Metastable Phase Equilibria of the Reciprocal Quaternary System Containing Sodium, Potassium, Chloride, and Borate Ions at 308.15 K

Abstract

The metastable solubility of the reciprocal quaternary system containing sodium, potassium, chloride, and borate ions and the physicochemical properties corresponding to density, viscosity, pH value, and refractive index at 308.15 K have been studied with the isothermal evaporation method. According to the experimental data, the metastable equilibrium phase diagrams of dry salt and the water phase diagram of the system were plotted. In the dry-salt phase diagram, there are two invariant points, five univariant curves, and four crystallizing regions corresponding to sodium chloride, potassium chloride, borax (Na 2 B 4 O 7 · 10H 2 O), and potassium tetraborate tetrahydrate (K 2 B 4 O 7 · 4H 2 O). The crystallized region of borax is the largest, while the phase region of NaCl is the smallest with the highest concentration and a strong salting-out effect to borax. There are neither double salts nor solid solutions formed in the metastable system. When compared with the stable phase diagram at 298.15 K of the system, the areas of both metastable phase regions of borax and potassium chloride are enlarged, while other metastable phase regions are decreased. The calculated values of densities and refractive index in the metastable quaternary system with the empirical equations are in good agreement with the experimental values.

Phase Equilibria and Phase Diagrams for the Aqueous Ternary System Containing Sodium, Chloride, and Metaborate Ions at 288.15 and 308.15 K and 0.1 MPa

“…Empirical equations for predicting density and refractive index of the salt-water system were applied to have correlation with the experimental results [18]: Table 3 for comparison, and the relative deviations between the experimental and calculated values are within 0.73%. Yangtze Scholars and Innovative Research Team in Chinese University (IRT_17R81).…”

Metastable Equilibria of the Quinary System NaCl + Na2CO3 + Na2B4O7 + KCl + K2CO3 + K2B4O7 + H2O at 273.15 K

“…As to the crystalline form of the potassium carbonate–sodium carbonate double salt, Shang Shihua, Harvie, and Zeng Ying et al. found that, in the system including potassium and sodium carbonate, the crystalloid form of the sodium and potassium carbonate double salt is K 2 CO 3 ·Na 2 CO 3 ·12H 2 O at 288 and 298 K. The research studied by our research group found that, , in the system containing K 2 CO 3 and Na 2 CO 3 , the sodium and potassium carbonate double salt exist as K 2 CO 3 ·Na 2 CO 3 ·12H 2 O at 273 K, which is agree with the result of this paper.…”

“…The brine of Zabuye Salt Lake in Tibet is famous for its abundance of lithium, potassium, and boron resources, which has significant exploitation value, and it is classified as a carbonate-type alkaline brine; the main composition of this salt lake brine can be attributed to Li + , Na + , K + , Mg 2+ ∥SO 4 2– , Cl – , CO 3 2– , B 4 O 7 2– – H 2 O system. To understand the thermodynamics behavior of the system mentioned above, a series of water–salt systems containing elemental borate have been studied, such as the ternary system K + ∥BO 2 – , OH – – H 2 O at 263 K, K + ∥Cl – (SO 4 2– ), B 4 O 7 2– – H 2 O at 308.15 K, Mg 2+ (K + )∥Cl – , B 4 O 7 2– – H 2 O, Na + ∥B 4 O 7 2– , SO 4 2– – H 2 O, and Li + , Na + ∥B 4 O 7 2– – H 2 O at 273.15 K, and the quaternary system Na + , K + ∥Cl – , borate – H 2 O at 308.15 K, K + ∥Cl – , SO 4 2– , B 4 O 7 2– – H 2 O at 298.15 and 308.15 K, and Li + , Na + ∥SO 4 2– , B 4 O 7 2– – H 2 O at 273.15 K . Commonly, the crystalloid form of the borate is affected by the coexisting ions.…”

Phase Equilibria and Phase Diagrams for the Ternary Aqueous System Containing Lithium, Sodium, and Pentaborate Ions at 298.15 and 323.15 K and 101.325 kPa

“…In order to evaluate and test the reliability of the experimental method in this work, a comparison of the solubilites in the boundary subsystems [20], shown as equations ( 1) and ( 2), the density and refractive index of the experimental solution were calculated, and the results are listed in Table 3.…”