One step effective separation of platinum and palladium in an acidic chloride solution by using undiluted ionic liquids

Imidazolium-based ionic liquids (ILs) with Tf²N- as anions were studied as extractants without dilution for the extractive separation of platinum and palladium in an acidic chloride solution. The effect of the alkyl chain length on the extraction performance was evaluated and, based on the performance, the IL, 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl) imide ([Omim][Tf²N]), was selected to be studied in detail. The extraction of Pt(IV) underwent little change over the HCl concentration studied, while that of Pd(II) decreased with increasing HCl concentration. The separation of Pt(IV) and Pd(II) was highly effective, and the highest separation factor between Pt(IV) and Pd(II) reached 312 at the optimum conditions in a binary component system composed of Pt(IV) and Pd(II). The effect of the initial Pt(IV) concentration on loading capacity and extraction efficiency of Pt(IV) was also investigated.