Solubility Measurement and Thermodynamic Modeling of Solid–Liquid Equilibria in the MCl–M₂B₄O₇–H₂O (M = Li, Na) Systems

Abstract

The solubilities in the MCl–M2B4O7–H2O (M = Li, Na) systems at 323.15 K were studied with the isothermal solid–liquid equilibrium method. Both the phase diagrams in the above systems belong to the simple eutectic type. Combining the Pitzer binary parameters of LiCl and NaCl obtained from the literatures, the lacking Pitzer binary parameters of Li2B4O5(OH)4 and Na2B4O5(OH)4, Pitzer mixing parameters θCl–,B4O5(OH)4 2– , ψLi+,Cl–,B4O5(OH)4 2– , and ψNa+,Cl–,B4O5(OH)4 2– , and the solubility product constants of Li2B4O5(OH)4·H2O and Na2B4O5(OH)4·8H2O at 298.15 and 323.15 K were fitted with the experimental solubility data by the Pitzer model. The agreement between the experimental water activities and calculated results with parameters fitted with solubilities in the system LiCl–Li2B4O7–H2O at 298.15 K shows that the parameters fitted with solubilities are reliable. The comparison between the experimental and calculated solubilities of the two systems at 298.15 and 323.15 K shows that calculated solubility data are in agreement with 0.03 of experimental results in the two systems.

Solid–Liquid Phase Equilibria and Boron Species Distribution in the Quaternary System LiCl–LiBO2–Li2B4O7–H2O at T = 323.15 K and P = 0.1 MPa

“… a Standard uncertainties u are u ( T ) = 0.1 K, u ( p ) = 0.005 MPa, u ( w (LiCl)) = 0.003, u ( w (LiBO 2 )) = 0.005, and u ( w (Li 2 B 4 O 7 )) = 0.005. b w, mass fraction. c J, Jänecke index . d Abbreviations: LC: LiCl·H 2 O; LB: LiBO 2 ·2H 2 O; LB4: Li 2 B 4 O 7 ·3H 2 O. e The solubility data were cited from refs , , . …”

“…In Figures and , points A, B, and C are the co-saturation points in the systems LiCl–Li 2 B 4 O 7 –H 2 O, LiCl–LiBO 2 –H 2 O, and LiBO 2 –Li 2 B 4 O 7 –H 2 O. The solubility data for points A, B, and C were cited from the literature by our laboratory. ,, The dry-salt phase diagram in the quaternary system LiCl–LiBO 2 –Li 2 B 4 O 7 –H 2 O at 323.15 K in Figure has one invariant point E (LiCl·H 2 O, Li 2 B 4 O 7 ·3H 2 O, and LiBO 2 ·2H 2 O). The X-ray diffraction patterns of the invariant point E are given in Figure .…”

“…The system LiCl–LiBO 2 –Li 2 B 4 O 7 –H 2 O containing two different lithium borates is a subsystem of the above system. The phase equilibria in this system have not been reported in the literature, but the phase equilibria of its subsystems LiCl–LiBO 2 –H 2 O at 288.15, 298.15, 308.15, and 323.15 K; − LiBO 2 –Li 2 B 4 O 7 –H 2 O at 288.15, 298.15, and 323.15 K; , and LiCl–Li 2 B 4 O 7 –H 2 O at 273.15–323.15 K have been reported in the literature. − There are two lithium metaborate salts, LiBO 2 ·2H 2 O and LiBO 2 ·8H 2 O, in the system LiCl–LiBO 2 –H 2 O at 288.15, 298.15, and 308.15 K. As temperature increases, the crystallization field for LiBO 2 ·8H 2 O disappears. There was no solid solution, and double salts were found in the above systems.…”

Thermodynamic and Dynamic Modeling of the Boron Species in Aqueous Potassium Borate Solution

“…The Pitzer electrolyte solution theory and Harvie–Weare (HW) equations (Pitzer model), , which is described in our previous study, , was widely used in the solubility calculation of the brine systems containing borate. ,, The concentration of various boron species can be calculated if the parameters and standard chemical potentials of boron species are known. In the literature, , the concentration of B­(OH) 3 , B­(OH) 4 – , B 3 O 3 (OH) 4 – , and B 4 O 5 (OH) 4 2– in the solution saturated with Na 2 B 4 O 5 (OH) 4 ·8H 2 O or NaB­(OH) 4 ·2H 2 O and solubilities in the system containing borate or B­(OH) 3 were calculated.…”

Thermodynamic Modeling of Boron Species in the Ternary System Na2O-B2O3-H2O at 298.15 K

“…e phase equilibria of water-salt systems can supply theoretical basis for the development of salt lake brine resources [10]. erefore, the research on the phase equilibrium of the brine systems containing boron is meaningful to the comprehensive utilization and development of boron resources from brines [11].…”