Highly Acidic Macro-Porous Cation Exchange Resin D001 for Efficient Separation of Co(II) from Nd(III) and Dy(III) During Rare Earth Recycling

Addressing the need for efficient separation of critical elements from NdFeB magnets, this study introduces, for the first time, a D001 cation exchange resin for the selective separation Co(II) from Nd(III) and Dy(III). At pH 5, the resin adsorbs Nd and Dy with high capacities (97.57 and 86.38 mg/g, respectively) and efficiencies (over 98%), but shows low affinity for Co (26.6% efficiency). The resin exhibits excellent stability across a wide pH range of 2–7 and maintains high adsorption performance over five consecutive cycles. The process follows pseudo-second-order kinetics and the Langmuir model. Co(II) is effectively desorbed with high purity (>99%) using 2.5 M H2SO4. Characterization confirms that adsorption occurs via ion exchange on –SO3Na groups. This method successfully separates Co, providing a high-purity stream for further rare earth purification and demonstrating strong industrial potential.