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>

颗粒活性炭（Granular activated carbon, GAC）是一种极具应用前景的吸附剂（sorbent），可高效从发酵过程中回收羧酸盐（carboxylates）。然而，传统解吸（desorption）方法通常需要使用化学试剂或高能耗输入。本研究提出一种集成GAC于阴极（cathode）构型的概念验证型电化学方法（electrochemical approach），用于解吸已吸附的羧酸盐。研究以多种含羧酸盐的溶液作为阴极液（catholyte），开展了10组重复吸附（sorption）-解吸实验。在以含3 g/L乙酸盐（acetate）、5.7 g/L正丁酸盐（n-butyrate）及10.5 g/L正己酸盐（n-caproate）的发酵液作为阴极液的吸附实验中，诺芮特PK 1-3型活性炭（Norit PK 1-3）对正己酸盐展现出优异的吸附选择性（sorption selectivity, S_S）：正己酸盐的吸附选择性达94%，而乙酸盐仅为5%，正丁酸盐仅为1%。通过施加槽电压可实现解吸，此时电流密度约为4~10 mA/cm²。在此条件下，当阴极液中仅含正己酸盐时，其最大解吸产率（desorption yield, η_D）可达77%。从发酵液中解吸时，GAC上正己酸盐的解吸产率（η_D）可达54%，对应的解吸选择性（desorption selectivity, S_D）为97%。该电化学驱动的解吸工艺的解吸产率较NaOH驱动的对照方法高出3倍。当GAC未直接与阴极电极接触时，解吸产率降至原水平的40%。这一发现表明，GAC不仅作为吸附剂发挥作用，还在解吸过程中扮演了主动角色，尤其是当GAC被集成至阴极电极组件中时。该电化学驱动的解吸工艺有望与电渗析（electrodialysis）系统集成，用于从发酵过程中回收羧酸盐。