Thermodynamic properties of SrCl2(aq) from 252 K to 524 K and phase equilibria in the SrCl2–H2O system: Implications for thermochemical heat storage

Abstract

Abstract This paper reports a comprehensive thermodynamic treatment of the binary system SrCl2–H2O including solution properties and various phase equilibria. Published thermodynamic data of SrCl2(aq), solubilities of the hydrates of strontium chloride and equilibrium data of the hydration–dehydration reactions have been collected and critically assessed. Using an internally consistent database of solution properties in the temperature range (252–524) K at 0.1 MPa or at saturation pressure (whichever is larger), the parameters of an ion interaction (Pitzer) model were determined. With this model, activity coefficients and water activities of saturated solutions of SrCl2 hydrates were calculated yielding, together with equilibrium data of hydration–dehydration reactions, the thermodynamic solubility products of SrCl2·6H2O, SrCl2·2H2O and SrCl2·H2O. The complete phase diagram of the system SrCl2–H2O has been established and the potential use of SrCl2 hydrates as thermochemical heat storage materials is discussed.