pp. 480-487.
G.Bruuner:Topics in Physical Chemistry, Gas Extraction, Dr. Ditrich Steinkopff Verlag,
Darmstad, 1994.
[3]
M.B. Pozin, Tehnologija mineralnih solej, pp.364-368, Goschizdat 1961.
Anorganischen Chemie, 1998. god.
H.J. Emelëus unleme der d J.S. Anderson Ergebnisse und Probleme der modernen
Anorganischen Chemie, 1998. god.
Karl Heinz Buchel, Hans- Heinrich Morreto, Peter Woditsch, Industrielle Anorganische
Chemie, Weinheim; New York; Chichester ; Brisbane; Sigapore; Toronto VCH, 1999.
Peter Hellmold, Merseburg, Technische Anorganische Chemie, Deutscher Verlag für
Grundstoffindustrie Gmbh. Leipzig, 1990.
H. Z. Kister, Distilation - Operation, McGraw-Hill, New York, 2000.
[4]
[5]
[6]
[7]
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M. Burgić, A. Fazlić, J. Sadadinović, M. Burgić-Salihović
DOI: 10.7251/JEPMSR1406099B
UDK: 546.224:546.33
Scientific paper
DEFINING REGULATING PARAMETERS
OF SODIUM DITHIONYTE Na2S2O4
Mustafa Burgić1, Amir Fazlić1, Jasminka Sadadinović1, Mirela Burgić-Salihović2
[email protected]
1
University of Tuzla, Faculty of Technology, 75000 Tuzla, B&H
2
SISECAM Soda Lukavac, 75300 Lukavac, B&H
Abstract
Dithionites of sodium and zinc (Na2S2O4 and ZnS2O4), also known asn hydrosulphites, are efficient
reducing materials widely used in various industries.Mosto common application of Na2S2O4 is in
textile industry and also as important ingredient in painting, printing and bleaching materials. In
pharmacy it is widely used for drugs synthesis, in foof industry for fruit syrups bleaching, edible oil
and gelatyne. During the experiment we tested parameters of Na2S2O4 dithionites synthesis by
reducing sulphuric acis with zinc powder. Results of experiment clearly indicate that most
appropriate temperature for synthesis is around 400C, reaction time 65 minutes at constant mixer
speed and continuous cooling.
Keywords: dithioonites of sodium zinc, reducing materials, sulphuric acid, zinc powder, synthesis,
temperature regime.
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DOI: 10.7251/JEPMSR1406109B
UDK: 628.3.03:628.336
Naučni rad
ISTRAŽIVANJE KARAKTERISTIKA PROCESA NEUTRALIZACIJE
KISELIH OTPADNIH VODA VAPNENIM MULJEM
Sabina Begić1, Vladan Mićić2, Zoran Petrović2, Selma Tuzlak1
[email protected]
1
2
Univerzitet u Tuzli, Tehnološki fakultet, 75000 Tuzla, BiH
Univerzitet u Istočnom Sarajevu, Tehnološki fakultet, 75400 Zvornik, Republika Srpska, BiH
Izvod
Vapneni mulj koji nastaje u industrijskim procesima mekšanja vode predstavlja značajno
okolinsko i ekonomsko opterećenje, obzirom na sve strožije domaće i međunarodne propise koji se
odnose na upravljanje otpadnim tokovima. Visok sadržaj kalcijum karbonata u navedenom
materijalu otvara mogućnost njegove primjene u procesima neutralizacije kiselih otpadnih voda. U
ovom radu vršeno je istraživanje karakteristika procesa neutralizacije kiselosti vode u uslovima
različitih početnih pH vrijednosti i režima strujanja, primjenom vapnenih muljeva koji su generisani
tretmanom slanih i slatkih voda. Rezultati istraživanja pokazali su da početna pH vrijednost vode, i
prisustvo NaCl imaju značajan uticaj na topivost kalcijum karbonata u procesu neutralizacije, dok
je ispitivani režim strujanja ( brzina mešanja magnetne mešalice) imao neznatan uticaj.
Ključne riječi: vapneni mulj, neutralizacija kisele vode, kalcijum karbonat.
