Selective Adsorption of Rare-Earth Elements: Loading and Stripping Behavior of the 2D MOF NCU-1 Across pH and Time Domains

Rare-earth elements (REEs) are integral in a wide range of advanced technologies. Increasing demand for REEs, geopolitical tensions that threaten supply chains, and environmental strain due to extraction operations necessitate the development of new separation and purification methods. Novel selective adsorbents offer a promising alternative to traditional precipitation and solvent extraction due to high selectivity, surface area, and reusability. This research provides insight into the loading and stripping behavior of the 2-D Metal–Organic Framework (MOF) ‘NCU-1’ over multiple pH conditions and time domains in chloride media. NCU-1 structures were synthesized using standard methods, then evaluated for kinetics and equilibria via batch testing. Pseudo-first-order kinetics was used to model the adsorption behavior of all REEs tested. The kinetic trends between elements support a mechanism in which sorption affinity and rate correlate with REE ionic radius and surface interaction strength. The preliminary evaluation presented here suggests that such units are highly useful for both solution purification and the separation of light rare-earth (LREE) from heavy rare-earth elements (HREE).