Microemulsion Extraction of Gold(III) from Hydrochloric Acid Medium Using Ionic Liquid as Surfactant and Extractant

A microemulsion consisting of cyclohexane, n-hexanol, hydrochloric acid solution, and the ionic liquid 1-n-tetradecyl-3-methylimidazolium bromide ([C(14)mim]Br) was investigated for Au(III) extraction. In the extraction system, [C(14)mim]Br bears double functions of surfactant and extractant. The anion-exchange mechanism of Au(III) extraction by [C(14)mim]Br was confirmed by the method of continuous variation and infrared spectrum analysis. The effects of extraction time and various material concentrations were examined for Au(III) extraction. Under optimum conditions, almost all the Au(III) in hydrochloric acid solution was extracted to the microemulsion phase, which also has high selectivity for Au(III) over some metals (Cu(II), Cd(II), Co(II), Ni(II), Fe(III), Al(III), and Sn(IV)). Therefore, the extraction of Au(III) by the [C(14)mim]Br/cyclohexane/n-hexanol/HCl microemulsion is an efficient and effective approach with high selectivity.