Transfer and Separation of Zn(II)/Co(II

ABSTRACT

Transfer of Zn(II) ions from a mixed sulphate and thiocyanate solution through a supported liquid membrane (SLM) containing CYANEX 925 in kerosene as carrier has been studied as a function of stirring rate, [H⁺], [CYANEX 925], [SCN^–], [H₂SO₄] and ammonia solution concentrations. The experimental results show that the transfer of Zn(II) ions increases with the increase in stirring rate, thiocyanate concentration in the feed and concentration of NH₄OH used as the stripping solution. The transfer experiments of Zn(II) from its admixture with Co(II) indicated that Zn(II) could be extracted more than Co(II) by CYANEX 925; the transfer rate increased with time. The investigated SLM system could be used for removal of Zn(II) from an aqueous mixed thiocyanate/sulphate medium of [H⁺] = 0.01. In addition, the present system is selective for Zn-Co separation from aqueous mixed thiocyanate/sulphate medium. This selectivity was found to decrease with time and a maximum value of 25 is reached after 60 min. Repeated transfer of Zn(II) individually and from its admixture with Co(II) through the same membrane film with reasonable efficiency indicate that the used SLM is stable and durable.