Chemically Based Models to Predict Distribution Coefficients of Metals : Prediction of distribution coefficients and separation factors for metal ions in single and binary extraction systems

Chemically Based Models are derived for copper (II) and zinc (II) chloride tri-n-octylamine extraction single and binary systems. The predictive model makes use of the aqueous phase metal chloride complexes stability constants, their extraction mechanism, and the equilibrium constant for the extraction reaction. The distribution coefficients of the metals can be predicted by the equation D=K(alpha)(phi square), where phi is the product of the equilibrated organic concentration and the chloride ion concentration in the aqueous phase, K is the effective equilibrium constant containing the quotient of the activity coefficients of the reacting species and alpha is the degree of formation of the free metal ion in the equilibrated aqueous phase. Excellent agreement between experimental data and predicted values was obtained.The multi-component, binary metal extraction is examined in a quantitative manner. The separation factor can be predicted by the ration of distribution coefficients. This model was based on the assumption of constant activity coefficients. The experimental results show that the data fit the binary model very well.