The Effect Of Graphene On The Interaction Of As(?) With Shewanella

Recent studies have shown that graphene oxide(go)can be used as an efficient adsorbent to remove heavy metal ions from water.A large number of oxygen-containing functional groups exist on the surface of go,which not only ensure its good hydrophilicity,but also provide the site of complexation with the surface of heavy metal ions.However,oxygen-containing groups may be deoxidized in anaerobic environment.In view of the stability of the adsorbed heavy metals on the surface of go into the actual environment,this paper uses Shewanella putrefaciens(S.p)to construct the source reduction conditions,and investigates the interaction between S.p and As(V)under the participation of GO.The conclusion of this paper are:(1)Characterization of morphology before and after GO reactionThe structure of GO was characterized by XRD,Raman,FTIR and XPS.The results show that GO can be reduced by S.p to MRG,and there are some oxygen-containing functional groups on its surface.SEM images show that with the reduction of GO,S.p and GO can form small agglomerates,which shows that the hydrophilic dispersion of MRG decreases,and the MRG formed has continuous and uniform morphology characteristics,with obvious edge wrinkles.(2)Characterization of morphology of graphene before and after reactionGo was converted into reduced graphene oxide(r GO)by chemical reduction.After adding different kinds of graphene in the system of S.p reduction As(V),it was found that GO and rGO could improve the reduction rate of S.p to As(V).When the concentration of As(?)is increased from 20 ?g/L to 200 ?g/L,the reduction rate of S.p to As(?)has not been significantly improved under the condition of 50 mg/L of GO or rGO,which may be due to the high density of bacteria,while As(?)at 200?g/l still shows a relative deficiency to bacteria,so the reduction rate mainly depends on the rate of electron transfer,and has nothing to do with the concentration of As(?).(3)Study on the mechanism of arsenic reduction by GO and S.pIn the culture system with GO,CV curve obtained by cyclic voltammetry is much larger than that without GO,which shows that MRG obtained by GO reduction has good electronic conductivity and can promote the electronic conduction between micro organism and electrode.By scanning the S.p/GO and S.p systems at different scanning rates,it is found that the redox peak current in the S.p system at different scanning rates is directly proportional to the scanning rate(or square root),indicating that the electronic conduction mode in the S.p system is direct conduction and indirect conduction.In S.p/go system,no redox peak has been observed,indicating that the direct conduction mode may be mainly involved in pigment C protein.By applying +0.2V potential to the S.p/go system,under the action of high positive polarization,the pigment C protein used for electron transfer outside the cell of bacteria will be oxidized,which will affect the process of electron conduction to the electron acceptor,resulting in the reduction rate of As(V)by the Shewanella putrefaciens.