(297f) Oxidation-Enhanced H2TiO3 ion Sieve for Use As a High-Efficiency Adsorbent for Direct Lithium Extraction from Dilute, Yet Chemically Complex Influents

The increasing demand for lithium, predominantly driven by electric vehicle and energy storage markets, necessitates innovative strategies to recover lithium from unconventional brine resources. Furthermore, to reduce reliance on foreign lithium supplies, the U.S. must prioritize domestic lithium recovery from these unconventional resources. The U.S. possesses the third largest lithium resource in the world, albeit only accounts for a small percentage of current global lithium production. Significant lithium deposits are present in geothermal, Salt Lake, and oilfield brines. Oilfield production water, an underutilized byproduct, can contain lithium concentrations exceeding 500 mg Li⁺/L, presenting a promising domestic source of lithium. However, these influents are often chemically complex thereby challenging current lithium capture processes.

Proposed technologies for lithium extraction from these resources include adsorption, membrane separation, solvent extraction, or combinations thereof. Although significant research has been performed to overcome the inherent challenges associated with lithium extraction from hyper-saline brines, both technical and economic challenges remain. Solvent extraction requires the use of hazardous chemicals and generates secondary waste streams. Membrane materials are attractive for engineering applications but are prone to fouling if pre-treatment requirements are not met. Adsorption materials offer an environmentally friendly alternative to solvent extraction, but economic feasibility depends critically on adsorbent performance.

This work addresses these challenges by advancing ion-exchange adsorption for lithium recovery. Titanium-based lithium-ion sieves, such as metatitanic acid (H₂TiO₃, HTO), are attractive due to their recyclability and high selectivity However, despite the attractive aspects, only about 30% of the theoretical adsorption capacity has been observed in its application at lithium concentrations found in brine sources. To address this, a novel hydrothermal treatment using hydrogen peroxide dosing at alkaline conditions was developed to modify the surface chemistry of lithiated HTO precursors. By increasing the density of surface hydroxyl groups on HTO, the accessibility of lithium-binding sites can be improved significantly. This adsorbent modification achieved a 32% increase in lithium capture capacity and X-Ray Photoelectron Spectroscopy confirmed a 65% increase in the relative amount of hydroxyl groups present in HTO.

This advancement addresses a key limitation of adsorption-based lithium extraction: low lithium adsorption capacity. Improved adsorbent performance improves the economic feasibility of lithium extraction projects. When applied to U.S. brine sources, this technology could help support a more secure lithium supply chain and reduce reliance on foreign lithium chemicals.