Covalent Organic Frameworks for Adsorption of Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) present persistent threats to global water systems due to their environmental persistence and bioaccumulation. The removal efficiency of short-chain PFAS (such as GenX, PFBA, and HFPO-TA) by conventional adsorbents, including activated carbon and ion-exchange resins, is typically limited, primarily due to the higher water solubility and reduced hydrophobicity of short-chain PFAS, which diminish interfacial affinity and adsorption performance. Recently, covalent organic frameworks (COFs) have demonstrated enhanced adsorption potential, especially for short-chain PFAS, through structural tunability, precise pore design, and customizable surface functionality. This review systematically summarizes how COF structural modifications─specifically functional group engineering and pore optimization─regulate PFAS adsorption mechanisms via electrostatic, hydrophobic, and fluorine–fluorine interactions. For addressing challenges including high synthesis costs of COFs and insufficient adsorption efficiency toward short-chain PFAS, this review also outlines future research priorities. Thus, this work not only provides theoretical guidance for designing high-performance COF-based adsorbents but also supplies ideas and methods for the control of PFAS.