Photodegradation Mechanism Of Methylmercury In Environmental Surface Water

Methylmercury?MeHg⁺?is a highly toxic form of mercury that has neurotoxic and lipophilic.It can be bioaccumulated by penetrate the cell membrane in aquatic organisms and pose a serious threat to human health.Although most related researches on the photodegradation of MeHg⁺ has been studied in surface water,much remains unclear about the mechanism of MeHg⁺ degradation.So the research about the photodegradation of MeHg⁺ should be further studied.In this paper studied the production of reactive oxygen species in aqueous solution of fulvic acid,Fe³⁺,NO₃^-and the effect of direct illumination,p H values of the solution,FA,Fe³⁺,NO₃^-,N2 purging on the photodegradation of MeHg⁺ under the simulated solar light.The results showed that after 8h simulated solar light irradiation,11.6% MeHg⁺ direct photodegradated,while 35%,22.43%,19.1% MeHg⁺ photodegradated in 16mg/L FA,5.0 mM NO₃^-,20?M Fe³⁺solution,respectively.It also indicated that the degradation efficiency of MeHg⁺ was increased with the p H value of the solution and N2 purging.Under the sunlight,the increase in the photodegradation rate in the presence of FA is may due to the effective production of singlet oxygen?¹O₂?and excited triple state of FA?³FA*?,while Fe³⁺ and NO₃^-ion through generated ¹O₂ and hydroxyl free radical??OH?to promoted the photodegradation of MeHg⁺.O₂ and dissolved gaseous mercury?DGM?in solution were released into the air,inhibiting the reoxidation of zero mercury and promoting the photodegradation of MeHg⁺ by N2 purging.