Experimental determination and modeling of the solubility phase diagram of the ternary system (Li2SO4 + K2SO4 + H2O) at 288.15 K.

The solubility and density in the thermodynamic phase equilibria ternary system (Li 2 SO 4 + K 2 SO 4 + H 2 O) at 288.15 K and 0.1 MPa were investigated experimentally with the method of isothermal dissolution equilibrium. This system at 288.15 K consists of two invariant points, three univariant isothermal dissolution curves; and three crystallization regions. The salt Li 2 SO 4 ·K 2 SO 4 belongs to the incongruent double salt, and no solid solution was found. Based on the Pitzer model and its extended Harvie–Weare (HW) model, the mixing ion-interaction parameters of θ Li,K , ψ Li,K,SO4 at 288.15 K and the solubility equilibrium constants K sp of solid phases Li 2 SO 4 ·H 2 O and Li 2 SO 4 ·K 2 SO 4 , which are not reported in the literature were acquired. A comparison between the calculated and experimental results at 288.15 K for the ternary system shows that the calculated solubilities obtained with the extended HW model agree well with experimental data. [ABSTRACT FROM AUTHOR]