(400i) Li2TiO3/PVC Composites for Lithium Recovery from Alkaline Leachates

This work presents the development and performance evaluation of H₂TiO₃/PVC composite sorbents for lithium recovery from simulated alkaline leachates produced during processing of ores. The sorbent material is based on H₂TiO₃, a highly selective ion-exchanger for Li⁺, which was synthesized by solid-state reaction of TiO₂ and Li₂CO₃ to produce Li₂TiO₃ and activated via protonation to H₂TiO₃. The active material was shaped into mechanically robust spheres using a phase inversion technique with polyvinyl chloride (PVC) as a binder, enabling their use in fixed-bed column systems. The composite spheres, with diameters of 1.5–2.0 mm, retained high porosity and offered efficient mass transfer while maintaining structural integrity during handling and cycling. Lithium sorption tests conducted at pH 9 in synthetic solutions containing 80 ppm Li⁺ showed an uptake capacity of 3.1 mmol/g of active material (21.5 mg/g), corresponding to 12–15 mg/g based on the total composite mass. These values are consistent with high-performance ion-exchange sorbents and confirm that the shaping process does not compromise Li⁺ uptake.

Selectivity tests in multicomponent systems representative of ore leachates (Li⁺ 0.2–0.6 g/L; Na⁺, K⁺, Ca²⁺ up to several g/L) demonstrated strong discrimination in favor of lithium. Separation factors exceeded 100 for Na⁺ and K⁺ and remained above 20 for Ca²⁺, confirming the applicability of the material to real competitive matrices. Regeneration enabled over 98% lithium recovery with no detectable Ti leaching. The composite spheres retained more than 95% of their sorption capacity after 10 adsorption–desorption cycles, demonstrating excellent stability and reusability. In tests with real spodumene leachates, the composite material maintained its performance, effectively concentrating lithium from a background of abundant alkali and alkaline earth metals. The combination of high lithium selectivity, efficient regeneration, and mechanical resilience makes these Li₂TiO₃/PVC composites a strong candidate for integration into direct lithium extraction (DLE) processes targeting ore leachates.

Acknowledgements: This work is supported by the European climate, infrastructure and environment executive agency (CINEA) through the project 101069644 – LiCORNE – HORIZON-CL5-2021-D2-01. Part of this work is also supported by the EIT KIC RawMaterials (EIT RM) in the frame of the OLiVer KIC Upscaling project.