Solid–liquid Phase Equilibria of Li⁺, Na⁺, Ca²⁺//Cl^––H₂O Quaternary System at 298.15 and 323.15 K

Abstract

The solid−liquid phase equilibria of the Li + , Na + , Ca 2+ //Cl − −H 2 O quaternary system at 298.15 and 323.15 K are studied via the isothermal solubility phase equilibrium method. The solubility data and liquid properties of density and pH are obtained. The phase diagrams of the quaternary systems, including the water free diagram, the water diagram, and the dry salt diagram, are plotted to show the phase regions, water content, and salting-in effect. NaCl occupies the largest phase region at both 298.15 and 323.15 K. One double salt LiCl•CaCl 2 •5H 2 O occurs at 298.15 K and builds up two invariant points; one incommensurate invariant point saturated by (NaCl, LiCl•H 2 O, LiCl•CaCl 2 •5H 2 O) and one commensurate invariant point saturated by (NaCl, CaCl 2), but at 323.15 K, no double salt forms. The salting-in effect that happened in ternary systems still occurs in the quaternary Li + , Na + , Ca 2+ // Cl − −H 2 O system at both temperatures. NaCl saturated concentration increases with LiCl and CaCl 2 contents and results in a very high total salt content at commensurate invariant points, e.g., they are 56.92 and 60.62% at 298.15 and 323.15 K, respectively.