Enhanced separation of Pd(II) and Pt(IV) from hydrochloric acid aqueous solution using 2‐((2‐methoxyethyl)thio)‐1H‐benzimidazole

Abstract

Abstract Separation of palladium (Pd) and platinum (Pt) by solvent extraction is difficult because of their extremely similar physicochemical properties. Development of new extractants with a high extraction efficiency and excellent separation selectivity is the primary focus for enhancing the separation of Pd and Pt by solvent extraction. In this study, a new extractant, 2‐((2‐methoxyethyl)thio)‐1H‐benzimidazole (MOBI), which contains N, S, and O atoms, was synthesized and used to separate Pd(II) and Pt(IV) from a hydrochloric acid aqueous solution. The experimental results revealed that Pd(II) and Pt(IV) were effectively separated under the optimal conditions: MOBI concentration of 0.005 mol·L −1 , HCl concentration of 0.2 mol·L −1 , organic/aqueous (O/A) phase ratio of 1.0, and contact time of 15 min. The separation coefficient between Pd(II) and Pt(IV) was 1246.40, which indicates that MOBI has a higher selectivity for Pd(II) than Pt(IV). In addition, the mechanism of coordination between Pd(II) and MOBI was demonstrated through the slope method, Fourier transform infrared spectroscopy (FTIR), hydrogen‐1 nuclear magnetic resonance spectroscopy ( 1 H NMR), and carbon‐13 nuclear magnetic resonance spectroscopy ( 13 C NMR). The results revealed that MOBI could coordinate with Pd(II) via the N atom in the benzimidazole ring of MOBI molecules to form [Pd(MOBI) 2 Cl 2 ] (O) .