Investigation on influence factors and mechanism of microbial fuel cell

Microbial fuel cell is a equipment in which microbial is used as anodic catalyst and chemical energy directly changed electrical energy. In this paper, a mediator- and membrane-less microbial fuel cell was constructed, domestic waste water was used as inoculant and sodium acetate was used as its fuel. The effects of concentration of acetate, outer resistance, temperature and oxygen addition on the cell were investigated, outer voltage and electrode potentials were monitored and microcosmic mechanism was proposed. The results show that the activity of the microbe adsorbed on the electrode is a key factor of the cell voltage, and the more active the microbe, the higher the outer voltage; the activity is affected by the concentration of the solution, temperature and oxygen addition; the voltage increases with the concentration increases and the relationship between outer electrical pressure and concentration is in agreement with Monod equation; the voltage remarkably reduces with the existence of oxygen that restrain the growth of the microbe; the voltage increases and the microbial activity gets enhanced, but when the temperature rapidly rises to 50 degrees C, the microbial activity is lost and outer voltage is very low; the cathodic potential is controlled by the H+ concentration; the polarized cell is in agreement to general battery; the output power density is the function of outer resistance, and reach the biggest, 346 mW/m(2), when outer resistance is 200 Omega.