| Photo?assisted MES uses semiconductor photo?generated electrons to increase the current and photo?generated holes to increase the anode"extraction"electron driving force,to improve the cathode electrochemically active bacteria(EAB)use electrons directly or use mediators indirectly to reduce inorganic carbon to product acetate.In the research of photo?assisted MES reduction of inorganic carbon,the MES improves the performance and efficiency of acetate production by improving the modification or loading of the cathode material,the concentration of the substrate and the physical and chemical properties of the solution,and EAB.There are few reports on the relationship of cathode of photo?assisted MES,cellular electron transfer(CET)and acetate production.In this study,the production of acetate from inorganic carbon reduction in the photo?assisted WO3/MoO3/g?C3N4 cathode of MES incorporating with Serratia marcescens Q1 and.Stenotrophomonas sp.JY6.By adding 2,4?dinitrophenol(2,4?DNP),a respiratory chain inhibitor,through changes in system performance(Such as the production of acetate,residual hydrogen,current,coulombic efficiency,inorganic carbon conversion rate),electrochemical analysis,and changes in the amount and composition of extracellular polymeric substances to explore the close relationship and interaction between photo?assisted cathode,CET and acetate production.Main results include:The addition of DNP significantly reduces the production of acetate(Q1:38±1 mg/L vs.93±6mg/L;JY6:31±1 mg/L vs.80±1 mg/L),current(Q1:0.66±0.02 m A vs.0.88±0.01 mg/L;JY6:0.60±0.01 m A vs.0.88±0.01 mg/L),coulombic efficiency of acetate(Q1:44±1%vs.74±4;JY6:40±2%vs.71±1),residual hydrogen(Q1:0.028 m3/m3/d vs.0.0033 m3/m3/d;JY6:0.042 m3/m3/d vs.0.026 m3/m3/d),inorganic carbon conversion rate(Q1:62±1%vs.86±4%;JY6:65±4%vs.82±1%)in photo?assisted MES.CV analysis showed that the reduction of Eonset after adding DNP(Q1:?0.39 V vs.?0.30 V;JY6:?0.45 V vs.?0.34 V)and the reduction of Ip(Q1:?0.23 m A vs.?0.30 m A;JY6:?0.19 m A vs.?0.41m A).DPV analysis showed that the content of cytochrome c protein on the two bacteria biofilms decreased after adding DNP.EIS analysis showed that the Rct increases after adding DNP(Q1:54.3?vs.32.8?;JY6:63.7?vs.35.4?).EEM analysis showed that the peak absorption values of the five Peaks all decreased,there are two Peaks of JY6,the peak absorption values are all reduced,which all after the addition of DNP.The disappearance of the inhibitory effect of DNP is mainly manifested in system performance(the production of acetate,current),resistance of each part of the system,and the total amount of EPS,but the content of each component of EPS has increased or decreased(operational time:7.5 d).The results show that in the photo?assisted cathode MES,the EAB utilize the hydrogen?producing mediator of the photo?assisted cathode,relying on cellular electron transfer,and the biofilms released EPS have different components and contents. |
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