Fluorinated urea-based ionic polymers via molecular engineering strategy for efficient capture of PFAS and iodine

The urgent need for effective removal of per - and polyfluoroalkyl substances (PFAS) and iodine from contaminated water necessitates the development of adsorbents with high affinity, rapid kinetics, and robust performance in aqueous environment. In this study, a series of fluorinated urea-based ionic polymers were constructed via a facile one-step solvothermal approach. The synthesized fluorine-rich polymer PFDT-2 demonstrates exceptional performance in capturing PFAS performance. The theoretical adsorption capacity of PFOA on the adsorbent, determined by the Langmuir isothermal adsorption model, reaches 85.9 mg·g −1 at 25 °C in an aqueous solution with various initial concentrations. Additionally, at an initial concentration of 100 μg·L −1 , the removal rate of PFOA exceeds 90% within 25 min, indicating excellent rapid adsorption kinetics. Notably, PFDT-2 efficiently removes ppb-level concentrations of PFBS, PFHxA, PFOA, and PFDA from aqueous solutions, maintains high removal efficiency in the presence of humic acid, and exhibits stable recyclability over five cycles. Combined density functional theory (DFT) calculations and experiments reveal synergistic hydrogen bonding, electrostatic attraction, and fluorine‑fluorine interactions as the primary mechanisms. Furthermore, the bromide-rich polymer PXAM demonstrates superior iodine capture capacities, achieving a saturated iodine vapor adsorption capacity of 5.73 g·g −1 and an aqueous-phase uptake of 1337.95 mg·g −1 , involving both chemical and physical adsorption. This study introduces a versatile ionic polymer platform for efficient removal of pollutants, with promising potential for practical water treatment.