Data underlying the publication: Selective Electrochemical Desorption of Fermentation-derived n-Caproate from Activated Carbon

Granular activated carbon (GAC) is a promising sorbent for efficiently recovering carboxylates from fermentation processes. However, conventional desorption methods typically require chemicals or high-energy inputs. This study presents a proof-of-concept electrochemical approach integrating GAC into a cathode configuration to desorb sorbed carboxylates. Ten replicate sorption and desorption experiments were conducted using various carboxylate-containing solutions as the catholyte. In sorption experiments with a fermentation broth containing 3 g/L of acetate, 5.7 g/L of n-butyrate, and 10.5 g/L of n-caproate, the activated carbon Norit PK 1-3 exhibited high sorption selectivity (<em>S</em>_<em>S</em>) for n-caproate (94%) compared to acetate (5%) and n-butyrate (1%). Desorption was achieved by applying a cell potential, resulting in a current density of approximately 4 to 10 mA/cm². Under these conditions, a maximum desorption yield (<em>η</em>_<em>D</em>) of 77% was achieved for n-caproate when it was the sole carboxylate in the catholyte. From the fermentation broth, the desorption yield (<em>η</em>_<em>D</em>) of n-caproate from GAC reached 54%, with a desorption selectivity (<em>S</em>_<em>D</em>) of 97%. This electricity-driven desorption process achieved a yield (<em>η</em>_<em>D</em>) threefold higher than the NaOH-driven benchmark method. When GAC was not in direct contact with the cathode electrode, the desorption yield dropped by 2.5 times. This finding highlights that GAC functions as a sorbent and plays an active role in desorption, particularly when incorporated into the cathode electrode assembly. This electricity-driven desorption concept holds the potential for integrating electrodialysis systems to recover carboxylates from fermentation processes. <br>