Selective transport and simultaneous separation of Cu(II), Zn(II) and Mg(II) using a dual polymer inclusion membrane system

Abstract

A dual polymer inclusion membrane (PIM) system is proposed for the simultaneous separation and enrichment of Cu(II), Zn(II) and Mg(II). PIMs containing 2-hydroxy-5-nonylacetophenone oxime (LIX 84I) and di(2-ethylhexyl) phosphoric acid (D2EHPA) as carriers were prepared in order to separate Cu(II) and Zn(II) from solutions containing multiple cations. The transport results indicate that the simultaneous separation of the three metal ions is highly dependent on the feed pH. At pH 2, Zn(II) and Cu(II) can be selectively transported into the respective stripping solutions, leaving Mg(II) in the raffinate. The dynamic transport model was established and confirms that the kinetic reaction rate is the controlling factor in the transport and separation of the metal ions. XPS and IR spectral analyses were carried out to elucidate the membrane extraction mechanism. As a novel application of the PIMs, the stability and uphill effect of the dual PIM system were also tested and has been compared with the performances of liquid membrane systems.