Solid–liquid Equilibria in the Quaternary System Na+, Mg2+//Cl–, SO2–4–H2O at 25 and 30°C

Abstract

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