Research Article Photodegradation of Sulfadiazine in Aqueous …downloads.hindawi.com/journals/jchem/2016/8358960.pdf · Research Article Photodegradation of Sulfadiazine in Aqueous

Research ArticlePhotodegradation of Sulfadiazine in Aqueous Solution andthe Affecting Factors

Xuesen Bian and Jibing Zhang

Nanjing Institute of Environmental Sciences Ministry of Environmental Protection of the Peoplersquos Republic of China8 Jiangwangmiao Street Nanjing 210042 China

Correspondence should be addressed to Jibing Zhang zhangjbofdcorgcn

Received 29 March 2016 Revised 7 June 2016 Accepted 13 June 2016

Academic Editor Athanasios Katsoyiannis

Copyright copy 2016 X Bian and J ZhangThis is an open access article distributed under the Creative CommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Knowledge about photochemical behavior of sulfonamides underUV light is limited In this study photodegradation of sulfadiazinein water by ultraviolet (UV) light was studied using a 300W 365 nmUV lampThe degradation process followedwell the first-orderkinetics with a half-life of 976min in water with air saturation The photodegradation was slower at acidic pH 452 than at pH698 and pH 890 Addition of H

2O2and nitrate enhanced the photodegradation rate while addition of ethanol nitrite sulfate

and bicarbonate depressed the reaction rate This study suggested that sulfadiazine photodegradation under UV light is generallyfavored by the attack of hydroxyl radicals

1 Introduction

Antibiotics are a sort of organic compounds synthesizedby industry or generated by organisms including microor-ganisms plants and animals in their life activities whichcould selectively depress or influence functions of otherorganisms at low or even micro level concentrations In thelast six decades large quantities of antibiotics were employedworldwide for prevention or treatment of diseases of bothhumans and livestock as well as for some nontherapeuticpurposes such as promoting the growth of cattle [1] Antibi-otics can enter the environment through many ways likeirrigation using sewage water disposal of unused drugs landapplication of biosolids and animalmanure [1] and have beenfound ubiquitously in different environmental media likewater [2] sediments [3] soils [4] excrements of organisms[4] and so forth The antibiotics in the environment couldlead to various negative effects such as microbial resistanceswhich have been regarded as a global problem changes ofindigenous microbial composition [5] disturbances of plantgrowth [6] acute or chronic toxicities on aquatic species [7]and the potential adverse effects on humans through foodchains [8] Therefore study on the fate of antibiotics in theenvironment has been receiving worldwide concerns [9 10]

Sulfadiazine is one of the commonly used sulfon-amide antibiotics Sulfonamides are frequently employed asmedicines to treat both human and livestock diseases Forexample the annual usages as veterinary medicine were78 t in the European Union (1999) and 94 t in England(2000) [9] Reported half-lives of such chemicals were lt8 dto 30 d in manure [11] and gt21 d to 100 d in water orsediments [10] The environmental behaviors like sorptionand biodegradation were already documented for some ofthese chemicals but the removal efficiency of these chemicalsfrom aqueous phase seemed to be quite limited or evenignorable [12ndash14] Photodegradation is one important degra-dation process in natural environment Photodegradationboth direct (reaction between substrates and photons) andindirect (reaction between substrates and reactive speciesformed by photons) of sulfadiazine under natural or simu-lated sunlight was investigated by previous studies [15 16]The expected environmental half-lives were 47ndash659 daysin Kolkata India and Berlin Germany in different seasons[15] and 28ndash5200 h through various degradation pathwaysin near surface waters in Lake Josephine [16] But in otherways the photodegradation behavior under pure UV lighthas not yet been reported to our knowledge UV occupiesabout 7 percent in the sunlight irradiation energy and it is

Hindawi Publishing CorporationJournal of ChemistryVolume 2016 Article ID 8358960 5 pageshttpdxdoiorg10115520168358960

2 Journal of Chemistry

No addition

10 20 30 40 50 60000

01

02

03

04

05

06

07

08

09

10

t (min)

CC

0

1 (v v) ethanol

Figure 1 Photodegradation of 11mgsdotLminus1 sulfadiazine in ultrapurewater under UV 365 nm (300W) with pumping-in of air in thepresence and absence of 1 ethanol The solid lines represent themodeling results of first-order kinetics (119862

