Solid-Liquid Phase Equilibria in the Quinary System NaCl + NaOH + NaCO + NaSO + HO at 363.15 K.

Solid-liquid equilibria in the quinary system NaCl + NaOH + NaCO + NaSO + HO 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, mNaSO·NaCO) and co-saturation complex salts (S3, NaSO·NaCl·NaOH and S1, NaOH·NaSO) formed in this quinary system. Based on Xu's activity coefficient model, the solubilities of the quinary system NaCl + NaOH + NaCO + NaSO + HO 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.