Green and charge-tuned β-cyclodextrin polymers for efficient removal of PFAS and anionic dyes from water

Water contamination by per- and polyfluoroalkyl substances (PFAS) poses a major environmental challenge due to their persistence. This study evaluates positively charged, green-synthesized β-cyclodextrin polymers (β-CDP + ) for the removal of perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) as short- and long-chain PFAS, respectively, from water. Methyl orange (MO) and acid red 1 (AR1), as anionic dyes, were used as proxies to optimize PFAS adsorption conditions. β-CDP + exhibited high removal efficiencies (>90%) for all pollutants within 15–50 mg/L, reaching equilibrium within 30 min. Maximum adsorption capacities (Q m ) were achieved for MO (335 mg/g), AR1 (384 mg/g), PFOA (405 mg/g), and PFBA (378 mg/g). Over 80% PFBA and PFOA removal was maintained in the presence of competing anions, demonstrating the potential of β-CDP + for simultaneous removal of PFAS, NOM, and anionic dyes. The use of MO and AR1 as proxies was validated by high Spearman's ρ values (>0.9), reflecting similar adsorption trends to PFAS. The adsorbent's performance depended on glycidyltrimethylammonium chloride (GTMAC) loading and adsorbent dosage, with optimal conditions at a 1:5 β-CD:GTMAC molar ratio, 0.5 g/L, and pH 7. Adsorption followed the Langmuir isotherm (R 2 > 0.98) and pseudo-second-order kinetics (R 2 > 0.9). The polymer retained its adsorption performance over five cycles with minimal loss, demonstrating a sustainable strategy for the removal of emerging pollutants. • Green charge-tuned β-CDP + synthesized for efficient PFOA and PFBA removal. • Strong charge density enabled high adsorption capacity in broad pH conditions. • Anionic dyes (MO, AR1) were used as proxies to optimize PFAS uptake. • Rapid removal efficiency (>97%) was achieved within 60 min by electrostatic attraction. • β-CDP + retained high stability and reusability over six cycles.