The Smart Hydrogels for the Controllable Adsorption and Desorption of PFAS

In order to address the regeneration issue of adsorbents for the elimination of per- and polyfluoroalkyl substances (PFAS), this work synthesized a novel smart hydrogel based on a temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAm). These hydrogels exhibit hydrophobicity and hydrophilicity above and below the the lower critical solution temperature (LCST) of PNIPAm, respectively. Concurrently, the monomer 2-(methacryloyloxy)ethyl)trimethylammonium chloride (MTAC), distinguished by its quaternary ammonium groups, was co-polymerized with NIPAM to augment its electrostatic effect. Utilizing perfluorooctanoic acid (PFOA) as a case study, the smart hydrogel attained an 80% desorption efficiency through the mere adjustment of temperature, obviating the necessity for salt solution or organic solvent. This work is expected to overcome the challenges associated with the regeneration of adsorbents and contribute to the sustainable management of PFAS.