1. UVOD
Sniţavanje tvrdoće vode predstavlja jedan od glavnih uslova kvalitetne pripreme vode, kako
bi se ovaj visokovrijedni resurs mogao koristiti kao sirovina ili pomoćno sredstvo u razliĉitim
industrijskim procesima i proizvodima. Naširoko primijenjen industrijski postupak sniţavanja
tvrdoće sastoji se u dodavanju odgovarajućih hemikalija, kao što su kalcijum hidroksid ili natrijum
karbonat [1], koje reaguju sa rastvorenim solima u vodi i taloţe ih na dno ureĊaja u kojima se vrši
tretman pomenute sirovine. Nastali taloţni sloj periodiĉno se ispušta sa dna ureĊaja u vidu vapnenog
mulja i predstavlja otpadni industrijski tok.
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Koliĉina otpadnog mulja koja nastaje mekšanjem vode ovisi, kako o sadrţaju rastvorenih soli
koje je potrebno ukloniti iz sirove vode raspoloţivog izvorišta, tako i o proizvodnom kapacitetu
posmatranog postrojenja, odnosno zahtijevanim koliĉinama omekšane vode za primjenu u datoj
industriji.
Obzirom da ĉvrsta faza otpadnog efluenta ima visok sadrţaj kalcijum karbonata i pH
vrijednost iznad 9, odlaganje vapnenog mulja predstavlja posebnu problematiku jer bi direktno
ispuštanje pomenutog materijala u prirodni vodotok narušilo ekološku ravnoteţu recipijenta.
Rezultati objavljenih istraţivanja i studija izvodljivosti upućuju na mogućnost korišćenja
obezvodnjenog vapnenog mulja u neutralizaciji kiselih otpadnih voda [2, 3], obzirom na visok
sadrţaj kalcijum karbonata [4] kao osnovnog neutralizacionog reaktiva. Radovi u kojima su
istraţivani faktori topivosti kalcijum karbonata navode da je brzina njegove rastvorljivosti u velikoj
zavisnosti od pH vrednosti sredine u kojoj se vrši rastvaranje [5, 6], te da se ista povećava u
prisustvu NaCl. Uzimajući u obzir varijabilnost sastava i porekla vapnenih muljeva, nuţno je ispitati
eventualne razlike u njihovoj reaktivnosti kao neutralizacionih agenasa u procesima neutralizacije
kiselih voda i utvrditi uticaj hidrodinamike na efikasnost procesa.
U ovom radu, vršeno je istraţivanje uticaja razliĉitih poĉetnih pH vrednosti kisele vode i
hidrodinamike na efikasnost procesa neutralizacije primenom razliĉitih vapnenih muljeva,
generisanih mekšanjem slanih i slatkih voda.
2. EKSPERIMENTALNI DIO
Za eksperimentalno istraţivanje u ovom radu korišćeni su vapneni muljevi, uzorkovani na
izlaznim tokovima procesa tretmana vode u ĉetiri razliĉita industrijska objekta:
1.Solana d.d., Tuzla (mulj nastao tretmanom podzemne slane vode izvorišta Tetima);
2.Sisecam Soda d.o.o., Lukavac (muljevi generisani tretmanom podzemne slane vode izvorišta
Tetima i površinske vode jezera Modrac);
3.Koksno hemijski kombinat, d.d., Lukavac (mulj generisan tretmanom površinske vode jezera
Modrac);
4.Rudnik i termoelektrana Ugljevik (mulj nastao tretmanom površinske vode rijeke Janja).
Uzorci vapnenih muljeva su obezvodnjeni na Bihnerovom levku, a zatim sušeni u sušnici na
105 ºC do sadrţaja vlage 1-1,5 %. Osušeni talozi su usitnjeni i prosijani na vibracionim sitima, da
se dobiju uzorci veliĉina ĉestica od 0,1-0,5 mm. Pripremljeni uzorci su volumetrijskom metodom
analizirani na sadrţaj kalcijum karbonata i magnezijum hidroksida, metodom po Mohru na sadrţaj
NaCl, a pH vrijednost je odreĊena otapanjem 10 gr uzorka u 50 ml destilovane vode.
