Polymer-stabilized porous architecture of H2TiO3 ion-sieve beads for selective Li+ adsorption

Porous PVA@SA/HTO hydrogel beads were fabricated via a dual-crosslinking strategy. • A high Li + capacity of 23.36 mg·g −1 was achieved with rapid adsorption kinetics. • Robust stability was maintained over 20 cycles with negligible Ti loss (<0.1%). • Continuous lithium separation was successfully validated in fixed-bed column tests. Lithium-ion sieves (LISs) are promising adsorbents for lithium recovery, but powdered LISs often suffer from difficult solid–liquid separation, poor recoverability, and limited continuous-flow applicability. Herein, spherical PVA@SA/H 2 TiO 3 (PVA@SA/HTO) composite hydrogel bead adsorbents were fabricated through crosslinking-assisted shaping and freeze-drying. The optimized PVA@SA/HTO-4 exhibited a three-dimensional porous network with a specific surface area of 24.97 m 2 ·g −1 , nearly twice that of pristine HTO powder (12.52 m 2 ·g −1 ). Under optimized batch conditions, PVA@SA/HTO-4 achieved an equilibrium Li + adsorption capacity of 23.36 mg·g −1 , retained 86.7% of its capacity after 20 adsorption–desorption cycles, and showed Ti dissolution loss below 0.1% in each cycle. In Xitaijinair Salt Lake brine, PVA@SA/HTO-4 showed preferential Li + adsorption, with separation factors of 582.90, 326.66, 324.23, and 86.59 over Na + , K + , Mg 2+ , and Ca 2+ , respectively. Kinetic, isotherm, FTIR, and XPS analyses indicated that Li + adsorption mainly proceeded through H + /Li + ion exchange at HTO exchange sites. Fixed-bed breakthrough and closed-loop recirculation experiments further demonstrated the continuous-flow operability of PVA@SA/HTO-4 under the tested LiCl solution conditions. This work offers a promising shaped hydrogel strategy for recoverable, cycling-stable, and dynamically applicable HTO-based lithium-ion sieves Download: Download high-res image (217KB) Download: Download full-size image