research article treatment of sulfonated azo dye...

Research ArticleTreatment of Sulfonated Azo Dye Reactive Red 198 by UVH2O2

Jefferson P Ribeiro1 Juliene T Oliveira2 Andreacute G Oliveira2

Francisco W Sousa1 Eliezer F Abdala Neto1 Carla B Vidal1 Denis de Keukeleire3

Andreacute B dos Santos1 and Ronaldo F Nascimento2

1 Department of Hydraulic and Environmental Engineering Federal University of Ceara Rua do Contorno SN Campus do PiciBloco 713 60451-970 Fortaleza CE Brazil

2 Department of Analytical Chemistry and Physical Chemistry Federal University of Ceara Rua do ContornoHumberto Monte SN Campus do Pici Bloco 940 60451-970 Fortaleza CE Brazil

3 Faculty of Pharmaceutical Sciences Ghent University Harelbekestraat 72 9000 Ghent Belgium

Correspondence should be addressed to Ronaldo F Nascimento ronaldoufcbr

Received 7 July 2014 Accepted 8 August 2014 Published 8 September 2014

Academic Editor Vijay K Thakur

Copyright copy 2014 Jefferson P Ribeiro et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

UVH2O2system was tested on the color removal of sulfonated azo dye Reactive Red 198 (RR) which is widely used in textile

process The effects of hydrogen peroxide concentration temperature pH and the in-line addition of hydrogen peroxide on highcolor and chemical oxygen demand (COD) removals were investigatedThe kinetic of dye decolorization was also determinedTheresults showed that 2 H

2O2decreased the process efficiency while 1 H

2O2solution led to a better performance of the system

Despite the fact that the pH increase had small effect on color removal it affects positively COD removals The same behavior wasfound for temperature increase A high temperature resulted in a slight decrease in color removal and a sharp decrease for CODremoval In addition the H

2O2in-line provided a small improvement in both color and COD removals UV1 H

2O2treatment

was the most efficient the good performance was linked to higher amount of hydroxyl radicals formed

1 Introduction

The contamination of natural waters has been identified asone of the biggest problems in modern society The textileindustry has been a particular focus because it is associatedwith the use of inputs (dyes detergents and fabric softeners)and the generation of large volumes of effluent due to theoveruse of water [1 2]

Textile effluents are often highly colored due to thepresence of dyes that are not fixed onto the fiber during thedyeing process and these effluents contain large amounts ofsuspended solids In addition textile effluents have highlyfluctuating pH values elevated temperatures high chemicaloxygen demands (CODs) and considerable concentrationsof toxic metal ions (Cr Ni and Cu) [3] It has beenestimated that approximately 1ndash15 of textile dyes used arelost during the dyeing process and are released in effluents[4 5]

The release of effluents into aquatic ecosystems maydecrease the water transparency and solar radiation pen-etration thus decreasing photosynthetic activity and gasessolubility causing irreversible damage to the flora and fauna[6]

The different pollutants produced by the textile indus-try can be treated by physical-chemical andor biologicalprocesses which like other technological processes forwastewater treatment have advantages and disadvantagesBiological processes are widely used for the treatment oftextile wastewaters usually in combination with a physical-chemical posttreatment However these processes usuallydemand high hydraulic retention times (HRT) and transferpart of the dyes to a different phase leading to otherenvironmental consequences (sludge) [7 8] Moreover traceamounts of dioxins and furans can be formed as byproductsof incomplete oxidation [9] Because of these limitations aswell as the low efficiencies that can be found with many dye

Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 619815 11 pageshttpdxdoiorg1011552014619815

2 Journal of Chemistry

SO

O

O

O

O

O

O

O

O

Na

OH NH

N N

N Cl

HN SO

Na

SO

O

O

Na

NN

S

SONa

Figure 1 Chemical structure of the sulfonated azo dye Reactive Red 198 (RR)

classes new technologies for the treatment of effluents fromtextile industry have been developed

Advanced oxidation processes (AOPs) are highly effec-tive at destroying organic compounds that are difficult todegrade They function by generating hydroxyl radicals thatact as a very reactive oxidizing agent and can quickly andnonselectively cleave chemical bonds leading to partial orcomplete mineralization of the contaminant Examples ofAOPs include FeH

2O2 UVO

3 O3H2O2 O3UVH

2O2

UVTiO2 and UVH

2O2 and the use of this technology on

textile wastewater is well documented [10ndash14]A combined process using UV and H

2O2is one of the

AOPs that have been successfully applied to the treatment ofvarious aqueous pollutants [15]Oxidation processes are asso-ciated with very reactive species such as hydroxyl radicalswhich are generated by the direct photolysis of H

2O2under

UV irradiation [16]

H2O2+ ℎV 997888rarr 2HO∙ Φ

pri119868119886H2O2

(1)

This study investigated the use of UVH2O2system on

degradation of the sulfonated azo dye Reactive Red 198 (RR)Figure 1 The kinetics of dye decolorization were determinedas well as the effects of hydrogen peroxide concentrationtemperature pH and the in-line addition of hydrogen per-oxide on dye removal

