Simulation studies on metastable phase equilibria in the aqueous ternary systems (NaCl-MgCl₂-H₂O) and (KCl-MgCl₂-H₂O) at 308.15 K

Abstract

The solubilities and densities of the aqueous metastable ternary systems (NaCl-MgCl₂-H₂O) and (KCl-MgCl₂-H₂O) at 308.15 K were determined by the isothermal evaporation method. On the basis of the experimental results, the phase diagrams for those systems were plotted. It was found that the former system belongs to the hydrate-I type with one invariant point of (NaCl+ MgCl₂·6H₂O), two univariant curves, and two crystallization regions corresponding to halite (NaCl) and bischofite (MgCl₂·6H₂O); and the latter system belongs to the type of incongruent-double salts with two invariant points of (KCl+ KCl·MgCl₂·6H₂O) and (MgCl₂·6H₂O+ KCl·MgCl₂·6H₂O), three univariant curves, and three crystallization regions corresponding to potassium chloride (KCl), carnallite (KCl·MgCl₂·6H₂O) and bischofite (MgCl₂·6H₂O). No solid solutions were found in both systems.

Keywords

green chemistry / solar pond technique / simulation / metastable phase equilibrium / solubility

References

[1] Zheng X Y, Tang Y, Xu C. Tibet Saline Lake. Beijing: Sci Press,1988, 23-28

[2] Jin Z M, Xiao X Z, Liang S M. Study of the metastable equilibrium for pentanary system of (Na⁺, K⁺, Mg²⁺), (Cl^–, SO42-), H₂O. Acta Chim Sinica, 1980, 38(4): 313-321

[3] Jin Z M, Zhou H N, Wang L S. Study on the metastable phase equilibrium of Na⁺, K⁺, Mg²⁺//Cl^–, SO42--H2O Quinary system at 35°C. Chem J Chin Univ, 2001, 22: 634-638

[4] Jin Z M, Zhou H N, Wang L S. Studies on the metastable phase equilibrium of Na⁺, K⁺, Mg²⁺//Cl– SO42--H2O Quinary system at 15°C. Chem J Chin Univ, 2002, 23: 690-694

[5] Su Y G, Li J, Jiang C F. Metastable phase equilibrium of K⁺, Na⁺, Mg²⁺//Cl^–, SO42--H2O Quinary system at 15°C. J Chem Ind Eng, 1992, 43:549-555

[6] Deng T L, Wang S Q, Sun B J. Metastable phase equilibrium on the aqueous quarternary system (KCl+ K₂SO₄+ K₂B₄O₇+ H₂O) at 308.15 K. Chem Eng Data, 2008, 53(2), 411-414

[7] Deng T L, Meng L Z, Sun B. Metastable phase equilibria of the reciprocal quaternary system containing sodium, potassium, chloride and borate ions at 308.15 K. J Chem Eng Data, 2008, 53(3):704-709

[8] Deng T L, Li D C, Wang S Q. Metastable phase equilibrium on the aqueous quaternary system (KCl-CaCl₂-H₂O) at (288.15 and 308.15) K. J Chem Eng Data, 2008, 53(4), 1007-1011

[9] Wang S Q, Deng T L. Solid-liquid isothermal evaporation phase equilibria in the aqueous ternary system (Li₂SO₄+ MgSO₄+ H₂O) at T= 308.15 K. J Chem Thermodyn, 2008, 40(6): 1007-1011

[10] Analytical Laboratory of Qinghai Institute of Salt Lakes at Chinese Academy of Sciences. Analytical Methods of Brines and Salts, 2nd ed. Beijing: Sci Press, 1988, 82-88

RIGHTS & PERMISSIONS

Higher Education Press and Springer-Verlag Berlin Heidelberg