Comparative assessment of activated carbon and anion exchange resin for short- and long-chain per- and poly-fluoroalkyl substances sorption: Insight into performance and mechanism

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants that have adverse effects on human health. Even though numerous studies have evaluated the performance and sorption mechanisms of activated carbon and anion exchange resins for PFAS removal, a comparative study of the sorbents has not been reported thus far. In this study, we compared the sorption performance, selectivity, reusability, and sorption mechanisms of pulverized activated carbon (PAC) and a commercial anion exchange resin, A520E, for the removal of two short-chain PFAS [perfluorobutanoic acid (PFBA) and potassium nonafluoro-1-butanesulfonate (PFBS)] and two long-chain PFAS [pentadecafluorooctanic acid (PFOA) and perfluorooctane sulfonate (PFOS)] from water samples. Both showed good removal efficiencies at environmentally relevant concentrations. However, at higher concentrations, A520E exhibited higher sorption than PAC. Moreover, PAC demonstrated faster sorption kinetics (<5 min) owing to its lower Biot number, indicating the influence of both intraparticle and external diffusion. In contrast, A520E primarily involves intraparticle diffusion, particularly for short-chain PFAS, resulting in a slower sorption rate (48 h). Notably, the PFAS sorption efficiencies of PAC and A520E decreased in real-field water, especially PFBA removal by PAC. A520E demonstrated higher regeneration ability than PAC. Our results highlight the importance of sorbent selection for the removal of PFAS compounds from contaminated water and could promote the development of effective and sustainable PFAS removal strategies.