High Performing Gas Diffusion Biocathode for Microbial Fuel Cells Using Acidophilic Iron Oxidizing Bacteria

Abstract

The development of a sustainable catalyst for the oxygen reduction reaction (ORR) is still a major bottleneck for the scale-up and commercialization of Microbial Fuel Cells (MFCs). In this work, we have studied the utilization of iron-oxidizing bacteria (IOB) enriched from natural environment and Fe 2+ in MFCs equipped with gas diffusion electrodes (GDEs) as an alternative to traditional Pt-based catalysts. In half-cells systems, the oxidation of Fe 2+ into Fe 3+ by IOB and its regeneration at the cathode produced constant current densities close to 2 A m −2 for more than 45 days. In MFCs operated in batch mode, significant pH changes in both compartment led to the instability of the system. However, when operated in continuous mode, pH remained stable in both compartments and MFCs produced maximum power densities of 1.1 W m −2 were then reached, compared to 0.5 W m −2 for MFCs equipped with Pt catalyst. Diffusion of oxygen through the GDEs improved mass transport and the performance of the MFCs, and avoided the utilization of costly aeration system. This IOB GDE system also provides a reproducible and fast start-up for biocathode for MFCs.

Bioelectricity generation using long-term operated biocathode: RFLP based microbial diversity analysis

“…The presence of free electrons on the cathode of MFC initiates a reduction response of oxygen to produce water. In this case, microorganisms, namely bacteria, will take electrons at the cathode by the reduction of electron acceptors such as nitrate, sulfate, perchlorates and metals [9] , [10] , [11] , [12] . Biodegradable organic matter is, thus, converted into electricity, hydrogen or other value added materials through MFCs [13] , [14] , [15] .…”

Oxygen-reducing bidirectional microbial electrodes designed in real domestic wastewater

“…3.B). These kinetics were less than those reported for the very best mono-directional O 2reducing microbial cathodes, which reached 2 to 2.5 A.m − 2 (Wang et al, 2013;Izadi et al, 2019) when developed on gas-diffusion electrodes, and up to 3 A.m − 2 at 0.4 V vs Ag/AgCl under forced aeration (Milner and Yu, 2018). Nevertheless, they can be reasonably compared with efficient conventional O 2 -reducing microbial cathodes.…”

Electrified bioreactors: the next power‐up for biometallurgical wastewater treatment

“…An added advantage is the possibility of achieving a selective and sequential recovery of the target metals, and eventually an easier production of marketable and functional materials (Logan et al ., 2008; Sleutels et al ., 2012). However, the implementation of BES remains challenging: In addition to the characteristics listed in generation I, the employed microorganisms often must be electroactive (Arends et al ., 2014; Ntagia et al ., 2016; Izadi et al ., 2019). Secondly, the electrodes have to be biologically compatible, display low electrical resistance and provide a large surface area for electron exchange and biofilm growth (Desloover et al .; Guo et al ., 2015; Sharma et al ., 2019).…”

“…Instead of transferring the electrons directly to and from microorganisms, an intermediary product such as hydrogen gas, products of CO 2 reduction (e.g. as CO and formic acid), iron and oxygen gas can be generated at the electrode (Ter Heijne et al ., 2007 ; Izadi et al ., 2019 ). As abiotic electrochemical cells can achieve higher current densities than BES, coupling these cells to high rate bioreactors similar to those developed for generation II may unlock the high required rates that have proven elusive for BES, provided gas transfer is managed adequately (Sleutels et al ., 2012 ).…”