Glycopolymer‐Mediated Selective Separation of Middle Rare Earth Elements

The selective separation of rare earth elements (REEs), particularly middle REEs (MREEs) with intermediate ionic radii, poses significant challenges for current methods. In this study, we introduce a novel approach that leverages negatively charged glycopolymers for size-specific separation of MREEs. By varying glycopolymer properties such as degree of polymerization (DP) and charge density, we achieved a distinct U-shaped selectivity profile, with a pronounced preference for Samarium (Sm) and Europium (Eu) over other REEs like Cerium (Ce), Gadolinium (Gd), and Holmium (Ho). Enrichment experiments demonstrated the practical potential of this methodology, achieving over 10% selectivity for Sm in Ce/Sm and Ho/Sm mixtures (10:1 ratios). Further, a separation experiment with a 1:1 Ce/Sm mixture yielded 15% enrichment after five filtration cycles with minimal glycopolymer, underscoring the approach's effectiveness. This work highlights the promise of glycopolymer-based strategies for targeted MREE separation, offering an efficient and tunable pathway for refining separation processes in REE applications.