Adsorption-Based Separation of Rare Earth Elements Using Metal-Organic Frameworks: Sustainable Critical Material Recovery

Rare earth elements (REEs) are indispensable for clean energy, advanced electronics, and defense technologies; however, environmental concerns, geopolitical risks, and unsustainable reliance on conventional separation processes challenge their use. Metal-organic frameworks (MOFs) have emerged as a promising alternative for adsorption-based rare-earth separation, thanks to their tunable porosity, large surface area, and adaptable chemistry, which enable selective adsorption even in complex matrices, such as acidic leachates, e-waste, seawater, or industrial effluents. This study critically evaluates the potential of MOFs to bridge the gaps in efficiency, selectivity, and sustainability that conventional technologies struggle to address. Design strategies, including host-guest interactions, pore engineering, post-synthetic modification, and functional motifs, are highlighted alongside advances in composite systems, such as membranes and ion-imprinted MOFs. Emerging directions, such as green synthesis, continuous-flow production, AI-driven design, and in situ & comprehensive characterization, are discussed as pathways to accelerate industrial implementation. Policy frameworks, pilot-scale demonstrations, and techno-economic analyses are crucial for successful scaling-up from laboratory to real-world deployment. The current study offers a balanced perspective on whether MOFs are likely to be disruptive game changers or niche materials, emphasizing the need for interdisciplinary efforts to advance them toward scalable, sustainable, and economically viable REEs separation technologies.