(548a) Chemical-Free Lithium Separation Using Zwitterionic Chromatography Towards Sustainable Direct Lithium Extraction

Lithium (Li) is a critical mineral essential for high-performance batteries. Since the projected Li demand far exceeds current supply chains, extracting lithium from unconventional resources, such as oil-produced water, brackish water, mining waste streams, and geothermal brine, has drawn increasing attention. However, these resources typically contain lithium at low concentrations with orders of magnitude higher concentrations of competing cations, limiting the technoeconomic viability of conventional chemical precipitation methods. To overcome this, Direct Lithium Extraction (DLE) technologies are being actively explored to selectively extract Li from complex brines via ion exchange, adsorption, solvent extraction, and electrochemical-based separations. Despite this progress, DLE methods still face challenges including low Li adsorption capacity, slow kinetics, short material lifetimes, and scalability.

To address these limitations, Choi’s group has developed a novel DLE method based on a mineral fractionation approach using zwitterionic chromatography. Among the designed zwitterionic
adsorbents, carboxybetaine-functionalized resins, modified from commercial ion exchange resins, showed the most efficient lithium separation from divalent cations using only water as the eluent,
leveraging selective salt partitioning through zwitterionic interactions and ion hydration shell shedding within the pore phase. The system exhibited unique anti-Langmuir elution behavior, which was captured using a modified Langmuir isotherm to support process modeling and design. Finally, we achieved over 97% lithium recovery from real brines using a multi-column process, offering a sustainable, chemical-free, and scalable pathway for lithium recovery from
complex aqueous environments.