Behavior, mechanism and equilibrium studies of Au(iii) extraction with an ionic liquid [C4-6-C4BIm]Br2. Issue 2 (17th December 2019) - Su, Hongmei
Abstract : The first gemini-type benzimidazole ionic liquid ([C4 -6-C4 BIm]Br2 ) with two sites of action was synthesized and applied for gold extraction. Abstract : The first gemini-type benzimidazole ionic liquid ([C4 -6-C4 BIm]Br2 ) with two sites of action was synthesized and applied for gold extraction. The effects of [C4 -6-C4 BIm]Br2 concentration, initial gold(iii ) concentration, acidity, and the loading capacity of [C4 -6-C4 BIm]Br2 were examined in detail. It was found that [C4 -6-C4 BIm]Br2 has excellent extraction ability for obtaining high purity gold. The anion exchange mechanism between [C4 -6-C4 BIm]Br2 and Au(iii ) was proved by Job's method and 1 H NMR and FTIR spectroscopy. Quantum chemical calculations were carried out to prove the mechanism theoretically. The extraction equilibrium process was modeled using Langmuir and Freundlich isotherms. Thermodynamic parameters Δ H, Δ G and Δ S indicated that the extraction process was exothermic and spontaneous. The pseudo-second-order kinetic model well fitted the experimental data ( R = 0.99). In addition, [C4 -6-C4 BIm]Br2 has high selectivity for Au(iii ) compared to other base metals. In summary, [C4 -6-C4 BIm]Br2 has great application prospects in industry due to its excellent characteristics such as low cost, easy availability, and high extraction capacity.