Solid-liquid equilibria in the quaternary system Na+, Mg2+//Cl-, SO42--H2O at 25 and 30°C

The isoplethic sections in the diagram of the quaternary system Na+, Mg2+//Cl-, SO42--H2O were established at 25 and 30 degrees C by analytical and conductometric measurements. Three compounds can be observed in the isoplethic sections: NaCl, Na2SO4 and MgNa2(SO4)(2). 4H(2)O. Seven fields are determined, relating to the precipitation of one, two or three salts. The solubility range of MgNa2(SO4)(2). 4H(2)O is wide, while the liquidus curve of Na2SO4 is very short. The compositions, expressed in Jenecke coordinates, at the eutonic and peritonic points, respectively, were: 42.70% Cl- and 745% H2O; 79.47% Cl- and 787% H2O; 71.6% Cl- and 744% H2O at 25 degrees C; and 48.80% Cl- and 715% H2O; 80.20% Cl- and 778% H2O; 70.14% Cl- and 707% H2O at 30 degrees C.