Stable phase equilibria in the ternary system (Na2SO4 + Li2SO4 + H2O) at 308.15 K and 313.15 K

Phase equilibrium data in the ternary system (Na2SO4 + Li2SO4 + H2O) at 308.15 K and 313.15 K were measured using the isothermal dissolution method, and the corresponding stable phase diagrams were plotted. The results showed that there were three invariant points, four univariant curves and four crystallization regions: Li2SO4·H2O (Ls), LiNa(SO4) (Db1), Na3Li(SO4)2·6H2O (Db2), and Na2SO4 (Th); and no solid solution was found in the ternary system at 308.15 K and 313.15 K. A comparison of the stable phase diagrams for the ternary system at different temperature indicates that the areas of the crystallization regions of Th and Db1 are increased with the increase of temperature, and the one belonging to Db2 is disappeared along with the increase of temperature.