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Extraction of gold(III) from hydrochloric acid solutions by CTAB/n-heptane/iso-amyl alcohol/Na₂SO₃ microemulsion

Lu, Wenjuan, Lu, Yanmin, Liu, Fei, Shang, Kai, Wang, Wei, Yang, Yanzhao
Journal of hazardous materials 2011 v.186 no.2-3 pp. 2166-2170
alcohols, cetyltrimethylammonium bromide, enthalpy, entropy, equations, gold, hydrochloric acid, hydrogen, surfactants, temperature, waste treatment, wastewater
The extraction of Au(III) from hydrochloric acid solutions by microemulsion was studied. The extraction experiments were carried out using cetyltrimethylammonium bromide (CTAB) as surfactant and iso-amyl alcohol as co-surfactant. Au(III) was found to be extracted into the microemulsion phase due to ion pair formation such as AuCl₄ ⁻CTAB⁺. The influence of temperature on the extraction of Au(III) has been investigated at temperatures ranging from 288 to 313K. Temperature was found to decrease the distribution of Au(III). Thermodynamic parameters like enthalpy and entropy of the extraction, calculated by applying Van’t Hoff equation, were −36.76kJmol⁻¹ and −84.87Jmol⁻¹K⁻¹, respectively. Furthermore, the influence of the concentrations of hydrogen ion and chloride anion on the extraction efficiency (E%) were verified. Au(III) was extracted quantitatively (E%>99%) and selectively at the whole range of HCl concentrations (0.2–5M). Recovery of gold from electrical waste and treatment of CTAB wastewater generated from the extraction were also discussed. Thus, the extraction of Au(III) from hydrochloric acid solutions by microemulsion is an effective approach.