1199051198620= 119890minus119896119905)

also used artificially to remove the microorganism toxicity ofantibiotics as a pretreatment method to make the activatedsludge system in the following step run more efficientlyTherefore results from UV photodegradation study notonly will be useful to learn the behavior of photolysis byultraviolet inwater environment but alsowill be helpful to thedesign of the artificial wastewater treatment system throughUV photolysis of such chemicals This work is designedto study kinetics and possible mechanisms of sulfadiazinephotodecomposition under pure UV by investigating theinfluences of some common affecting factors

2 Experimental

21 General Sulfadiazine (996purity) was purchased fromSigma USA Other chemicals were at least of analytical gradeand used without further purification

The photoreactor was designed according to Jiang et al[17]The ultraviolet lamp (365 nm 300W) used in our exper-iments was purchased from the Xujiang ElectromechanicalPlant Nanjing China

The HPLC system used in this study was an Agilent 1200series HPLC system which consisted of a G1322 A degassera G1311 A Quat Pump a G1329 A thermostatted autosamplerand a G1316A column oven The column for separation wasAgilent Eclipse XDB-C18 (5 120583m 46 times 250mm)

22 Photodegradation Procedures and HPLC Analysis About11mgsdotLminus1 sulfadiazine solution was prepared by dissolving55mg sulfadiazine into 500mL ultrapure water and was

transferred into the glass reactor To investigate the effectsof affecting factors additives were introduced respectivelyat the following concentrations ethanol of 1 in volume ofthe solution 438mgsdotLminus1 H

2O2 sodium salts with 005mM

NO2

minus 05mM NO3

minus 1 mM and 5mM SO4

2minus and 05 24and 119mM HCO

3

minus The pH effect was studied by addingappropriate HCl or NaOH The first sample (defined as time0) was taken immediately after the addition of one of thesechemicals to the reactor The ultraviolet lamp in the centralhollow was then turned on and photodegradation processwas started All experimental processes were accompanied byvigorous stirring and air-pumping into the system at 1mLsdotsminus1except that in the case of nitrogen effect N

2instead of air

was pumped in Sampling was performed at different timeintervals The samples were frozen at minus20∘C until analysisThemobile phase used for HPLC analysis of sulfadiazine wasmethanol water = 30 70 (v v) isocratically running at a flowrate of 1mLsdotminminus1 Calibration curves were used to read thevalues of sulfadiazine for all samples and the quality controlofHPLCwas carried out by injecting and analyzing the lowestand highest concentrations of standard sulfadiazine solutionsat the beginnings and ends of all analytical circles Controlexperiment without any irradiationwas carried out under thesame conditions All experiments were performed at least induplicate

3 Results and Discussion

31 Effect of Ethanol Control experiment under dark condi-tions showed ignorable disappearance of sulfadiazine in thesolution (data not shown) indicating that the compound wasstable in the dark that is hydrolysis of sulfadiazine was notsignificant which is in agreement with the observations ofBoreen et al [18] who found thatmost sulfa drugs were stablein solutions of various pH values

Under radiation sulfadiazine in pure water was degradedby 99 percent in one hour with a half-life of 976min (Fig-ure 1) The first-order kinetic model (119862

1199051198620= 119890minus119896119905) was used

to describe the degradation process under various conditionsresulting in a relationship of the ratio of remaining sulfadi-azine (119910) versus time (119909) as 119910 = 119890minus0071119909 (1198772 = 098 Figure 1and Table 1) Sulfadiazine in natural water might be degradedby irradiation through both direct and indirect waysTheUV-Vis absorption spectrum of sulfadiazine has a tailing band inthe region of wavelength over 290 nm [15] which suggeststhat the way of direct photolysis for this compound cannotbe preexcluded [15]When ethanol a hydroxyl scavenger wasadded to the solution 119896 value decreased to 0009 (1198772 = 100)This indicates that the dominant mechanism for sulfadiazinedegradation might be the attack of hydroxyl radicals andtherefore that degradation of sulfadiazine through the directabsorption of light was limited to a very small extent Thephotolysis of water by UV irradiation may involve 25ndash30reactions and 14 different species including H∙ HO

2

∙ and∙OH [19] Under the radiation of a xenon lamp sulfadiazinein pure water had a rather longer half-life (32 h) with 119896 valueof 00094 [15]

