Covalent organic frameworks: a review of synthesis methods, properties and applications for per- and poly-fluoroalkyl substances removal

Adsorption using covalent organic frameworks (COFs) is very effective and favoured for removing per- and polyfluoroalkyl substances (PFAS) from various matrices. The prominent classes of COF, their synthesis methods, and their application in COF-based technologies for PFAS adsorption in myriad environments are discussed. Furthermore, the influencing PFAS adsorption characteristics of the distinct COF classes are also examined. COFs have large specific surface areas and porosity, offering PFASs a host of adsorption sites and thus high adsorption capabilities. β -Cyclodextrin-based COFs ( β -CD-COFs), ionic COFs (iCOFs), amine-functionalised COFs, porphyrin-based COFs and hydrophobic COFs are some of the most notable examples of COFs and as such have been employed for large-scale PFAS remediation. Direct and post-synthetic modification are the two main COF design methodologies. The general approach in constructing various frameworks involves the reaction of ion monomers with other neutral monomers. For COFs, solvothermal synthesis is currently the main direct synthetic method. The process used to synthesise COFs tremendously impacts how effectively they adsorb PFAS. High-performance materials for PFAS remediation are created by researchers by customising COF characteristics and using suitable synthesis techniques. The authors’ objective is to give readers and researchers alike a broad overview of the current status of COF research and development, including numerous challenges and prospects associated with the adsorption of PFASs by COFs.