Josephine Baffoe, Eliasu Issaka, Eric Danso-Boateng
Per- and polyfluoroalkyl substances (PFAS) are hazardous, persistent, and widely used compounds that pose significant risks to human health and the environment. Urgent and effective techniques for removing PFAS from aquatic environments are needed. Carbon-based materials, including activated hydrochar (AHC), biochar (BC), graphene oxide (GO), carbon nanotubes (CNT), and granular activated carbon (GAC), have become valuable adsorbents due to their high surface area, porosity, and adaptable properties. This review comprehensively discusses these five carbon-based materials, outlining their synthesis and applications for PFAS adsorption. Additionally, the review explains the underlying mechanisms of adsorption and the models used, such as the Langmuir and Freundlich isotherms, as well as Pseudo-first- and second-order kinetic models. Furthermore, the study contributes to the current body of knowledge by suggesting and explaining practical modification options tailored to capture low-molecular-weight, short-chain PFAS (S-C PFAS). By moving the focus from classical hydrophobic partitioning to electrostatic-driven design, revealing cationic functionalisation and metal oxide doping as critical approaches for overcoming short-chain compounds' water mobility. Functional group analysis, linkage of molecular structure to adsorption potential, comparison of carbon-based materials for adsorption, and practical cases and techniques for regeneration and reuse of the five carbon-based materials have all been discussed. The review paper also explores potential research directions to improve material design, cost-effectiveness, and sustainability, considering current limitations of each carbon-based adsorbent. To conclude, it references recent publications to examine the various applications of these materials for removing PFAS from the environment. This review aims to assist researchers and academics working towards reducing PFAS contamination.