Experimental and thermodynamic modeling study of solid-liquid equilibrium in ternary systems NaBr–SrBr2–H2O and KBr–SrBr2–H2O at 288.15 K and 0.1 MPa

The solubilities and refractive indices of the NaBr–SrBr 2 –H 2 O and KBr–SrBr 2 –H 2 O systems at 288.15   K were investigated with the isothermal dissolution method. The phase diagrams and refractive index diagrams were plotted for the two systems at 288.15   K. The phase diagrams consist of one two-salt cosaturated invariant point , two univariant solubility isotherms, and two stable crystallization fields. The two systems belong to the simple eutectic type, and neither double salt nor solid solution was found. The refractive indices change regularly with the strontium bromide concentration increasing in solution, and reach the maximum value at the eutectic point. On the basis of Pitzer and Harvie-Weare (HW) model, the binary and mixing Pitzer parameters and solubility equilibrium constants of equilibrium solid salts for the two ternary systems at 288.15   K were acquired. And then, the solubilities for the ternary systems at 288.15   K were demonstrated. A comparison shows that the calculated solubilities agree well with the experimental data.