Journal of Chemistry 3

Table 1 First-order kinetic constants 119896 of sulfadiazine photodegra-dation in ultrapure water irradiated by UV light of 365 nm and300W with air pumping in (except the condition of N

2instead)

under various conditions

Condition 119896 1198772

Without addition (only sulfadiazine in H2O) 0071 098

Plus 1 (V V) ethanol 0009 100With nitrogen instead of air 0045 100Plus 438mgsdotLminus1 H

2O2

013 100Plus 005mM NO

2

minus 0034 084Plus 05mM NO

3

minus 01 095Plus 1mM SO

4

2minus 0054 095Plus 5mM SO

4

2minus 0057 096Plus 05mMHCO

3

minus 0017 089Plus 24mMHCO

3

minus 0042 093Plus 119mM HCO

3

minus 0046 096At pH 452 0046 091At pH 698 0065 098At pH 820 0057 094

32 Effect of N2H2O2 When N2instead of air was pumped

into the solution degradation of sulfadiazine was obviouslyslowed down and the kinetic equation varied to 119862

1199051198620=

119890minus0045119905 (1198772 = 100 Table 1)The important role of oxygen wasalso observed in TiO

2photocatalytic degradation of 24-

dichlorophenol and cyclohexane [20 21] The involvementof air might also be one reason for the much higher rateof sulfadiazine photodegradation observed by us than thatby Sukul et al [15] supporting again that this reaction wasfavored mainly by ∙OH in the system

H2O2can be photocleaved to two hydroxyl radicals by

homogeneous crack [22 23]

H2O2+ ℎ] 997888rarr 2∙OH (1)

Therefore H2O2can significantly enhance reaction rates A

cleaning technology by advanced oxidation processes (AOPs)has been developed to utilize H

2O2UV or Fe2+H

2O2UV as

the source of hydroxyl radicals [22 23] When 438mgsdotLminus1H2O2was added to our system the first-order constant rate of

sulfadiazine degradation increased to 013 (1198772 = 100) beingalmost two times of that under air alone (0071) (Table 1)Thepromoting effect by H

2O2was also reported in sulfadiazine

sunlight photodegradation by Sukul et al [15]

33 Effect of Nitrate and Nitrite Nitrite in the water environ-ment might come from various sources like photodegrada-tion of DOM (dissolved organic matter) oxidation of ammo-nia and organic N and can be oxidized to nitrate throughdifferent pathways [24] Both anions are commonly existingin natural water and have potentials to affect photodegra-dation behavior of some chemicals [24ndash28] Table 1 showsthat the degradation rate of sulfadiazine was enhanced from0071 to 010 (1198772 = 095) when nitrate was added into thesolution This is because nitrate can be photolyzed to nitroso

and negative oxygen ions and the latter further combinedwith H+ to form ∙OH [26]

NO3

minus+ ℎ] 997888rarr ∙NO

2+O∙minus

O∙minus +H+ larrrarr ∙OH(2)

The promoting effects of nitrate on photodegradation havealso been observed for Diuron [26] Lam and coworkersfound that nitrate significantly enhanced the photodegra-dation rates of atrazine bensulfuron methyl fluometuronand hexazinone in solutions containing low concentrationsof color DOM irradiated by Xe lamp and a significantlypositively proportional correlation (1198772 gt 099) was observedbetween nitrate concentration and 119896obs in synthetic fieldwater matrixes [29] However nitrate played an almost neg-ligible role in electrochemically assisted TiO

2photocatalytic

degradation of methyl orange [28] probably because in aheterogeneous system photons were preferentially absorbedby solid particles like TiO

2and therefore the sensitization

of chemicals dissolved in liquid phase cannot be activated[28] while in a homogeneous system light energy can bedistributed more evenly

Nitrite is also considered as one source of ∙OH in aphotolytic system and may be comparably or even moreeffective comparedwith nitrate in some surfacewater samples[24 30] But in our study the addition of 005mM nitriteresulted in a marked decrease of the rate constant from 0071(1198772 = 098) to 0034 (1198772 = 084) (Table 1) In addition toacting as ∙OH source nitrite might also be a scavenger for∙OH according to the following equation [24]

NO2

minus+∙OH 997888rarr ∙NO

2+OHminus (3)

