微生物阳极燃料电池极性反转现象研究

本文在构建出微生物阳极燃料电池系统的基础上，研究了微生物燃料电池极性反转现象. 实验表明，由活性污泥混合菌源接种的微生物阳极在电极表面形成电化学生物膜，但平行构建的微生物阳极燃料电池系统在内阻、输出电压和放电时长等方面存在着不同程度差异. 在串联微生物燃料电池组中，放电操作会导致性能较差的微生物单电池首先出现极性反转. 电极电势测量表明，较高的放电电流使微生物阳极电势迅速正移，导致电池系统出现极性反转. 在室温范围内，温度升高可使MFC承受较高的放电电流，不易发生极化. 燃料物质缺乏时，MFC易发生极性反转，但过高的电流仍能使燃料物质充分的MFC出现极性反转. MFC极性反转会对微生物阳极性能造成影响. 极性反转时间较短(<5 min)，对微生物阳极影响不大，但延长极性反转时间，会导致微生物阳极性能下降.

Voltage Reversal Behavior in Microbial-Anode Fuel Cells

Voltage reversal behavior was investigated in microbial-anode fuel cells (MFCs). Electricity-producing biofilms were developed on the surface of anodes in MFCs inoculated with mixed inoculum from activated sludge. MFC duplicates generally exhibited different performances with respect to the internal resistance, the voltage output and the discharging duration when operating in batch mode. Voltage reversal was observed to occur first in the MFC with lower performance when connecting MFCs in series. Analysis of electrode potentials indicated that the potentials of microbial anodes quickly shifted to more positive values when enhancing discharge current, resulting in voltage reversal in MFCs. Increasing temperature would enhance the limiting current at room temperature, and avoiding the voltage reversal. Fuel shortage would enable the voltage reversal to easily occur. However, high discharge current still generates voltage reversal in fuel-rich MFCs. The performance of microbial anodes was observed to be affected with the voltage reversal. Transient voltage reversal had no obvious effect on the performance of the microbial anode. However, the performance of microbial anodes would decrease with increasing duration of voltage reversal. Microbial anodes were observed to be destroyed, and the performance of the microbial-anode fuel cells would not be recovered after long-time voltage reversal.