A New Approach in Hydrometallurgy for the Solvent Extraction of Cu(II) from Alkaline Solutions Leached with Tartrate Using Phenyl-2-Pyridyl Ketoxime

For the first time, an alternative and sustainable approach is reported using phenyl-2-pyridyl ketoxime (PPKO) as a selective extracting agent for the recovery of Cu(II) from alkaline solutions in the presence of tartrate ions. The advantages relative to conventional processes carried out in acidic media are outlined. Through potentiometric and spectrophotometric analyses, the sequential formation of a 1:2 metal cation–ligand Cu(II)-(PPKO)2 complex was identified as the predominant species in alkaline aqueous solutions. The high removal capacity of the extractant for Cu(II), as assessed from liquid–liquid extraction, and its efficient performance are comparable to widely used commercial extractants. Thermodynamic studies of the complexation between the copper(II) ion and PPKO demonstrated that the process exhibits an endothermic character. A progressive decrease in the performance of the extractant was observed after reuse without a regenerative treatment. This deterioration was partially reversed through a controlled reprotonation process using an acetate buffer solution. Overall, the results support the potential of PPKO as an effective and selective alternative ligand for hydrometallurgical applications in alkaline medium.