Abstract: In the present paper a microbial fuel cell(MFC) was constructed with acetate solution as the fuel in anode cell and potassium permanganate as oxidized agent in cathode cell. The influences of the concentration, flowing status and pH value of cathode solution, and outer resistance on the MFC were investigated, outer voltage and electrode potentials were monitored and the influence factors on cathode and cell were analyzed. The results show that: (1) MnO₂ deposition on the surface is the main factor resulting in cathode polarization, and the flowing of the solution can remarkably reduce this polarization. Furthermore, the buffered solution can reduce the polarization resulting from H+ concentration difference; (2) it is deduced from the polarization curve that the key factor influencing the performance of MFC is microbial number and metabolic rate and the electron transferring rate from microbial to electrode; (3) the power density arrives at the biggest, 824 mW/m², when outer resistance is 300 Ω, which is accordance to the inner resistance, (284±18) Ω, deduced from I-V curve; (4) the influences of pH and permanganate concentration on cathode potential is in agreement to Nernst equation.

Key words: Microbial fuel cell, Potassium permanganate, Polarization curve, Nernst equation