Liquid–Liquid equilibria of ternary and quaternary systems including 2,2,4-trimethylpentane, benzene, ethanol, and water at 303.15 K

Abstract

Tie-line data for ternary systems including ethanol (C2H6O), water (H2O), benzene (C6H6), and 2,2,4-trimethylpentane (C8H18) were investigated. Phase diagrams of {w 1H2O + w 2C2H6O + (1 − w 1 − w 2)C6H6} and {w 1H2O + w 2C2H6O + (1 − w 1 − w 2)C8H18} ternary systems were obtained at 303.15K, while {w 1H2O + w 2C8H18 + (1 − w 1 − w 2)C6H6} ternary system was taken from literature. A quaternary system containing these four compounds {w 1C2H6O + w 2C6H6 + w 3C8H18 + (1 − w 1 − w 2 − w 3)H2O} was also studied at the same temperature. From our experimental results, we can conclude that this quaternary system presents a very low water tolerance. Small quantities of water from ambient humidity or infiltration into storage tanks could produce phase separation with a considerable loss of C2H6O drawn into the aqueous phase. On the other hand, the results also show that the aqueous phase contains a higher concentration of C6H6 compared to C8H18. The ternary experimental results were correlated with the NRTL and UNIQUAC equations, and predicted with the UNIFAC group contribution method. The three models lead to accurate results according to the two overall errors. In order to predict the equilibrium data for the quaternary system the UNIFAC method was used. This method predicts the binodal surface, satisfactorily although its prediction of the ethanol distribution ratio is rather poor.