Fe(Ⅲ)-EDTA作为阴极电子穿梭体的微生物燃料电池持续产电机制

阴极氧还原反应（ORR）是影响微生物燃料电池（microbial fuel cell，MFC）性能的重要因素.采用双室MFC以Fe(Ⅲ)-EDTA为阴极液进行持续产电试验.结果表明，添加Fe(Ⅲ)-EDTA作为阴极液可显著加速氧还原反应速率，降低内阻，提高输出电压与功率.当阴极液中存在20.0 mmol/L的Fe(Ⅲ)-EDTA时，电池内阻仅为300　Ω，比对照降低了900　Ω，其输出电压（1 000　Ω下）与功率密度可维持在200.1 mV、 16.0 mW/m²左右，比不加的对照分别提高73.2%、 70.1%. Fe(Ⅲ)-EDTA氧化再生与持续产电试验表明，Fe(Ⅲ)-EDTA可通过曝气氧化再生、循环利用，即Fe(Ⅲ)-EDTA可作为阴极电子穿梭体加速电子至氧气的传递.Fe(Ⅲ)-EDTA首先接受阴极电子被还原成Fe(Ⅱ)-EDTA，在阴极室充分曝气条件下，Fe(Ⅱ)-EDTA将电子传递给O₂同时被氧化再生成Fe(Ⅲ)-EDTA，从而完成电子从电极传递到氧气的穿梭过程，MFC得以长期稳定运行.进一步优化试验显示，Fe(Ⅲ)-EDTA作为阴极电子穿梭体强化MFC产电的适宜条件为：浓度20.0 mmol/L、pH=5.0左右.在此条件下MFC的最大功率密度达100.9 mW/m².

Sustainable Electricity Generation in Microbial Fuel Cells Using Fe(Ⅲ)-EDTA as Cathodic Electron Shuttle

The rate of oxygen reduction reaction (QRR) at the cathode is a major factor affecting the perfonnance of the microbial fuel cells (MFC). Results showed that when using Fe( Ⅲ)-EDTA solution as catholyte, the ORR rate was significantly increased and the internal resistance was reduced,consequently leading to an increase in power output. With a concentration of Fe(Ⅱ )-EDTA at 20.0 mmol/L in the catholyte, the MFC produced the voltage and power density at approximate 200.1 mV and 16.0 mW/m~2,respectively,which was increased by 73.2% and 70.1% contrary to the MFC without the presence of Fe( Ⅰ )-EDTA. The further experiment suggested that Fe(Ⅲ)-EDTA functioned as electron shuttle to accelerate electron transfer. Fe(Ⅲ )-EDTA received electron and got reduced to Fe(Ⅱ )-EDTA,which further provided electrons to oxygen and got reoxidized at the same time. Therefore Fe( Ⅲ)-EDTA can act as recyclable electron shuttles between cathode electrode and oxygen. The optimum condition in the case of using Fe( IE )-EDTA as cathode electron shuttles was tested to be Fe( Ⅲ )-EDTA concentration at 20.0 mmol/L and pH at 5.0,which allowed MFC produced the maximum power density of 100.9 mW/m~2.