Solid–Liquid Phase Equilibria in the Ternary Systems (LiCl + MgCl₂ + H₂O) and (Li₂SO₄ + MgSO₄ + H₂O) at 288.15 K

Abstract

Solubility as well as solution density in aqueous systems (LiCl + MgCl 2 + H 2 O) and (Li 2 SO 4 + MgSO 4 + H 2 O) at 288.15 K have been studied using the isothermal dissolution method. In the ternary system (LiCl + MgCl 2 + H 2 O) at 288.15 K, two invariant points, three isothermal dissolution curves and three crystallization regions including MgCl 2 •6H 2 O, LiCl•2H 2 O, and double salt LiCl•MgCl 2 •7H 2 O were detected. Experimental results compared with values of this system at (273.15, 348.15, and 323.15) K shows that the LiCl•MgCl 2 •7H 2 O crystallization region is increased slightly with the increasing of temperature, while that of MgCl 2 •6H 2 O and LiCl•2H 2 O are decreased obviously. In the ternary system (Li 2 SO 4 + MgSO 4 + H 2 O) at 288.15 K, there are one invariant point, two isothermal dissolution curves, and two crystallization regions corresponding to Li 2 SO 4 •H 2 O and MgSO 4 •7H 2 O. When this experimental phase diagram at 288.15 K was compared with that at (298.15, 303.15, and 348.15) K, it shows that the Li 2 SO 4 • H 2 O crystallization region is increased with the increasing of temperature, while that of MgSO 4 •7H 2 O is decrease obviously. A Pitzer and Harvie−Weare thermodynamic model were applied to calculate the solubility for this ternary system, and the calculated solubilities agree reasonably with the experimental results.

Solid–Liquid Phase Equilibria of the Aqueous Ternary System (MgSO4 + Mg2B6O11 + H2O) at (288.15, 298.15, and 308.15) K

“…Although no data have been reported for the binary subsystem (Mg 2 B 6 O 11 + H 2 O), the solubility data for the binary subsystem (MgSO 4 + H 2 O) at three temperatures are reported in the literature and are shown in Table . − A comparison shows that the solubilities of magnesium sulfate at (288.15, 298.15, and 308.15) K in mass fraction are 100 w (MgSO 4 ) = 24.60 ± 0.12, 27.12 ± 0.16, 29.73 ± 0.13 at the 95% level of confidence. Those results indicate that our experimental procedure and analysis are reliable.…”

Solid–Liquid Phase Equilibria of the Ternary System (KBO2 + K2SO4 + H2O) at 288.15, 308.15 K, and 0.1 MPa

“…The isothermal dissolution equilibrium method was used for the equilibrium experiment in this work and reported previously. − From the beginning of the boundary binary system, a series of artificially synthesized complexes were prepared by gradually adding the third salt into the binary saturated point at 288.15 and 308.15 K . After loading into the hard polyethylene bottle, they were sealed and placed into the magnetic stirring thermostatic water baths at (288.15/308.15 ± 0.01) K. In order to accelerate the phase equilibria, a stirring speed of 200 rpm was applied.…”

Experimental and Thermodynamic Modeling Study of the Quaternary System Containing Lithium, Potassium, Magnesium, and Sulfate at 288.15 K

“…Based on the isothermal solution saturation method, phase equilibria study in the quaternary system (Li + K + Mg + SO 4 + H 2 O) at 288.15 K were carried out. − Suitable amouts of lithium sulfate, potassium sulfate, epsomite and water were agitated in 250.0 mL bottles, and the bottles were placed in a magnetic stirring thermostatic bath, with the temperature at (288.15 ± 0.02) K and stirring speed at 300 rpm to accelerate the establishment of equilibrium states. At regular intervals, the magnetic stirring was paused for 4 h to extract 3.0 cm 3 clarified solution, weigh accurately, dilute in a 250.0 mL flask for chemical analysis.…”

“…16 The parameters of θ Li,K , θ Li,Mg , ψ Li,K,SO4 , and ψ Li,Mg,SO4 , which have not been reported at 288.15 K, were fitted using the reliable thermodynamic data in this work. 12,13 Solubility Calculation. On the basis of parameters in Table 4, the solubilities of the quaternary system (Li + K + Mg + SO 4 + H 2 O) at 288.15 K were predicted by using the Pitzer's and its extended HMW electrolyte solution theoretical model.…”

“…The parameter of lithium sulfate at 288.15 K was calculated according to the temperature-dependent equation presented by Holmes and Mesmer . The parameters of θ Li,K , θ Li,Mg , ψ Li,K,SO4 , and ψ Li,Mg,SO4 , which have not been reported at 288.15 K, were fitted using the reliable thermodynamic data in this work. , All Pitzer parameters of the system (Li + K + Mg + SO 4 + H 2 O) at 288.15 K are shown in Table . The solubility equilibrium constants (ln K sp ) of solid phases K 2 SO 4 , MgSO 4 ·7H 2 O, Li 2 SO 4 ·H 2 O, Li 2 SO 4 ·K 2 SO 4 , and K 2 SO 4 ·MgSO 4 ·6H 2 O at 288.15 K were determined, and the results are −4.4571, −4.6193, 1.2168, −5.9385, and 9.5826, respectively.…”