Selective electrochemical desorption of fermentation-derived n-caproate from activated carbon

Granular activated carbon (GAC) is a promising material for the efficient recovery of carboxylates from fermentation processes. However, conventional desorption methods often rely on chemicals or high-energy inputs. This study introduces a proof-of-concept electrochemical approach that integrates GAC into a cathode configuration for selective desorption of carboxylates. Using a fermentation broth rich in carboxylates, GAC (Norit PK 1–3) demonstrated exceptional sorption selectivity (SS) for n-caproate (94 %) over other short-chain carboxylates. Desorption, driven by an applied cell potential, achieved a maximum yield (ηD) of 77 % for n-caproate in a single n-caproate solution and 54 % in a complex fermentation broth, with a remarkable selectivity (SD) of 97 %. Notably, this electricity-driven method tripled the desorption yield compared to a NaOH-driven benchmark. The results also revealed that incorporating GAC directly into the cathode assembly significantly enhances desorption performance, underscoring its dual role as a sorbent and active desorption facilitator. These findings highlight the potential of this electricity-driven process for sustainable carboxylates recovery, paving the way for integration with electrodialysis systems in fermentation-based resource recovery.