Water Activity and Solubility Measurements and Model Simulation of the CsCl–MgCl₂–H₂O Ternary System at 323.15 K

Abstract

Water activities in the ternary system CsCl–MgCl2–H2O and its sub-binary systems at 323.15 K were elaborately measured by an isopiestic method. Moreover, the solubility of the CsCl–MgCl2–H2O system at 323.15 K was also measured by the flow-cloud-point method. A Pitzer model was used to predict the measured water activity and solubility data. The binary parameters for the CsCl–H2O system at 323.15 K were obtained by fitting the measured water activities for this binary system. The calculated water activity and solubility isotherms for the CsCl–MgCl2–H2O system at 323.15 K, with binary parameters only, deviated from the experimental values. This means that it is insufficient with binary parameters only to predict the water activity and calculate the solubility isotherms of the CsCl–MgCl2–H2O system at 323.15 K. The calculated solubility isotherms with both binary and mixing parameters, obtained by fitting the measured water activity, also deviated from experimental values. A new set of reasonable ternary parameters for the CsCl–MgCl2–H2O system was obtained by fitting the measured water activity and solubility data of this work. The calculated solubility isotherms with these parameters agreed with experimental results.