Mark et al [25] observed nitrite scavenging effects on ∙OHat a concentration of 6 times 10minus6M which was about 110 of ourusage under UV suggesting that nitrite addition in the pho-tolytic system in our study might also carry out a scavengingfunction of hydroxyl radicals in this system

34 Effects of Sulfate With the addition of 1mM and 5mMsulfate the first-order kinetic constant varied slightly from0071 (1198772 = 098) to 0054 (1198772 = 095) and 0057 (1198772 = 096)(Table 1) respectively Sulfate in a photodegradation solutioncan cause the following reaction [31]

SO4

2minus+∙OH +H+ 997888rarr ∙SO

4

minus+H2O (4)

However the quenching role of sulfate was less effective whencompared with other anions like carbonate [28] This wasalso true in our study Only a little decreasing trend wasobserved for the rate constants between the nonaddition andthe treatments with addition of 1mM or 5mM sulfate

35 Effects of Bicarbonate Thefirst-order kinetic constants ofthe photodegradation of sulfadiazine were decreased to 0046(1198772 = 096) 0042 (1198772 = 093) and 0017 (1198772 = 089) with theaddition of 119 24 and 05mM bicarbonate respectively asshown in Table 1 indicating an inhibitory effect of bicarbon-ate on photolytic degradation of sulfadiazine which has also


been reported for photolytic or photocatalytic degradation ofnonylphenol and 2-chlorobiphenyl [32 33] Bicarbonate canact as a scavenger of ∙OH the mainmechanism of which is asfollows [34]

HCO3

minus+∙OH 997888rarr CO

3

minus∙+H2O (5)

The radical CO3

minus∙ is also an oxidant but less active than ∙OH[33 34]However although less reactive radicals generated insuchwaysmay bemore persistent in natural environment andhelp the slow but sustained removal of pollutants For exam-ple Schwarzenbach et al [35] argued that concentrations ofsteady-state CO

3

minus∙ in sunlit surface water were estimated tobe two orders higher than that of ∙OH radicals which alsoplays an important role in removal of environmental organicchemicals especially pollutants

All rate constants in the presence of bicarbonate werelower than those in the presence of sulfate suggesting thatbicarbonate has a higher quenching effect on hydroxyl radicalthan sulfate However the least bicarbonate addition in thisstudy resulted in the lowest rate constant Although moststudies demonstrated that the rate constant decreased withincreasing concentration of bicarbonate [36 37] as expectedfrom the scavenging mechanism some different phenomenawere also reported in some studies Zhang et al [38] foundthat the photodegradation rate of reactive brilliant orange K-R catalyzed by P25 TiO

2decreased significantly when the

conductivity increased from 05 to 31 or 123mSsdotcmminus1 owingto the existence of bicarbonate but did not further decreasesignificantly when the conductivity arrived at 241mSsdotcmminus1or at 472mSsdotcmminus1 The results might imply that increasingbicarbonate amounts generated more carbonate radicalswhich compensate the loss of the hydroxyl radicals sinceboth sulfur atom and benzene ring exist commonly in themolecular structure of sulfadiazine and reactive brilliantorange K-R [38]This might explain the less extent inhibitionof higher levels of bicarbonate observed in our study

36 Effects of pH Value As shown in Table 1 the initial pH452 resulted in lowest 119896 of 0046 (1198772 = 091) while atpH 698 and pH 820 119896 was 0065 (1198772 = 098) and 0057(1198772 = 094) respectively Sulfadiazine can be dissociatedto both cationic and anionic forms with 119901119870119886 values of 157and 650 respectively [39] In our study sulfadiazine existedmostly as neutral and anionic forms at pH 452 and pH 820respectively and as a mixture of both species but dominatedby the anionic form at pH 698 Therefore different reactionrates of ∙OH with various existence form of sulfadiazine maybe one explanation for the lower rate constant under pH 452However the discrepancy was not significant suggestingthat the solution acidity played a less important role in thisphotodegradation

4 Conclusions

Sulfadiazine was photolyzed at a high rate by irradiation ofUV 365 nm (300W) with a half-life of 976min as air wasintroduced inThe existence of nitrogen SO

