Extraction of gold(III) from chloride media in aqueous polyethylene glycol-based two-phase system

Abstract

Experimental results obtained for gold(III) extraction in aqueous polyethylene glycol (PEG)-based two-phase system using chloride ions as extracting agents are presented in this study. The experiments were performed by batch technique, using an aqueous two-phase system prepared by mixing equal volumes of 40% (w/w) PEG(1500) aqueous solution and 40% (w/w) (NH 4) 2SO 4 aqueous solution, both in absence and in presence of chloride ions extractants. The influence of several experimental parameters, such as initial gold(III) concentration, salt stock solution pH and chloride ions extractant concentration on gold(III) extraction efficiency was investigated. The experimental results have shown that gold(III) is quantitatively extracted (>98%) into PEG-rich phase in acid media (pH ⩽ 3.0) and at chloride ions concentration higher than 0.08 mol L −1. From the distribution coefficients determined as a function of chloride ions concentration into PEG-rich phase, the extracted species were identified. The comparison of the extraction behaviours of gold(III) and other metal ions (Cu(II), Co(II), Ni(II), Zn(II), Fe(III) and Pb(II)) was also examined. The validation of this method was done by recovery of gold from electrical wastes. The results present in this study show that the aqueous polyethylene glycol-based two-phase extraction system has potential for practical application in the extraction and separation of gold from chloride media.