Water Activity and Phase Equilibria Measurements and Model Simulation for the KCl-BaCl2-H2O System at 323.15 K and 0.1 MPa

Water activities for the ternary system of KCl-BaCl2-H2O and its sub-binary system BaCl2-H2O are elaborately measured using an isopiestic method at 323.15 K. The solubility isotherms for the KCl-BaCl2-H2O system are determined by isothermal equilibrium method. It is found that the measured isopiestic composition lines for the KCl-BaCl2-H2O system slightly deviated from Zdanovskii rule, especially at lower water activity. Pitzer-Simonson-Clegg model is used to correlate the measured water activity and solubility data, and simulate the thermodynamic properties and predict the solubility of the ternary system. The reliability of the solubility data measured in this work is evaluated by comparing with the solubility isotherms calculated with Pitzer-Simonson-Clegg model. The measured water activity and solubility results are of great importance for predicting the phase diagram of other multi-component systems that related to this ternary system.