Determination of saturated vapour pressure of aniline hydrochloride and vapour–liquid equilibrium of the water- aniline hydrochloride system

• The yB-xB phase diagrams exhibits strong negative deviations from Raoult's law.
• On the T-xB (yB) phase diagrams exists two solid-liquid-vapour coexistence regions.
• Correlation of the VLE data with the electrolyte-NRTL model gave satisfactory results.

The vapour–liquid equilibrium (VLE) data for water (A)-aniline hydrochloride (B) binary system is the basis for the design of distillation columns for recovery of aniline hydrochloride from condensate aqueous solution produced during the dehydration of bischofite by aniline hydrochloride composite salt method or from the wastewater containing aniline hydrochloride. In this study, a new dynamic condensate-circulation still was designed and used for the determination of saturated vapour pressure of pure aniline hydrochloride and VLE and vapour–liquid–solid equilibrium (VLSE) data for water (A)-aniline hydrochloride (B) binary system at 101.3 kPa. The phase diagrams of equilibrated vapour-phase composition versus overall liquid-phase composition yB-xB (where subscript B denotes aniline hydrochloride) and equilibrated temperature versus overall liquid-phase or vapour-phase composition T-xB(yB) were plotted by using the VLE and VLSE data and the data on solubility. The VLE data for this system were correlated with a binary non-electrolyte NRTL and an electrolyte-NRTL activity coefficient model respectively, and the results indicated that the use of electrolyte-NRTL gave satisfactory results (the root mean square deviations (RMSD) between predicted and measured are RMSD(ΔT) = 2.5 K, RMSD(ΔyB) = 0.0021).