Application of gas diffusion biocathode in microbial electrosynthesis from carbon dioxide

• Published in: Environmental science and pollution research international 2016-11, Vol.23 (22), p.22292-22308
• Main Authors: Bajracharya, Suman, Vanbroekhoven, Karolien, Buisman, Cees J.N., Pant, Deepak, Strik, David P. B. T. B.
• Format: Article
• Language: English
• Subjects: Acetates - chemistry; Activated carbon; Alternative energy sources; Anaerobiosis; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Autotrophic bioproduction; Bacteria - classification; Bacteria - metabolism; Biocatalysts; Biocathode; Bioelectric Energy Sources - microbiology; Biomass; Bioreactors; Carbon; Carbon dioxide; Carbon Dioxide - chemistry; Carbon sources; Catalysis; Chemicals; Climate change; CO reduction; Conservation of Natural Resources; Earth and Environmental Science; Ecotoxicology; Electric rates; Electrodes; Electrolytes; Environment; Environmental Chemistry; Environmental Health; Environmental Pollutants; Environmental science; Ethanol; Flue gas; Gas diffusion electrode; Gases; Hydrogen; Hydrogen - chemistry; Mass transfer; Microbial electrosynthesis; Renewable resources; Sewage - microbiology; Sludge; Studies; Technoeconomic Perspectives on Sustainable CO2 Capture and Utilization; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-016-7196-x

Microbial catalysis of carbon dioxide (CO 2 ) reduction to multi-carbon compounds at the cathode is a highly attractive application of microbial electrosynthesis (MES). The microbes reduce CO 2 by either taking the electrons or reducing the equivalents produced at the cathode. While using gaseous CO 2 as the carbon source, the biological reduction process depends on the dissolution and mass transfer of CO 2 in the electrolyte. In order to deal with this issue, a gas diffusion electrode (GDE) was investigated by feeding CO 2 through the GDE into the MES reactor for its reduction at the biocathode. A combination of the catalyst layer (porous activated carbon and Teflon binder) and the hydrophobic gas diffusion layer (GDL) creates a three-phase interface at the electrode. So, CO 2 and reducing equivalents will be available to the biocatalyst on the cathode surface. An enriched inoculum consisting of acetogenic bacteria, prepared from an anaerobic sludge, was used as a biocatalyst. The cathode potential was maintained at −1.1 V vs Ag/AgCl to facilitate direct and/or hydrogen-mediated CO 2 reduction. Bioelectrochemical CO 2 reduction mainly produced acetate but also extended the products to ethanol and butyrate. Average acetate production rates of 32 and 61 mg/L/day, respectively, with 20 and 80 % CO 2 gas mixture feed were achieved with 10 cm 2 of GDE. The maximum acetate production rate remained 238 mg/L/day for 20 % CO 2 gas mixture. In conclusion, a gas diffusion biocathode supported bioelectrochemical CO 2 reduction with enhanced mass transfer rate at continuous supply of gaseous CO 2 . Graphical abstract ᅟ