Hydrophobic natural deep eutectic solvents for lanthanides extraction

Abstract Lanthanides are critical elements in many modern technologies, yet their individual separation remains a major challenge. Here, we report, for the first time, the use of two natural hydrophobic deep eutectic solvents (DES) as diluents for the diglycolamide extractant N,N,N′,N′-tetraoctyl diglycolamide in intra-lanthanide separation. These DES-based extraction systems demonstrated highly efficient lanthanide recovery (E Lu ∼ 97%) and moderately improved selectivity between heavy and middle lanthanides compared with the molecular diluent, n-dodecane. These results highlight the potential of natural DES as sustainable alternatives to conventional solvents in rare-earth-element processing.