Quaternary-Ammonium-Grafted Flax Fibers for Removal and Release of Short-Chain PFAS from Water

Short-chain PFAS evade most commercial sorbents, leaving a critical treatment gap in drinking-water protection. Here, we couple advanced polymer grafting with a bioderived substrate to close that gap. Phormium tenax (New Zealand flax) fibers were functionalized via a two-step ATRP route that grafted 20% by weight [poly-2-methacryloyloxy]ethyl trimethylammonium chloride to yield cationic grafted flax fibers. The quaternary-ammonium-grafted fibers removed 86% PFBS and 57% PFBA within 24 h from 100 μg/L PFAS multi-solute at a 50 mg/L dose, outperforming the tested granular activated carbon and matching the performance of a strong-base ion-exchange resin. pH- and salt-dependent sorption, together with MeOH/1% NaCl elution that recovered >78% PFBS and 97% PFBA, point to electrostatic plus hydrophobic interactions and confirm that the sorbent is readily regenerable for cyclic use. The fibers are nonporous yet rigid, enabling direct use as packed media. Since the feedstock is low-cost, native, renewable, and regenerable with brine-assisted solvent wash, this work exemplifies how materials-science design can deliver scalable, greener solutions for emerging-contaminant removal and guides future optimization of biobased novel sorbents for PFAS remediation.