In this study, the extraction of nickel(II) ions from sulphate and sulphate/chloride solutions with 2-, 3-, and 4-pyridylketoximes was investigated. The effect of different variables influencing the extraction of nickel(II) ions such as the extractant structure and the concentration of hydrogen ion, sulphate, and chloride ions have been studied. The shaking time and temperature also influenced metal ion removal. It was found that the hydrophobic 2-pyridylketoximes are the most effective extractants for nickel ions from sulphate/chloride solutions. The discussion also includes the mechanism of nickel(II) complexation by the hydrophobic pyridylketoximes and the speciation of nickel(II) in the presence of chloride and sulphate ions.
The goal of this work was to study the extraction of zinc(II) ions from chloride solutions with the hydrophobic quaternary 3-pyridinium ketoximes. The influence of pH, contact time, concentration of chloride ions and extractant, as well as the effect of ligand structure on the zinc(II) extraction were investigated. The studies showed that at 4 M Cl − , regardless of the acidity of the aqueous chloride solutions and type of anions attached to pyridinium ring, the zinc(II) extraction increased with increasing length of the alkyl chain. Furthermore, the extraction from a multielemental solution is selective and the created complex can be decomposed after being shaken with the aqueous solutions of sodium sulfate or sodium hydroxide. It was also indicated that the zinc(II) extraction by the hydrophobic quaternary 3-pyridinium ketoximes proceeded via an ion-exchange mechanism, and the molar ratio of zinc to ligand to chloride in the complex molecule was 1:1:2, 1:1:3, and 1:2:2.
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