Membrane Extraction of Iron(III) by Diphenylthiocarbamide in the Presence of Palladium(II)

The process of iron(III) and palladium(II) extraction from binary mixtures containing 8.1∙10-2 М FeCl3 and 6.7∙10-3 M H2PdCl4 in 3.0 M HCl by diphenylthiocarbamide − 1,2-dichloroethane liquid membranes is studied at galvanostatic electrodialysis. It is demonstrated that the liquid membranes ensure a profound one-stage separation of iron(III) from palladium(II) at the stage of stripping (separation factor βFe/Pd > 100). Transport of FeCl4− ions through the liquid membrane is supposed to occur in the form of ionic associates with cationic palladium(II) complex PdL4Cl∙FeCl4. The effects of the current density as well as of composition of the liquid membrane and of aqueous solutions on the rate of metal transport are determined. It is found out that the iron(III) extraction degree into the strip solution increases as the current density (0 − 5.6 mA/cm2) and the duration of electrodialysis (0 − 80 min) increase. The increase of DPTC concentration in the organic phase as well as of composition of the stripping solution do not exert a considerable influence on the rate and selectivity of iron(III) and palladium(II) membrane extractio