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Separation of palladium(II) from mixtures of non-ferrous metal ions by solvent extraction

Radzyminska-Lenarcik E., Witt K.

Challenges of Modern Technology

2016

Vol. 7, no. 1

17-22

The possibility of Pd(II) ions separation from mixtures of Co(II), Ni(II), Cu(II) and Pd(II) ions by solvent extraction was studied, using 1-hexyl-2methylimidazole in chloroform as the extractant. The initial concentration of each ion was 10 mM. The tests were carried out at a temperature of 25°C, at a constant strength of the aqueous solution of I = 0.5, as maintained by the KCl solution. It was demonstrated that differences in the stability and structure of their coordination sphere as well as solubility of complexes with the extractant could be used for separating the Co(II), Ni(II), Cu(II) and Pd(II) ions by solvent extraction. Pd(II), which forms flat-square complexes in the solutions, passes easily into the organic phase and is easier separated from the mixture of Co(II), Ni(II), Cu(II) ions, which form octahedral or tetrahedral complexes. Extraction percentages were calculated. For the respective metals, their values increase for increasing concentrations of the extractant in the aqueous phase. The extraction percentage decreases in the following order: Pd(II) > Cu(II) > Co(II) > Ni(II). In the case of the quaternary mixture, the highest extraction percentage for Pd(II) (70%) was obtained at a pH=7.33. Separation coefficients were also calculated. The highest separation coefficients were obtained for the system: Pd(II)/Ni(II), Pd(II)/Co(II); at a pH of 5.4 for an aqueous solution, their values are 13.3 and 7.7, respectively.

Effect of coexisting sodium ion extractive separation of metal ions with calix[4]arene tetracarboxylic acid

Ohto K., Shioya A., Higuchi H., Oshima T., Inoue K.

Ars Separatoria Acta

2002

No. 1

61-70

Solvent extraction of metal ions with calix[4]arene tetracarboxylic acid has been carried out to elucidate effect of coexisting sodium ion. Extraction of metal ions examined, Pb(II), Fe(III), Cu(II), Zn(II), Ni(II), and Co(II), is enhanced by the addition of sodium ion. The enhancement degree of the metal extraction is not necessarily in proportion to the added sodium concentration. The addition of trace amount of sodium ion is necessary to specifically complex for calix[4]arene tetracarboxylic acid and to enhance the extraction ability. However, the addition of excessive amounts of sodium suppresses the extraction of other metal ions, since they act as a competitive ion with other metal ions; The relation between extractive pH1/2 of metal ions and sodium concentration is shown. Mutual separation of metal ions by using additional sodium ion is also investigated. Although complete mutual separation of three metal ions, Pb(II), Cu(II), and Zn(II), has not been achieved, the possibility that the sodium addition will enhance not only the extraction ability but also the separation efficiency is suggested.