Hydrothermal synthesis of lithium-enriched β-Li2TiO3 with an ion-sieve application: excellent lithium adsorption

Abstract

Lithium-enriched monoclinic lithium metatitanate (β-Li₂TiO₃) with a high molar ratio of Li to Ti (2.11) was synthesized by a hydrothermal method. The related lithium ion-sieve (H₂TiO₃), obtained by acid pickling of Li₂TiO₃, with a specific surface area of 45.35 m² g⁻¹ and a pore volume of 0.166 cm³ g⁻¹ possessed a maximum adsorption capacity of 76.7 mg g⁻¹ in LiOH solution (∼2 g L⁻¹ of Li⁺ ions) at 30 °C for 24 h, which was much higher than those reported for other lithium ion-sieves. Adsorption isotherms and kinetic analysis indicated that the adsorption of Li⁺ ions onto H₂TiO₃ followed the Langmuir isotherm model and a pseudo-second order kinetics equation. The adsorption mechanism showed that the improvement of lithium adsorption capacity was closely related to the free hydrogen formation of β-Li₂TiO₃ and HTi₂ layer exposure of H₂TiO₃, suggesting a clear direction for designing the lithium ion-sieve with high performance.