Solubility Isotherm Determinations at T = (273.15, 298.15, 323.15, 348.15 and 363.15) K and Thermodynamic Modeling of the H3BO3 + SrCl2 + H2O System

Abstract

Boron abundantly exists in salt lake brine system as various boron-containing aqueous species or minerals. The phase behavior of boron and other substances (Li, Na, K, Rb, Cs, Mg, Ca, Sr, Cl, S etc.) in the complicated salt brine system during the solar pool process needs to be simulated and predicted by models. Basic experimental data (e.g. solubility, etc.) of simple binary and ternary system are necessary for the model parameterizations. At present, the unavailability of solubility data in the H3BO3 + SrCl2 + H2O ternary system makes the model parameterization difficult. In this paper, we determined the solubility isotherms in the H3BO3 + SrCl2 + H2O ternary system at 273.15 K, 298.15 K, 323.15 K, 348.15 K and 363.15 K. The result show that the isotherms all consisted of the solubility branches H3BO3(cr) and SrCl2⋅nH2O(cr) (n = 6 and 2), and no new phase has been found. Then, a Pitzer–Simonson–Clegg (PSC) model in the ISLEC software package was used to simulate the thermodynamic properties of the H3BO3 + H2O, SrCl2 + H2O, and H3BO3 + SrCl2 + H2O systems, including solubility, water activity, activity coefficients, heat capacity and enthalpy of dilution. With the obtained model parameters, a complete polythermal phase diagram of the H3BO3 + SrCl2 + H2O system was predicted at temperatures from 255 to 373 K. The present work lays the foundation for the future simulations of complicated salt lake brine systems containing H3BO3 and SrCl2.