Development of a fluorophilic ion-exchange material with dual binding mechanism for solid-phase extraction of PFAS

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants for which authorities worldwide have imposed limits on drinking water, groundwater and surface water. This has created challenges in PFAS detection, leading to an urgent need for reliable and selective solid-phase extraction (SPE) materials for PFAS analysis. In addressing this demand, we have tailored highly crosslinked copolymers containing 3-(1H,1H,2H,2H-perfluorooctyl)-1-vinylimidazolium chloride as a comonomer with ethylene dimethacrylate in various molar ratios. For ionic fluorosurfactants, these copolymers feature a dual binding mechanism that synergistically combines fluorophilic interactions and electrostatic attraction, enhancing selectivity and efficiency. The adsorption behavior of short- and long-chain PFAS and their recoveries were evaluated and compared to commercial SPE cartridges. Characterization revealed the highest ion-exchange capacity (412.7 ± 22 µeq g⁻¹) for a monomer-to-crosslinker ratio of 2:1. The dynamic adsorption capacities for various PFAS ranged from 15.2 to 306 g⁻¹. Recovery experiments consistently demonstrated high PFAS recoveries (98.8–121.6 %), while enrichment studies from wastewater confirmed its robustness in complex environmental matrices (recoveries: 90.8–99.2 %). Additionally, reusability experiments showed consistent recoveries over five cycles (recoveries: 90.34–108.0 %). The findings underscore the potential of this innovative polyelectrolyte as a selective, regenerable, and efficient alternative to conventional SPE materials, qualifying it as a superior candidate for PFAS analysis.