Thermodynamic modeling of phase equilibrium in aqueous systems to recover boron acid from the brines

Abstract

• The Pitzer thermodynamic model for the quinary system was constructed. • The calculated solubility data agree well with the experimental data. • The Pitzer model was used to conduct computer simulation of H 3 BO 3 separation. The solid–liquid equilibria in the quinary system HCl−NaCl−MgCl 2 −H 3 BO 3 −H 2 O at 298.15 K was studied with Pitzer thermodynamic model. The Pitzer parameters for H 3 BO 3 in the quinary system were fitted with the solubility data from the literatures. The predicted solubility data of quinary system were obtained by dissolution equilibrium constants and Pitzer parameters. The comparison of calculated data with experimental data shows the Pitzer model of the quinary system was reliable. The phase diagrams and Pitzer model of HCl−NaCl−MgCl 2 −H 3 BO 3 −H 2 O quinary system were conducted for H 3 BO 3 separation from brine with computer simulation. The evaporation crystallization route and the order of salt precipitation were obtained with the model of the quinary system at 298.15 K. The results show that it’s easier to separate H 3 BO 3 under acidic conditions. The pure salt H 3 BO 3 and NaCl were separated with the phase diagrams of NaCl−H 3 BO 3 −H 2 O system at 298.15 K and 323.15 K.