2 Materials and Methods

21 Reagents Reactive Red 198 (RR) (CAS 145017-98-7) wassupplied by DyStar and was used to test the dye degradationcapacities hydrogen peroxide (30ww) (SYNTH) sodiumhydroxide (NaOH) (VETEC) and sulfuric acid (H

2SO4)

(SYNTH) All solutions were prepared with deionized water(Milli-Q Academic-Millipore)

The molecular weight of Reactive Red is approximately9682 gmol The chemical oxygen demand (COD) of a solu-tion containing 1 gL of this dye is 238130mgO

2L The UV-

VIS absorption spectrum at a concentration of 1 gL (purity

0

1

2

3

4

190 290 390 490 590 690 790

Abso

rban

ce (a

u)

120582 (nm)

Figure 2 Spectrum of UV-VIS absorption of the sulfonated azo dyeReactive Red 198 (RR)

disregarded) showed a strong absorption peak at 520 nm(black line) characterized by the presence of azo group(ndashN=Nndash) bound to aromatic rings as shown in Figure 2

22 UVH2O2AOP Reactor The dye degradation study was

performed in an irradiation chamber (95 cm long 28 cminternal diameter and useful volume 710mL) composed ofa quartz tube and an ultraviolet (UV) source a 30W UV-CPHILIPS TUV-T5 low-pressure mercury vapor lamp with anintensity of 100 120583Wcm2 (Figure 3)

The UV source was positioned inside the quartz tube thedye solution was on the outside of the tube hence there wasno direct contact between the UV source and the dye to beirradiated A stainless steel reflective dome was placed overthe experimental set-up to shield the rest of the laboratoryfrom the UV radiation The experiments were conducted ina glass jar covered with aluminum foil on a hot plate withmagnetic stirring Recirculation of the dye solution to betreated was performed using a peristaltic pump (GILSONmodel Miniplus 3)

Three degradation systems were used UV H2O2 and

UVH2O2 All experiments were performed with a total

volume of 2 L of the dye solution The dye was dissolved in

Journal of Chemistry 3

12

3

4

Figure 3 General schematic of the UVH2O2AOP photochemical

reactor (1 reservoir 2 peristaltic pump 3 UV lamp and 4photoreactor)

water and heated to a predetermined temperature and thenknown amounts of hydrogen peroxide and NaOH or H

2SO4

(to adjust the pH)were added to the solution All experimentswere performed at a flow rate of 25mLmin and a hydraulicretention time (HRT) of 284 minutes The decolorizationrate and the effects of temperature pH amount of hydrogenperoxide and in-line addition of hydrogen peroxide werestudied All experiments were performed in duplicate

221 Effect of the Hydrogen Peroxide Concentration Theeffect of the hydrogen peroxide concentration on dye removalwas evaluated using five different concentrations 03 05 071 and 2 (wv) The dye concentration used was 103mM Inthis part of the study the experiments were performed usingthree degradation systems UV H

2O2 and UVH

2O2 The

total irradiation time was 240 minutes and the initial pH was10 Determinations of residual H

2O2 pH conductivity color

and COD were performed every 60 minutes

222 Effect of the Initial pH After the investigation of theeffect of the hydrogen peroxide concentration experimentswere performed with initial pH values of 3 6 8 and 10 Thisstudywas runusing theUVH

2O2system hydrogen peroxide

concentration of 1 (wv) dye concentration of 103mM andtemperature of 25∘C

223 Effect of Temperature After the evaluation of hydrogenperoxide concentration and initial pH influence on color andCOD removals experiments were performed to elucidate theinfluence of temperature For this test four temperatureswereevaluated 25 45 60 and 80∘C This study was performedusing the UVH

2O2system hydrogen peroxide concentra-

tion of 1 (wv) and dye concentration of 103mM

224 Effect of the In-Line Addition of Hydrogen Peroxide Thelast part of the experiment consisted of an evaluation of in-line hydrogen peroxide addition in the AOP reactor There-fore small amounts of H

2O2were added to the UVH

2O2

systembyusing a peristaltic pump (GILSONmodelMiniplus3) in which the initial pH was 10 hydrogen peroxideconcentration of 1 (wv) dye concentration 103mM andtemperature of 60∘C It is worth mentioning that we addedin-line the same volume of hydrogen peroxide used for theexperiments 224 in which this compound was kept in acontainer with the dye and other chemicals

23 Physical and Chemical Analyses Dye characterizationwas performed by analyzing color amount of residual perox-ide pH conductivity and COD The pH was measured witha digital pH meter (TECNAL microprocessor model TEC-5) Hydrogen peroxide concentration was determined usinga volumetric titration method Conductivity was measuredwith a SCIENTIFIC THERMO (Orion 5 Star) conductivitymeter

The color was determined using a spectrophotometer(Thermo-Nicolet Evolution 100) and scans were performedevery 60minutesThe samples were diluted (1 5) in ultrapurewater and then centrifuged at 13000 rpm for 2 minutes(EppendorfMiniSpin)Dye removal efficiencywas estimatedfrom the absorbance measurements according to

Efficiency () = (1 minus [RR][RR]0) times 100 (2)

where [RR] and [RR]0are final and initial concentration of

Reactive Red 198 respectively COD was determined pho-tometrically (Thermo-Evolution Nicolet 100) according tostandardmethods (APHA 2005)The residual concentrationof hydrogen peroxide (H

