Electrically modulated PFOS adsorption and desorption by porous graphitic carbon in membrane and small-scale column systems.

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent, and legacy long-chain PFAS are of particular concern because of their persistence, bioaccumulation potential, and toxicity. Among them, perfluorooctane sulfonate (PFOS), widely used in aqueous film-forming foams and other historical surfactant-based industrial applications, remains one of the most frequently detected and regulated legacy PFAS in impacted water systems. Here, we report two independent electrified porous graphitic carbon (PGC) systems for PFOS removal: a PGC-coated membrane and PGC-packed small-scale columns. PGC structural characterization indicates a highly porous, locally graphitic architecture suitable for adsorption and electrical polarization. By applying external potentials to the PGC, PFOS adsorption and desorption can be actively modulated. In the membrane system, applying a positive potential enhanced PFOS adsorption, increasing uptake by 20% at + 1 V vs. Ag/AgCl, whereas applying a negative potential promoted desorption, decreasing uptake by 32% at -1 V vs. Ag/AgCl. In parallel, PGC-packed small-scale columns showed similarly improved adsorption-desorption performance under applied potentials, with uptake increasing by 35% at + 1 V and decreasing by 22% at -1 V. Both systems showed repeatable adsorption/desorption responses under controlled conditions, supporting further evaluation of electrically assisted PFOS capture and regeneration in flow-through configurations.