Activated Carbon-Catalyzed Degradation of Perfluorooctanoic Acid in Polar Aprotic Solvents.

Abstract

The destruction of per- and polyfluoroalkyl substances (PFAS) poses a formidable global environmental challenge owing to their extreme persistence and resistance to degradation. Here, we report that commercial granular activated carbon (GAC) significantly accelerates the degradation kinetics of perfluorocarboxylic acids (PFCAs) in dimethyl sulfoxide (DMSO), enhancing the degradation rate by 70% and the defluorination efficiency by 153% compared to GAC-free controls. In contrast, other adsorbents such as molecular sieves with varied pore structures showed no catalytic activity. Comparative experiments using modified carbon materials and resins functionalized with different groups identified oxygen-containing surface functional groups, specifically carboxyl moieties, as the key catalytic sites. Density functional theory (DFT) calculations showed that hydrogen-bonding interactions between surface carboxyl groups and pentadecafluorooctanoic acid (PFOA) lower the activation Gibbs free energy for decarboxylation by approximately 5.3-fold relative to the uncatalyzed pathway. This work reveals a new catalytic role of commercial GAC and suggests a practical pathway for simultaneous PFAS destruction and adsorbent regeneration under substantially milder conditions than conventional thermal treatment.