Solid–Liquid Phase Equilibria in the Quinary System NaCl + NaOH + Na2CO3 + Na2SO4 + H2O at 363.15 K

Solid-liquid equilibria in the quinary system NaCl + NaOH + Na 2 CO 3 + Na 2 SO 4 + H 2 O at 363.15 K were measured by the wet residue method, and the equilibrium solid phases and solubilities of saturated solutions were determined experimentally. Using the experimental results, dry-salt phase diagrams and water diagrams versus composition diagrams were plotted (saturated with saturated sodium chloride, sodium hydroxide, sodium carbonate, and sodium sulfate). The experimental results show that there are a solid solution (γ-salt, mNa 2 SO 4 · n Na 2 CO 3 ) and co-saturation complex salts (S3, Na 2 SO 4 ·NaCl·NaOH and S1, NaOH·Na 2 SO 4 ) formed in this quinary system. Based on Xu's activity coefficient model, the solubilities of the quinary system NaCl + NaOH + Na 2 CO 3 + Na 2 SO 4 + H 2 O at 363.15 K were calculated with corresponding parameters. Comparing the experimental and calculated results, it was shown that the calculated values had a good agreement with the experimental ones.