Solid-liquid Equilibria (SLE) of the System Containing the Sulfates of Lithium and Potassium at 303.2 and 318.2 K

The solid-liquid phase equilibria of aqueous system containing the sulfates of lithium and potassium (Li₂SO₄ + K₂SO₄ + H₂O) at T = 303.2 and 318.2 K were done by isothermal dissolution method. The phase equilibria data (solubility, density, and refractive index) of the system were determined experimentally. The corresponding solid-liquid phase diagram, density/refractive index versus composition diagrams, were plotted. There are two ternary invariant points and three crystallization regions corresponding to Li₂SO₄·H₂O, LiKSO₄, and K₂SO₄ in the phase diagram of system Li₂SO₄ + K₂SO₄ + H₂O at 303.2 and 318.2 K. A comparision of system Li₂SO₄ + K₂SO₄ + H₂O at different temperature (T = 288.2, 303.2, 318.2 and 348.2 K) shown that the double salt LiKSO₄ was formed in the above mentioned temperatures, and the crystallization region of the LiKSO₄ increases gradually with the increase of temperature.