Measurement of solubilities in the ternary system NaCl + CaCl2 + H2O and KCl + CaCl2 + H2O at 50 °C

Abstract

The solubility and the physicochemical property (refractive index) in the NaCl-CaCl2-H2O and KCl-CaCl2-H2O systems were determined at 50 °C and the phase diagrams and the diagrams of physicochemical property vs composition were plotted. One invariant point, two univariant curves, and two crystallization zones, corresponding to sodium Chloride (or potassium chloride), dihydrate (CaCl2·2H 2O) showed up in the phase diagrams of the ternary systems. The mixing parameters θM,Ca and ΨM,Ca,Cl (M = Na or K) and equilibrium constant Ksp were evaluated in NaCl-CaCl 2-H2O and KCl-CaCl2-H2O systems by least-squares optimization procedure, in which the single-salt Pitzer parameters of NaCl, KCl and CaCl2 beta;(0), beta;(1), beta;(2) and CΦ were directly calculated from the literature. The results obtained were in good agreement with the experimental data.