Solubility diagrams of Na2SO4–Rb2SO4–MgSO4–H2O, Na2SO4–Cs2SO4–MgSO4–H2O, and K2SO4–Cs2SO4–MgSO4–H2O at 298.15 K

Abstract

The Pitzer ion-interaction was applied to calculate the solubility isotherms of quaternary systems Na₂SO₄–Rb₂SO₄–MgSO₄–H₂O and Na₂SO₄–Cs₂SO₄–MgSO₄–H₂O at 298.15 K. The results were compared with experimental data from the literature. Phase equilibrium of K₂SO₄–Cs₂SO₄–MgSO₄–H₂O has been predicted assuming that no new solid phases crystallize in them. The calculated phase diagram consists of five crystallization fields, three invariant points, and seven univariant curves. The five crystallization fields correspond to K₂SO₄, Cs₂SO₄, MgSO₄ · 7H₂O, Cs₂SO₄ · MgSO₄ · 6H₂O and K₂SO₄ · MgSO₄ · 6H₂O. The results could provide a theoretical basis for exaction ofrubidium and cesium from salt lake brine resources.