A separation strategy of Au(III), Pd(II) and Pt(IV) based on hydrophobic deep eutectic solvent from hydrochloric acid media

A hydrophobic deep eutectic solvent (HDES) based on lidocaine and thymol was examined for selective extraction and separation of Au(III), Pd(II) and Pt(IV) in the acidic leaching solution of secondary resources. At first, the properties of HDES were characterized by 1 H NMR, DSC, TGA, RDF and ESP to prove its suitability for extraction process. In addition, extraction behaviors, maximum extraction capacities and competitive extraction experiment were investigated to explore the extraction ability of HDES. The results show that the maximum extraction capacity of Au(III), Pd(II) and Pt(IV) reached 761.2 g/L, 98.3 g/L and 299.3 g/L, respectively. Meanwhile, their extraction efficiency was affected by the changing acidity of aqueous. And then, ion-association mechanism in the extraction process was proposed through the analysis of FT-IR. Finally, a separation process was proposed for the recovery of Au(III), Pd(II) and Pt(IV) based on acidity control and KSCN, which achieved recovery efficiency of 97.8 % Au(III), 99.9 % Pd(II) and 89.5 % Pt(IV). After collecting and regenerating the used HDES, their extraction performance of Au(III), Pd(II) and Pt(IV) were still maintained.