2026-04-17T20:22:53Zhttps://recercat.cat/oai/request

oai:recercat.cat:10256/233742024-06-18T12:08:07Zcom_2072_452955com_2072_2054col_2072_453062

00925njm 22002777a 4500 dc Romans Casas, Meritxell author Feliu Paradeda, Laura author Tedesco, Michele author Hamelers, Hubertus M.V author Bañeras Vives, Lluís author Balaguer i Condom, Maria Dolors author Puig Broch, Sebastià author Dessì, Paolo author 2024-01 Microbial electrosynthesis (MES) is a promising carbon utilization technology, but the low-value products (i.e., acetate or methane) and the high electric power demand hinder its industrial adoption. In this study, electrically efficient MES cells with a low ohmic resistance of 15.7 mΩ m2 were operated galvanostatically in fed-batch mode, alternating periods of high CO2 and H2 availability. This promoted acetic acid and ethanol production, ultimately triggering selective (78% on a carbon basis) butyric acid production via chain elongation. An average production rate of 14.5 g m−2 d−1 was obtained at an applied current of 1.0 or 1.5 mA cm−2, being Megasphaera sp. the key chain elongating player. Inoculating a second cell with the catholyte containing the enriched community resulted in butyric acid production at the same rate as the previous cell, but the lag phase was reduced by 82%. Furthermore, interrupting the CO2 feeding and setting a constant pH2 of 1.7–1.8 atm in the cathode compartment triggered solventogenic butanol production at a pH below 4.8. The efficient cell design resulted in average cell voltages of 2.6–2.8 V and a remarkably low electric energy requirement of 34.6 kWhel kg−1 of butyric acid produced, despite coulombic efficiencies being restricted to 45% due to the cross-over of O2 and H2 through the membrane. In conclusion, this study revealed the optimal operating conditions to achieve energy-efficient butyric acid production from CO2 and suggested a strategy to further upgrade it to valuable butanol This research was carried out in the project “PANGEA – Process intensificAtioN for bioelectroCO2 recyclinG into carbon-nEutrAl products) funded by the Spanish Ministry of Innovation and Science (ref. PID2021-126240OB-I00). PD is supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement, project ATMESPHERE, No 101029266. MR-C is grateful for the support of the Spanish Government (FPU20/01362). S.P. is a Serra Hunter Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Academia award. LF-P is grateful for the Research Training grant from the Catalan Government (2021 FISDU 00132). LEQUIA and EcoAqua have been recognized by the Catalan Government (Ref 2021 SGR01352 and 2021 SGR01142) Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier http://hdl.handle.net/10256/23374 Química verda Green chemistry Bioelectroquímica Bioelectrochemistry Selective butyric acid production from CO2 and its upgrade to butanol in microbial electrosynthesis cells