Solvent extraction studies on cadmium and zinc using Cyphos IL 102 and recovery of zinc from zinc-plating mud

In the present studies trihexyl(tetradecyl)phosphonium bromide (Cyphos IL 102) diluted in toluene has been employed as a novel reagent for the extraction and recovery of Cadmium(II) and Zinc(II) from hydrochloric acid medium. The influence of different parameters such as concentration of H+, extractant and chloride ion, nature of acid (HCl, H2SO4 and HNO3), diluent and equilibration time and temperature on the extraction of Cd(II) and Zn(II) have been investigated. The stoichiometry of extracted metal species examined by Cyphos IL 102 was found to be [(R3RP)(2) MCl(2)A(2)](org) at low concentration of chloride ions < 10(- 2) mol L-1 for Cd(II) and < 1.5 mol L-1 for Zn(II) where M2+ = Cd(II)/Zn(II) and R(3)RP(+)A(-) = Cyphos IL 102. The maximum loading capacity for Cd(II) and Zn(II) were 86.46 mg and 61.91 mg per gram of extractant, respectively. Efficient stripping of Cd(II) and Zn(II) from the loaded organic phase was achieved with 1.0 mol L-1 HNO3. A series of successive extraction-stripping cycles with the extractant revealed good recyclability of the extractant. In addition to Cd(II) and Zn(II), the partition behaviour of other associated metal ions namely, Mn(II), Fe(II), Ni(II), Co(II) and Fe(III) from chloride medium at different acid molarity has been investigated. Binary separations of Cd(II) and Zn(II) from each other and other associated metal ions have been achieved using 3.0 x 10(-3) mol L-1 Cyphos IL 102. Based on the extraction data a separation scheme was designed and applied to a synthetic mixture. The developed separation scheme was successfully applied to zinc plating mud for the recovery of Zn (II). Zn(II) was quantitatively (96.64%) recovered with a purity > 99.00%.