Incorporation of chloride ion in a copper solvent extraction process: A thermodynamic view

•The impact of chloride ion on copper solvent extraction process was thermodynamically modeled for a LIX 984 N extractant.•A model was developed and validated by incorporating the nonideality of the organic and aqueous phases.•The chloride ion increases the transfer of copper to the organic phase by changing the copper ion speciation.•Chloride ion increases the aqueous phase viscosity, enhancing the co-extracted impurities and their transfer to the electrolyte. In this study, the impact of chloride content of the seawater on the solvent extraction equilibrium of copper using LIX 984 N was investigated. This effect was studied considering the nonideality of aqueous and organic phases. The presence of chloride ion was shown to increase the extraction tendency toward copper extraction, considering the changes that occur in the ratio of the activity of the dominant copper species to the hydrogen ion (H+). This phenomenon was further confirmed by calculating the equilibrium constant of the copper solvent extraction reaction in presence and absence of the chloride ion. The occurrence of the chloride ion resulted in involvement and dimerization of more organic molecules in the transfer of copper to the organic phase. As a result, a heterogeneous model incorporating the nonideality of the organic and aqueous phases for the solvent extraction of copper was developed and validated by experimental data.