Adsorption of Forever Chemical Pollutants: The Physical Chemistry of PFAS Near Surfaces

Due to their persistence, per- and polyfluoroalkyl substances (PFAS) raise concerns that challenge current water remediation strategies. While adsorption-based solutions appear promising, their development is limited by knowledge gaps on PFAS behavior near solid surfaces. This review provides a state of the art on the theoretical and experimental aspects of PFAS adsorption. By adopting a fundamental physical chemistry standpoint, we report recent advances in understanding PFAS adsorption under relevant thermodynamic and chemical conditions. First, we introduce the fundamental interactions involved in the adsorption of individual molecules on surfaces, before addressing collective behaviors such as self-aggregation, ionic bridging, and competition with organic matter. We also present the thermodynamics and kinetics of PFAS adsorption using classical models. In particular, an accurate definition of the adsorption and desorption rates is given along with the key factors determining the kinetic order (i.e., first-, second- or mixed-order). Both batch and kinetic adsorption experiments are analyzed to identify the role of surface and PFAS structure and chemistry. Then, we evaluate how environmental factors (pH, salinity, copollutants, organic matter) impact adsorption. We conclude this review by identifying the perspectives in this field.