Extraction of Copper(II) by CYANEX 302 in Kerosene from Different Aqueous Media.

The solvent extraction of Cu(II) with CYANEX 302 (bis(2,4,4-trimethyl-pentyl) monothiophosphinic acid) in kerosene from different aqueous solutions including sulphate, chloride, and nitrate media has been systematically investigated. The effect of various parameters such as the time of equilibration, pH, the extractant and metal concentrations, the temperature, as well as the effect of anions on the extraction process has been studied. An equilibrium equation is proposed assuming that copper was first extracted as Cu²⁺ followed by reduction of CuA₂(HA)₂ to Cu⁺ while the CYANEX 302 extractant is correspondingly oxidized. The thermodynamic parameters, free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), have been calculated. The stripping of Cu(II) from loaded organic solutions by using different stripping agents showed that effective stripping is obtained upon using high concentration of nitric acid which oxidizes the extracted Cu(I) to Cu(II). [ABSTRACT FROM AUTHOR]