Recent advances in rare earth adsorption and recovery using Fe₃O₄-based functionalized core-shell magnetic...

This review systematically summarizes recent advances regarding the use of Fe₃O₄-based functionalized core-shell magnetic nanomaterials (Fe₃O₄-based FCMNs) for adsorbing and recovering rare earth elements (REEs)-a practice pivotal to resource conservation, recycling, and sustainable management. As non-renewable critical resources, REEs' efficient recovery aligns with goals of reducing reliance on primary extraction and minimizing resource waste. Fe₃O₄, the widely used magnetic core, is favored for strong magnetic response, simple synthesis, low toxicity, and affordability-traits that lower the environmental and economic costs of REEs recovery, which is vital for long-term resource utilization. Its preparation methods shape properties key to practical application in resource systems. Functionalized shells (polymers, silica-based, carbon-based, MOFs/COFs, etc.) enable REEs adsorption via functional groups and specific mechanisms, directly advancing resource recovery efficiency. This review examines several key aspects: the construction of core-shell structures, the underlying adsorption mechanisms, and the performance of various shell materials. It also addresses practical challenges-such as secondary pollution and performance decline during reuse-that could undermine sustainable practices. Finally, it outlines future priorities, including the separation of light/heavy REEs, in-situ solidification, and stability in complex environments, to improve the suitability of these materials for large-scale recycling. This work offers a comprehensive overview of Fe₃O₄-based FCMNs in REE recovery, aiding advancements that bolster sustainable REEs management and protection.