Separation of azeotropic mixture (acetone + n-heptane) by extractive distillation with intermediate and heavy boiling entrainers: Vapour-liquid equilibrium measurements and correlation

Acetone and n -heptane are widely applied in pharmaceutical industry as benign solvents and are observed in the wastewater. Because acetone and n -hexane can form an azeotropic mixture, it is impossible to recover acetone and n -heptane with high purity from the wastewater using conventional distillation. In this research, for separating the azeotrope (acetone +  n -heptane) by homogeneous extractive distillation, 1-chlorobutane and butyl propanoate were chosen as the intermediate and heavy boiling entrainers. The isobaric vapour-liquid equilibrium (VLE) behaviour for the three binary systems (acetone + 1-chlorobutane), (butyl propanoate + acetone) and ( n -heptane + butyl propanoate) were reported at 101.3 kPa. The values of the excess Gibbs energy ( G E $G^E$ ) were calculated to explore the nonideal of the systems. The thermodynamic consistency of the determined VLE values was checked by the van Ness and Herington tests. In addition, the determined VLE data were fitted by the UNIQUAC, Wilson, and NRTL models. The parameters of those models were regressed, which are helpful for simulating the separation process with the intermediate and heavy boiling entrainers by extractive distillation.