Rapid, High-Capacity, and Reusable Bovine Serum Albumin-Based Adsorbents for Perfluoroalkyl and Polyfluoroalkyl Substance Removal

Albumin, a major carrier of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in humans and animals, has been rarely explored for PFAS removal. In this study, bovine serum albumin (BSA) is transformed into an efficient, low-cost, and reusable adsorbent for PFAS removal. BSA is modified with amine-rich poly(ethylenimine) (PEI) to create a positively charged surface. The optimal PEI:BSA mass ratio was determined to be 0.75 based on a combination of adsorption performance and material properties. The resulting PB(0.75) achieves rapid equilibrium for nine model PFASs, with a pseudo-second order rate constant range from 0.6 to 15.7 g/(mg.min), depending on the specific PFAS. In addition to fast kinetics, PB(0.75) exhibits exceptionally high adsorption capacities for PFHpA, PFOA, PFNA, and PFOS, each exceeding 1000 mg/g. These values rank among the highest reported to date for these PFAS. Adsorption of shorter-chain and emerging PFASs such as PFBA, PFBS, GenX, and 6:2 FTS is comparatively lower but still moderately better than conventional activated carbons reported in the literature. The adsorption mechanism is thoroughly investigated by examining adsorption behaviors under different water matrixes, constructing modified linear solvation energy relationships, and characterizing PB(0.75) before and after adsorption. The adsorption process is governed by electrostatic attraction and hydrophobic interactions, with short-chain PFAS relying more on electrostatic interactions due to their higher hydrophilicity. Furthermore, exhausted PB(0.75) can be effectively desorbed and regenerated by using alkaline solutions. Our study highlights albumin-based adsorbents as a highly promising and sustainable solution for addressing PFAS contamination in aquatic environments.