Experimental Study On Electricity Generation Performance Of MFC Air Cathode Prepared By Roll Pressing Method

Microbial fuel cell(MFC)is a bioelectrochemical technology which can generate electricity while treating wastewater,which has a good application prospect.In this experiment,PTFE/activated carbon was used as the catalytic layer and PTFE/conductive carbon black as the diffusion layer.The catalytic layer and the diffusion layer are respectively rolled on both sides of the carbon steel mesh to form an air cathode,building a sandwich structure.XRD,SEM,electrochemical workstation,electrophoresis gel and other physical,chemical and biological methods were used to examine the effects of different anodes,cathodes under different conditions and changes in conditions during operation on the reactor.(1)carbon paper and carbon felt were used as anodes respectively.after starting the reactor,the carbon paper did not start successfully,while the voltage of carbon felt reached 50 mV after 13 days.the following several cycles worked well and started successfully.Firstly,the characteristics of the electrode flora on the carbon felt anode and the carbon brush anode which were successfully started were analyzed and compared.It was found that proteobacter bacteria on the anode producing electricity were the dominant bacteria(accounting for80.36%and 78.52%of the total respectively).Secondly,by changing the potential and the surface area of the anode,it is concluded that when the potential of the anode is around-200mV,the best overall power density for operation is 58.7 mW/m~2 when the potential of the anode is-200 mV,while the removal rate of cod and the coulombic efficiency are 72%and7.3%respectively.The anode carbon felt was halved,electromotive force changed little,but the power density did not change obviously only at 30?.(2)the linear resistance density(350?/cm)of air cathode diffusion layer made of alcohol dispersion is much larger than the internal resistance(170?/cm)of air cathode diffusion layer made of water.at the same time,the air intake is also relatively weak,but the actual power density of the two is similar.(the power density of the reactor made of water as dispersant is 1172 mW/m~2,and that of the cathode made of alcohol as dispersant is 1021mW/m~2).Drying(power density 975 mW/m~2)instead of sintering(687 mW/m~2)can improve the operating effect of air cathode.Comparing the maximum power density(822.5mW/m~2)without removing cathode surface active molecules with the maximum power density(684 mW/m~2)without removing surface active molecules,the effect without removing electrode surface active molecules is better.(3)changing the temperature,substrate concentration,composition and biofilm will affect the metabolic status of anode microorganisms:the operating effect of 30?(power density,cod removal rate,power density)is the most suitable.The substrate was replaced by domestic sewage.it was found that the electromotive force(350 mV)of the reactor was close to that of the laboratory water distribution(413 mV)when the reactor was initially operated,and the power density would decrease(1165 mW/m~2 decreased to 786 mW/m~2 within 120days).The failure of industrial wastewater operation shows that the single-chamber air cathode MFC is currently only suitable for wastewater treatment with low salt and high organic matter concentration.