Selective extraction of gold(III) in the presence of Pd(II) and Pt(IV) by salting-out of the mixture of 2-propanol and water

The mixture of 2-propanol with water has been employed to extract Au(III) along with other precious metals such as Pd(II) and Pt(IV) by using NaCl in the concentration range of 2.5–4.0 mol dm−3. Upon the addition of NaCl within this concentration range (2.5–4.0 mol dm−3) phase separation was attained. Gold(III) in aqueous phase was quantitatively extracted into the 2-propanol phase at 2.5–4.0 mol dm−3 of NaCl. The extraction of the other metals such as Pd(II) and Pt(IV) was much lower than for that of Au(III). Thus a maximal selective separation of Au(III) from these metals could be attained using the mixture of 2-propanol with water. A reaction mechanism involving the ion-pair of Na+ and [AuCl4]− has been proposed to explain this extraction.