Ionic-Liquid-Type Imidazolium Gemini Surfactant Based Water-in-Oil Microemulsion for Extraction of Gold from Hydrochloric Acid Medium

A microemulsion with hydrochloric acid solution as the polar phase, n-heptane as the continuous phase, [C-14-4-C(14)im]Br-2 as an ionic-liquid type imidazolium gemini surfactant and extractant, and n-amyl alcohol as cosurfactant was studied on Au(III) extraction. Compared to its corresponding monomer [C14-mim]Br-based microemulsion fbr Au(III) extraction, the [C-14-4-C(14)im]Br-2-based microemulsion system showed excellent extractability of Au(III). The anion-exchange mechanism of Au(III) extraction was confirmed by the slope method and spectrum analysis (UV-vis, FT-IR, and H-1 NMR). Main influence factors such as phase ratio, extraction equilibrium time, amyl alcohol volume fraction, and the concentration of ionic liquid on the extraction efficiency (E%) were explored. Moreover, [C-14-4-C(14)im]Br-2-based water-in-oil microemulsion had high selectivity over a multimetal ion solution (Co (II), Cu(II), Fe(III), Ni(II), Sn(IV), and Al(III)). Therefore, it is indicated that [C-14-4-C(14)im]Br-2-based microemulsion provides an effective and potential approach for the separation and purification of Au(III) from HCl solution.