Viscosities of the ternary mixture (1-butanol+n-hexane+1-chlorobutane) at 298.15 K and 313.15 K
Introduction
A thorough knowledge of thermodynamic and transport properties of multicomponent liquid systems is essential in many industrial applications. So, the viscosities of multicomponent liquid mixtures are required in many chemical engineering calculations involving fluid flow, heat transfer, and mass transfer. It is impractical to measure viscosities at all external conditions of interest, and thus, methods for the estimation of viscosities of multicomponent mixtures are not only of theoretical but also of great practical interest. Although a number of predictive equations [1]are available for estimating thermodynamic excess properties (excess volume, excess enthalpy, and excess free energy) of multicomponent systems, such methods are rarely used for viscosity. However, many empirical or semi-empirical equations can correlate shear viscosity data of binary mixtures using multiple adjustable parameters [2]. But they usually cannot be immediately extensible to multicomponent mixtures or they may require more parameters (such as three- and four-body interaction terms) for mixtures containing more than two components. The literature of correlations of flow properties for ternary and multicomponent liquid mixtures is rather limited. Recently, new models have been developed for the prediction of viscosities of mixtures. Some of them are based on the molecular approach 3, 4while others are based on the group contribution concept 5, 6. The first models require binary interaction parameters for each binary system present in the multicomponent mixture, but no ternary (or higher) constants are generally needed.
In this work, viscosities of the ternary mixture (1-butanol+n-hexane+1-chlorobutane) and for the binary mixture (n-hexane+1-chlorobutane) have been measured at the temperatures 298.15 K and 313.15 K. The viscosity data have been used to calculate the viscosity deviations (Δη) and excess molar Gibbs energy of activation for viscous flow (G*E). The UNIMOD model [4]has been used to correlate the viscosity for the binary systems and then to predict the viscosity of the ternary mixture. The GC-UNIMOD model [6]and the group contribution method proposed by Wu [5]have been used to predict the viscosity of binary and ternary mixtures. Previously, we reported density measurements for these systems as a function of mole fraction and discussed their behavior in terms of excess thermodynamic functions [7].
Section snippets
Experimental section
The compounds used: 1-butanol (>99.8%), n-hexane (>99.0%) and 1-chlorobutane (>99.0%) were obtained from Aldrich. The purities of the chemicals were checked not only by comparing the measured densities and viscosities with those reported in the literature but also by gas chromatography using a semicapillary methyl silicone column (o.d. 530 μm) and a flame-ionization detector. No further purification was considered necessary. The butanol was dried with activated molecular sieve type 0.3 nm from
Results and discussion
The experimental viscosities of the binary mixture (n-hexane+1-chlorobutane) at 298.15 K and 313.15 K are given in Table 2. In previous papers, we reported the viscosities for the binary mixtures (1-butanol+n-hexane) [12]and (1-butanol+1-chlorobutane) [13]as a function of mole fraction.
The experimental viscosities for the ternary mixture (1-butanol+n-hexane+1-chlorobutane) at 298.15 K and 313.15 K are shown in Table 3.
The viscosity deviations, Δη, and excess Gibbs energies of activation of
UNIMOD model
The `viscosity–thermodynamic' model UNIMOD [4]is used for correlating the viscosities of binary mixtures, and from these results to predict the viscosities of multicomponent systems. This model, based on the statistical thermodynamics, the Eyring's absolute reaction rates theory [21], and the corresponding states principle, develops the local composition concept and states a theoretical background for predicting mixture viscosities as a function of composition and temperature. A detailed
Nomenclature
A empirical factor of Eq. (14) Ap adjustable coefficients of Eq. (3) Bp adjustable coefficients of Eq. (4) Gi* Gibbs energy of activation for viscous flow of pure liquid i G*E excess Gibbs energy of activation for viscous flow GE free energy of mixing h Planck's constant M molar mass of the mixture Mi molar mass of pure component i m number of experimental points N Avogadro's number ni proportional constant of segment i qi area parameter of molecule i R gas constant RMSDr Root Mean Square Deviation, relative ri number of
Acknowledgements
M. Domı́nguez gratefully acknowledges the support of Departamento de Educación y Cultura del Gobierno de Navarra. The authors also thanks the support of the CONSI+D of D.G.A (Project PCB0894).
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