2O2) is important because it affects

the COD by consuming K2Cr2O7[17]

Cr2O7

2minus+ 3H2O2+ 8H+ 997888rarr 2Cr3+ + 3O

2+ 7H2O (3)

This interference can be corrected taking into account theCOD of a hydrogen peroxide solution After determining theresidual hydrogen peroxide concentrations corrections weremade according to Lin and Lo [18] who reported that 1 gL ofhydrogen peroxide corresponds to COD of 270mgL

3 Results and Discussion

31 Effect of the Hydrogen Peroxide Concentration The effectof the oxidant concentration (H

2O2) was assessed in the

H2O2 UV H

2O2 and UV degradation systems During

UV H2O2treatment it was observed that increasing the

concentration of hydrogen peroxide from 03 to 1 anincrease in color removal was observed (Figure 4) Howevera negative effect was found when the hydrogen peroxideconcentrationwas 2 A negative effect of hydrogen peroxideon the decolorization rates was also verified on Chang et al[19] The color removal in the presence of only hydrogenperoxide (1) or UV was negligible Elmorsi et al [20] alsoobserved this effect in their study demonstrating that thecombination of UV and H

2O2is necessary


Table 1 Effect of the irradiation time and hydrogen peroxide concentration in some physical-chemical parameters Experimental conditions25∘C and initial pH of 10

Treatment Time (min) pH Conductivity (120583Scm) H2O2 residual ()

UV03 H2O2

0 1000 plusmn 002 81100 plusmn 281 030 plusmn 00160 824 plusmn 012 94700 plusmn 1273 028 plusmn 004120 393 plusmn 009 98250 plusmn 1202 026 plusmn 003180 330 plusmn 008 109750 plusmn 825 023 plusmn 002240 395 plusmn 011 134500 plusmn 633 020 plusmn 003

UV05 H2O2


UV07 H2O2


UV1 H2O2


UV2 H2O2


1 H2O2


UV

0 1000 plusmn 02 81100 plusmn 280 mdash60 847 plusmn 011 83200 plusmn 802 mdash120 786 plusmn 09 84500 plusmn 1291 mdash180 773 plusmn 08 85900 plusmn 1035 mdash240 755 plusmn 010 86100 plusmn 748 mdash

Table 1 presents the changes in the physical-chemicalproperties for each condition studied The conductivityresults generally show increases for all treatments (Table 1)which are most likely either due to the addition of hydrogenperoxide at the beginning of the experiment or due to theformation of ions in the solution after dye bond cleavage Forinstance some authors have observed the formation ofNO

3

minusSO4

2minus and Clminus during themineralization of Reactive Red 198[21]

The analyses confirmed a pH decrease for all treatments(Table 1) most likely due to the formation of acidic sub-stances by hydroxyl radicals during dye removal Similarresults were found by Kowalska et al [22] For instanceMahmoodi et al [21] reported the formation of organic

carboxylic acids during the photocatalytic degradation oftriazinic ring-containing azo dye (Reactive Red 198) by usingimmobilized TiO

2photoreactor The results for the residual

peroxide concentration (Table 1) showed a gradual decreasein this concentration for all treatments most likely due tothe formation of hydroxyl radicals from hydrogen peroxidecleavage

COD removal varied from 1483 to 7841 and theUV1H

2O2treatment was themost efficient (Figure 5)The

good performance was linked to higher amount of hydroxylradicals formed However no improvement in either coloror COD removals was found when the H

2O2concentration

increased from 1 to 2 (Figure 5) Therefore UV1 H2O2

was selected for the subsequent studies


0

10

20

30

40

50

60

70

80

90

100

240180120

Col

or re

mov

al (

)

Time (min)60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV

Figure 4 Effect of hydrogen peroxide dosage on color removalExperimental conditions 25∘C and initial pH of 10

0

10

20

30

40

50

60

70

80

90

100

COD

rem

oval

()

240180120Time (min)

60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV

Figure 5 Effect of hydrogen peroxide dosage on COD removalExperimental conditions 25∘C and initial pH of 10

According to Kalsoom et al when low-pressure mercuryvapor lamps and low concentrations of peroxide are usedin AOP system the amount of UV absorption during thegeneration of hydroxyl radicals is insignificant [23] Pub-lished studies showed that increasing the concentration ofhydrogen peroxide leads to a subsequent increase in thehydroxyl radical production Excess hydrogen peroxide inthe reaction may decrease the process efficiency since this

Col

or re

mov

al (

)

pH 3pH 6

pH 8pH 10

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

Figure 6 Effect of the initial pH on color removal Experimentalconditions UV1 H

2O2and 25∘C

compound is able to scavenge hydroxyl radicals to formwater and hydroperoxyl radicals (HO

2

∙) thus initiating otherreactions that affect the oxidation process [19]

H2O2+HO∙ 997888rarr HO

2

∙+H2O 119896

1= 2 7 times 10

7Mminus1Sminus1

(4)

H2O2+HO

2

∙997888rarr HO∙ +O

2+H2O 119896

2= 3 0Mminus1Sminus1

(5)

