Determination and modelling of solid-liquid phase equilibrium and phase diagram for multicomponent system of nitrobenzaldehyde isomers. (I) Ternary system of 4-nitrobenzaldehyde + 3-nitrobenzaldehyde + ethyl acetate

Abstract

In this work, the solid-liquid phase equilibrium data for ternary system of 4-nitrobenzaldehyde+3-nitrobenzaldehyde+ethyl acetate were determined by using an isothermal saturation method at three temperatures of 278.15K, 288.15K, and 298.15K under atmosphere pressure (101.2kPa). Three isothermal phase diagrams were built based on the measured solubility data. There were two pure solids formed in the ternary system at a certain temperature, which corresponded to pure 3-nitrobenzaldehyde and pure 4-nitrobenzaldehyde, and were confirmed by Schreinemaker's method of wet residue and X-ray powder diffraction. The crystallization region of 4-nitrobenzaldehyde was larger than that of 3-nitrobenzaldehyde at each temperature. Two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the system of 4-nitrobenzaldehyde+3-nitrobenzaldehyde+ethyl acetate. The largest value of RMSD for the ternary system was 5.95×10−3, and the maximum value of RAD was 3.02%. The calculated results with NRTL model agreed well than those with Wilson model. The solid-liquid equilibrium phase diagrams and the thermodynamic models for the ternary system can provide the foundation for separating high purity3-nitrobenzaldehyde or 4-nitrobenzaldehyde from its isomeric mixtures.