Extraction of gold(III) using novel gemini-type benzimidazole ionic liquid from hydrochloric acid medium

In this study, a novel gemini-type benzimidazole ionic liquid [C 6 BIM 2 ][NTf 2 ] 2 was synthesized for efficient extract gold(III) from hydrochloric acid medium. Firstly, a series of parameters (e.g., vibrating time, the extractant concentration, acidity and salinity) were optimized and obtained the optimal extraction condition. Under this condition, the extraction efficiency can reach 98.42%, along with the distribution ratio of 186.87. Through the response surface methodology (RSM) model optimization, the amount of [C 6 BIM 2 ][NTf 2 ] 2 corresponding to different HCl concentration was determined for gold(III) extraction during actual operation. Then, verified the anion exchange mechanism with the aid of Job’s method, UV–vis, FT-IR and 13 C NMR. Thermodynamic parameters were calculated and implied that the extraction reaction was an exothermic and spontaneous process. Furthermore, organic phase loaded with gold(III) was easy to be completely stripped by CS(NH 2 ) 2 / HCl solution and its extraction ability was kept constant after 5 cycles extraction experiments. Meanwhile, [C 6 BIM 2 ][NTf 2 ] 2 has a superb ability to select gold(III) in the multi-metal solution. In general, [C 6 BIM 2 ][NTf 2 ] 2 showed distinguished selectivity and extraction ability for gold(III) from secondary resources, which was claimed to be a promising new style extractant.