4

2minus HCO3

minus andNO2

minus inhibited this reaction while H2O2 NO3

minus enhanced

the reaction rateTheneutral pH valuewasmost beneficial forthis photolytic reaction These phenomena suggest that thisreaction is possibly mediated mainly by hydroxyl radicalsResults of this study will also provide valuable reference forthe design and running of the system of pretreatment by UVphotodegradation of such chemicals

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

References

[1] A K Sarmah M T Meyer and A B A Boxall ldquoA global per-spective on the use sales exposure pathways occurrence fateand effects of veterinary antibiotics (VAs) in the environmentrdquoChemosphere vol 65 no 5 pp 725ndash759 2006

[2] T X Le and Y Munekage ldquoResidues of selected antibiotics inwater and mud from shrimp ponds in mangrove areas in VietNamrdquoMarine Pollution Bulletin vol 49 no 11-12 pp 922ndash9292004

[3] D G Capone D P Weston V Miller and C ShoemakerldquoAntibacterial residues in marine sediments and invertebratesfollowing chemotherapy in aquaculturerdquo Aquaculture vol 145no 1ndash4 pp 55ndash75 1996

[4] T Christian R J Schneider H A Farber D Skutlarek MT Meyer and H E Goldbach ldquoDetermination of antibioticresidues inmanure soil and surfacewatersrdquoActaHydrochimicaet Hydrobiologica vol 31 no 1 pp 36ndash44 2003

[5] S Thiele-Bruhn and I-C Beck ldquoEffects of sulfonamide andtetracycline antibiotics on soil microbial activity and microbialbiomassrdquo Chemosphere vol 59 no 4 pp 457ndash465 2005

[6] B G Bradel W Preil and H Jeske ldquoRemission of the free-branching pattern of Euphorbia pulcherrima by tetracyclinetreatmentrdquo Journal of Phytopathology vol 148 no 11-12 pp 587ndash590 2000

[7] L Wollenberger B Halling-Soslashrensen and K O Kusk ldquoAcuteand chronic toxicity of veterinary antibiotics to Daphniamagnardquo Chemosphere vol 40 no 7 pp 723ndash730 2000

[8] L Migliore G Brambilla P Casoria C Civitareale S Coz-zolino and L Gaudio ldquoEffect of sulphadimethoxine contami-nation on barley (Hordeum distichum L Poaceae Liliopsida)rdquoAgriculture Ecosystems and Environment vol 60 no 2-3 pp121ndash128 1996

[9] S Thiele-Bruhn ldquoPharmaceutical antibiotic compounds insoilsmdasha reviewrdquo Journal of Plant Nutrition and Soil Science vol166 no 2 pp 145ndash167 2003

[10] P Sukul and M Spiteller ldquoSulfonamides in the environment asveterinary drugsrdquoReviews of Environmental Contamination andToxicology vol 187 pp 67ndash101 2006

[11] A B A Boxall L A Fogg P A Blackwell P Kay E JPemberton and A Croxford ldquoVeterinary medicines in theenvironmentrdquo Reviews of Environmental Contamination andToxicology vol 180 pp 1ndash91 2004

[12] K M Doretto L M Peruchi and S Rath ldquoSorption anddesorption of sulfadimethoxine sulfaquinoxaline and sulfamet-hazine antimicrobials in Brazilian soilsrdquo Science of the TotalEnvironment vol 476-477 pp 406ndash414 2014

[13] A B A Boxall P Blackwell R Cavallo P Kay and J TollsldquoThe sorption and transport of a sulphonamide antibiotic in soilsystemsrdquo Toxicology Letters vol 131 no 1-2 pp 19ndash28 2002


[14] F Ingerslev and B Halling-Sorensen ldquoBiodegradability prop-erties of sulfonamides in activated sludgerdquo EnvironmentalToxicology and Chemistry vol 19 no 10 pp 2467ndash2473 2000

[15] P Sukul M Lamshoft S Zuhlke and M Spiteller ldquoPhotolysisof 14C-sulfadiazine in water and manurerdquo Chemosphere vol 71no 4 pp 717ndash725 2008

[16] A L Boreen W A Arnold and K McNeill ldquoTriplet-sensitizedphotodegradation of sulfa drugs containing six-memberedheterocyclic groups identification of an SO

2extrusion photo-

productrdquo Environmental Science and Technology vol 39 no 10pp 3630ndash3638 2005

