Małgorzata ULEWICZ SEPARATION OF ZINC AND CADMIUM IONS FROM SULFATE SOLUTIONS BY ION FLOTATION AND TRANSPORT THROUGH LIQUID MEMBRANES

An experimental investigation is presented on zinc(II) and cadmium(II) ions separation from aqueous sulfate solutions, containing equimolar mixture on both metal ions, by ion flotation (IF) and transport through polymer inclusion membrane (PIM) processes. The IF experiments from dilute aqueous solutions (c Me = 1·10 -5 M) with an anionic surfactant (sodium dodecylbenzene sulfonate) and a cationic surfactant (hexadecylpyridinium chloride) are shown. With a cationic surfactant, the flotation separation of Cd/Zn grows with SO 4 2-concentration increase. In addition, the selective transport of Zn(II) and Cd(II) from aqueous sulfates source phase (c Me = 1·10 -2 M) through PIM containing cellulose triacetate (support), o-nitrophenyl pentyl ether (plasticizer) and di(2-ethylheksyl)phosphoric acid D2EHPA (ion carrier) is shown. The transport selectivity of Zn/Cd decreases with Na 2 SO 4 concentration increase in source phase. Results obtained are discussed in terms of the stability constants of sulfate complex species for zinc(II) and cadmium(II)