Facilitated selective transport of Co(II), Ni(II), Zn(II) and Cd(II) across polymer inclusion membranes containing 1-decyl-imidazole as a carrier

The work aimed to investigate the possibility of selective separation of Co(II), Ni(II), Zn(II) and Cd(II) ions from chloride solution with variable chloride ion concentration (0.25, 0.5 and 1.0 M) using polymer inclusion membranes. In the studies, polymer inclusion membranes were used, with cellulose triacetate as the matrix, o-nitrophenyl octyl ether as the plasticizer, and 1-decylimidazole as a metal ion carrier. The receiving phase was demineralized water. The results of the studies on the transport of metal ions through polymer inclusion membranes with 1-decylimidazole as an ion carrier indicate a strong influence of the chloride ion concentration in source phase on the transport rate, and their separation properties. The kinetic parameters such as the transport flux, the recovery factor, as well as the separation coefficients were determined for the experimental data. It was found that zinc(II) ions were the easiest to separate from the aqueous chloride solution. The recovery rates (%) of zinc ions, for chloride ion concentrations of 0.25 M, 0.5 M, and 1.0 M, were 71%, 88%, and 65%, respectively. The lowest recovery observed was for nickel(II) ions, which did not exceed 2%. In contrast, cadmium ions had removal recovery rates ranging from 5.5% to 6.5%, and for cobalt ions – from 2.5% to 14.5%, depending on chloride anion concentration in the source phase. The separation coefficient for zinc ions was the highest compared to the other ions. The results from studies on the transport of nickel(II), cobalt(II), cadmium(II), and zinc(II) ions through polymer inclusion membranes with 1-decylimidazole suggest that this process can be effectively used for the selective separation of Zn(II) ions from a multi-metal aqueous solution.