[17] F Jiang Z Zheng Z Xu and S Zheng ldquoPreparation and char-acterization of SiO

2-pillared H

2Ti4O9and its photocatalytic

activity for methylene blue degradationrdquo Journal of HazardousMaterials vol 164 no 2-3 pp 1250ndash1256 2009

[18] A L Boreen W A Arnold and K McNeill ldquoPhotochemicalfate of sulfa drugs in then aquatic environment sulfa drugscontaining five-membered heterocyclic groupsrdquo EnvironmentalScience and Technology vol 38 no 14 pp 3933ndash3940 2004

[19] M G Gonzalez E Oliveros M Worner and A M BraunldquoVacuum-ultraviolet photolysis of aqueous reaction systemsrdquoJournal of Photochemistry and Photobiology C PhotochemistryReviews vol 5 no 3 pp 225ndash246 2004

[20] L Zang C-Y Liu and X-M Ren ldquoPhotochemistry of semi-conductor particles Part 4mdasheffects of surface condition on thephotodegradation of 24-dichlorophenol catalysed by TiO

2sus-

pensionsrdquo Journal of the Chemical Society Faraday Transactionsvol 91 no 5 pp 917ndash923 1995

[21] C B Almquist and P Biswas ldquoThe photo-oxidation of cyclo-hexane on titanium dioxide an investigation of competitiveadsorption and its effects on product formation and selectivityrdquoApplied Catalysis A General vol 214 no 2 pp 259ndash271 2001

[22] M Muruganandham and M Swaminathan ldquoPhotochemicaloxidation of reactive azo dye with UV-H

2O2processrdquoDyes and

Pigments vol 62 no 3 pp 269ndash275 2004[23] Q Hu C Zhang Z Wang et al ldquoPhotodegradation of methyl

tert-butyl ether (MTBE) by UVH2O2and UVTiO

2rdquo Journal

of Hazardous Materials vol 154 no 1ndash3 pp 795ndash803 2008[24] C Minero S Chiron G Falletti et al ldquoPhotochemincal

processes involving nitrite in surface water samplesrdquo AquaticSciences vol 69 no 1 pp 71ndash85 2007

[25] GMark H-G Korth H-P Schuchmann and C Von SonntagldquoThe photochemistry of aqueous nitrate ion revisitedrdquo Journalof Photochemistry and Photobiology A Chemistry vol 101 no2-3 pp 89ndash103 1996

[26] M V Shankar S Nelieu L Kerhoas and J Einhorn ldquoPhoto-induced degradation of diuron in aqueous solution by nitritesand nitrates kinetics and pathwaysrdquo Chemosphere vol 66 no4 pp 767ndash774 2007

[27] I K Konstantinou A K Zarkadis and T A Albanis ldquoPho-todegradation of selected herbicides in various natural watersand soils under environmental conditionsrdquo Journal of Environ-mental Quality vol 30 no 1 pp 121ndash130 2001

[28] Z Zainal C Y Lee M Z Hussein A Kassim and N A YusofldquoEffect of supporting electrolytes in electrochemically-assistedphotodegradation of an azo dyerdquo Journal of Photochemistry andPhotobiology A Chemistry vol 172 no 3 pp 316ndash321 2005

[29] M W Lam K Tantuco and S A Mabury ldquoPhotoFate a newapproach in accounting for the contribution of indirect pho-tolysis of pesticides and pharmaceuticals in surface watersrdquoEnvironmental Science and Technology vol 37 no 5 pp 899ndash907 2003

[30] D Vione G Falletti V Maurino et al ldquoSources and sinks ofhydroxyl radicals upon irradiation of natural water samplesrdquoEnvironmental Science and Technology vol 40 no 12 pp 3775ndash3781 2006

[31] K-H Wang Y-H Hsieh C-HWu and C-Y Chang ldquoThe pHand anion effects on the heterogeneous photocatalytic degra-dation of o-methylbenzoic acid in TiO

2aqueous suspensionrdquo

Chemosphere vol 40 no 4 pp 389ndash394 2000[32] MNeamtu and F H Frimmel ldquoPhotodegradation of endocrine

disrupting chemical nonylphenol by simulated solar UV-irradiationrdquo Science of the Total Environment vol 369 no 1ndash3pp 295ndash306 2006

