Application Research Of Benthic Microbial Fuel Cell With Carbon Fiber Cathode And Metal Anode

In recent years, the energy crisis and environmental problems have becomeincreasingly prominent, develop new energy technologies become the key to solvethese problems. Microbial fuel cell (MFC) is a new method of producing electricpower from organics by the use of bacteria, which is the most simple and practicablemeans to purifying wastewater. The research of MFC has made great progress inrecent years, but there is still some way to practical application.In MFCs, the benthic microbial fuel cell (BMFC) may be practical application inshort term, it’s a device which produces electric power from organics in sea mud bythe use of bacteria. More and more researchers pay attention to BMFC for its rich rawmaterial resources, simple configuration and high efficiency of electricity production,how to further increase the efficiency of electricity production to practical applicationbecome the focus of the current study. This paper studied the anode and cathode ofBMFC to increase its power density, the major content of research and results are asfollows:(1) The electrode performance of BMFC is mainly controlled by specificsurface area, cathode material generally uses the PAN-based carbon fiber (CF-P) atpresent, but the Rayon-based carbon fiber (CF-R) have larger specific surface areaand lower strength compare with CF-P. In this paper the two carbon fibers areheat-treated to obtain the modified carbon fibers (CF-P-H and CF-R-H), andcompare BMFCs performance when CF-P, CF-R, CF-P-H and CF-R-H are used ascathode. Results indicate that CF-R-H has the largest specific surface area644m2·g-1and when CF-R-H used as cathode its anti-polarize ability is more betterthan other cathodes, the BMFC uses CF-R-H cathode has the biggest output powerdensity112.4mW·m-2. The reasons are some quinone compound form on carbonfiber surface and the specific surface area of CF increases at heat treatment process,the synergistic effect of these two aspects enhance the reduction rate of oxygen on cathode, the performance of BMFCs improve accordingly.(2) The cathode of BMFC, floating in seawater at practical application process,might be attached by marine algae and degrade the performance of cathode. In orderto avoid this phenomenon, CF cathode modified by polytetrafluoroethylene (PTFE)for a hydrophobic property. Results indicate that the contact angle of the carbon fiberincreases after the modified methode, and the hydrophobic property was significantpositive correlated with the concentration of PTFE emulsion, these results enhancecathode’s property of anti-halobios adhesion. The output power density of BMFCsdecrease when PTFE with15%,30%and45%concentration modified CFs cathode,this is because PTFE is a insulating material, when it coats on the surface of the CFs itmakes the resistance of electrodes increase. Compare to blank control cell, the outputpower density of BMFC which modified by60%PTFE increases, this is due to PTFEform gas diffusion layer on electrode surface, oxygen and water can get to the cathodemuch easier, and the performance of cathode enhance accordingly.(3) This paper uses magnesium and aluminum as the anode of BMFC toincrease its output power density, and compare the performance of BMFC and sea cellwhen metal uses as anode. Results indicate that the output power density of BMFC islower than sea cell, but the corrosion rate of metal anode in BMFC slower than in seacell, the output power density of cells with magnesium anode is higher than withaluminum anode. This paper uses BMFC with metal anode and CF cathode combinewith booster device to drive marine instrument–bathythermograph, Both BMFC andsea cell can driver marine instrument, but BMFC can last much longer, it moresuitable for long-term application in ocean. These researches can lay the foundationfor practical application of BMFC.