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Mešanjem hlorovodoniĉne kiseline i destilovane vode pripremljeni su uzorci kisele vode
poĉetnih pH vrednosti 2 i 4.
Eksperimentalno istraţivanje uslova neutralizacije vršeno je šarţnom metodom rada.
Efikasnost neutralizacije kisele vode vapnenim talozima u zavisnosti od razliĉitih poĉetnih vrednosti
pH sredine ispitivana je dodavanjem razliĉitih koliĉina uzoraka taloga u otvorene staklene ĉaše sa po
200 ml vodenog rastvora hlorovodoniĉne kiseline odreĊenih pH vrednosti (2; 4), uz mešanje
rastvora magnetnom mešalicom brzinom od 100, 200 i 300 o/min u trajanju od jedne minute.
Oĉitavanje promena pH vrednosti vodenih rastvora vršeno je korišćenjem pH metra (OAKTON
pH/CON 510 series).
U cilju ispitivanja uticaja reţima strujanja na promenu kiselosti vode pri dodavanju
odreĊenih koliĉina vapnenog mulja izvršeno je odreĊivanje Rejnoldsovog broja. Rejnoldsov broj je
odreĊen prema izrazu:
Re 
ns  d m2  
(1)

gde je:
ns – brzina mešanja, min-1
dm – preĉnik mešala, m
ρ – gustina, kg/m3
μ – dinamiĉka viskoznost, Ns/m2
3. REZULTATI I DISKUSIJA
Rezultati analiza obezvodnjenih i osušenih uzoraka vapnenih muljeva prikazani su u tabeli 1.
Tabela 1. Osnovne karakteristike obezvodnjenih i osušenih uzoraka vapnenog mulja
Naziv
uzorka
Solana
Soda slana
Soda slatka
Koksara
Ugljevik
Objekat uzorkovanja
CaCO3 %
NaCl %
pH
71,25
72,5
86,25
80
Mg(OH)2
%
6
2,92
5,11
4,37
Solana, Tuzla
Sisecam Soda, Lukavac
Sisecam Soda,Lukavac
Koksno-hemijski
kombinat, Lukavac
Rudnik i termoelektrana
Ugljevik
19,1
9,28
0,3
0,28
10,02
10,24
9,53
9,04
81,25
5,83
0,34
9,31
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Rezultati analiza obezvodnjenih i osušenih uzoraka vapnenih muljeva (tabela 1) pokazuju
variranje sadrţaja CaCO3, od 71,25% za uzorak Solana, do 86,25% u uzorku Soda slatka, te se
uoĉava da muljevi dobiveni mekšanjem slane vode (Solana i Soda slana) imaju znatno viši sadrţaj
NaCl u poreĊenju sa onima koji nastaju tretmanom slatkih voda. Svi analizirani uzorci otapanjem u
destilovanoj vodi daju pH vrednost iznad 9 (9,04 – 10,24).
Ispitivanje promene kiselosti vode poĉetne vrednosti pH = 2 nakon njene neutralizacije
vapnenim talozima u zavisnosti od vrednosti Rejnoldsovog broja nakon vremena mešanja od 1
minut, vršeno je na temperaturi 23°C. Rezultati su prikazani na slikama: 1, 2, 3, 4 i 5.
Slika 1. Uticaj promene pH vrednosti uzoraka od mase taloga Solana
pri različitim režimima strujanja (Re)
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Slika 2. Uticaj promene pH vrednosti uzoraka od mase taloga Soda slana
pri različitim režimima strujanja (Re)
Slika 3. Uticaj promene pH vrednosti uzoraka od mase taloga Soda slatka
pri različitim režimima strujanja (Re)
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Slika 4. Uticaj promene pH vrednosti uzoraka od mase taloga Koksara
pri različitim režimima strujanja (Re)
Slika 5. Uticaj promene pH vrednosti uzoraka od mase taloga Ugljevik
pri različitim režimima strujanja (Re)
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U procesima neutralizacije kisele vode poĉetnih pH vrednosti 2 svi vapneni talozi (slani i
slatkovodni) pokazuju pad efikasnosti neutralizacije nakon postizanja pH vrednosti sredine 5,5.
