Harnessing carbon-based adsorbents for poly- and perfluorinated substance removal: A comprehensive review

Poly- and perfluoroalkyl substances (PFAS) are synthetic, highly fluorinated chemicals commonly used in products like water-resistant materials, personal care items, non-stick cookware, and cleaning agents. Due to the strength of their C-F bonds, PFAS are extremely persistent in the environment, creating significant challenges for pollution control. Traditional degradation methods often prove ineffective, making adsorption a promising alternative for PFAS removal from contaminated water. Carbon-based adsorbents, valued for their sustainability and efficiency, are particularly effective for this purpose. This review provides a detailed analysis on PFAS properties and their removal using various carbon-based adsorbents, including activated carbon, biochar, graphene oxide, carbon nanotubes, and magnetic composites. Adsorption capacities of these materials were seen vary significantly, from as low as 10.7 mg/g for Fe3O4-hybrid biochar, to as high as 713.85 mg/g for functionalized graphene-based adsorbent, highlighting the superior adsorption efficiency of modified graphene adsorbents compared to traditional biochar and activated carbons. Most of these adsorbents fit the Langmuir isotherm model and pseudo-second-order kinetic model with high coefficient of determination, indicating efficient monolayer adsorption and strong interaction with PFAS. The review also explores different adsorption mechanisms, the effects of process parameters on adsorption efficiency, strategies for adsorbent regeneration, and concludes with a bibliometric analysis that highlights key research gaps. These insights are intended to guide future advancements in the development of effective, scalable PFAS remediation technologies using carbonbased adsorbents.