Solid–Liquid Phase Equilibria of the Aqueous Ternary System (MgSO4 + Mg2B6O11 + H2O) at (288.15, 298.15, and 308.15) K

Abstract

Solubilities, densities, refractive indices, and pH values for the ternary system (MgSO4 + Mg2B6O11 + H2O) at (288.15, 298.15, and 308.15) K and 0.1 MPa, obtained using the method of isothermal dissolution equilibrium, are reported for the first time. On the basis of the experimental data, the phase diagrams and the physicochemical properties of density, refractive index, and pH versus concentration of magnesium sulfate were plotted. It was found that there are one invariant point, two univariant curves, and two crystallization regions corresponding to inderite (Mg2B6O11·15H2O, Inde) and epsomite (MgSO4·7H2O, Eps). The crystallized area of inderite is larger than that of epsomite at three temperatures, indicating that the solubility of inderite is lower than that of epsomite. Comparison of the phase diagrams at (288.15, 298.15, and 308.15) K shows that the areas of Inde and Eps increase with increasing temperature. There are no solid solutions and double salts at these three temperatures in this system. T...