Measurement and prediction of (solid + liquid) equilibria of (alkanediamine + biphenyl) mixtures (original) (raw)
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The vapour pressures of {ethanediamine (EDA) + water}, {1,2-diaminopropane (1,2-DAP) + water}, {1,3diaminopropane (1,3-DAP) + water} or {1,4-diaminobutane (1,4-DAB) + water} binary mixtures, and of pure EDA, 1,2-DAP, 1,3-DAP, 1,4-DAB, and water components were measured by means of two static devices at temperatures between (293 and 363) K. The data were correlated with the Antoine equation. From these data, the excess Gibbs function (G E ) was calculated for several constant temperatures and fitted to a fourth-order Redlich-Kister equation using the Barker's method. The {ethanediamine (EDA) + water}, and {1,2-diaminopropane (1,2-DAP) + water} binary systems show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative deviations in G E for all investigated temperatures over the whole composition range whereas the (1,4-DAB + water) binary mixture shows negative G E for temperatures (293.15 < T/K < 353.15) and a sinusoidal shape for G E at T = 363.15 K.
Solid–liquid equilibria of the n-alkanes (n-oc-tadecane, n-eicosane, n-tetracosane, n-pentacosane, n-triacon-tane) in biphenyl were measured by DSC 7 (Perkin-Elmer). It was found that all systems are simple eutectic. The solubility of the biphenyl in n-alkanes was studied in the temperature range 301–370 K. The experimental results were correlated using modified UNIFAC (Larsen and Gmehling versions) and ideal models. Good representation of solubility diagrams was obtained using partly readjusted UNIFAC parameters of Larsen version. Taking into account the large range of applicability of UNIFAC and the predictions of the activity coefficients for many other components in different classes of mixtures, we can conclude that the new experimental data for the systems mentioned in this work should be included in the database used by UNIFAC in order to evaluate better interaction parameters and to improve predictions.
Solid–liquid equilibria of biphenyl binary systems
Solid–liquid equilibrium temperatures, obtained by means of a differential scanning calorimetry (DSC) technique , are reported for biphenyl + n-C 21 , or +n-C 31 , or +n-C 41 systems. Biphenyl + alkane, or +heterocyclic compound (diphenyl ether, dibenzofuran, indole, diphenylamine, 1-octadecanol or octadecanoic acid) have been investigated using DISQUAC and the ideal solubility model. This model provides good results for alkane solutions whose components which largely differ in size. Interactional effects are relevant in solutions with hep-tane, octadecane or mixtures involving dibenzofuran, indole, 1-octadecanol or octadecanoic acid.
Experimental and Modelling of liquid –solid equilibria
XXXV JEEP – 35th Conference on Phase Equilibria, 2009
Solid-liquid equilibria are less considered in inorganic thermochemistry, comparatively to the other two types of phase equilibria involving vapour and/or liquid phases. The great majority of the relevant models, particularly for the calculation of the activity coefficient, concern these last two cases, although their use is extended to handle the solid-liquid equilibria. The first part of the present work concerns an experimental study for the determination of the liquid-solid phase equilibrium diagrams, for various binary systems such as salicylic acid in water, ethanol and chloroform, and naphthalene in phenol, by the means of Differential Scanning Calorimetry. The second part consists of a modeling of these phase equilibria by means of various thermodynamic models such as NRTL, UNIFAC which are also tested for binary systems such as naphthalene in organic solvents. The use of these models requires interaction parameter values which are not always available. Therefore, this work was an opportunity to compute these parameters for the different systems considered. The results obtained experimentally and by modeling, concerning the phase diagrams showed a good agreement, particularly for the NRTL model, compared to UNIFAC which is based on the concept of group contribution and thus is approximate.
Industrial & Engineering Chemistry Research, 2004
All are congruently melting compounds. Compound formation is attributed to a strong A-B interaction. The excess molar volumes, V m E , have been determined for these mixtures at 298.15 K and atmospheric pressure. The systems exhibit very large negative excess molar volumes, V m E , and excess molar enthalpies, H m E. The V m E curves are nearly symmetrical. Strong crossassociation between hydroxyl and amine groups (OH‚‚‚NH 2) is a dominant effect, and it causes high negative values of V m E and H m E and 1:1 congruently melting solid compounds at lower temperatures. Our experimental data on V m E and the literature data on H m E were treated in terms of the ERAS model, DISQUAC, and modified UNIFAC. The ERAS model consistently describes V m E and H m E of the studied mixtures.
Fluid Phase Equilibria, 2015
Isobaric vapor-liquid equilibria at p = 101.32 kPa (iso-p VLE) and the mixing properties, h E and v E , are determined for a set of twelve binary solutions: HCOOC u H 2u+1 (1)+C n H 2n+2 (2) with u = (1-4) and n = (7-9). The (iso-p VLE) present deviations from the ideal behavior, which augment as u diminishes and n increases. Systems with [u = 2,3 n = 7] and [u =4 , n = 7,8] present a minimum-boiling azeotrope. The nonideality is also reflected in high endothermic values, h E > 0, and expansive effects, v E > 0, for all the binaries, which increase regularly with n. However, for a same hydrocarbon, the properties diminish with increasing u. This, in turn, causes the dipolar effect of the methanoates to decrease, with the resulting reduction in mixing effects. As a result, other interpretations on the behavioral structural model of these systems are established. Modeling of the experimental quantities is carried out using the authors' model with good results, and comparisons are made with an adapted version of the NRTL model. Energetic properties of the solutions are predicted with the UNIFAC group contribution model, but the values obtained are not as good. Hence, parameters corresponding to the specific interaction HCOO/CH 2 are recalculated using a wider database, resulting in slightly better values. COSMO-RS methodology is also employed to assess the energetic effects of the mixing process. Apart from some exceptions, also mentioned here, the method gives an acceptable estimation of the behavior of these systems. 2015 Elsevier B.V. All rights reserved.
1992
This report documents a Fortran version of a chemical thermodynamic model for calculating liquid-liquid equilibria in mixtures of organic compounds. The model applies the Gibbs energy minimization method for phase equilibria computation combined with the UNIFAC routine and thermodynamic database for calculating activity coefficients of organic substances in multicomponent organic liquids on the basis of the group contribution theory The model can be extended without modifications of the Gibbs energy minimization program to take into account also chemical interactions between organic components.
Solid-liquid equilibria (SLE) of binary mixtures of several n-alkanes (n-octadecane, n-eicosane, n-tetracosane, n-pentacosane, n-triacontane) and dibenzofuran covering the whole composition range were measured by differential scanning calorimetry (DSC) in a temperature range of 301-356 K. The dibenzofuran and the n-alkanes are completely miscible in the liquid state but non-miscible in the solid-state, and in the context of this work, they seem to exhibit eutectic behavior. A linear trend is obtained for the eutectic temperature and eutectic composition versus the number of carbon atoms of n-alkane. The experimental data were compared to predictions made by using the ideal solution model, the DISQUAC model and several versions of the UNIFAC model, including the classical UNIFAC, the modified versions of Lyngby and Dortmund, and the recently proposed modified UNIFAC (NIST) model, to account for non-ideality in the liquid phase. Moreover, the experimental data were also compared with ...