Tailored Polyanilines Are High-Affinity Adsorbents for Per- and Polyfluoroalkyl Substances

Remediation of water contaminated by per- and polyfluoroalkyl substances (PFAS) relies heavily on separation techniques. This work tested the adsorption of seven PFAS (including short-chain congeners) on polyaniline-derived polymers under simulated environmentally relevant conditions including a range of natural organic matter (NOM) and ion concentrations, mineral anionic and cationic species, and multi-component PFAS solutions. Results were benchmarked against commercial activated carbon and polymeric resin. The polymers poly-o-toluidine and polyaniline exhibited high PFAS removal efficiencies of over 98 and 75% of each PFAS in the compound mixture, respectively. The adsorption capacity of the polymers was comparable to that of activated carbon on a mass basis at low equilibrium concentrations (<50 μg L-1) and higher when adsorption was based on the surface area for the tested concentration range (1-1000 μg L-1). The tailored polymers performed similar to or better than the activated carbon and resin in the presence of elevated NOM. In addition, the fast PFOA adsorption kinetics (6.20 and 4.92 g mg-1 h-1 for poly-o-toluidine and polyaniline, respectively), the low desorption of adsorbed PFAS to aqueous media, and the facile regeneration using methanol with 10 g kg-1 NaCl at ambient temperature make these polymers ideal for flow-through sorption technology.