Conductive Magnetite Nanoparticles Enhance the Microbial Electrosynthesis of Acetate from CO₂ while Diverting Electrons away from Methanogenesis

Abstract

Microbial electrosynthesis (MES) is an emerging technology which exploits microbial cells to convert CO2 into fuels, and value‐added chemicals using electrons supplied by a solid‐state cathode. Methane and acetic acid are typically the main CO2‐reduction products attained in microbial electrosynthesis studies, although the production of other more valuable products has also been reported. So far, however, practical strategies to manipulate and steer the distribution of CO2 reduction products during microbial electrosynthesis, particularly when mixed microbial cultures are employed as catalysts, are lacking. To specifically address this issue, here we investigated the influence of magnetite nanoparticles (NPs) supplementation (to a final concentration of 300 mg Fe L−1) on the microbial electrosynthesis process. Results demonstrated, that cells supplemented with magnetite NPs, exhibited a substantially higher yield of acetate production relative to unamended controls (up to 8.5 times higher, during the run with the cathode set at a potential of −700 mV vs. SHE, with a corresponding cathode capture efficiency of 17%) and, correspondingly, a lower yield of methane production (52% in the magnetite‐supplemented cell vs. 74% in the unamended control cell). Abiotic experiments indicated that the observed effects derived from magnetite catalyzing the biotic and abiotic hydrogen evolution reaction.

Enhancing the Anaerobic Biodegradation of Petroleum Hydrocarbons in Soils with Electrically Conductive Materials

“…scribed [26]. In brief, 5.2 g of FeCl3 and 2.0 g of FeCl2 were dissolved into an acidic aqueous solution (HCl 0.4 M).…”

“…The magnetite nanoparticles used in this study were synthesised as previously described [ 26 ]. In brief, 5.2 g of FeCl 3 and 2.0 g of FeCl 2 were dissolved into an acidic aqueous solution (HCl 0.4 M).…”