Studies of Phase Equilibria in Ternary KBr–SrBr₂–H₂O and NaBr–SrBr₂–H₂O Systems at 308 K

Abstract

The phase equilibria of the KBr–SrBr₂–H₂O and NaBr–SrBr₂–H₂O ternary systems at 308 K were measured using the isothermal dissolution equilibrium method. The compositions of the liquid and solid phases were expressed as the mass fraction, and the phase diagrams constructed from the experimental data show that both ternary systems are simple co-saturated types with only one invariant point, two univariant curves, and two crystallization regions. Neither of the two ternary systems forms a double-salt or solid solution. The solid-phase crystallization regions of the KBr–SrBr₂–H₂O ternary system correspond to KBr and SrBr₂·6H₂O, and the invariant point of the NaBr–SrBr₂–H₂O ternary system is saturated with NaBr·2H₂O and SrBr₂·6H₂O. From the phase diagrams, the salting-out effect of SrBr₂ on KBr is clear, which indicates that the solubility of KBr is lower and it is easier to separate KBr from solution in the ternary KBr–SrBr₂–H₂O system at 308 K.