The extraction of Zn(II) in aqueous PEG (1550) - (NH4) 2SO4 two-phase system using Cl- ions as extracting agent

Abstract

The extraction of Zn(II) in an aqueous PEG (1550) - (NH4) 2SO4 two-phase system as a function of several experimental parameters was studied. PEG-based aqueous two-phase systems are composed of two immiscible phases: a polymer-rich phase and a salt-rich phase, which can be used for extraction experiments. In the absence of a suitable extracting agent, for the system consisting of a mixture of equal volumes of 40 mass%PEG and 40 mass%(NH4)2SO4 aqueous solutions, Zn(II) remained predominantly in the salt-rich phase. Variation of the pH of the salt stock solution did not change very much the extraction efficiency. By adding chloride ions, an enhancement of the Zn(II) extraction was observed. The Zn(II) extraction efficiency in presence of Cl- depends on the acidity of the salt stock solution and on the concentration of chloride ions added into the system.