Safe and Sustainable by Design MOF Beads for Selective Entrapment and Recovery of Rare Earth Elements
Prathmesh Bhadane, Pankti Dhumal, Émilie Brun, Andrew J. Britton, Iseult Lynch, Swaroop Chakraborty
Abstract
We report the development of CA-BNMG-1 composite beads-cellulose acetate macrobeads embedded with nanosized copper imidazolate MOFs (BNMG-1) -engineered via nonsolvent-induced phase separation for the selective recovery of rare earth elements (REEs) from complex aqueous environments. This encapsulation strategy ensures uniform MOF dispersion, enhanced mechanical integrity, and minimized Cu(II) leaching (<1%), fulfilling the Safe and Sustainable by Design (SSbD) criteria. The CA matrix not only mitigates copper toxicity but also enables facile bead handling, recyclability, and scalable deployment in fixed-bed systems. Adsorption studies across a 10-REE standard solution and two simulated waste streams demonstrated significantly improved REE selectivity over pristine BNMG-1. Separation factors (SFs) for Yb(III) over Mn(II), Ni(II), and Na(I) reached 194.5, 325.8, and 339, respectively; Eu(III) showed SFs of 155.5, 260.5, and 271.2. The beads retained over 95% of their uptake capacity across multiple adsorption and single desorption cycles using mild acidic eluents, confirming excellent reusability and structural stability. This work advances a robust, low-toxicity, and scalable REE recovery platform that integrates adsorptive performance with environmental safety. CA-BNMG-1 beads offer a compelling alternative to solvent extraction, with potential for integration into circular economy strategies targeting REE recovery from e-waste, mine tailings, and industrial effluents-addressing both resource security and sustainability challenges.