Solubility, Density, and Refractive Index in the Ternary System (K2B4O7 + Mg2B6O11 + H2O) at 298.15 K

Abstract

Solubilities, densities, and refractive indices for the ternary system (K₂B₄O₇ + Mg₂B₆O₁₁ + H₂O) at 298.15 K have obtained using the method of isothermal dissolution equilibrium. On the basis of the experimental data, the phase diagram and its corresponding physicochemical properties versus composition diagram in the system have been plotted. It has been found that there is one eutectic point and two crystallization regions corresponding to the large area of inderite (L + Mg₂B₆O₁₁ · 15H₂O) and the relative small area of potassium borate tetrahydrate (L + K₂B₄O₇ · 4H₂O), respectively. Neither double salt nor solid solution have been found in this system. The physicochemical properties (density and refractive index) of the ternary system at 298.15 K change regularly with the increasing of potassium borate concentration. The calculated values of density and refractive index using empirical equations of the ternary system are in good agreement with the experimental values.