Thermodynamic modeling of high salinary phosphate solutions II. Ternary and higher systems

•Thermodynamic modeling of phosphate solutions of high ionic strengths.•Comprehensive revision and addition of thermodynamic data by the isopiestic method.•Interaction Pitzer parameters of phosphate ions in the Na–K–Cl–SO4–H2O system.•Reliable thermodynamic properties of phosphates solid phases.•Physicochemical interpretation of Pitzer parameters.

A comprehensive set of ternary interaction Pitzer parameters for solutions of the system Na–K–Cl–SO4–PO4–HPO4–H2PO4 was calculated from water activity and solubility data acquired from an extensive literature review and water activity data obtained from isopiestic experiments. This work is a continuation of part I, wherein results concerning binary phosphate systems are presented.