Confinement-effect adsorbents based on titanium-based lithium ion sieve for efficient lithium adsorption under natural pH conditions

Lithium, a key element across diverse industries, is experiencing rapidly growing global demand. Liquid lithium resources, accounting for over 67 % of total lithium reserves, are primary targets for extraction. Among various extraction methods for liquid lithium, adsorption has shown great potential. Lithium ion sieves (LIS), especially titanium-based lithium ion sieves (LTO), are promising adsorbents but often exhibit poor performance under natural pH conditions due to interference from H + and Mg 2+ . Conventional LTO adsorption requires initial alkalization of the bulk solution to achieve satisfactory adsorption capacity, which leads to excessive alkali consumption and increased carbon footprint. Herein, a novel LTO adsorbent is reported, which achieves high lithium adsorption capacity under natural pH conditions. We doped LTO onto an organic carrier functionalized with quaternary ammonium groups and preloaded hydroxide ions onto these groups. The groups generate a positive electrostatic field that repels interfering cations such as Mg 2+ and H + , while the preloaded hydroxide promptly neutralizes the H + ions released during Li + exchange within the LTO structure. Together, these two mechanisms create a microscale confinement environment that accelerates Li + transport to adsorption sites. Under natural pH conditions, this confinement-effect adsorbent achieves a theoretical maximum adsorption capacity of 70.88 mg/g while reducing alkali consumption to 1/600 that required by traditional LTO adsorption, without the need to adjust the bulk solution pH. This innovative approach enables more efficient and sustainable lithium extraction and shows strong potential for real-world application.