H2O2+HO∙ 997888rarr O

2

∙minus+H+ +H

2O

1198963= 2 7 times 10

7Mminus1Sminus1(6)

H2O2+O2

∙minus997888rarr HO∙ +OHminus +O


(7)

32 Effect of the Initial pH According to the results shown inFigure 6 pH had no influence on the color removal capacityElmorsi et al [20] also found no differences in color removalvarying the pH from 2 to 9 which is in agreement with ourobservations Under a technological perspective this is animportant characteristic and an advantage of the UVH

2O2

AOP system because there is no need of pH corrections inthe treatment plant and usually the pH of textile wastewatersis alkaline

Table 2 displays the results of the physical-chemicalanalyses highlighting an increase in the conductivity aftertreatment However it was observed that at higher pHvalues there was a greater variation between initial andfinal conductivities This was likely due to further molecularfragmentations leading to ionized reaction products

The residual peroxide concentrations decreased for alltreatments but it is worth noting that at basic pH valuesthere is a higher rate of peroxide decomposition (Table 2)


Table 2 Effect of the irradiation time and pH in some physical-chemical parameters Experimental conditions UV1 H2O2 and 25∘C

Initial pH Time (min) pH Conductivity (120583Scm) H2O2 residual ()

30


60


80


100


as previously reported [24] UV radiation which promotesthe formation of hydroxyl radicals also favors the rate ofperoxide decomposition Legrini et al [25] indicated that atalkaline pH the rate of photolysis of H

2O2increases likely

due to HO2

minus anion formation which has a higher molarabsorption coefficient (240Mminus1 cmminus1 at 254 nm) than hydro-gen peroxide (186Mminus1 cmminus1 at the same wavelength) Someauthors have reported that the rate of H

2O2decomposition

(see (8)) increases as the pH value approaches to pKa value(117) [25] The hydroxyl radical is deactivated approximately100 times faster in the presence of the HO

2

minus anion than inthe presence of H

2O2(see (9) and (10)) [19] Consider the

following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)

HO∙ +H2O2997888rarr H

2O +HO

2

∙ (10)

Contrary to the color removal COD removal showed a pHdependence (initial values of 3 6 8 and 10) which increaseswith the pH increase The highest COD removal was foundat an initial pH of 10 which resulted in a reduction of7881 (Figure 7) This likely indicates that COD removalwas not affected by the formation of the hydroperoxyl anion(HO2

minus) or maybe the dye oxidation by the hydroxyl radicalswas not taking place initially in the chromophore which isresponsible for the observed color but in the auxochromesTherefore further experiments to determine the oxidationpathways should be required

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()

Figure 7 Effect of the initial pH on COD removal Experimentalconditions UV1 H

2O2and 25∘C

33 Effect of Temperature It is well known that usuallytextile wastewater is discharged at high temperatures Hencea study of the effect of temperature on dye removal wasperformed The results presented in Figure 8 indicate thatthere was a small increase in the rate of decolorization bythe temperature increase However the temperature of 80∘Cnegatively impacted the process


Table 3 Effect of the irradiation time and temperature in some physical-chemical parameters Experimental conditions UV1 H2O2 andinitial pH of 10

Temperature (∘C) Time (min) pH Conductivity (120583Scm) H2O2 residual ()

25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C

Figure 8 Effect of temperature on color removal Experimentalconditions UV1 H

2O2and initial pH of 10

The results for COD removal are shown in Figure 9and a slight improvement was observed by the temperatureincrease However 80∘C decreased COD removal as nega-tively affecting color removal The highest COD removal wasfound at 60∘C which corresponded to 8705

COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C

Figure 9 Effect of temperature on COD removal Experimentalconditions UV1 H


Another important point verified was the increase in thedecomposition rate of hydrogen peroxide as the temperatureincreases (Table 3) For this parameter 80∘C was the besttemperature However it seems that the species formed uponhydrogen peroxide oxidation were not involved either in


color or in COD removals as there was a decrease in the rateswhen the temperature changed from 60∘C to 80∘C

The pH did not vary significantly between the treatmentsbut there was an increase in conductivity with the tempera-ture increase (Table 3)

34 Kinetic Modeling The HO∙ radicals in aqueous solutionmay be produced by UV irradiation and hydrogen peroxide(see (1)) To develop the kinetic model we use (1) and (4)ndash(7)and compile the reaction steps

RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)

The reaction of hydroxyl radical with S119894corresponds to the

reactions of the hydroxyl radical with other scavenger suchas chloride nitrate sulfate and carbonateThe correspondingkinetic equation of decolorization for RR is

minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)

Considering the HO∙ and HO2

∙ radicals major species indecolorization

119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)

For state-steady approximation it follows that

119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)

As a consequence of state-steady concentration and from(14)ndash(17) the concentration of hydroxyl radical can bedescribed by (21)

[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)

where 120601pri is the initial quantum yield of hydrogen peroxidedisappearance equal to 05 and 119868

119886H2O2

is the radiationintensity absorbed by H

2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)

Irradiation time (min)

03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2

Figure 10 Zero order representation for RR decolorization versustime pH = 10 119879 = 25∘C the irradiation time calculated from thehydraulic detention time (HDT)

Also119868119886H2O2

= 1198680119891H2O2

1 minus exp [minus23119897 (120576H2O2

[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)

