Lithium-Selective Adsorbents and Membranes for Electrochemical Wastewater Refining

With global lithium supplies projected to fall short of demand between 2023 and 2027, there is great motivation to develop new technologies capable of lithium recovery from alternative sources such as battery waste, produced water, and geothermal brines. In these sources, the co-existence of other impurities at much higher concentrations than lithium (e.g., >60,000 ppm Na+ versus 50-1000 ppm Li+ in brines) presents a challenge for high-purity lithium extraction. Selective electrodialysis is a candidate for lithium recovery that aligns with recent resource extraction priorities including developing electrified separation processes, although it requires the development of ion-selective membranes. To inform the design of such membranes, we first studied fundamental ion transport and selectivity mechanisms in commercially available membranes. We then synthesized a library of novel ligand-functionalized membranes (including acrylic acid and vinylpyridine ligands) to study the impact of additional ion-specific coordinative interactions on lithium selectivity in the selective electrodialysis process. Finally, we integrated selective ion exchange resins into electrodialysis to accomplish in situ electrochemical regeneration that helps concentrate lithium from dilute sources and recovery high-purity lithium in electrochemical ion exchange reactors.