Long-chain ligand design in creating magnetic nano adsorbents for separation of REE from LTM

A series of magnetic adsorbents was created by grafting selected functional ligands directly on the surface of iron oxide nanoparticles (NP). The produced materials were characterized by SEM-EDS, TEM, AFM, FTIR, XRD, Mo center dot ssbauer spectroscopy, low temperature gas sorption, and in relation to functional properties. Each of the applied ligands carried two functional groups including phosphonic acid involved in grafting, and either alcohol, thiol, amino, carboxylic- or phosphonic acid. The kinetics and thermodynamics of metal cation adsorption were investigated for Rare Earth (REE, Sm3+, Nd3+, Dy3+ and Tb3+) and Late Transition Metals (LTM, Co2+ and Ni2+) as representative for the content of magnetic materials, requiring recycling. Long linear alkyl chain (C10-C12) and, in case of phosphonic acid, even a shorter one (C6), were used to trace potential stabilization of the particles against iron leaching on desorption of adsorbed cations in acidic medium. The NP demonstrated high adsorption capacity, efficient desorption and considerable selectivity in separation of REE from LTM. Modification with ligands offers appreciable protection of magnetic particles against iron leaching.