New forms of McKay-Perring equations for mixed electrolyte solutions

Pan, H. and Han, S., 1993. New forms of McKay-Perring equations for mixed electrolyte solutions. Fluid Phase Equilibria, 90: 289-306.

A rigorous derivation is given for new forms of the McKay-Perring equations and the partial differential equation relating the activity coefficients of two electrolytes in mixed electrolyte solutions. They all have simple and symmetrical forms when the independent variables are the total ionic concentration and the fraction of ionic concentration. However, the simple and symmetrical forms remain only when the electrolytes are of the same charge types and when the independent variables are ionic strength and the fraction of ionic strength. The method of surface fitting is introduced to evaluate the McKay-Perring equations. The calculated results for four systems are in good agreement with those from the Pitzer equations.