In (19) 1198680is the incidentUV light intensity 119897 is the optical path

length of system and 120576H2O2

and 120576RR are the molar extinctioncoefficient forH

2O2andRR respectively Considering theRR

and H2O2having a high absorbance in the early stages of the

process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2

∙minus]1198964≪ 1 it can be written as

[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)

And then (22) can be changed into (13)

minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)

In the present study the results Figure 10 show that thedecolorization of dye RR corresponds to zero order kineticsthus [RR]119896

5≫ sum[S

119894]119896119894+ [H2O2]1198963 and the overall rate

expression simplifies

minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)

The results in Table 4 reveal that 1198960increases with increasing

concentration of H2O2and decreases above at 1


Table 4 Zero order rate constant for RR decolorization under different H2O2

H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977

Table 5 Effect of the irradiation time and in-line addition in some physical-chemical parameters Experimental conditions initial pH of 10and 60∘C


UV1 H2O260∘C

(beginning of theexperiment)


UV1 H2O260∘C

(addition of H2O2 in-line)


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line

Figure 11 Effect of the in-line hydrogen peroxide addition on colorremoval Experimental conditions initial pH 10 UV1 H

2O2 and

60∘C

35 Effect of the In-Line Addition of Hydrogen PeroxideThe effect of the in-line peroxide addition was studied todetermine if this operational strategy would benefit theprocess The decolorization process was not significantlyaffected although it should be noted that after 180 minutesof treatment there was a slight improvement (Figure 11)compared to the conventional hydrogen peroxide feeding Asmall but higher effect of hydrogen peroxide in-line additionwas found for COD removal (Figure 12)

The results of the physical-chemical analyses are pre-sented in Table 5 There was an increase in the conductivity

COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line

Figure 12 Effect of the in-line hydrogen peroxide addition on CODremoval Experimental conditions initial pH of 10 UV1 H

2O2

and 60∘C

for the two operational strategies tested and a significant pHvariation during in-line addition of H

2O2

The gradual addition of hydrogen peroxidemay positivelyinfluence the mineralization process This behavior can beexplained by the fact that H

2O2in excess in solution even

under optimal operational conditions is able to act as ahydroxyl radical (HO∙) scavenger Additionally intermedi-ates can compete with the target molecules of the HO∙radicals Nonetheless an economic evaluation should bedone to verify if a new line is composed of a different pump(including energy costs) as well as a separate container for


stock solution mixer and so forth would be compensated bythe efficiency increase

4 Conclusions

High color and COD removals were achieved by treatingthe sulfonated azo dye Reactive Red 198 by the UVH

2O2

advanced oxidation process even when low radiation timeswere used 1H

2O2solution showed to be the best concentra-

tion in which 2 H2O2decreased the process efficiencyThe

pH increase had a small effect on color removal but impactedpositively COD removals The same behavior was foundfor temperature increase but changing from 60∘C to 80∘Cresulted in a slight decrease for color removal and a sharpdecrease for COD removal In-line addition provided a smallimprovement in both color and COD removals Thereforethe UVH

2O2AOP system seems to be an interesting option

for textile wastewaters and themost important parameters forcolor and COD removals are irradiation time and hydrogenperoxide concentration

Conflict of Interests

The authors declare no conflict of interests in the research

Acknowledgments

The authors would like to thank the Brazilian agencies CNPqCAPES and FUNCAP for the scholarship and financialsupport

References

[1] F Ciner and O Gokkus ldquoTreatability of dye solutions contain-ing disperse dyes by fenton and fenton-solar light oxidationprocessesrdquo Clean Soil Air Water vol 41 no 1 pp 80ndash85 2013

[2] C R L Souza and P P Zamora ldquoDegradacao de corantesreativos pelo sistema ferro metalicoperoxido de hidrogeniordquoQuımica Nova vol 28 no 2 pp 226ndash228 2005

[3] H-Y Shu and W-P Hsieh ldquoTreatment of dye manufacturingplant effluent using an annular UVH

2O2reactor with multi-

UV lampsrdquo Separation and Purification Technology vol 51 no3 pp 379ndash386 2006

[4] C Galindo P Jacques and A Kalt ldquoPhotooxidation of thephenylazonaphthol AO20 on TIO

2 kinetic and mechanistic

investigationsrdquo Chemosphere vol 45 no 6-7 pp 997ndash10052001

[5] N Modirshahla and M A Behnajady ldquoPhotooxidative degra-dation of Malachite Green (MG) by UVH

2O2 influence

of operational parameters and kinetic modelingrdquo Dyes andPigments vol 70 no 1 pp 54ndash59 2006

[6] M Vautier C Guillard and J-M Herrmann ldquoPhotocatalyticdegradation of dyes in water case study of indigo and of indigocarminerdquo Journal of Catalysis vol 201 no 1 pp 46ndash59 2001

[7] V J P Vilar L X Pinho A M A Pintor and R A RBoaventura ldquoTreatment of textile wastewaters by solar-drivenadvanced oxidation processesrdquo Solar Energy vol 85 no 9 pp1927ndash1934 2011

