Lithium recovery with LiTi2O4 ion-sieves

Highlights: • The titanium oxide ion-sieves can capture lithium from salt water with a negligible dissolution of Ti^{4 +}. • The ion sieves have lithium capture capacities of up to 9.5 mg/g during the repeated Li⁺/H⁺ exchanges for 24 h. • Recovery of lithium from salt water by the titanium oxide ion-sieves is chemically feasible. - Abstract: A feasibility study for the recovery of lithium from salt water with the protonated lithium titanium oxide ion-sieves was carried out in this work. Lithium ions (Li⁺) in LiTi₂O₄ having a similar ion density with H⁺ allow repeated exchanges and regeneration with high selectivity. By Li⁷ magic angle spinning solid-state magnetic resonance, it is apparent that chemical structure of lithium in the ion-sieves is not perturbed during the repeated Li⁺/H⁺ exchange processes. As the dissolution of titanium is negligible (+/H⁺ exchanges with H_0.23Li_0.77Ti₂O₄/LiTi₂O₄ for 24 h, and the captured Li⁺ may be recovered in the form of Li₂CO₃. Accordingly, the lithium capture method developed in this work could be integrated with current desalination processes for valuable lithium recovery.