Tao Zhang,Ao Li,Xin Xu,Yixin Ma,Dongmei Xu,Lianzheng Zhang,Jun Gao,Yinglong Wang
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 ) 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.
Kai Liu,Zhaojie Wang,Yi Zhang,Dongmei Xu,Jun Gao,Zhun Ma,Yinglong Wang
Dimethyl carbonate and ethanol can form an azeotrope with the minimum boiling point. To separate the azeotrope (dimethyl carbonate + ethanol) by extractive distillation , p -xylene, butyl propionate , and isobutyl acetate were chosen as entrainers , and the isobaric vapour-liquid equilibrium (VLE) data for the binary systems of (dimethyl carbonate + p -xylene), (dimethyl carbonate + butyl propionate), (dimethyl carbonate + isobutyl acetate) and (ethanol + isobutyl acetate) were measured at 101.3 kPa using a modified Rose type recirculating still. The thermodynamic consistency of the VLE experimental data for the four binary mixtures was tested by the Herington and van Ness methods. Furthermore, the measured VLE data were correlated by the NRTL, UNIQUAC and Wilson thermodynamic models and the binary interaction parameters of the three models were regressed. Based above, an extractive distillation process with the entrainer of p -xylene was proposed and simulated to separate the azeotrope (dimethyl carbonate + ethanol).
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