Excess enthalpies of binary and ternary mixtures.

Abstract

The research work involved in this study can be described in two aspects: the experimental determination of excess enthalpies, H$\rm\sp{E},$ for some binary and ternary liquid mixtures; and a theoretical study of various approaches for the representation of experimental H$\rm\sp{E}$ data. To determine the excess enthalpies of desired systems, a series of calorimetric experiments have been carried out for 15 binary and six ternary mixtures with an LKB flow microcalorimeter. A new model, based on statistical thermodynamic principles, has been developed for representing and predicting the excess enthalpy of a ternary mixture from correlation of the H$\rm\sp{E}$ values of its constituent binaries. The analyses of experimental results were carried out with several solution models, such as the Flory theory model, an association model, the DISQUAC model, the NRTL model, the UNIQUAC model, and the model developed in this study. The applicability of the proposed model for predicting ternary H$\rm\sp{E}$ values was further investigated. In addition to the six ternary systems experimentally studied in this work, six more ternary systems were selected from the literature. For comparison, the same calculations were also carried out with the 3-parameter NRTL and 2-parameter UNIQUAC models.