[33] Y Wang C-S Hong and F Fang ldquoEffect of solution matrix onTiO2photocatalytic degradation of 2-chlorobiphenylrdquo Environ-

mental Engineering Science vol 16 no 6 pp 433ndash440 1999[34] R Andreozzi V Caprio A Insola and R Marotta ldquoAdvanced

oxidation processes (AOP) for water purification and recoveryrdquoCatalysis Today vol 53 no 1 pp 51ndash59 1999

[35] R P Schwarzenbach P M Gschwend and D M ImbodenldquoIndirect photolysis reactions with photooxidants in naturalwaters and in the atmosphererdquo in Environmental OrganicChemistry pp 655ndash686 John Wiley amp Sons New Jersey NJUSA 2002

[36] I Gultekin and N H Ince ldquoDegradation of reactive azo dyesby UVH

2O2 impact of radical scavengersrdquo Journal of Environ-

mental Science and Health Part A ToxicHazardous SubstancesampEnvironmental Engineering vol 39 no 4 pp 1069ndash1081 2004

[37] W Zhang X Xiao T An et al ldquoKinetics degradationpathway and reaction mechanism of advanced oxidation of4-nitrophenol in water by a UVH

2O2 processrdquo Journal of

Chemical Technology and Biotechnology vol 78 no 7 pp 788ndash794 2003

[38] W Zhang T An M Cui G Sheng and J Fu ldquoEffects of anionson the photocatalytic and photoelectrocatalytic degradationof reactive dye in a packed-bed reactorrdquo Journal of ChemicalTechnology and Biotechnology vol 80 no 2 pp 223ndash229 2005

[39] P Sukul M Lamshoft S Zuhlke and M Spiteller ldquoSorptionand desorption of sulfadiazine in soil and soil-manure systemsrdquoChemosphere vol 73 no 8 pp 1344ndash1350 2008

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Advances in

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Hindawi Publishing Corporationhttpwwwhindawicom

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SpectroscopyInternational Journal of


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Applied ChemistryJournal of



Theoretical ChemistryJournal of


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Spectroscopy

Analytical ChemistryInternational Journal of


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Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


No addition

10 20 30 40 50 60000

01

02

03

04

05

06

07

08

09

10

t (min)

CC

0

1 (v v) ethanol

Figure 1 Photodegradation of 11mgsdotLminus1 sulfadiazine in ultrapurewater under UV 365 nm (300W) with pumping-in of air in thepresence and absence of 1 ethanol The solid lines represent themodeling results of first-order kinetics (119862

1199051198620= 119890minus119896119905)

also used artificially to remove the microorganism toxicity ofantibiotics as a pretreatment method to make the activatedsludge system in the following step run more efficientlyTherefore results from UV photodegradation study notonly will be useful to learn the behavior of photolysis byultraviolet inwater environment but alsowill be helpful to thedesign of the artificial wastewater treatment system throughUV photolysis of such chemicals This work is designedto study kinetics and possible mechanisms of sulfadiazinephotodecomposition under pure UV by investigating theinfluences of some common affecting factors

2 Experimental

21 General Sulfadiazine (996purity) was purchased fromSigma USA Other chemicals were at least of analytical gradeand used without further purification

The photoreactor was designed according to Jiang et al[17]The ultraviolet lamp (365 nm 300W) used in our exper-iments was purchased from the Xujiang ElectromechanicalPlant Nanjing China

The HPLC system used in this study was an Agilent 1200series HPLC system which consisted of a G1322 A degassera G1311 A Quat Pump a G1329 A thermostatted autosamplerand a G1316A column oven The column for separation wasAgilent Eclipse XDB-C18 (5 120583m 46 times 250mm)

22 Photodegradation Procedures and HPLC Analysis About11mgsdotLminus1 sulfadiazine solution was prepared by dissolving55mg sulfadiazine into 500mL ultrapure water and was

transferred into the glass reactor To investigate the effectsof affecting factors additives were introduced respectivelyat the following concentrations ethanol of 1 in volume ofthe solution 438mgsdotLminus1 H

