Capturing PFAS with Partly Fluorinated Macromolecules: The Influence of the Fluorinated Group Structure

In this work, we prepare and evaluate four ion exchange resins with varying fluorinated segments for per- and polyfluoroalkyl substance (PFAS) removal (i.e., PFAS-based Sorb-PFPE+ (perfluoropolyether) and Sorb-NFN+ (nonadecafluoro-1-decanol) as well as non-PFAS-based Sorb-PFS+ (pentafluorostyrene) and Sorb-DFE+ (2,2-difluoroethanol)), with a particular interest being the removal of (ultra)short-chain PFAS. Among all these types of fluorinated sorbents, Sorb-PFS+ achieves removal performance comparable to the previously reported highly efficient Sorb-PFPE+ sorbent. Sorb-PFS+ demonstrates >90% removal of all tested PFAS, including (ultra)short-chain perfluoropropionic acid (PFPrA, 97.7%), perfluoro-2-methoxyacetic acid (PFMOAA, 98.8%), perfluoro-2-methoxypropanoic acid (PMPA, 99.1%), and difluoroacetic acid (DFA, 92.2%). A further sorption kinetic trial evidenced its rapid, efficient, and nonreversible removal of (ultra)short-chain PFAS within 5 min. Sorption capacity was estimated using the Langmuir model, with DFA, PFPrA, PFMOAA, and PMPA achieving 275.2, 357.4, 475.7, and 758.7 mg/g, respectively. No significant drop in sorbent performance was observed over five repeated sorption and desorption cycles, validating the great regeneration and reusability of Sorb-PFS+. In two real water matrices, Sorb-PFS+ also demonstrates commendable performance, with the removal of PFMOAA and PMPA achieving >93% in the landfill leachate and >99% in sewage water, outperforming the commercially available PFA694E sorbent. This work provides important insights into the development of fluorinated but non-PFAS sorbents, emphasizing the potentials of non-PFAS alternatives to meet future regulatory requirements while retaining the benefits of fluorine–fluorine interactions, thus contributing to a greener and more sustainable future.