Extraction of Cu(II) From Acidic Sulfate Media by Palm Kernel Fatty Acid Distillate: Stoichiometry and Thermodynamic Studies

Abstract

In efforts to develop a novel low-cost and eco-friendly organic solvent, namely, palm kernel fatty acid distillate (PKFAD), with free fatty acids (FFAs) as the active components, for Cu(II) extraction from acidic sulfate media, this work aimed to gain insight into the stoichiometry of Cu(II)-FFA complexes (extracted species) in PKFAD and their extraction thermodynamics. The former was explored by both the equilibrium slope and numerical analyses, while the latter was determined from the extraction of Cu(II) by PKFAD at different temperatures. Both the equilibrium slope and numerical analyses revealed that the stoichiometry of Cu(II)-FFA complexes in PKFAD was 1:6, whereas the thermodynamic study indicated that Cu(II) extraction by PKFAD was exothermic, nonspontaneous, and enthalpy-driven over the temperature range studied. A plausible structure of Cu(II)-FFA complexes in PKFAD was also postulated based on the thermodynamic data obtained.