Rezultati fitovanja kiselosti vode izraţene preko pH vrednosti tokom dodavanja vapnenih
taloga pri datim uslovima dati su u tabeli 2.
Tabela 2. Jednačine za izračunavanje pH vrednosti kisele vode u zavisnosti od mase dodatog vapnenog
taloga za date vrednosti Rejnoldsa
Re
2,15∙105
4,3∙105
6,46∙105
2,15∙105
4,3∙105
6,46∙105
2,15∙105
4,3∙105
6,46∙105
2,15∙105
4,3∙105
6,46∙105
2,15∙105
4,3∙105
6,46∙105
Zavisnost pH od mase dodatog vapnenog taloga
Talog Solana
3
2
pH = 0,036m -0,604m +2,947m+1,753
pH = 0,039m3-0,646m2+3,053m+1,872
pH = 0,045m3-0,709m2+3,215m+1,926
Talog Soda slana
3
pH = 0,036m -0,620m2+2,966m+1,716
pH = 0,041m3-0,682m2+3,177m+1,807
pH = 0,042m3-0,69m2+3,173m+1,927
Talog Soda slatka
pH = 0,022m3-0,411m2+2,346m+1,81
pH = 0,022m3-0,415m2+2,379m+1,935
pH = 0,025m3-0,471m2+2,587m+1,930
Talog Koksara
3
2
pH = 0,020m -0,383m +2,226m+1,814
pH = 0,022m3-0,414m2+2,346m+1,929
pH = 0,022m3-0,420m2+2,387m+1,982
Ugljevik
3
2
pH = 0,020m -0,380m +2,231m+1,789
pH = 0,020m3-0,385m2+2,243m+1,914
pH = 0,022m3-0,416m2+2,367m+1,938
Koeficijent korelacije, r
0,979
0,982
0,987
0,974
0,977
0,982
0,974
0,977
0,965
0,972
0,975
0,980
0,978
0,977
0,971
Na osnovu vrednosti koeficijenata korelacije prikazanih tabelom 2., a koji su iznosili od
0,965 – 0,987 zakljuĉeno je da su postignute jako dobre korelacije izmeĊu ispitivanih veliĉina
(kiselosti vode i mase dodatog vapnenog taloga). Najbolja korelacija postignuta je primenom
vapnenog taloga Solana a najslabija primenom vapnenog taloga Soda slatka.
Rezultati istraţivanja neutralizacije kisele vode poĉetne vrednosti pH=4 pri istim uslovima
strujanja i primenom istih vapnenih taloga su prikazani na slikama: 6, 7, 8, 9, 10 i u tabeli 3.
Kao i u sluĉaju neutralizacije uzoraka kisele vode poĉetne pH vrednosti 2, svi vapneni talozi
(slani i slatkovodni) pokazuju pad efikasnosti neutralizacije uzoraka kisele vode poĉetne pH
vrednosti 4, nakon postizanja pH sredine 5,5.
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Slika 6. Uticaj promene pH vrednosti uzoraka od mase taloga Solana
pri različitim režimima strujanja (Re)
Slika 7. Uticaj promene pH vrednosti uzoraka od mase taloga Soda slana
pri različitim režimima strujanja (Re)
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Slika 8. Uticaj promene pH vrednosti uzoraka od mase taloga Soda slatka
pri različitim režimima strujanja (Re)
Slika 9. Uticaj promene pH vrednosti uzoraka od mase taloga Koksara
pri različitim režimima strujanja (Re)
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Slika 10. Uticaj promene pH vrednosti uzoraka od mase taloga Ugljevik
pri različitim režimima strujanja (Re)
Rezultati fitovanja kiselosti vode ĉija je poĉetna kiselost bila pH=4 tokom dodavanja vapnenih
taloga pri datim uslovima dati su u tabeli 3.
