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

The isoplethic sections in the diagram of the quaternary system Na+ , Mg2+ //Cl– , SO2–4 –H2 O were established at 25 and 30oC by analytical and conductometric measurements. Three compounds can be observed in the isoplethic sections: NaCl, Na2 SO4 and MgNa2 (SO4 )2 4 H2 O. Seven fields are determined, relating to the precipitation of one, two or three salts. The solubility range of MgNa2 (SO4 )2 4 H2 O is wide, while the liquidus curve of Na2 SO4 is very short. The compositions, expressed in Jänecke coordinates, at the eutonic and peritonic points, respectively, were: