Scalable and sustainable cellulose xerogels for high-capacity enrichment of per- and polyfluoroalkyl substances.

The phase-out of long chain per- and polyfluoroalkyl substances (PFAS) has accelerated the adoption of alternative emerging PFAS, posing a dual pollution challenge with persistent long-chain residues and their substitutes unclear fate in water treatment. Herein, we develop a scalable and closed-loop strategy producing aminated cellulose xerogel (CNPK) for PFAS removal. CNPK demonstrates excellent mechanical strength (1.96 MPa) and superior PFAS adsorption capacities (3.26 g-1 HFPO-TrA, 1.82 g-1 PFOA, 2.14 g-1 HFPO-DA, 1.27 g-1 PFHxA, 1.02 g-1 PFBA and 1.01 g-1 PFPrA) at pH 3. Its ability to absorb several times its own weight of PFAS is orders of magnitude higher than that of traditional adsorbents. In multi-component systems, the enhanced kinetics and affinity for short/ultra-short chain PFAS facilitate their near-complete removal. This is due to the preferential capture of long chains that provide additional van der Waals (vdW) interactions to accelerate short/ultra-chain adsorption. After five consecutive cycles, CNPK still achieves removal rates of 82%-99% for six types of PFAS and can be dissolved and reproduced. The proof-of-concept filter column achieves over 95% removal for short/ultra-short chain PFAS. The life cycle assessment (LCA) highlights xerogels having lower carbon footprint (161.28-161.71 kg CO2eq kg-1 PFAS) compared to most carbon-based adsorbents. Overall, this xerogel strategy tackles the urgent PFAS contamination through high-capacity enrichment under the principles of the circular economy.