LAUSR

Abstract The extraction equilibria of Cu(II) from HCl and HCl-KCl solutions at different ionic strengths (0.05–0.50 mol/L) by LIX 84 in toluene is reported. Copper speciation in the aqueous solutions has been previously calculated using the Specific Interaction Theory (SIT) for the calculation of the activity coefficients. The effect of the concentrations of extractant, H+ and Cl− has been examined. Graphical and numerical treatments of the experimental extraction data indicate the extraction of a single complex of stoichiometry CuL2, HL being 2-hydroxy-5-nonylacetophenone oxime, the active component of LIX 84. EPR measurements of the organic extracts have confirmed the proposed stoichiometry. The copper extraction constant values at 0.05, 0.10, 0.25 and 0.50 mol/L HCl and at 0.50 mol/L (H+,K+)Cl − have been determined and successfully correlated with the ionic strength based on the previously developed aqueous phase chemical model. The value of the copper extraction constant at infinite dilution is also reported.