Thermodynamics and Phase Equilibrium of the System CsCl–MgCl2–H2O at 298.15 K

Water activities of the CsCl–MgCl2–H2O ternary system and its sub-binary systems were elaborately measured by an isopiestic method at 298.15 K. The solubility of this ternary system at 298.15 K was also measured by two different methods, namely isothermal method and Flow-Cloud-Point method. The solubilities measured by the two different methods were consistent with each other. A Pitzer model was used to represent the thermodynamic properties and calculate the solubility isotherms for the CsCl–MgCl2–H2O ternary system at 298.15 K. Both the equal water activity lines and the solubility isotherms are calculated with parameters reported in literature. It was found that only the calculated equal water activity lines with the parameters reported by Scharge et al. are consistent with the experimental values of this work. However, all the calculated solubility isotherms deviated from the experimental data in this work. New set of ternary parameters were obtained by fitting the water activities and solubility data of this work. Using the new parameters, the calculated equal water activity lines and solubility isotherms agreed with experimental values measured in this work.