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Tabela 3. Jednačine za izračunavanje pH vrednosti kisele vode u zavisnosti od mase dodatog vapnenog
taloga za date vrednosti Rejnoldsa
Re
Zavisnost pH od mase dodatog vapnenog taloga
Koeficijent korelacije, r
Talog solana
2,15∙105
pH = 1349m3-483,3m2+53,18m+4,315
0,974
5
3
2
4,3∙10
pH = 1927m -650,8m +64,77m+4,347
0,974
5
3
2
6,46∙10
pH = 2048m -666,1m +60,24m+4,580
0,896
Talog soda slana
2,15∙105
pH = 1910m3-625,1m2+59,34m+4,157
0,985
5
3
2
4,3∙10
pH = 2036m -656,6m +60,89m+4,270
0,975
6,46∙105
pH = 2366m3-745,6m2+66,11m+4,376
0,960
Talog soda slatka
5
3
2
2,15∙10
pH = 2165m -750,2m +79,29m+4,389
0,979
5
3
2
4,3∙10
pH = 13213m -2275m +129m+4,244
0,985
6,46∙105
pH = 11025m3-9418m2+249,4m+4,095
0,990
Talog Koksara
5
3
2
2,15∙10
pH = 2679m -895,4m +84,02m+4,144
0,989
4,3∙105
pH = 2708m3-904,2m2+85,29m+4,248
0,983
5
3
2
6,46∙10
pH = 3109m -1007m +91,16m+4,311
0,980
Ugljevik
5
3
2
2,15∙10
pH = 2016m -684,8m +66,74m+4,250
0,981
4,3∙105
pH = 1923m3-669,7m2+69,23m+4,247
0,986
5
3
2
6,46∙10
pH = 2348m -778m +76,36m+4,278
0,984
Na osnovu vrednosti koeficijenta korelacije prikazanih tabelom 3., a koje su iznosile od
0,960 – 0,989 uoĉeno je da su takoĊe postignute jako dobre korelacije izmeĊu ispitivanih veliĉina
(kiselosti vode i koliĉine dodatog vapnenog taloga). Jedino u sluĉaju neutralizacije kisele vode
vapnenim talogom Solana, pri brzini obrtaja magnetne mešalice n= 300 obrt/min (Re=6,46∙105)
dobijena je nezadovoljavajuća vrednost koeficijenta korelacije (r=0,896). Najbolja korelacija
postignuta je primenom vapnenog taloga Koksara a najslabija primenom vapnenog taloga Soda
slana.
Dobijeni rezultati su ukazali na neznatan uticaj reţima strujanja na promenu kiselosti vode
tokom njene neutralizacije sa ispitivanim uzorcima vapnenih taloga, bez obzira na poĉetnu kiselost
vode.
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4. ZAKLJUČAK
Na osnovu provedenih eksperimentalnih istraţivanja i dostupnih teoretskih saznanja moţe se
zakljuĉiti da je otpadni vapneni mulj, koji nastaje mekšanjem vode u industriji, moguće koristiti u
postupcima obrade kiselih otpadnih voda, sa aspekta njegove efikasnosti u neutralizaciji pH
vrednosti. Radi lakše manipulacije i doziranja vapnenog mulja kao alternativnog neutralizacionog
sredstva, isti je potrebno prethodno obezvodniti i osušiti.
Efikasnost neutralizacije vode slatkovodnim talozima direktno je ovisna o udelu CaCO3 u njima, na
naĉin da veći udio povećava efikasnost taloga. PoreĊenjem efikasnosti slanih i slatkovodnih
vapnenih taloga moţe se zakljuĉiti da sadrţaj NaCl u talozima povoljno utiĉe na brzinu
rastvorljivosti kalcijum karbonata taloga u vodi i time uvećava njihovu efikasnost u procesu
neutralizacije.
Rezultati neutralizacije kisele vode poĉetnih pH vrijednosti 2 i 4 prilikom doziranja svakog
pojedinog uzorka vapnenog mulja pokazuju pad efikasnosti neutralizacije nakon postizanja pH
vrednosti sredine 5,5. Navedeno ukazuje na mogućnost relativno dobre kontrole procesa, što znaĉi
da bi u sluĉaju „predoziranja― vode vapnenim talogom rizik za nagle promene pH vrijednosti vode i
prekoraĉenje dozvoljenih vrednosti bio sveden na minimum. Radi obezbeĊenja efikasnosti reakcije
kalcijum karbonata iz vapnenih taloga sa kiselinama otpadne vode, pri ĉemu dolazi do njihove
neutralizacije, potrebno je obezbediti adekvatno mešanje ĉvrstog materijala sa tekućom fazom.
