Highly hydrophilic H₂TiO₃ ion sieve with neodymium (Nd) doping enables fast and high-efficiency Li extraction

The metatitanic acid H2TiO3 (HTO) with high selectivity shows potential in lithium extraction from salt lake brine. Nevertheless, the sluggish adsorption kinetics and unsatisfying actual adsorption capacity hinder H2TiO3 industrial application. Herein, a rare earth element Nd-doped H2TiO3 (Nd-HTO-1 %) was synthesized. The crystallinity, morphology, hydrophilicity, adsorption property and mechanism of Nd-HTO-1 % were systematically characterized by a series of techniques. Interestingly, Nd-doping promotes the generation of oxygen vacancies, thereby increasing the density of surface hydroxyl groups and making the surface high-hydrophilic and particle size decreased. After 1 % Nd-doping, high-hydrophilic HTO was obtained with a contact angle of 16.5 degrees. The adsorption capacity of Nd-HTO-1 % increased by 12.5 % compared with HTO, and the equilibrium time of adsorption reduced by half to 4 h. After eight cycles, Nd-HTO-1 % still showed a considerable adsorption capacity of 39.69 mg.g(-1). In the meantime, the dissolution loss of titanium is merely 0.14 %, showing excellent cycling stability. Combined with the considerable selectivity exhibiting in Qarhan salt lake brine, it demonstrates potential in utilization of Nd-doped H2TiO3 for lithium extraction from salt lake brine.