2O2 sodium salts with 005mM

NO2

minus 05mM NO3

minus 1 mM and 5mM SO4

2minus and 05 24and 119mM HCO

3

minus The pH effect was studied by addingappropriate HCl or NaOH The first sample (defined as time0) was taken immediately after the addition of one of thesechemicals to the reactor The ultraviolet lamp in the centralhollow was then turned on and photodegradation processwas started All experimental processes were accompanied byvigorous stirring and air-pumping into the system at 1mLsdotsminus1except that in the case of nitrogen effect N

2instead of air

was pumped in Sampling was performed at different timeintervals The samples were frozen at minus20∘C until analysisThemobile phase used for HPLC analysis of sulfadiazine wasmethanol water = 30 70 (v v) isocratically running at a flowrate of 1mLsdotminminus1 Calibration curves were used to read thevalues of sulfadiazine for all samples and the quality controlofHPLCwas carried out by injecting and analyzing the lowestand highest concentrations of standard sulfadiazine solutionsat the beginnings and ends of all analytical circles Controlexperiment without any irradiationwas carried out under thesame conditions All experiments were performed at least induplicate

3 Results and Discussion

31 Effect of Ethanol Control experiment under dark condi-tions showed ignorable disappearance of sulfadiazine in thesolution (data not shown) indicating that the compound wasstable in the dark that is hydrolysis of sulfadiazine was notsignificant which is in agreement with the observations ofBoreen et al [18] who found thatmost sulfa drugs were stablein solutions of various pH values

Under radiation sulfadiazine in pure water was degradedby 99 percent in one hour with a half-life of 976min (Fig-ure 1) The first-order kinetic model (119862

1199051198620= 119890minus119896119905) was used

to describe the degradation process under various conditionsresulting in a relationship of the ratio of remaining sulfadi-azine (119910) versus time (119909) as 119910 = 119890minus0071119909 (1198772 = 098 Figure 1and Table 1) Sulfadiazine in natural water might be degradedby irradiation through both direct and indirect waysTheUV-Vis absorption spectrum of sulfadiazine has a tailing band inthe region of wavelength over 290 nm [15] which suggeststhat the way of direct photolysis for this compound cannotbe preexcluded [15]When ethanol a hydroxyl scavenger wasadded to the solution 119896 value decreased to 0009 (1198772 = 100)This indicates that the dominant mechanism for sulfadiazinedegradation might be the attack of hydroxyl radicals andtherefore that degradation of sulfadiazine through the directabsorption of light was limited to a very small extent Thephotolysis of water by UV irradiation may involve 25ndash30reactions and 14 different species including H∙ HO

2

∙ and∙OH [19] Under the radiation of a xenon lamp sulfadiazinein pure water had a rather longer half-life (32 h) with 119896 valueof 00094 [15]



2instead)


Condition 119896 1198772



2O2


2


3


4


4


3


3


3




1199051198620=






H2O2+ ℎ] 997888rarr 2∙OH (1)



2O2UV or Fe2+H

2O2UV as







NO3


2+O∙minus



2photocatalytic





NO2


2+OHminus (3)



SO4


4

minus+H2O (4)





HCO3


3

minus∙+H2O (5)

The radical CO3


3






4 Conclusions


4

2minus HCO3

minus andNO2


minus enhanced


Competing Interests


References


















2extrusion photo-



2-pillared H






2sus-







2rdquo Journal


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



2instead)


Condition 119896 1198772



2O2


2


3


4


4


3


3


3




1199051198620=






H2O2+ ℎ] 997888rarr 2∙OH (1)



2O2UV or Fe2+H

2O2UV as







NO3


2+O∙minus



2photocatalytic





NO2


2+OHminus (3)



SO4


4

minus+H2O (4)





HCO3


3

minus∙+H2O (5)

The radical CO3


3






4 Conclusions


4

2minus HCO3

minus andNO2


minus enhanced


Competing Interests


References


















2extrusion photo-



2-pillared H






2sus-







2rdquo Journal


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



HCO3


3

minus∙+H2O (5)

The radical CO3


3






4 Conclusions


4

2minus HCO3

minus andNO2


minus enhanced


Competing Interests


References


















2extrusion photo-



2-pillared H






2sus-







2rdquo Journal


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2extrusion photo-



2-pillared H






2sus-







2rdquo Journal


































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

Documents

Research Article Photodegradation of Sulfadiazine in Aqueous …downloads.hindawi.com/journals/jchem/2016/8358960.pdf · Research Article Photodegradation of Sulfadiazine in Aqueous