Brzina mešanja sistema vapneni talog – kisela voda nema znaĉajniji uticaj na efikasnost procesa
neutralizacije kiselih voda. U svim sluĉajevima radilo se o turbulentnom reţimu strujanja sa jako
visokim vrednostima Rejnoldsovog broja koje su se kretale od 2,15∙105 do 6,46∙105. U procesima
neutralizacije kiselih voda poĉetnih vrednosti pH=2 i pH =4 sa vapnenim muljevima dobijene su
visoke korelacije izmeĊu kiselosti vode i koliĉine dodatog vapnenog mulja (0,960 – 0,989).
Neznatno bolja korelacija je dobijena kod manje kisele poĉetne vode.
LITERATURA
[1]
[2]
M. Che, T. J. Logan, S. J. Traina, J. M. Bigham, Properties of water treatment lime sludges
and their effectiveness as agricultural limestone substitutes, J. Water Poll. Control,
60(1988), pp.674-680.
J. H. Van Leeuwen, D. J. White, R. J. Baker, C. Jones, Reuse of water treatment residuals
from lime softening, Part I: Applications for the reuse of lime sludge from water softening,
Land Contamination & Reclamation, 18(2010) pp.393-415.
Journal of Engineering & Processing Management|
120
Volume 6, No. 1, 2014
_____________________________________________________________________________________
[3]
[4]
[5]
[6]
H. Van Leeuwen, D. J. White, R. J. Baker, Reuse of Lime Sludge from Water Softening and
coal combustion byproducts, Department of Civil, Construction and Environmental
Engineering, Iowa State University, 2004, pp.12-13.
S. D. Lin, C. D. Green, Wastes from water treatment plants: literature rewiew, results of an
Illinois survey and effects of alum sludge application to cropland, Illinois Department of
Energy and Natural Resources, 1987, pp.8-9.
K. Dewi, J. Draxsler, Limestone dissolution in FGD scrubbers, 13th World Clean Air and
Environmental Protection Congres, London, 2004, pp.3-4
B. Coto, C. Martosa, J. L. Pena, R. Rodriguez, G. Pastora, Effects in the solubility of CaCO3:
Experimental study and model description, Fluid Phase Equilibria 324(2012), pp.1–7.
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Volume 6, No. 1, 2014
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S. Begić, V. Mićić, Z. Petrović, S. Tuzlak
DOI: 10.7251/JEPMSR1406109B
UDK: 628.3.03:628.336
Scientific paper
RESEARCH OF CHARACTERISTICS OF PROCESS NEUTRALIZATION
OF ACID WASTEWATER BY LIME SLUDGE
Sabina Begić1, Vladan Mićić2, Zoran Petrović2, Selma Tuzlak1
[email protected]
1
2
University of Tuzla, Faculty of Technology, 75000 Tuzla, B&H
University of East Sarajevo, Faculty of Technology, 75400 Zvornik, Republic of Srpska, B&H
Abstract
Lime sludge which is generated in the industrial processes of water softening is a significant
environmental and economic burden, due to increasingly stringent of national and international
regulations relating to the management of waste streams. The high content of calcium carbonate in
this material opens the possibility of its application in the processes of acidic waste water
neutralization. In this paper, a research of characteristics of the process of neutralizing the acidity
of water in terms of different initial pH value and flow regime, applying lime sludges which are
generated in treatment of salt and fresh water, was conducted. Results of research showed that the
initial pH value of water and the presence of NaCl have a significant effect on the solubility of
calcium carbonate in the process of neutralization, while the examined flow regime (mixing speed of
magnetic stirrer) had a negligible impact.
Key words: lime sludge, acid water neutralization, calcium carbonate.
