Enhanced rare earth element recovery from NdFeB leachates using magnetically responsive vermiculite–alginate nanocomposites

Abstract

Rare Earth Metals (REMs) are vital for advanced technologies, yet they face increasing supply risks, emphasising the need for efficient recovery from secondary resources such as NdFeB magnet waste. The present work details the development and characterisation of magnetically responsive vermiculite-based nanocomposites, with and without alginate immobilisation, aimed at the selective recovery of neodymium (Nd(III)) and dysprosium (Dy(III)) ions from synthetic solutions and real NdFeB magnet leachate. The composites were synthesised by incorporating Fe 3 O 4 nanoparticles into vermiculite, and, in some cases, the resulting material was encapsulated in alginate beads. X-ray diffraction was utilised to confirm the formation of magnetite, while the magnetic responsiveness of all sorbents was sufficient for straightforward separation. The presence of additional functional groups, including hydroxyl, carboxyl, and silicate, was shown to enhance sorption performance. Although alginate immobilization significantly reduced sorption kinetics, it led to higher sorption capacities and enhanced structural stability. Non-immobilised materials exhibited greater selectivity for Nd(III) over Dy(III), a critical challenge in the separation of REMs. Regeneration studies confirmed the efficient metals desorption when complexing agents were utilised. The high sorption performance of these low-cost and eco-friendly nanocomposites in real leachate systems demonstrates their applicability for sustainable REM recovery from e-waste streams.

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