ExperimentalstudyontheabsorptionbehaviorsofgasphasebivalentmercuryinCa-basedwetfluegasdesulfurizationslurrysystemAbstractiGasphaseoxidationandcatalyticoxidationofelementmercury(IIg°)tobivalentmercury(Hg2')wereproposedtoimprovethemercuryremovalefficiencyinthewetfluegasdesulfurization(WFGD)system.However,there-emissionofHg°,generatedbythereductionofabsorbedHg2",wouldleadtoadampingofthetotalmercuryremovalefficiency.Inthispaper,theabsorptionandreductionbehaviorsofbivalentmercuryintheCa-basedWFGDslurrywereevaluatedinourpurpose-builtdevice.Accordingtoourexperimentalresults,theslurrychemistry(suchasCaS〇3content,SO42,ClandpHvalue)hadastronginfluenceonthereductionofabsorbedbivalentmercury.AndtheinletconcentrationsofSO2and〇2contributelittletothemercuryabsorption.WithinthetypicalpHvaluerangeof4.5-5.5,about70%ofinletbivalentmercurywasconvertedtoHg°.There-emissionofHgwouldbegreatlyretardedwiththeincreaseof[SO42]duetotheformationofHgS〇4orHg3〇2S〇4.Moreover,itwasfoundthatClwouldalsoinhibitthereductionofbivalentmercurythroughtheligandsreactionsbetweenClandHgz.IntroductionMercury,duetoitspersistence,bio-accumulationandneurologicaltoxicity,hadreceivedconsiderableattentionfromenvironmentalengineersandenvironmentalprotectinginstitutions[1].AccordingtotheconservativeestimationofEnvironmentalProtectionAgency(EPA),theexposurereferencedoseof0.1fig(mercury)/kg(bodyweight)/daywasjustifiedtoprotectagainstharmfulneurologicaleffectsduringfetaldevelopmentandearlychildhood[2].Coalcombustionwasconsideredasthelargestsourceofanthropogenicmercuryemission.Mercuryexistedinthefluegasmainlyinthreeforms:elementmercury(HgO),oxidizedmercury(Hg2一）andparticle-boundmercury(Hg(P))[3].Inthecombustionzone,themercuryinthecoalwasfirstevaporatedandturnedtotheelementalform(Hg°),whichwasthenpartlyoxidizedtooxidizedmercury(Hg2)bysomefluegascomponentssuchasIIC1,S〇2,NOxandflyashaspassingthroughthedownstreamofthecombustionzone.Somemercurywasassociatedtoflyashorparticulatesandturnedtoparticle-boundmercury(Hg(P)),whichwa