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

摘要

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 and the solubilities in the system KCl–K_(2)SO_(4)–K_(2)B_(4)O_(7)–H_(2)O and its subsystems were calculated on the basis of the Pitzer model. The mole fraction of the four boron species is mainly affected by m (B) in the solution but less by m (Cl~(–)) and m (SO_(4)~(2–)). m (Cl~(–)) and m (SO_(4)~(2–)) mainly affect the solubility of K_(2)B_(4)O_(5)(OH)_(4)·2H_(2)O. The calculated solubilities in the system KCl–K_(2)B_(4)O_(7)–H_(2)O agree well with the experimental data. The results show that the standard chemical potentials of K_(2)B_(4)O_(5)(OH)_(4)·2H_(2)O at 298.15 K obtained in this work is reliable. The transformation between the boron species at 298.15 K was also conducted with the density functional theory (DFT) method. The results affirm that the boron species can transform other boron species as the boron concentration in the solution changes.