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Volume 6, No. 1, 2014
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UPUTSTVO ZA AUTORE RADOVA
1. Rukopise radova (puna imena i prezimena svih autora, puna adresa autora za korespondenciju),
napisane u Wordu, poslati iskljuĉivo putem elektronske pošte, na adresu: [email protected]
2. Ĉasopis objavljuje sljedeće kategorizovane radove:
a) nauĉni radovi (Scientific papers),
b) saopštenja (Short and Preliminary communications),
c) pregledi (Reviews),
d) struĉni radovi (Professional papers),
e) izlaganja sa nauĉnih skupova, samo ako nisu štampana u zbornicima radova (Conference
papers).
3. Maksimalan obim rada je do 12 strana (a, d, e), do 6 strana (b) i do 30 strana (c) A4 formata,
ukljuĉujući tekst, priloge i ilustracije (slike, fotografije i tabele) i to:
- Font
12 pt Times New Roman
- Margine
gornja i donja 2.0 cm, leva 3.0 cm i desna 1.5 cm
- Naslov (na srpskom)
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4. Kroz uvod, eksperimentalni dio, rezultate i diskusiju i zaključke treba da budu korišćeni
standardni sistemi jedinica i opšte prihvaćeni pojmovi u tehniĉkoj struci. Izbjegavati matematiĉka
izvoĊenja. Neophodna matematiĉka izvoĊenja se, po potrebi, mogu dati kao cjeline u vidu jednog ili
više priloga. Pozive na jednaĉine navesti i malim zagradama, pozive na literaturu obiljeţavati u
uglastim zagradama, a citira se na uobiĉajeni naĉin prema redoslijedu korišćenja.
5. Reference radova moraju da citiraju naziv ĉlanka i njegove poĉetne i krajnje stranice, primjer:
[1] P. P. Sangiovanni, A. S. Bergen, Chem. Eng. Sci., 26(1971) pp.533-547.
Navodi iz knjiga trebaju da citiraju autore, naziv knjige, izdavaĉa, godinu izdanja i
stranice,
primjer:
[2] A.B. Smith, Textbook of Organic Chemistry, D. C. Jones, New York, 1961, pp.123-126.
6. Pri tekstualnoj obradi rukopisa koristiti stranice bez paginacije, prored multiple 1,3. Koristiti
iskljuĉivo obraĊene crno-bijele ilustracije. Tekst i oznake na ilustracijama treba da budu ĉitljivi. Slike
i dijagrami moraju biti kvalitetno obraĊeni sa kvalitetnim papirnim otiskom.
Journal of Engineering & Processing Management|
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Volume 6, No. 1, 2014
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INSTRUCTIONS FOR AUTHORS
1.
Word processing manuscripts should be submitted in Serbian, English or official languages of the
people of former Yugoslavia and sent only by e-mail to: [email protected]
2.
There should be next categorized papers:
a) Scientific papers,
b) Short and Preliminary communications,
c) Reviews,
d) Professional papers,
e) Conference papers (if conference proceedings are not printed)
3.
The maximum length of the paper is up to 12 pages (a, d, e), up to 6 pages (b), up to 30 pages (c), A4
page size, including text, figures and tables.
- Font
12 pt Times New Roman
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top and bottom 2.0 cm, left 3.0 cm and right 1.5cm
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4. The SI system nomenclature and commonly used expressions in techniques should be used in the
introduction, experimental part, results and discussion and conclusions. Detailed mathematical
expressions should be avoided. References should be in square brackets [ ], and placed before the
punctuation; citation should be made in usual manner by the using order.
5. Journal references must cite the title of the paper and its starting and ending pages, thus:
[1] P. P. Sangiovanni, A. S. Bergen, Chem. Eng. Sci., 26(1971) pp.533-547.
References to books should cite the authors, title, publisher, publication date, and page:
[2] A.B. Smith, Textbook of Organic Chemistry, D. C. Jones, New York, 1961, pp.123-126.
6. Text should be multiple spaced (1.3) and pages must not be numbered. Only black and white
Widespread PC format illustrations should be used. Text and signs on the illustrations should be
visible and readable.
Journal of Engineering & Processing Management|
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