Abstract
Abstract Cobalt was successfully recovered with simultaneous methane and acetate production in biocathode microbial electrolysis cells (MECs). At an applied voltage of 0.2 V, 88.1% of Co(II) was reduced with concomitantly achieving yields of 0.266 ± 0.001 mol Co/mol COD, 0.113 ± 0.000 mol CH 4 /mol COD, and 0.103 ± 0.003 mol acetate/mol COD. Energy efficiencies relative to the electrical input were 21.2 ± 0.05% (Co), 100.9 ± 3.2% (CH 4 ), and 1.0 ± 0.01% (acetate), and overall energy efficiencies relative to both electrical input and energy of anodic substrate averaged 3.7 ± 0.05% (Co), 17.5 ± 1.4% (CH 4 ) and 0.5 ± 0.001% (acetate). Applied voltage, initial Co(II) concentration, and temperature affected system performance. The apparent activation energy ( E a ) obtained in MECs was 26.7 kJ/mol compared to 40.5 kJ/mol in the abiotic controls, highlighting the importance of cathodic microbial catalysis to Co(II) reduction. Dominant microorganisms most similar to Geobacter psychrophilus , Acidovorax ebreus , Diaphorobacter oryzae , Pedobacter duraquae , and Prolixibacter bellariivorans were observed on the biocathodes. This study provides a new process for cobalt recovery and recycle of spent lithium ion batteries with simultaneous methane and acetate production in the biocathode MECs.
Published Version
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