Granulation and Molding of Nb‐Doped H 2 TiO 3 Spherical Lithium‐Ion Sieve for Efficient Lithium Recovery From Aqueous Solution: Adsorption Performance and Mechanism

ABSTRACT The granulation and molding of titanium‐based lithium‐ion adsorbents are of great significance for their industrial application. In this work, Nb‐HTO spherical particle lithium‐ion sieve adsorbent material was prepared by the phase transformation method with PVC and PAN polymers as the bonding agents. The spherical lithium‐ion sieve fabricated by the granulation method exhibit high porosity, excellent structural stability and good hydrophilicity. Notably, these particles preserve distinct microporous and small mesoporous architectures, with a maximum BET specific surface area of 78.417 m 2 /g. The equilibrium adsorption capacity value calculated by the quasi‐second‐order kinetic model ( q e,cal = 26.9 mg/g) is closer to the experimental measurement value ( q e,exp = 27.4 mg/g), indicating that the adsorption process is mainly controlled by chemical adsorption. Under different temperature conditions, the ∆ G ϴ values of the adsorption reactions were all negative, while the ∆ H ϴ values were all positive. This indicates that the adsorption process of Li + by the Nb‐HTO‐2% spherical lithium‐ion sieve for granulation is a spontaneous endothermic reaction. In the brine of the Xitaijini'er Salt Lake (containing Li + , Na + , K + , Mg 2+ , Ca 2+ ), the Nb‐HTO spherical lithium ion sieve exhibited a relatively high adsorption capacity for Li + (8.27 mg/g), with a distribution coefficient of 166.8 mL/g, verifying its excellent adsorption selectivity in a mixed alkali metal ion system. After five cycles of adsorption/desorption experiments, the adsorption capacity of the spherical particle composite adsorbent stabilized at 25.35 mg/g, and the titanium loss rate remained at 0.007%, indicating that the granulated Nb‐HTO possesses high structural stability and cycling performance. The granulated Nb‐HTO has excellent performance in lithium ion adsorption and separation and is a highly promising material for lithium recovery.