Comprehensive biocompatible hemp fibers improved by phosphate zwitterion with high U(VI) affinity in the marine conditions

The accelerated consumption of land-based uranium (VI) (U(VI)) ores is gradually transformed into seawater U(VI) recovery and extraction to meet the needs of energy strategy and environmental safety. However, the extreme low concentration, multiple co-existing ions with high concentration and numerous marine biofoulings pose challenges to the adsorbents utilized in marine. Considering the compatibility with biological marine systems, the natural abundant, economical and eco-friendly hemp fibers (HFs) were functionalized by 2-hydroxyethyl acrylate (HEA) induced side-chains, which supports future modification with Vinylphosphonic acid (VPA) and 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC). The optimized product named as HFHPC exhibits an outstanding distribution coefficient of 1.44 ± 0.19 × 10⁴ mL·g⁻¹ for U(VI) in a 100 times concentration of co-existing ion solution than those in seawater, an ultra-fast total infiltration time of 0.2 s and a hydration layer induced antifouling property. After immersed in marine for 35 days (Yellow Sea, China), the adsorption capacity of HFHPC is 432.49 ± 7.90 μg·g⁻¹ (a high U/V mass ratio of 8.3), which is 3.5 times higher than that of HFP (only prepared by VPA). This phosphate zwitterion promoted biocompatible HF-based material will be an alternative adsorbent for seawater U(VI) extraction with great affinity and antifouling property.