[8] S G Schrank J N R D Santos D S Souza and E E S SouzaldquoDecolourisation effects of Vat Green 01 textile dye and textile

wastewater using H2O2UV processrdquo Journal of Photochemistry

and Photobiology A Chemistry vol 186 no 2-3 pp 125ndash1292007

[9] R F P Nogueira andW F Jardim ldquoA fotocatalise heterogenea esua aplicacao ambiental (The heterogeneous photocatalysis andits environmental application)rdquoQuımica Nova vol 21 no 1 pp69ndash72 1998

[10] M S Lucas A A Dias A Sampaio C Amaral and JA Peres ldquoDegradation of a textile reactive Azo dye by acombined chemical-biological process fentonrsquos reagent-yeastrdquoWater Research vol 41 no 5 pp 1103ndash1109 2007

[11] S Harimurti A U Rahmah A A Omar and T MurugesanldquoKinetics of Methyldiethanolamine mineralization by usingUVH

2O2processrdquo CLEANmdashSoil Air Water vol 41 no 12 pp

1165ndash1174 2013[12] I T Peternel N Koprivanac A M L Bozic and H M Kusic

ldquoComparative study of UVTiO2 UVZnO and photo-Fenton

processes for the organic reactive dye degradation in aqueoussolutionrdquo Journal of Hazardous Materials vol 148 no 1-2 pp477ndash484 2007

[13] A Aleboyeh M B Kasiri M E Olya and H Aleboyeh ldquoPre-diction of azo dye decolorization by UVH

2O2using artificial

neural networksrdquoDyes and Pigments vol 77 no 2 pp 288ndash2942008

[14] J P Ribeiro D S Araujo F W Sousa N S M Filho L MCorreia and R F Nascimento ldquoUso do processo H

2O2UVmdash

adsorcao no tratamento de efluente textilrdquoRevista DAE no 183pp 4ndash8 2010

[15] A G Oliveira J P Ribeiro J T Oliveira D de Keukeleire MS Duarte and R F Nascimento ldquoDegradation of the pesticidechlorpyrifos in aqueous solutions with UVH

2O2 optimization

and effect interfering anionsrdquo Journal of Advanced OxidativeTechnologies vol 17 no 1 pp 133ndash138 2014

[16] B H J Bielski and D E Cabelli ldquoHighlights of current researchinvolving superoxide and perhydroxyl radicals in aqueoussolutionsrdquo International Journal of Radiation Biology vol 59 no2 pp 291ndash319 1991

[17] I Talinli and G K Anderson ldquoInterference of hydrogenperoxide on the standard COD testrdquo Water Research vol 26no 1 pp 107ndash110 1992

[18] S H Lin andC C Lo ldquoFenton process for treatment of desizingwastewaterrdquoWater Research vol 31 no 8 pp 2050ndash2056 1997

[19] M-W Chang C-C Chung J-M Chern and T-S Chen ldquoDyedecomposition kinetics by UVH

2O2 initial rate analysis by

effective kineticmodellingmethodologyrdquoChemical EngineeringScience vol 65 no 1 pp 135ndash140 2010

[20] T M Elmorsi Y M Riyad Z H Mohamed and H M HAbd El Bary ldquoDecolorization of Mordant red 73 azo dye inwater using H

2O2UV and photo-Fenton treatmentrdquo Journal of

Hazardous Materials vol 174 no 1ndash3 pp 352ndash358 2010[21] N M Mahmoodi M Arami and N Y Limaee ldquoPhotocatalytic

degradation of triazinic ring-containing azo dye (Reactive Red198) by using immobilized TiO

2photoreactor Bench scale

studyrdquo Journal of Hazardous Materials vol 133 no 1ndash3 pp 113ndash118 2006

[22] E Kowalska M Janczarek J Hupka and M GrynkiewiczldquoH2O2UV enhanced degradation of pesticides in wastewaterrdquo

Water Science and Technology vol 49 no 4 pp 261ndash266 2004[23] U Kalsoom S S Ashraf M A Meetani M A Rauf and

H N Bhatti ldquoDegradation and kinetics of H2O2assisted

photochemical oxidation of Remazol Turquoise BluerdquoChemicalEngineering Journal vol 200ndash202 pp 373ndash379 2012


[24] C Galindo and A Kalt ldquoUV-H2O2oxidation of monoazo dyes

in aqueous media a kinetic studyrdquo Dyes and Pigments vol 40no 1 pp 27ndash35 1999

[25] O Legrini E Oliveros and A M Braun ldquoPhotochemicalprocesses for water treatmentrdquo Chemical Reviews vol 93 no2 pp 671ndash698 1993

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


SO

O

O

O

O

O

O

O

O

Na

OH NH

N N

N Cl

HN SO

Na

SO

O

O

Na

NN

S

SONa

Figure 1 Chemical structure of the sulfonated azo dye Reactive Red 198 (RR)

classes new technologies for the treatment of effluents fromtextile industry have been developed

Advanced oxidation processes (AOPs) are highly effec-tive at destroying organic compounds that are difficult todegrade They function by generating hydroxyl radicals thatact as a very reactive oxidizing agent and can quickly andnonselectively cleave chemical bonds leading to partial orcomplete mineralization of the contaminant Examples ofAOPs include FeH

