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Nickel-cobalt separation by solvent extraction method

100%

Radzyminska-Lenarcik E. , Wasilewska A.

Challenges of Modern Technology

2015

tom Vol. 6, no. 3

20--23

Separation of cobalt(II), and nickel(II) ions from nitrate solutions using liquid-liqiud extraction process was reported. The measurements were run at 25oC and at fixed ionic strength equal to 0.5 (KNO3,HNO3). Initial concentrations of Co(II) and Ni(II) nitric acid in the aqueous phase were constant (0.01 M and 0.15 M, respectively). Both 1-hexylimidazole (1), and 1-hexyl-2-methylimidazole (2), both in dichloromethane were used as extractants. Their concentrations in organic phase were varied from 0.01 to 0.25 M. Cobalt(II) in an aqueous solution forms both tetrahedral and octahedral complexes. Nickel(II) forms only a six-coordinate complexes. These general differences help to provide the basis for the various separation processes currently used for cobalt-nickel separation. The steric effect for extractant 2 facilitates the extraction of tetrahedral Co(II) complexes. Extraction percent (%E) of cobalt(II) and nickel(II) in the systems studied were calculated. The percentage extraction increases for increasing values of pH of aqueous phase and is the highest for pH = 7.2. In the aqueous phase, of which the pH = 7.2, there remain 75%Ni(II) and 40% Co(II) for extractant 1 and the respective values for extractant 2 are 85% Ni(II) and 20% Co(II). The steric effect increases selectivity coefficients Co(II)/Ni(II). The highest selectivity coefficients for both extractants were obtained at a pH of aqueous phase = 6.2; their values were 5 and 8.9 for extractants 1 and 2, respectively.

Application of polymer inclusion membranes doped with 1-hexyl-4-methylimidazole for pertraction of zinc(II) and other transition metal ions

100%

Ulewicz M. , Radzyminska-Lenarcik E.

tom Vol. 51, iss. 2

447--460

Transport of Zn(II) from unary aqueous chloride solutions and from solutions which contain mixtures of Cd(II), Co(II) and Ni(II) ions in source phases (cMe = 0.001 mol/dm3, pH = 6.0) across polymer inclusion membranes (PIMs) doped with 1-hexyl-4-methylimidazole as ion carrier was studied. The use of 1-hexyl-4-methylimidazole enables the separation of 98.5% Zn(II) from a unary solution and 96.9% from a quaternary solution of Zn(II)-Cd(II)-Co(II)-Ni(II) after running the process for 24 hours. Using that ion carrier, the metals are transported in the following order: Zn(II) > Cd(II) > Ni(II) > Co(II), and the selectivity coefficients of Zn(II)/Cd(II), Zn(II)/Ni(II), and Zn(II)/Co(II) are 12.9, 23.4 and 40.8, respectively. Findings of atomic force microscopy (AFM) examinations as well as thermograms of a polymer inclusion membrane containing 1-hexyl-4-methylimidazole are also presented. A membrane with 1.0 mol/dm3 of carrier has a porosity of 15.8%, and roughness of 6.6 nm. The membranes remain thermally stable at temperatures up to 200oC. The findings were compared with earlier-reported results for 1-hexylimidazole.