Multiproperty modeling for a set of binary systems. Evaluation of a model to correlate simultaneously several mixing properties of methyl ethanoate+alkanes and new experimental data

Abstract

a b s t r a c tThis work makes a theoretical-experimental contribution to the study of ester and alkane solutions. Experimental data of isobaric vapor-liquid equilibria (VLE) are presented at 101.3 kPa for binary systems of methyl ethanoate with six alkanes (from C 5 to C 10 ), and of volumes and mixing enthalpies, v E and h E . An interpretation of the behavior and a verification of structural models proposed previously by the same group are also given. For the treatment of thermodynamic data a polynomial model is proposed to obtain a simultaneous correlation of different properties available for a same system. Liquid-liquid equilibrium (LLE) data at low pressure are also used and c E p values, taken from literature, to perform the correlations described, generating a working procedure which is started on LLE data. The properties used for correlating are obtained in very different working conditions making it difficult to obtain a single correlation. However, the procedure followed produces good multiproperty correlations for each of the systems. An extended version of the NRTL model is also used with the purpose of comparing the efficacy of the method and model proposed, and produces acceptable results for the isobaric and isothermal VLE equilibrium but not for the LLE. Specifically, the model does not take into account the variation in h E = ϕ(T), as it does not reproduce the c E p . Estimates of the same properties made with the UNIFAC group contribution method are comparable to those obtained with the correlative NRTL method.

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

“…To perform a consistency analysis with the model proposed here requires using a mathematical model that obeys the Gibbs‐Duhem equation and that suitably represents the experimental behavior of the study system. For several years, we have been using our own model, with excellent results, for the simultaneous correlation of different thermodynamic properties of binary systems. When applying the method, this model is used for both data correlation and consistency analysis.…”

“…Owing to the length of the proposed method, we give now an outline of it: The first part shows the equations used in the proposed test, arising from Eq. , and its application to, in reference to liquid phase, homogeneous (isothermal and isobaric) and non‐homogeneous systems. The second part of the paper presents our own mathematical model used as a data correlation tool. It is important that the model used to evaluate data consistency be the same as that used in the correlation; the results of most tests vary depending on the equation chosen. A third section analyses the feasibility of the test, applied first to a set of synthetic/artificial systems and then to a database of 300 systems (270 homogeneous and 30 non‐homogeneous) reported in literature.…”

Solutions of alkyl methanoates and alkanes: Simultaneous modeling of phase equilibria and mixing properties. Estimation of behavior by UNIFAC with recalculation of parameters

“…Inc. [36] that has already been used in previous works [18]. For correlation of h E and c E p the expressions derived from Eq.…”

Experimentation and thermodynamic representations of binaries containing compounds of low boiling points: Pentane and alkyl methanoates

“…For the h E , the average uncertainty of the direct measurements was lower than 1%. At 298.15 K the calorimeter was checked as indicated previously [27]. Refractive indices of the pure compounds were measured with a Zuzi 320 Abbe type refractometer with a uncertainty of ±0.0002 units and thermostatized with an external circulating water bath from Heto that provided excellent control of the water temperature and was used to maintain the apparatus at (T ± 0.02) K. The proper functioning of the apparatus was checked by measuring the n D of ultrapure water at 298.15 K, giving the exact value published in the literature [11].…”

“…The zones of LLE that define the corresponding saturation curve may or not overlap with the VLE. If they do then a system of VLLE is generated, otherwise, two independent zones are obtained (each with two phases) for a single mixture [27], see Fig. 1.…”