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The effect of the polarised cathode, formate and ethanol on chain elongation of acetate in microbial electrosynthesis

Lookup NU author(s): Paniz Izadi, Dr Jean-Marie Fontmorin, Professor Ian Head, Professor Eileen Yu



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2020. Reduction of CO2 to acetate in microbial electrosynthesis has been widely studied. However, the selective and quantitative production of longer chain chemicals and biofuels is still a bottleneck. Lack of sufficient energy provided by only the cathode electrode in Bio-electrochemical systems during chain elongation is one of the key challenges. It is assumed that additional electron donors than a polarised cathode is required to steer the production towards longer chain of carboxylates than acetate. In this study, formate and ethanol were supplied separately in the reactors fed by CO2 for 45 days in addition to the cathodes poised at −1.0 V vs. Ag/AgCl to investigate their effect on production. Although acetate was still the major product, supplying electron donors directed the production towards more diverse and longer chain organic chemicals than that in presence of the polarised cathode only. Significant improvement in the production of butyrate (×3.8 increase in maximum concentration) and butanol (maximum of 6.8 ± 0.3 mmol C L−1) was observed after supplying formate, while ethanol increased the diversity of the products. Supplying formate and ethanol in reactors for another 30 days under open circuit potential clarified that only ethanol could provide sufficient energy for butyrate production from acetate in the absence of polarised cathode, which reached the highest butyrate concentration of 19.1 ± 2.3 mmol C L−1. Formate was only consumed in presence of polarised cathode. It is proposed in our study that production of C4 products in presence of only cathodic electrode or cathodic electrode and formate could be associated to initial reduction of acetate to ethanol, consumed for production of C4 products through acetate. Trace levels of caproate and hexanol were detected in both reactors supplied with formate and ethanol only in the presence of polarised cathode.

Publication metadata

Author(s): Izadi P, Fontmorin J-M, Virdis B, Head IM, Yu EH

Publication type: Article

Publication status: Published

Journal: Applied Energy

Year: 2021

Volume: 283

Print publication date: 01/02/2021

Online publication date: 02/12/2020

Acceptance date: 14/11/2020

Date deposited: 01/02/2021

ISSN (print): 0306-2619

ISSN (electronic): 1872-9118

Publisher: Elsevier Ltd


DOI: 10.1016/j.apenergy.2020.116310


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