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liquid Hybrid Discharge Reactor for 4-CP Containing Wastewater Treatment

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liquid Hybrid Discharge Reactor for 4-CP Containing Wastewater Treatmentliquid

    liquid Hybrid Discharge Reactor for 4-CP

    Containing Wastewater Treatment ChineseChemicalLettersVo1.17,No.4,PP541544,2006

    http://www.imm.ac.cn/journal/cc1.html

    541

    NovelGasliquidHybridDischargeReactorfor4CPContaining

    stewateratment

    YiZHANG,MingHuaZHOU,LeChengLEI*

    InstituteofEnvironmentalEngineering,Zh@angUniversity,Hangzhou310027 Abstract:Inordertoimprove4CPdegradationemciency,anovelgas

    liquidhybriddischarge

    (HD)reactorwasdeveloped.Removalof4CPwithspark

    sparkdischarge(SSD)washigher

    thanthatwithspark

    coronadischarge(SCD).AmountofH20,and03producedwithSSDwere largerthanthatwithSCD.?OHformationwasincreasedbythecombinationofH,O,andO1. Thecontributionof?0H(38%formedbyO1conversion)oxidationonmmovalof4

    CPaccounted

    f0rnearly60%.Theothereffectsofultraviolettadiation.intenseshockwavesandpyrolysis. playedpartialrolesinabout40%ofremovalrate.

    Keywords:Gasliquidhybrid,sparksparkdischarge,03,H202,?OH

    Pulsedhighvoltagedischargetechnologyisanewlydevelopedmethodfordegradation oforganicpollutantsinwaterwithvariouselectrohydraulicreactorsRecently,a noveltypeofgasliquidhybriddischarge(HD)reactorwithgroundelectrodeabove water1evelandhighvoltageelectrodesubmergedinwaterisreporte.ThisHD

    reactorutilizesbothgasphasenonthermalplasmaformedabovethewateranddirect

    liquidphasecoronalikedischarge(sparkcoronadischarge,SCD).Asreportedby

    severalstudies,sparkdischargeinliquidisadvantagetotreatpollutantmore completelythancoronadischarge.Inourstudy.theHDreactorcouldproduceboth sparkdischargeingasphaseandliquidphase(sparksparkdischarge,SSD).Ournovel

    HDreactorcanproducemoreactivespecies,suchas03,I'-I202,?Oand?OHbyintense sparkdischarge.

    ThispaperreportedthatSSDwasusedforremovalof4CPinsteadofSCD.The

    concentrationofO3andH2O2wasdeterminedtoexplorethepossibledegradation mechanismwithSSDstyle.Andtheeffectsof03.H202and?OHonremovalof4CP

    werealsoexplored.

    Figure1showstheschematicdiagramoftheexperimentalapparatus.The electricalsourceusedinthepresentstudywasidenticaltothatusedinpreviouswork. ThereactorwasaPlexiglascylindercontaininganeedleplategeometryelectrodesystem

    111ehighvoltageelectrodeswere7hollowstainlesssteelinjectionneedles.Theground electrodewasastainlesssteeldiskwith90mmjndiameterabovethewaterleve1. E?mail:lclei@zju.edu.cn

542

    Ox

    cyl

    YiZHANGf

    Figure1Schematicdiagramoftheexperimentalapparatus

    OxygenwasinjectedintothereactorthroughthetipofneedleelectrodeswimtheflUXof 0.2m/h.4.CP(500mE)wascirculatedwithaperistalticpumpandmaintainedthe temperatureat25.Cbycoolingwater.

    Theconcentrationof4.CPwas50mg/Lforthedegradationexperiments.The concentrationoftert.butylalcohol,usedinthisstudy,was300timesof4.CPtoensure scavenging?OHcompletely.The4?CPwasanalyzedbyHPLC(KnauerK?2005)with themobilephaseofsuperpurifiedwaterandmethanolfVPc,50:50).Andme concentrafionofOindistilledwaterwasmeasuredbyUVabsorptionat254nm.The concentrationofH202wasdeterminedcolorimetricallybythereactionofH2O2wim

titanylions.

