Application of polyethylene glycol based aqueous two-phase systems for extraction of heavy metals

In this work the partitioning behavior of Hg(II), Zn(II) and Co(II) was measured in a polyethylene glycol based aqueous two phase system (PEG-ATPS) containing Na2CO3 as a phase forming salt. The experiments were performed by mixing equal weights of 30% (w/w) PEG-6000 solution and 10% (w/w) Na2CO3 solution. The partitioning of ions was studied at various concentration of iodide as extracting agent, stock salt solution pH, temperature and initial metal ion concentration. The experimental results showed that extraction of metal ions mainly depends on concentration of iodide. In the other words the extraction of metal ions increases as the amount of iodide ions increases. It was observed that the extraction of mercury increases as pH increases, while in the case of zinc and cobalt it was insignificant meanwhile temperature has a minor effect on metal ions extraction. In this work the maximal extraction percentages of Hg(II), Zn(II) and Co(II) were obtained as 99.3%, 98.62% and 58.2%, respectively.