A. Bolon
University of California - Merced,
United States
Keywords: rare earth elements (REEs), separation technologies, ligand design
Summary:
In recent years, there has been a steadily increasing demand for the development of secure and sustainable REE supply chains globally, driven by their essential roles in magnets, catalysts, and renewable energy technologies. However, establishing domestic REE production remains challenging due to the chemical similarity of lanthanides, which makes rapid, efficient separation extremely difficult. Existing techniques, including hydrometallurgy, gas phase extraction, and traditional electrodialysis (ED), face limitations in selectivity, efficiency, and cost. To address these challenges, we propose a chemically enhanced electrodialysis (CEED) strategy that couples ED with targeted ligand complexation to improve REE separation. Our work emphasizes ligand design and ion recognition, exploiting our ability to synthesize crown ethers and related molecular or macromolecular sequestrants with tunable conformations and metal-binding specificity to create a versatile and cost-effective separation platform. Candidate sequestrants will be evaluated through binary solvent extraction experiments and analyzed by atomic absorption spectroscopy (AAS) or inductively coupled plasma mass spectrometry (ICP MS). Extraction equilibrium constants (Kex) will be measured as a function of pH and ionic strength (NaCl), and binding selectivity (SA/B) will be assessed relative to Na+, Mg2+, and Ca2+ at varying concentration ratios to determine the most effective ligands for enhancing CEED-based REE separation.