Yttrium doping Li+ Ion-Sieve porous Fluorinated hydrogel adsorbents for enhanced selective lithium recovery

H 2 TiO 3 (HTO), recognized as a promising lithium-ion sieve, encounters significant challenges related to slow kinetics and particle agglomeration that hinder its industrial applicability. This study aims to mitigate these limitations by employing a dual-modification strategy that integrates rare-earth doping and hydrogel immobilization. Specifically, yttrium doping was found to induce lattice expansion in HTO, thereby broadening lithium ion (Li + ) diffusion channels and enhancing hydrophilicity, as evidenced by a reduction in contact angle from 31.8° to 17.4°. The modified yttrium-doped HTO (Y-HTO) was further incorporated into a semi-interpenetrating poly(vinyl alcohol)/poly(2-fluoroacrylic acid) (PVA/PFAA) hydrogel through UV-initiated in-situ polymerization. The PFAA component provided fluorine-mediated coordination sites and carboxyl-driven electrostatic gradients, which synergistically accelerated Li + transport. Concurrently, PVA facilitated the formation of hydrogen-bonded networks that immobilized Y-HTO particles and ensured mechanical robustness. The optimized Y-HTO-PVA/PFAA-30 % composite demonstrated a maximum Li + adsorption capacity of 52.36 mg·g −1 at pH 10. Cyclic tests exhibited a remarkable capacity retention of 89.5 % after 10 adsorption–desorption cycles with minimal Ti loss (0.26 %). This innovative strategy offers a sustainable solution for lithium extraction from high-salinity brines.