Preparation And Application Of Gr/Pani Composite Anode For Mfc

Microbial Fuel cell (or MFC) is a new integration technology of electricity producing and sewage treatment, using microorganism for catalyst, and with organic or part of the inorganic pollutants for the fuel. The discovery of MFC technology is of great importance to solve the energy crisis and environmental pollution problem. At present, low electricity production capacity limits its commercial applications. There are many factors influence the MFC’s electricity producing performances, and anode material is one of the most important factors.This article focuses on the anode material modfication, for the problems of the common chemical methods of electrodes modfication, such as long preparation time, material of high toxicity and so on. Using the method of electrochemical, polyaniline (or PANI) membrane electrode and graphene/polyaniline (GR/PANI) composite electrode were prepared, and applied to microbial fuel cell. Its electricity producing and sewage treatment performance were investigated. The main conclusions were as follows:(1) In acidic solution, deposition power and oxidative polymerization reaction rate increase with the increasing of proton acid concentration. Under the condition of, the order of oxidative polymerization reaction rate in different proton acids is H2SO4>HCl>HNO3>HClO4. Polymerization of PANI in different protonic acid, the cyclic voltammetric curves of current with voltage changing tendency is similar, and the peak voltage is the same, which implies that in four kinds of proton acid, the nucleation and growth mechanisms of polyaniline are the same.(2) The optimal preparation parameters of PANI film electrode by electrochemical methods: voltage sanning range is-0.1V-1.1V, scan rate50mV·s-1, aniline monomer concentration is0.3mol·L-1and H2SO4is0.5mol·L-1. Under these conditions, the preparation of PANI film electrode electron transfer rate is the fastest, and applied to the MFC, the least affected by the polarization under the condition.(3) PANI film obtained by cyclic voltammetry is shaped like a network fibrous structure with large specific surface area, which can provide more attachment sites for microbial growth. Compared with the constant voltage method and pulse polarization method, the transfer charge capacity of PANI film electrode is the strongest and the conductivity is the best by cyclic voltammetry method. The electrode resistance(3.65Ω) is decreased by51.8Ω relative to the electrode prepared by constant voltage (55.45Ω). PANI films anodic prepared by Cyclic voltammetry applied to MFC, the maximum power density and open circuit voltage are215.6mW·m-2and849.3mV respectively, is increased by50.6%and45.1%respectively than that of PANI film electrode prepared by constant voltage.(4) GR/PANI composite material with sandwich shaped porous structure can be obtained by cyclic voltammetry. The conductivity of GR/PANI composite modified electrode is greatly enhanced, while the anode film impedance decreased. The GR/PANI film electrode was applied to the MFC, the maximum power density and open circuit voltage are230.2mW·m-2and834.6mV respectively, increased by110.6%and34.8%respectively than that of unmodified anode, while apparent internal resistance is reduced obviously. The starting time of GR/PANI film electrode MFC is1d shorter than unmodified anode MFC. The power stability and sewage treatment capacity were enhanced.(5) When GR content is25%, the prepared GR/PANI composite film anode has the best performance. The open circuit voltage of MFC reached to a maximum value,961.3mV, the maximum output power density is268.4mW-m’3, and the apparent internal resistance of the battery is lowest. The new GR/PANI composite membrane anode material provides a new way for MFC anode material preparation.