2O2 UVO

3 O3H2O2 O3UVH

2O2

UVTiO2 and UVH

2O2 and the use of this technology on

textile wastewater is well documented [10ndash14]A combined process using UV and H

2O2is one of the

AOPs that have been successfully applied to the treatment ofvarious aqueous pollutants [15]Oxidation processes are asso-ciated with very reactive species such as hydroxyl radicalswhich are generated by the direct photolysis of H

2O2under

UV irradiation [16]

H2O2+ ℎV 997888rarr 2HO∙ Φ

pri119868119886H2O2

(1)

This study investigated the use of UVH2O2system on

degradation of the sulfonated azo dye Reactive Red 198 (RR)Figure 1 The kinetics of dye decolorization were determinedas well as the effects of hydrogen peroxide concentrationtemperature pH and the in-line addition of hydrogen per-oxide on dye removal

2 Materials and Methods

21 Reagents Reactive Red 198 (RR) (CAS 145017-98-7) wassupplied by DyStar and was used to test the dye degradationcapacities hydrogen peroxide (30ww) (SYNTH) sodiumhydroxide (NaOH) (VETEC) and sulfuric acid (H

2SO4)

(SYNTH) All solutions were prepared with deionized water(Milli-Q Academic-Millipore)

The molecular weight of Reactive Red is approximately9682 gmol The chemical oxygen demand (COD) of a solu-tion containing 1 gL of this dye is 238130mgO

2L The UV-

VIS absorption spectrum at a concentration of 1 gL (purity

0

1

2

3

4

190 290 390 490 590 690 790

Abso

rban

ce (a

u)

120582 (nm)

Figure 2 Spectrum of UV-VIS absorption of the sulfonated azo dyeReactive Red 198 (RR)

disregarded) showed a strong absorption peak at 520 nm(black line) characterized by the presence of azo group(ndashN=Nndash) bound to aromatic rings as shown in Figure 2

22 UVH2O2AOP Reactor The dye degradation study was

performed in an irradiation chamber (95 cm long 28 cminternal diameter and useful volume 710mL) composed ofa quartz tube and an ultraviolet (UV) source a 30W UV-CPHILIPS TUV-T5 low-pressure mercury vapor lamp with anintensity of 100 120583Wcm2 (Figure 3)

The UV source was positioned inside the quartz tube thedye solution was on the outside of the tube hence there wasno direct contact between the UV source and the dye to beirradiated A stainless steel reflective dome was placed overthe experimental set-up to shield the rest of the laboratoryfrom the UV radiation The experiments were conducted ina glass jar covered with aluminum foil on a hot plate withmagnetic stirring Recirculation of the dye solution to betreated was performed using a peristaltic pump (GILSONmodel Miniplus 3)

Three degradation systems were used UV H2O2 and

UVH2O2 All experiments were performed with a total

volume of 2 L of the dye solution The dye was dissolved in


12

3

4




2SO4



2O2 and UVH

2O2 The












2O2









Cr2O7


2+ 7H2O (3)





H2O2 UV H




2O2is necessary




UV03 H2O2


UV05 H2O2


UV07 H2O2


UV1 H2O2


UV2 H2O2


1 H2O2


UV



3

minusSO4









2O2concentration




0

10

20

30

40

50

60

70

80

90

100

240180120

Col

or re

mov

al (

)

Time (min)60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV


0

10

20

30

40

50

60

70

80

90

100

COD

rem

oval

()

240180120Time (min)

60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV



Col

or re

mov

al (

)

pH 3pH 6

pH 8pH 10

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60


2O2and 25∘C


2



2

∙+H2O 119896

1= 2 7 times 10

7Mminus1Sminus1

(4)

H2O2+HO

2

∙997888rarr HO∙ +O

2+H2O 119896


(5)


2

∙minus+H+ +H

2O

1198963= 2 7 times 10

7Mminus1Sminus1(6)

H2O2+O2



(7)


2O2







30


60


80


100



2O2increases likely

due to HO2


2O2decomposition


2



following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)


2O +HO

2

∙ (10)



0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()


2O2and 25∘C





25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


12

3

4




2SO4



2O2 and UVH

2O2 The












2O2









Cr2O7


2+ 7H2O (3)





H2O2 UV H




2O2is necessary




UV03 H2O2


UV05 H2O2


UV07 H2O2


UV1 H2O2


UV2 H2O2


1 H2O2


UV



3

minusSO4









2O2concentration




0

10

20

30

40

50

60

70

80

90

100

240180120

Col

or re

mov

al (

)

Time (min)60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV


0

10

20

30

40

50

60

70

80

90

100

COD

rem

oval

()

240180120Time (min)

60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV



Col

or re

mov

al (

)

pH 3pH 6

pH 8pH 10

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60


2O2and 25∘C


2



2

∙+H2O 119896

1= 2 7 times 10

7Mminus1Sminus1

(4)

H2O2+HO

2

∙997888rarr HO∙ +O

2+H2O 119896


(5)


2

∙minus+H+ +H

2O

1198963= 2 7 times 10

7Mminus1Sminus1(6)

H2O2+O2



(7)


2O2







30


60


80


100



2O2increases likely

due to HO2


2O2decomposition


2



following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)


