Experimental isobaric vapour–liquid–liquid equilibrium data for the quaternary systems water (1)–ethanol (2)–acetone (3)–n-butyl acetate (4) and water (1)–ethanol (2)–acetone (3)–methyl ethyl ketone (4) and their partially miscible-constituent ternaries

Abstract

Experimental vapour–liquid–liquid equilibrium data for the (type B) quaternary systems water (1)–ethanol (2)–acetone (3)–n-butyl acetate (4) and water (1)–ethanol (2)–acetone (3)–methyl ethyl ketone (4) were measured using a circulation equilibrium still employing vigorous mechanical mixing in the boiling chamber. The first quaternary system was measured isobarically at pressures of 760, 600 and 360 mm Hg, and the other system measured isobarically at atmospheric pressure. The partially miscible constituent ternaries of both quaternary systems, water (1)–acetone (2)–n-butyl acetate (3), water (1)–ethanol (2)–n-butyl acetate (3), water (1)–acetone (2)–methyl ethyl ketone (3) and water (1)–ethanol (2)–methyl ethyl ketone (3) were also measured at the same conditions. The measured experimental data were found to be thermodynamically consistent according to the isobaric point-by-point thermodynamic consistency criterion of Wisniak.

Introduction

Azeotropic behaviour is relatively a common phenomenon; one of the most efficient methods of treating an azeotrope is the introduction of an entrainer (mass separation) through the process of heterogeneous azeotropic and/or extractive distillation [1], [2], [3]. For the design of such a process the need for vapour–liquid–liquid equilibrium data remains of fundamental importance. It is a well-known fact that the number of ternary and quaternary vapour–liquid–liquid equilibrium data available in the literature is very scarce in comparison with homogeneous binary vapour–liquid equilibrium data [4], [5]. This scarcity is not only because this kind of measurements increases the experimental effort by several orders of magnitude (the third and/or fourth component and the third phase), but also due to certain difficulties encountered in measuring such systems. Another important reason for having abundant multicomponent vapour–liquid–liquid equilibrium data is to increase data availability in the various data compilation sources that can provide an invaluable field for investigating the prediction capability of various thermodynamic models frequently appearing in the literature. In this work, experimental isobaric vapour–liquid–liquid equilibrium data are reported for the quaternary system water (1)–ethanol (2)–acetone (3)–n-butyl acetate (4) (at atmospheric and sub-atmospheric pressures of 760, 600 and 360 mm Hg) and for the system water (1)–ethanol (2)–acetone (3)–methyl ethyl ketone (MEK) (4) at atmospheric pressure. Both systems studied in this work are type B. In this type of quaternary mixture components (1) and (4) are only partially miscible with each other and completely miscible with the other two components in all proportions. The partially miscible constituent ternaries of both quaternary systems, namely, water (1)–acetone (2)–n-butyl acetate (3), water (1)–ethanol (2)–n-butyl acetate (3), water (1)–acetone (2)–methyl ethyl ketone (3) and water (1)–ethanol (2)–methyl ethyl ketone (3) were also measured at the same conditions in order to construct the entire heterogeneous envelopes of the quaternary systems. All ternary systems measured in this work are type 1 (plait-point). The point-by-point method of Wisniak [6] for testing the thermodynamic consistency of isobaric measurements has been used to test the data. A complete analysis and correlation of the measured systems will be presented in a separate paper.