turhan2009.docx

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Desalination 242 (2009) 256263

Decolorization of direct dye in textile wastewater by

ozonization in a semi-batc b!bble col!mn reactor

"adir #!ran$% &!al #!r'!t

Yildiz Technical University, Chemistry Department,34220 Esenler, Istanbul,

Turey

Tel! "#0 $2%2& 44#%'42( )a* "#0 $2%2& 44#%+%4( email tu rhanadir-yah..!c.m

eceied 6 *ebr!ary 200+, acceted reised 2 .ay 200+

Abstract

Decolorization of wastewater containin' direct dye (/iri!s l!e /) by ozonization was st!died in an

attemt to abate oll!tion ca!sed by textile dyein' o!ses and dye-rod!cin' lants1 #e decolorization rocess

of te direct dye was carried o!t by b!bblin' ozone at te bottom of a b!bble col!mn reactor containin' te dye

sol!tion1 #e effect of dye concentration% ozone dose% ozone-air flow rate and sol!tion on te rate of

decolorization was st!died1 #e reaction rate was followed by meas!rin' te dye concentration at different times

of te decolorization rocess1 #e rate of dye oxidation was fo!nd to increase wit increasin' ozone

concentration in te air-ozone and to decrease wit increasin' te dye concentration1 #e rate of dye oxidation

increases wit increasin' te air ozone flow rate and sol!tion % reaces a maxim!m and ten decreases wit a

f!rter increase in te airozone flow rate1 #e res!lts wit te direct dyest!ff wastewater sowed tat

decolorization was remarable !nder te basic condition of 21 lar'e amo!nt of b!bbles was formed at a

i' ozoneair flow rate1 fter 26 min of ozone treatment% decolorization was comleted1 *rom tese res!lts% te

ozone treatment of te dyest!ff wastewater in decolorization was excellent1

/ey.rds 7zone, /iri!s l!e /, 8astewater treatments, Decolorization, Direct l!e

1. Introduction

#extile ind!stries cons!me lar'e amo!nts ofwater and teir effl!ents contain a wide ran'e ofcontaminants1 :nironmentally% tese contami-nants mean s!sended solids% ;7D% 7D% aswell as i' and stron' color1 #e remoalof dye

$;orresondin' a!tor1

color in te treatment of textile dyein' and dyeman!fact!re wastewaters is one of te main

rob- lems of textile ind!stry n te late950?s% te triclin' filter and actiated sl!d'e

rocesses were sown to be caable of today?snew dyes wic is m!c more diffic!lt to betreated wit ysical tecni@!es% s!c asadsortion and remoal +4-93A of te color from textile effl!ents


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a'!lation aciees comlete decolorization% es-ecially for i'ly sol!ble dyes1 .ost of te dyemolec!les are treated i'ly efficiently by anac- tiated sl!d'e rocess or any combination of

biolo'ical% cemical and str!ct!red olymers,ence it is ery diffic!lt to biolo'ically breatem down and terefore tey cannot be treated

by ysical metods t is reorted tat ozone is aneffec- tie a'ent for red!cin' te color ofdyest!ff wastewater n most cases 7DB;7D ratio of te comositetex- tile wastewater is aro!nd 0125 wicimlies tat te wastewater contains lar'eamo!nts of non-bio- de'radable or'anic matter


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#able 2

7xidizin' otential for conentional oxidizin' a'ents


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*i'1 1 /cematic dia'ram of te benc-scale reactor system1

stream from te ozonizer containin' 73

and 72

mixt!re was allowed to ass tro!' #y'on t!b-in' connected to te bottom of te b!bble col-!mn1 #e 'as flow rate was controlled by aneedle ale and meas!red by air flow meters1#e tem- erat!re was fixed at 20NO; d!rin'all te ex- eriments P 27>2 +2"7 P

72

(2) concentrations (00+00 m'BH) on te time re-

#e res!ltin' iodine was titrated !sin' stan-

dard sodi!m tios!lfate% in te resence ofstarc as indicator1 #e al!es of !n!sed ozonewere de- termined% accordin'ly


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SO3Na OH

N N N N N N

SO3Na

*i'1 21 /tr!ct!re of /iri!s l!e / (Direct l!e )1

NaO3S

SO3Na

NH2

52

48

44

40

36

32

28

24

20

16

12

8

4

0

0 4 8 12 16 20 24 28Ozonization time (min)

*i'1 31 ;oncentration time 'ra for different /iri!s l!e / dye concentrations treated wit ozone at different times(ozone conc1 24 'Bm3, dye sol!tion 2000 mH, ozoneair flow rate 20 HB, +10)1

28

24

20

16

12

8

4

0

0 100 200 300 400 500 600 700 800

Dye conce ntr ation (mg/L)

*i'1 41 :ffect of initial dye concentration on te decolorization time of /iri!s l!e / dye treated by ozone (ozone

conc1 24 'Bm3, dye sol!tion 2000 mH, ozoneair flow rate 20 HB, +10)1

200 250

300 350

400 450

500 550

600 650

700 750

800

Dyeconcentratio

n

(mg/L)

Deco

lorizationtime(min)


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sition inetics of /iri!s l!e / in te res-ence of ozone was calc!lated !sin' maxim!mrate constants% from 'raics of concentration s1time1

*i'1 5 sows te effect of ozoneconcentration on te decolorization time, it isery clear tat te decolorization time decreaseslinearly wit increasin' ozone concentration1*or examle% increasin' ozone concentrationfrom 412 'Bm3 to24103 'Bm3 in te 'as ase red!ces decoloriza-tion of 400 m'BH (initial dye concentration) byabo!t 9015+A1 #is res!lt is consistent wit teteories of mass transfer


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a'ent in te decomosition of aromatic coalentcomo!nds% and it is 'ood for te decolorizationof te dyest!ff wastewater


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ization of textile wastewater-a reiew% :niron1

#ecnol1% 5 (994) 99291

mroement of wastewater

coa'!lation !sin' ozone1 7zone /ci1 :n'1% 20

(99+) 561

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