Solid-liquid equilibria in the ternary system NaBr–KBr–H2O at 398 K

The solubilities of the ternary system NaBr–KBr–H2O were investigated by isothermal method at 398 K. On the basis of the experimental data, the phase diagram was plotted. In the phase diagram of ternary system NaBr–KBr–H2O at 398 K, no complex salt or solid solution was found. It belongs to simple co-saturation type. There are only one invariant point, two univariant curves, and two crystallization fields corresponding to NaBr and KBr. Using the equilibrium solubilities data of the ternary system at 398 K, mixing ioninteraction parameter ΨNa,K,Br of Pitzer’s equation was fitted by multiple linear regression method. Based on the Pitzer model and its extended Harvie–Weare (HW) model, the solubilities of phase equilibrium in the ternary system NaBr–KBr–H2O at 398 K were calculated. The phase diagram of the ternary system was plotted. The results show that calculated values have a good agreement with measured experimental data. It can demonstrate the accuracy of the experimental data, and it also shows that reasonable parameters of the Pitzer model can be used in ternary system NaBr–KBr–H2O at 398 K.