Solid–Liquid Isothermal Evaporation Metastable Phase Equilibria in the Aqueous Quaternary System LiCl + KCl + RbCl + H2O at 298.15 K

Abstract

The metastable phase equilibria in the aqueous quaternary system LiCl + KCl + RbCl + H2O were investigated at 298.15 K using an isothermal evaporation method. The solubilities and physicochemical properties such as the density and refractive index of the equilibrated solution were determined. On the basis of the experimental results, the stereo phase diagram, the projected phase diagram, the water content diagram, and the physicochemical properties versus composition diagrams were constructed. The projected phase diagram consists of two invariant points, five isothermal univariant curves, and four crystallization fields corresponding to single salts potassium chloride (KCl), rubidium chloride (RbCl), lithium chloride monohydrate (LiCl·H2O), and a solid solution of potassium and rubidium chloride [(K, Rb)Cl]. The two invariant points are cosaturated with three salts, which are LiCl·H2O + RbCl + (K, Rb)Cl and LiCl·H2O + KCl + (K, Rb)Cl, respectively. No double salt was formed. The crystallization region of ...