Electric field induced salt precipitation into activated carbon air-cathode causes power decay in microbial fuel cells

• Published in: Water research (Oxford) Vol. 123; pp. 369 - 377
• Main Authors: An, Jingkun, Li, Nan, Wan, Lili, Zhou, Lean, Du, Qing, Li, Tian, Wang, Xin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.10.2017
• Subjects: Activated carbon; Air-cathode; Bioelectric Energy Sources; Catalysis; Charcoal; Electric field; Electricity; Electrodes; Fouling; Microbial fuel cell; Microbial fuel cell; Air-cathode; Fouling; Electric field; Activated carbon
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2017.06.087

As a promising design for the real application of microbial fuel cells (MFCs) in wastewater treatment, activated carbon (AC) air-cathode is suffering from a serious power decay after long-term operation. However, the decay mechanism is still not clear because of the complex nature of contaminations. Different from previous reports, we found that local alkalinization and natural evaporation had an ignorable effect on cathode performance (∼2% decay on current densities), while electric field induced salt precipitation (∼53%) and biofouling (∼37%) were dominant according to the charge transfer resistance, which decreased power desities by 36% from 1286 ± 30 to 822 ± 23 mW m−2 in 6 months. Biofouling can be removed by scrapping, however, electric field induced salt precipitation under biofilm still clogged 37% of specific area in catalyst layer, which was even seen to penetrate through the gas diffusion layer. Our findings provided a new insight of AC air-cathode performance decay, providing important information for the improvement of cathodic longevity in the future. [Display omitted] •Power densities decayed by 36% from 1286 to 822 mW/m2 in 6 months.•Local alkalinization and natural evaporation had an ignorable effect on performance.•Electric field induced salt precipitation contributes ∼53% of Rct at month 6.•Biofouling contributes ∼37% of Rct at month 6.•Electric field induced ion precipitation under biofilm clogged 37% of cathodic area.