J.A. Mattocks, Z. Dong, G.J.-P. Deblonde, Y. Jiao, D.M. Park, J.A. Cotruvo Jr
The Pennsylvania State University,
Keywords: rare earths, protein, biomining, bioseparations, hydrometallurgy
Summary:Technologically critical rare earth elements (REEs) are notoriously difficult to separate, owing to their subtle differences in ionic radius and coordination number. We have recently discovered the natural lanthanide-binding protein, lanmodulin, demonstrated its remarkable affinity and selectivity for rare earth elements (and trivalent actinides), and leveraged it for applications in detection, extraction, and separation of REEs, under all-aqueous conditions. A column-immobilized lanmodulin maintains the attractive properties of the soluble protein, including unparalleled REE selectivity, the ability to bind REEs at low pH, and high stability over numerous low-pH adsorption/desorption cycles. We demonstrate the ability of immobilized lanmodulin to transform a low-grade leachate (0.043 mol % REEs) into separate heavy and light REE fractions (88 mol % purity of total REEs) in a single column run while using ∼90% of the column capacity. Furthermore, lanmodulin achieves high-purity separation of the clean-energy-critical REE pair Nd/Dy. We will also present improvements to this process that enable even more streamlined recovery and separation of REEs. The ability to achieve tandem extraction and separation of REEs from very complex aqueous feedstock solutions without requiring organic solvents establishes this lanmodulin-based approach as an important advance for sustainable hydrometallurgy.