Metastable phase equilibrium in the aqueous ternary system (Li2SO4 + MgSO4 + H2O) at 323.15 K

摘要

The metastable solubilities and physicochemical properties (densities and refractive index) of the aqueous ternary system (Li2SO4 + MgSO4 + H2O) at 323.15 K were determined in the first time with the isothermal evaporation method. According to the experimental results, the metastable phase diagram and the diagram of physicochemical properties vs. composition were plotted. It was found that there are one eutectic point (Li2SO4·H2O + MgSO4·6H2O), two univariant curves, and two crystallization regions corresponding to lithium sulfate monohydrate (Li2SO4·H2O) and hexahydrite (MgSO4·6H2O) in the metastable ternary system. The system belongs to a simple eutectic type, and neither double salts nor solid solutions were found. It can be found that the solution density and refractive index of the metastable ternary system is changed regularly with the content change of lithium sulfate, and all reach the maximum value at eutectic point. The calculated values of densities and refractive index with empirical equations are in good agreement with the experimental data.