Copper recovery from chloride solutions using liquid extraction with pyridinecarboximidamides as extractants

In this study, hydrophobic N′-alkyloxypyridine-2-, -3- and -4-carboximidamides were used to extract copper(II) from chloride solutions. The effect of different variables influencing the extraction of copper(II) such as the extractant structure and the concentration of metal and chloride ions have been studied. The shaking time also had influence on copper(II) removal. The discussion also includes the mechanism of complexation and the speciation studies indicated that examined N′-alkyloxyimidamides (L) formed complexes with Cu(II) and chloride heaving a molar ratio of Cu:Cl:L of 1:2:2, 1:2:4 and 1:2:5, or complex has additionally the outer-sphere Cl− anions as was indicated for O-3IA. The loading and selectivity tests indicated that Eh-3IA can be proposed as the extractant from the concentrated copper(II) solutions and the re-extraction can also be realised efficiently with the selected striping agents.