2O +HO

2

∙ (10)



0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()


2O2and 25∘C





25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




UV03 H2O2


UV05 H2O2


UV07 H2O2


UV1 H2O2


UV2 H2O2


1 H2O2


UV



3

minusSO4









2O2concentration




0

10

20

30

40

50

60

70

80

90

100

240180120

Col

or re

mov

al (

)

Time (min)60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV


0

10

20

30

40

50

60

70

80

90

100

COD

rem

oval

()

240180120Time (min)

60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV



Col

or re

mov

al (

)

pH 3pH 6

pH 8pH 10

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60


2O2and 25∘C


2



2

∙+H2O 119896

1= 2 7 times 10

7Mminus1Sminus1

(4)

H2O2+HO

2

∙997888rarr HO∙ +O

2+H2O 119896


(5)


2

∙minus+H+ +H

2O

1198963= 2 7 times 10

7Mminus1Sminus1(6)

H2O2+O2



(7)


2O2







30


60


80


100



2O2increases likely

due to HO2


2O2decomposition


2



following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)


2O +HO

2

∙ (10)



0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()


2O2and 25∘C





25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

10

20

30

40

50

60

70

80

90

100

240180120

Col

or re

mov

al (

)

Time (min)60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV


0

10

20

30

40

50

60

70

80

90

100

COD

rem

oval

()

240180120Time (min)

60

UV03 H2O2

UV05 H2O2

UV07 H2O2

UV1 H2O2

UV2 H2O2

1 H2O2

UV



Col

or re

mov

al (

)

pH 3pH 6

pH 8pH 10

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60


2O2and 25∘C


2



2

∙+H2O 119896

1= 2 7 times 10

7Mminus1Sminus1

(4)

H2O2+HO

2

∙997888rarr HO∙ +O

2+H2O 119896


(5)


2

∙minus+H+ +H

2O

1198963= 2 7 times 10

7Mminus1Sminus1(6)

H2O2+O2



(7)


2O2







30


60


80


100



2O2increases likely

due to HO2


2O2decomposition


2



following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)


2O +HO

2

∙ (10)



0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()


2O2and 25∘C





25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




30


60


80


100



2O2increases likely

due to HO2


2O2decomposition


2



following

H2O2+HO

2

minus997888rarr H

2O +O

2+OHminus (8)

HO∙ +HO2

minus997888rarr H

2O + ∙O

2(9)


2O +HO

2

∙ (10)



0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

pH 3pH 6

pH 8pH 10

COD

rem

oval

()


2O2and 25∘C





25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




25


45


60


80


Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C




COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

25∘C

45∘C

60∘C

80∘C








RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





RR +HO∙ 997888rarr P 1198965

(11)

S119894+HO∙ 997888rarr P

119894119896119894

(12)



minus

119889 [RR]119889119905

= 1198965[HO∙] [RR] (13)



119889 [HO∙]119889119905

= 2Φpri119868119886H2O2

minus [H2O2] [HO∙] 119896

1

+ [H2O2] [HO

2

∙] 1198962minus [H2O2] [HO∙] 119896

3

+ [H2O2] [O2

∙minus] 1198964minus [RR] [HO∙] 119896

5

minussum[S119894] [HO∙] 119896

119894

(14)

119889 [HO2

∙]

119889119905

= [H2O2] [HO∙] 119896

1minus [H2O2] [HO

2

∙] 1198962 (15)


119889 [HO∙]119889119905

= 0 (16)

119889 [HO2

∙]

119889119905

= 0 (17)


[HO∙] =2Φ

pri119868119886H2O2

+ [H2O2] [O2

∙minus] 1198964

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(18)


119886H2O2


2O2

0

00

02

04

06

08

10

12

20 40 60 80

[RR]

(mM

)


03 H2O2

05 H2O2

07 H2O2

1 H2O2

2 H2O2

Without H2O2


Also119868119886H2O2

= 1198680119891H2O2


[H2O2] + 120576RR [RR])]

(19)

119891H2O2

=

120576H2O2

[H2O2]

120576H2O2

[H2O2] + 120576RR [RR]

(20)






process


[H2O2] + 120576RR [RR])] asymp 1 (21)

And [O2


[HO∙] =2Φ

pri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

(22)


minus

119889 [RR]119889119905

= 1198965

2Φpri1198680119891H2O2

[H2O2] 1198963+ [RR] 1198965 + sum [S119894] 119896119894

[RR] (23)


5≫ sum[S



minus

119889 [RR]119889119905

= 2Φpri1198680119891H2O2

(24)





H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



H2O2

03 05 07 1 2 Without1198960

00095 00120 00130 00132 00111 00001119877 0985 0976 0987 0984 0981 0977



UV1 H2O260∘C



UV1 H2O260∘C



Col

or re

mov

al (

)

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2 and

60∘C



COD

rem

oval

()

0

10

20

30

40

50

60

70

80

90

100

240180120Time (min)

60

UV1 H2O2

UV1 H2O2 in-line


2O2

and 60∘C


2O2






4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



4 Conclusions


2O2









Acknowledgments


References










2O2 influence















2O2using artificial



2O2UVmdash



2O2 optimization































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of














Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article treatment of sulfonated azo dye...

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