Development of Cationic Hydrogels for Pfas Remediation

Per- or polyfluoroalkyl substances (PFAS) are a group of man-made chemicals found in packaged food, drinking water, and common household products. As a result of bioaccumulation from long elimination half-lives, PFAS are detrimental to human health, with consequences ranging from hormone disruption to cancer. Current methods of PFAS remediation rely on sorption in neutral environments, where these contaminants exist in an anionic form. Hydrogels are crosslinked, hydrophilic polymers that swell in aqueous environments. Binding of PFAS is impacted by electrostatic and hydrophobic interactions, as well as the sorbent morphology; therefore, the aim of this study is to develop cationic hydrogels to maximize anionic organic contaminant selectivity. Acrylamide based hydrogels were synthesized via free radical polymerization with different densities of the crosslinker, N,N’methylenebisacrylamide (NNMBA). Varying crosslinker concentrations allow size selectivity by controlling the structure of the mesh network. To further increase the affinity for anionic contaminants, a range of cationic monomers were introduced to the hydrogel system. Polymerization and conversion were confirmed using FTIR spectroscopy. Swelling studies in deionized water provide insight to the expansion capacity of the polymer in these neutral conditions. As expected, an increase in the crosslinking density of the hydrogel restricts the hydrophilic network, and therefore is accompanied by a decrease in swelling. Additionally, a greater percentage of cationic monomer present in the hydrogel increases swelling as well because of charge repulsion and the osmotic effect. Future studies aim to develop these polymeric systems for PFAS elimination in humans through the gastrointestinal tract.