Transport of mass in ternary liquid-liquid systems. Part II. Mass transfer and interfacial studies (original) (raw)
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Measurements of molecular and thermal diffusion coefficients in ternary mixtures
The Journal of Chemical Physics, 2005
Thermal diffusion coefficients in three ternary mixtures are measured in a thermogravitational column. One of the mixtures consists of one normal alkane and two aromatics ͑dodecane-isobutylbenzene-tetrahydronaphthalene͒, and the other two consist of two normal alkanes and one aromatic ͑octane-decane-1-methylnaphthalene͒. This is the first report of measured thermal diffusion coefficients ͑for all species͒ of a ternary nonelectrolyte mixture in literature. The results in ternary mixtures of octane-decane-1-methylnaphthalene show a sign change of the thermal diffusion coefficient for decane as the composition changes, despite the fact that the two normal alkanes are similar. In addition to thermal diffusion coefficients, molecular diffusion coefficients are also measured for three binaries and one of the ternary mixtures. The open-end capillary-tube method was used in the measurement of molecular diffusion coefficients. The molecular and thermal diffusion coefficients allow the estimation of thermal diffusion factors in binary and ternary mixtures. However, in the ternaries one also has to calculate phenomenological coefficients from the molecular diffusion coefficients. A comparison of the binary and ternary thermal diffusion factors for the mixtures comprised of octane-decane-1-methylnaphthalene reveals a remarkable difference in the thermal diffusion behavior in binary and ternary mixtures.
Remarks on the analysis method for determining diffusion coefficient in ternary mixtures
Comptes Rendus Mécanique, 2013
The objective of this work is the determination of diagonal and cross-diagonal molecular diffusion coefficients in a ternary mixture, using the 'Sliding Symmetric Tubes' (SST) technique. The analyzed mixture consists of two aromatics and one normal alkane (tetrahydronaphthalene-dodecane-isobutylbenzene) with an equal mass fraction for all components (1:1:1) at 25 • C. The analytical solution corresponding to the SST technique has been successfully derived. The different fitting procedures were utilized by two scientific teams to subtract diffusion coefficients from the experimentally measured time-dependent concentration field. None of the attempts provided reliable results for the data from a single experiment. The "simplex"-based methods display reasonable results assuming that crossdiagonal coefficients are close to zero, i.e. quasi-binary and diluted mixtures. The results obtained by "trust region method" are satisfactory if the initial guess is good. To achieve better results, it is necessary to increase the number of experimental data.
Effect of molecular association on diffusion in binary liquid mixtures
Aiche Journal, 1989
A predictive equation for the mutual diffusion coefficient is developed for binary solutions which contain a self-associating component. The solution is modeled as a nonideal multicomponent mixture consisting of the solvent molecules and various association complexes. The model provides for a unique mobility for each of the species present and accounts for both physical and chemical contributions to the solution thermodynamics and their effects on the diffusive fluxes. The predictions of the theory were evaluated for n-alcohols in nonpolar solvents using data for six systems at temperatures ranging from 293 to 363 K. In each case, the predictions of this theory are found to be superior to other currently available methods.
The Journal of Chemical Physics, 2014
A new analytical methodology has been developed to determine the diagonal and cross-diagonal molecular diffusion coefficients in ternary mixtures by the Sliding Symmetric Tubes technique. The analytical solution is tested in binary mixtures obtaining good agreement with the results of the literature. Results are presented for the ternary mixture formed by tetralin, isobutylbenzene and dodecane with an equal mass fraction for all the components (1-1-1) which is held at 25ºC. Diagonal and cross-diagonal coefficients are determined for the three possible orders of components, in order to compare the results with those available in the literature. A comparison with published results shows a good agreement for the eigenvalues of the diffusion matrix, and a reasonable agreement for the diagonal molecular diffusion coefficients.
Diffusion in the Three-Component Liquid System Acetone-Benzene-Carbon Tetrachloride
The Journal of Physical Chemistry
The diffusional behavior of the system acetone-benzene-carbon tetrachloride was studied at 25°. The diffusion coefficients for the binary systems which form the borders of the ternary system as well as those for the ternary system were measured using the diaphragm cell method. The binary data were found to be in agreement with previous measurements by other techniques. The four ternary diffusion coefficients were found to exhibit considerable nonlinear concentration dependence as do two of the three binary pairs. The concentration dependence of the ternary diffusion coefficients was qualitatively predicted by a modified form of the Stefan-Maxwell equations.