    Figure2depictstheSSDstyleat10.10mm(theformernumberindicatesthe distancefromhighvoltageelectrodetoWatersurface,andthelatternumberindicatesthe distancefromWatersurfacetogroundelectrode)andSCDstyleat30.10nllTl, respectively.Thedischargecouldoccurbominliquidphasebelowmewaterleveland gasphaseabovethewaterleve1.Inliquidphasethesparkdischargewasmoreintense thancoronadischarge.Andingasphasethesparkchannelswerealsobrighterwith SSDthanwithSCD.

    Figure3presentsthe4.CPremovalinHDreactonThedegradationof4CPwith

    SSDreached100%after40min.andthatwithSCDwasonlyabout10%.Andthe energyemciencywas1.18x10mol/JwimSSDwhile0.13x10mol/JwimSCD. Figure2SCD(a)andSSD(b)inHDreactor

    NovelGas-liquidHyb~dDischargeReactorfor4-CPContaining543 WastewaterTreatment

    Figure34CPremovalatdifferent

    conditionsinHDreactor

    TiI11e(min)

    

    

    }

    0

    

    IU

    Figure4H202and03formationinHD

    reactor

    Time(rma)

    Theactivespeciesformationwasinvestigatedtoexplorethemechanismforhigher Femovalefnciencywitl1SSDthallSCD.TheconcentrationofO1indistilledwaterat 60minwas3.9mg/L,asdepictedinFigure4,whichwasfourtimeshigherthallwitl1

    SCD(0.88mg/L),andtheconcentrationofH2O2was154.8mg/Lindistilledwaterat60 min,whichwasmuchhigherthanthatofwitl1SCD(18.3mg/L).InthecaseofSSD, 03producedingasphasewas350mg/mwhile57mg/mobservedintailgas,indicating tl1atnearly84%ofOwasutilizedforremovalof4CEBecauseOwasarelatively

    selectiveoxidant,therateofFemovalof4.CPbydirectoxidationwit}lOwasonly6o0 L/(mol?s)".Directoxidationof4CPbyH2O,wasalsonoteffective,onlylittleamount Of4CPwasdegradedinourexperiment.Theresultsindicatedthattheremoval efficiencyforH202and03oxidationwassmallrespectively.However,the concentrationofH2O2in4CPsolutionwasonly26.4mg/Lat60min,asseeninFigure 4,indicatingthatnearly80%H2O,participatedin4-CPremova1.Therefore,the combinationofO3andH2O2,and/oralongwithultravioletlight,canincrease?0H formationanddegrade4CPcompletely.The?0Hgeneratedwitl1SSDprobablycould beexplainedbythefollowingreactions'':

    O3(aq.

    )+H2002+H2O2

    H2O22g0H

    H20HggOH

    H2O2-?HO2+H

    O3+HO2-->gOH-1-O2+02

    (1)

    (2)

    (3)

    (4)

    (5)

    Tbeeffectsof.OHon4.CPremovalarepresentedinFigure3.Itwasonlyabout 40%removalof4CPat40minwith.OHscavengeradded.whichvalidatedtheopinion abovethat?OHplayedmostimportantroleinremovalof4CP(nearly60%1.From

    Figure3,whenOwasnotcirculatedintoHDreactor,therateofremovalof4CPat40

    minwas20%lessthanthatwitl1O,circulationwitl1SSDstyle,andtheconcentrationof liquidphaseOwasonly0.5mg/Lafter60min,whichwas13%O3residualinHD

    reactor.ThereforeOplayedonlyapartofrolein-0Hformation(about38%). 啦一蹬0^0

544YiZHANGf

    Ultravioletradiation,intenseshockwaves,pyrolysis,ect.,effecttheremovalof4CP

    about40%.

    Inconclusion.SSDinthenovelHDreactordegrades4CPefficiently.Thisnew

    dischargestyleisexpectedtobevaluableforenvironmentaltreatmentwithhighenergy utilization.OptimizationofSSDsystemtoobtainhigherenergyutilizationandachieve quickermineralizationwillbesolvedinthefurtherWOrk.

    Acknowledgments

    Thisworkisfinancialsuppo~fromNationalKeyNaturalScienceFoundmionofChina (No.20336030)andDistinguishedYouthFoundationofZhejiangProvince(RC02060). References

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Received22August,2005

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