pn型异质结催化剂Ag2OBiVO4对微囊藻毒素MCRR的光化学氧化机理研究

ChineseJournalofCatalysis38(2017)192-198催化学报2017年第38卷第2期|(SpecialIssueontheInternationalSymposiumonEnvironmentalCatalysis(ISEC2016))Photochemicaloxidationmechanismofmicrocystin-RRbyp-nheterojunctionAg/Ag2〇-BiV〇4ChunhongWua,b,c,d,YanfenFang气ArayaHailuTirusewb,c,MiaomiaoXiang气YingpingHuangb，c，1*,ChunchengChenb，c，#aCollegeofbiologyandpharmacy,ChinaThreeGorgesUniversity,Yichang443002,Hubei,ChinabInnovationCenterforGeo-HazardsandEco-EnvironmentinThreeGorgesArea,Yichang443002,Hubei,ChinacEngineeringResearchCenterofEco-environmentinThreeGorgesReservoirRegion,MinistryofEducation,ChinaThreeGorgesUniversity,Yichang443002,Hubei,ChinadMedicalCollegeofChinaThreeGorgesUniversity,Yichang443002,Hubei,ChinaARTICLEINFOArticlehistory:Received25September2016Accepted23October2016Published5February2017Keywords:Photochemicalp-nheterojunctionSilverSilveroxideBismuthorthovanadateMicrocystin-RR(MC-RR)MechanismABSTRACTMicrocystin-RR(MC-RR),aformofmicrocystinwithtwoargininemoieties,isacyanobacterialtoxinthathasbeendetectedacrossawidegeographicrange.Itisagreatconcerngloballybecauseofitspotentiallivertoxicity.Herein,theabilitiesofBiV〇4,Ag-BiV〇4,Ag2〇-BiV〇4andAg/Ag2〇-BiV〇4tophotocatalyticallydegradeMC-RRundervisible-lightirradiation(入》420nm)wereinvestigatedandcompared.Thepossibledegradationpathwayswereexploredthroughanalysisofthereactionintermediatesbyhigh-performanceliquidchromatography-massspectrometry.TheresultsshowedthatthepresenceofAg0enhancedthephotocatalyticefficiencyofAg/Ag2〇-BiV〇4viaasynergeticeffectbetweenAg2〇andAg0atthep-nheterojunction.Moreover,thepresenceofAg0alsogreatlypromotedtheadsorptionofMC-RRonthephotocatalystsurface.ToxicologicalexperimentsonmiceshowedthatthetoxicityofMC-RRwassignificantlyreducedafterphotocatalyticdegradation.©2016,DalianInstituteofChemicalPhysics,ChineseAcademyofSciences.PublishedbyElsevierB.V.Allrightsreserved.1.IntroductionThegrowthofblue-greenalgaeasaresultofeutrophicationpromotestheformationofmicrocystins,aclassoftoxins,whichhasbecomeanissueofglobalconcern[1].Inadditiontopoi­soningwildanimals,livestockandpoultry,microcystinscanalsocontaminatedrinkingwater,leadingtoliverdamageinhumansandanincreasedincidenceoflivercancer[2-5].Toxi­cologicalresearchhasfoundthatmicrocystinsinhibitmamma­lianliverfunctionbybindingto1A(PP1)and2A(PP2),thuscausingliver-tissuenecrosisandresultinginprimarytumors[6-9].Avarietyofconventionalwater-treatmentmethods,includ­ingflocculation,activated-carbonadsorptionandmembraneseparation,havebeenemployedtopurifywatercontaminatedbymicrocystins.However,becauseofthelowconcentrationsandstablestructuresofthemicrocystins,thepurificationeffi­ciencieswerefarfromsatisfactory[10-12].Inrecentyears,theusesofadvancedoxidationtechnologiesfortheremovalofmicrocystinshasreceivedwideattention.Ofthevariousmi-*Correspondingauthor.Tel:[phone];Fax:[phone];E-mail:[e-mail]#Correspondingauthor.Tel:[phone];Fax:[phone];E-mail:[e-mail]theNationalNaturalScienceFoundationofChina(21677086,21407092,21377067,21577078)andtheNaturalScienceFoundationforInnovationGroupofHubeiProvince,China(2015CFA021).DOI:10.1016/S1872-2067(16)62583-4||Chin.J.Catal.,Vol.38,No.2,February2017ChunhongWuetal./ChineseJournalofCatalysis38(2017)192-198193crocystinsidentifiedtodate,MC-LR,MC-RRandMC-YRarethemosttoxicandabundant[13-15].Microcystin-RR(MC-RR)hasbeenfoundtobewidespreadinwaterbodiespollutedbyblue-greenalgaeinChina[16].Inaddition,furtherstudieshaverevealedthatMC-RRisthemostresistanttophotocatalyticdegradationbyTi〇2underUltravioletirradiation[17].Photocatalysishasbeenestablishedasaneffectivetech­niquefortheremovalofmicrocystins.ForMC-RR,thestudyofphotocatalyticdegradationhasparticularlyfocusedonphoto­catalystssuchasBi2W〇6[18]andTi〇2[19,20]underUVirra­diation.Becauseonlyaverysmallportionofsunlight(about4%)isultraviolet,itisimportanttoextendtheresponseofthesephotocatalyststothemoreabundantvisibleregion.However,littleworkhasbeendoneonthevisible-light-inducedphotocatalyticdegradationofMC-RR.Inourpreviousstudy,wereportedanAg-BiV〇4compositephotocatalystpreparedbyaone-stephydrothermalmethod[21].Inthiscatalyst,bothAgandAg2〇coexistedonthesurfaceofBiV〇4,formingap-nhet­erojunctionandthusgreatlyimprovingthephotocatalyticeffi­ciency[22-31].Asaresult,thecompositephotocatalystexhib­itedexcellentphotocatalyticactivityforthedegradationofthedyerhodamineBandcolorlesssalicylicacidundervisible-lightirradiation(A420nm)[21].Inthepresentstudy,weextend­edtheapplicationofthiscompositephotocatalysttothedeg­radationofthegeographicallywidespreadtoxinMC-RRtore­alizeitsvisible-lightdegradation.Inaddition,tofabricatemoreefficientheterojunctionstructuresbetweentheAgspeciesandtheBiV〇4,atwo-stephydrothermalmethodwasemployed.ItwasfoundthattheAg/Ag2〇-BiV〇4couldbeusedasanefficientphotocatalystforthephotodegradationofMC-RRunder