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

Abstract

The solubilities; concentration of four boron species B(OH)3, B(OH)4−, B3O3(OH)4−, and B4O5(OH)42−; and H+ (OH–) in the system Na2O–B2O3–H2O were calculated with the Pitzer model. The boron species B5O6(OH)4− was not considered in the model calculation. The calculated solubility and pH data are in accordance with the experimental results. The Pitzer model can be used to describe the experimental values. The distributions of the four boron species in the solution were obtained. The mole fractions of the four boron species are mainly affected by the ratio of B2O3 and Na2O in the solution. The dominant boron species in the solution saturated with different salts vary greatly. The results can supply a theoretical reference for sodium borate separation from brine.