Mutual diffusivity in binary mixtures of n-heptane with n-hexane isomers
International Journal of Thermophysics, 1989
This paper presents a study of the influence of branching in the binary diffusion coefficients of n-heptane+n-hexane isomers, in the liquid state. The measurements have been made with the Taylor dispersion technique, at several compositions, at 283 and 298 K, for the X+n-heptane mixtures, where X= n-hexane, 3-methylpentane, 2, 3-dimethylbutane, and 2, 2-dimethylbutane. The results show a very interesting behavior of the composition dependence of the binary diffusion coefficients, presenting a maximum, for compositions about a molar fraction of n-heptane of 0.5, which increases with the increase in the degree of branching, suggesting the possibility of order~tisorder effects caused by stereochemically favored packing in the liquid phase and energetically favored segment interaction in the liquid mixtures. An attempt to apply the van der Waals model to these data could not predict the experimental binary diffusion coefficients of these systems within the experimental accuracy.
A Study of Molecular Transport in Liquid Mixtures Based on the Concept of Ultimate Volume
Industrial & Engineering Chemistry Fundamentals, 1976
A method for the characterization of transport properties of multicomponent liquid systems is developed by combining the concept of ultimate volume of pure liquids with the known behavior of the self-diffusion coefficient and extending the results to liquid mixtures. Comparison of the predictions of the resulting model with available data for several binary, ternary, and quaternary liquid systems yields excellent agreement. It is demonstrated that this approach, which does not involve any hypothesis concerning the existence of activated states, is capable of yielding accurate predictions of diffusion coefficients of liquid mixtures. These predictions require only readily accessible properties of the constituents of the mixtures.
Mutual diffusion in the ternary mixture of water + methanol + ethanol and its binary subsystems
Physical Chemistry Chemical Physics, 2013
Mutual diffusion is investigated by means of experiment and molecular simulation for liquid mixtures containing water + methanol + ethanol. The Fick diffusion coefficient is measured by Taylor dispersion as a function of composition for all three binary subsystems under ambient conditions. For the aqueous systems, these data compare well with literature values. In the case of methanol + ethanol, experimental measurements of the Fick diffusion coefficient are presented for the first time. The Maxwell-Stefan diffusion coefficient and the thermodynamic factor are predicted for the ternary mixture as well as its binary subsystems by molecular simulation in a consistent manner. The resulting Fick diffusion coefficient is compared to present measurements and that obtained from the classical simulation approach, which requires experimental vapor-liquid equilibrium or excess enthalpy data. Moreover, the self-diffusion coefficients and the shear viscosity are predicted by molecular dynamics and are favorably compared to experimental literature values. The presented ternary diffusion data should facilitate the development of aggregated predictive models for diffusion coefficients of polar and hydrogen-bonding systems.
The European physical journal. E, Soft matter, 2014
In this study, the thermodiffusion, molecular diffusion, and Soret coefficients of 12 binary mixtures composed of toluene, n-hexane and n-dodecane in the whole range of concentrations at atmospheric pressure and temperatures of 298.15 K and 308.15 K have been determined. The experimental measurements have been carried out using the Thermogravitational Column, the Sliding Symmetric Tubes and the Thermal Diffusion Forced Rayleigh Scattering techniques. The results obtained using the different techniques show a maximum deviation of 9% for the thermodiffusion coefficient, 8% for the molecular diffusion coefficient and 2% for the Soret coefficient. For the first time we report a decrease of the thermodiffusion coefficient with increasing ratio of the thermal expansion coefficient and viscosity for a binary mixture of an organic ring compound with a short n-alkane. This observation is discussed in terms of interactions between the different components. Additionally, the thermogravitationa...
The Canadian Journal of Chemical Engineering, 1986
The diffusion coefficient of benzoic acid in water at 25°C has been measured as a function of concentration using the Taylor dispersion technique. The diffusion coefficient was found to decrease from 1.25 x lo-' m'/s to I .07 x lo-' m'/s when the concentration increased from 0.27 mol/m' to 5.44 mol/m3. Two different models describing the concentration dependence of the diffusion coefficient have been develo d. They are fitted to the measured data and experimental data from literature at infinite dilution (D = I .57 X 10-m'/s) and at higher concentrations up to 20 mol/mg (D = 0.75 X m'/s). The significance of the concentration dependence is evaluated by measurement and by computer simulations of liquid-solid mass transfer in a tube. The simulations show that 0.80 X m'/s is the constant diffusivity that gives the best approximation in dissolution studies.