Metal Free Polymer/Graphite Electrode-Ferricyanides Catholyte System for MFC with High Performance

• 作者: Jiang Bolong Ulrich Kunz
• 来源期刊: 中国炼油与石油化工（英文版）
• 年，卷（期）: 2020,（3）
• 页码范围: 9-18
• 页数: 10页
• 语种: 英文

摘要

A Microbial fuel cell (MFC) with metal free polymer/graphite electrodes (150 mm×150 mm) was constructed. The electrodes with flowing channels, which were different in roughness, were designed. No additional catalyst was coated on the electrode, therefore the MFC was cheaper and possessed good durability with high performance. The effect of roughness, K3Fe(CN)6 concentration and sprayed air on the performance of the constructed MFC was investigated. Results showed that the roughness of electrode can significantly affect the performance of MFC. The power density of MFC increased by 1.56 times owing to the arithmetic mean roughness which has increased by 1.41 times. With an increasing K3Fe(CN)6 concentration, the performance of MFC also improves. The MFC with K3Fe(CN)6 only (30 mM) showed the highest power density of 1260 mW/m2, which is by 21.4 times and 1.3 times higher than those of MFCs with spraying air only (59 mW/m2) and with K3Fe(CN)6+air (1005 mW/m2), respectively. This showed that the appropriate concentration of K3Fe(CN)6 can significantly improve the power density, while the air has a negative effect when it is sprayed onto K3Fe(CN)6 catholyte. A coulombic efficiency of 34.2％ and an energy efficiency of 13.3％ with a COD degradation rate of 73.5％ were achieved with MFC using K3Fe(CN)6 only. The overpotentials of MFC were also calculated. It can be seen that both the ηohmic and ηconcentration were very low as compared to the ηactivation, and the ηconcentration can be ignored because its effect was less than 3 mV. The theoretical calculation suggested that with an increasing conversion rate of K3Fe(CN)6, the cathode potential decreased and reached 0.31 V at a conversion rate of 0.99. While the anode behaves differently for constant pH and changeable pH as the reaction progresses, which reveals that the buffer solution and removal of protons play an important role in maintaining the anode potential.