High Acetic Acid Production Rate Obtained by Microbial Electrosynthesis from Carbon Dioxide

Ludovic Jourdin, Timothy Grieger, Juliette Monetti, Victoria Flexer, Stefano Freguia, Yang Lu, Jun Chen, Mark Romano, Gordon G. Wallace, Jurg Keller

High product specificity and production rate are regarded as key success parameters for large-scale applicability of a (bio)chemical reaction technology. Here we report a significant performance enhancement in acetate formation from CO2, reaching comparable productivity levels as in industrial fermentation processes (volumetric production rate and product yield). A biocathode current density of -102 ± 1 A m 2 and acetic acid production rate of 685 ± 30 g m-2 day 1 have been achieved in this study. High recoveries of 94 ± 2% of the CO2 supplied as sole carbon source and 100 ± 4 % of electrons into the final product (acetic acid) were achieved after development of a mature biofilm, reaching an elevated product titer of up to 11 g L-1. This high product specificity is remarkable for mixed microbial cultures, which would make the product downstream processing easier and the technology more attractive. This performance enhancement was enabled through the combination of a well acclimatized and enriched microbial culture (very fast start up after culture transfer), coupled with the use of a newly synthesized electrode material, EPD-3D. The throwing power of the electrophoretic deposition technique, method suitable for large-scale production, was harnessed to form multi-walled carbon nanotubes coatings onto reticulated vitreous carbon to generate a hierarchical porous structure.