A Comprehensive Review of Novel Adsorbents for Per- and Polyfluoroalkyl Substances in Water

Recent literature has seen a significant surge in studies focusing on new adsorbent materials for per- and polyfluoroalkyl substances (PFASg), a class of contaminants found in natural waters worldwide that pose a considerable threat to human and environmental health. Despite growing interest, the fundamental mechanisms of PFAS adsorption on these materials are not fully understood, thus hindering the progress of developing effective solutions for PFAS removal. This Review aims to bridge that knowledge gap by offering a critical appraisal of recent innovations in adsorbent materials specifically designed for treating PFAS. Strategies aimed at enhancing nanopore capacity or introducing anion-exchange capabilities in adsorption materials have shown promise. Innovative materials such as carbon nanotubes, graphene, and graphene oxide are evaluated. Modified clay-based and silica-based adsorbents have demonstrated efficacy in removing PFAS, driven by the hydrophobic effect, Coulombic interactions, and electrostatic interactions. Polymers, ranging from natural types to synthetic variants, have shown promise in PFAS removal across a wide pH range. We discuss mechanisms including F-F interactions, ion-pair adsorption, and ion exchange for chemically and thermally modified adsorbents and provide a general guideline for the design of PFAS adsorbents. This Review offers a holistic view of the advances related to PFAS adsorbent materials.