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 [C6BIM2][NTf2]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 [C6BIM2][NTf2]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 13C 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 (NH2)2/ HCl solution and its extraction ability was kept constant after 5 cycles extraction experiments. Meanwhile, [C6BIM2][NTf2]2 has a superb ability to select gold(III) in the multi-metal solution. In general, [C6BIM2] [NTf2]2 showed distinguished selectivity and extraction ability for gold(III) from secondary resources, which was claimed to be a promising new style extractant.