Effects of water matrix on per- and poly-fluoroalkyl substances (PFAS) treatment: Physical-separation and degradation processes – A review

Per- and poly-fluoroalkyl substances (PFAS) have emerged as contaminants of great concern that are ubiquitously detected in natural aquatic environments. Strict health advisories and regulations have triggered development of several treatment processes to remove or degrade PFAS. However, the main challenge that affects implementation of both physical-separation and degradation processes in real world applications is the quality of the water to be treated. Organic and inorganic constituents, defining the water quality, accompany PFAS in the influent of treatment processes. Thus, this article aims to provide a detailed review of the impacts of such water constituents on PFAS physical-separation (i.e., carbon-based, natural, and synthetic adsorbents, ion-exchange resins, and membranes) and degradation (i.e., sonolysis, photochemical, electrochemical, heat-activated persulfate, plasma-based treatment, and ionizing radiation) processes. Depending on PFAS treatment mechanisms, water solutes have shown inhibitory, promotive, or neutral effects on PFAS treatment. This review elucidates that the impacts of water matrix on PFAS treatment is largely dependent on (1) organic and inorganic matters characteristics (e.g., molecular weight, aromaticity, and functional groups), (2) operational parameters (e.g., type of resin, anode material, surface charge of adsorbents, and solution pH), and (3) PFAS properties (e.g., chain length and functional group). The information and data presented here are beneficial from both theoretical and practical perspectives for the implementation of processes for PFAS physical-separation or degradation.