Solid Liquid Phase Equilibria in the Ternary Systems NaCl–ZnCl₂–H₂O and MgCl₂–ZnCl₂–H₂O at 298 K

Abstract

The solid−liquid equilibria relationship in the two ternary systems sodium chloride−zinc chloride−water and magnesium chloride−zinc chloride−water at 298 K were investigated based on the isothermal dissolution equilibrium method, integrated with the methods of humid residue, X-ray powder crystal diffraction, and density bottle. According to the determined solubility data combined with the humid residue composition and equilibrium solid phase, the phase diagrams of the two systems were depicted. It is concluded that the two isothermal phase diagrams are categorized as a complex type due to the precipitation of double salt between the two inorganic salt components rather than solid solution. Both of them can be divided into three single solid phase crystalline regions and an unsaturated region. Three solid crystalline phase regions in the ternary system NaCl−ZnCl 2 −H 2 O at 298 K were saturated with NaCl, ZnCl 2 , and 2NaCl•ZnCl 2 •2H 2 O, and those for the ternary system MgCl 2 −ZnCl 2 −H 2 O at 298 K were deposited for MgCl 2 •6H 2 O, MgCl 2 •ZnCl 2 •5H 2 O, and ZnCl 2 . The densities in the equilibrated liquid phase were determined experimentally and simulated by the Laliberte model. As a result, the model can basically describe the density of two electrolytes in an aqueous solution at normal temperature.

Solid-liquid phase equilibria in the ternary systems H2O+ZnCl2+NaCl at temperatures of 298, 313 and 333 K

“…Obviously, the hydrated double salt turned into anhydrous double salt with the increase in temperature. Comparing our study with data from Zhang et al 18 in 298 K, it was observed that the solubility of the solid phase compositions and double salts were compatible with each other.…”

“…It was stated that the solubility of ZnCl 2 decreases from 66.6 to 60.37 % and the solubility of NaCl decreases sharply from 26.25 to 5.24 % to the invariant point as shown in the ternary system of NaCl-ZnCl 2 -H 2 O at 273 K, which was conducted by Adiguzel et al 12 Zhang et al implied that the solubility of ZnCl 2 decreases from 80.77% to 77.25% to the invariant point and the solubility of NaCl decreases from 26.71 to 6.24 %. These results show a sharper drop compared to that of ZnCl 2 in the ternary system at 298 K. 18 O n L i n e F i r s t средине. Растворљивост систему натријум-хлорид + цинк-хлорид + вода (NaCl + ZnCl2 + H2O) је испитивана у изотермским условима на температурама 298, 313 и 333 K. Schreinemakers-ова графичка метода је коришћена за анализу течне и чврсте фазе и за одређивање састава испитиваног система.…”

“…The composition change belonging to six temperatures in total were compared by also using the data between 273 and 373 K temperatures belonging to the ternary system NaCl-ZnCl 2 -H 2 O taking place in the literature. 12,[16][17][18] When the binary systems of NaCl-H 2 O were examined between 273 and 373 K, the mass percentage composition change of the solubility of NaCl shows a low value as 2 %. However, it was seen that mass percentage composition change of temperature and solubility was a noteworthy value with 19.32 % in the binary system of ZnCl 2 .…”