Preparation And Characteristics Of Various Anodes Material For Microbial Fuel Cell

Microbial fuel cells （MFCs） are the devices used bacterias as the catalysts to convertbiochemical into electrical energy. MFCs play an important role for solving the energycrisis and environmental problems in the world, which is characterized by promising wideapplications. Due to its lower output voltage and power density, the main research is stillin the laboratory stage.Materials used for anode and their structrue are key factors for the successfulapplication performance of MFCs. The specific performances consist of its affects onbacteria adsorption, electron transfer, matrix oxidation, etc. The most commonly usedanode materials are carbon, graphite, etc. To further improve the performance of MFCs,the modified and embellished anodes prove to be an active research field.In this thesis, graphite rods modified by polyaniline （PANI） and multi-walled carbonnanotubes （MWNTs） were synthesized using different electrochemical method, involvingCV （cyclic voltammetry） method and potentiostatic method. This method suffered fromthe shortcoming of chemical method such as long time preparation, complex process,poor actual application performance, high cost, etc. When the film anodes were used inthe anaerobic fluidized bed microbial fuel cell （AFBMFC）, the performance of electricityproduction and the wastewater COD strain-away efficiency were evaluated. The mainresults were as follow: Firstly, it indicates that the electrochemical method, cotaining CV（cyclic voltammetry） method and potentiostatic method etc., is a high-efficiency methodto perapare the electrode material, which can shorten the preparation route and obtain thecomposited film anodes directly as well as reduce the danger of using poisonous reagents.The optimal polymerization time is250³00s when potentiostatic method was used. Andthe optimal condition for film anodes by cyclic voltammetry method were usedhydrochloric acid as the proton acid, and its concentration is1mol·L^-1in the electrolyte.Meanwhile the aniline concentration is0.1mol·L^-1, the appropriate number ofpolymerization cycles is20³0. Secondly, the electricity production was increasedsignificantly as a small amount of MWNTs were doped. Meanwhile,5wt.%MWNT inthe PANI/MWNT film anodes prepared by potentiostatic method were optimal, whosemaximum output voltage was926.5mV with its power density112.3mW·m^-2.Futhermore,5wt.%MWNT in the PANI/MWNT film anodes prepared by CV methodpolymerizing24cycles were optimal, whose maximum output voltage was967.7mV as its power density was286.63mW·m^-2. And the maximum voltage is approximately950mV for four days. The COD removal rate of the wastewater after a cycle is reached95.3%.In addition, the doping of MWNT reduced the start time of MFC nearly one day and thestability of electricity gerneration while the electrodes working in the AFBMFC wasverbessern, subsequently demonstrated that the stability of composited electrodes wereimproved.The carbon cloth with one side is carbon black layer and copper foam and carbonfiber brush were selected as anodes in AFBMFC. It has been found that the start timewere obviously shorten if the anodes hang the microbes film before used. And the obviousredox peaks could be observed from the CV curves of the anodes in the AFBMFC. Itindicates that there was catalytic active material in the anodes with microbial film.Moreover, the carbon brush anode AFBMFC had a maximum output voltage of907.4mV,while the output power density was222.2mW·m^-2. The COD removal rate was up to93%after ten days. The internal resistance decreased gradually, and then increased in onecycle.