Solid Liquid Phase Equilibria in the Ternary Systems KCl–ZnCl2–H2O and MgCl2–ZnCl2–H2O at 278 K

Abstract

This paper presents the solid–liquid equilibria phase diagrams of two ternary systems KCl–ZnCl2–H2O and MgCl2–ZnCl2–H2O at 278 K using the method of isothermal dissolution equilibrium. Integrated with the determined equilibrated liquid phase and humid residue composition, the phase diagrams of the two systems were generated. At the same time, the invariant points, the univariant solubility curves and the solid crystalline phase regions are displayed and discussed. The results of the experiment show that the two ternary systems are classified as complex owing to the formation of double salt. The phase diagram of the ternary system KCl–ZnCl2–H2O at 278 K is comprised of two invariant points, three univariant solubility curves and three solid crystalline phase regions corresponding to KCl, ZnCl2·2H2O and 2KCl·ZnCl2·2H2O. The phase diagram of the ternary system MgCl2–ZnCl2–H2O at 278 K includes two invariant points, three univariant solubility curves and three solid crystalline phase regions corresponding to MgCl2·6H2O, MgCl2·ZnCl2·6H2O and ZnCl2·2H2O. The densities of ternary mixtures at 278 K were measured. The possibility of Laliberte model to predict densities of investigated ternary saturated solution was checked. The results show that this model is allowed to offer fundamental description for densities of ternary mixtures and calculated results are in good agreement with the experimental values.