Grupo Especializado en Termodinámica de los Equilibrios entre Fasesenglish versionGETEF emblema


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Año 1998

  • Rubio, MA; Gonzalez, JA; de la Fuente, IG; Cobos, JC; Thermodynamic properties of n-alkoxyethanols plus organic solvents mixtures - VIII. Liquid-liquid equilibria of systems containing 2-methoxyethanol and alkanes (C6H12 and CH3-(CH2)u-CH3, u=3, 4, 6, 8); Fluid Phase Equilibr, 143 (1-2) 1998 111-123
Liquid-liquid equilibria (LLE) data are reported for 2-methoxyethanol + n-pentane, + n-hexane, + n-octane, + n-decane, or + cyclohexane mixtures at atmospheric pressure, between 281 K and the upper critical solutions temperatures (UCST). The coexistence curves were determined visually. These curves are rather symmetrical, with the asymmetry increasing with the size of the n-alkane. The UCSTs increase almost linearly with the number of the carbon atoms of the n-alkane. The system with cyclohexane shows the lower UCST. The (x,T) data were fitted to the equation T = Tc + k|y-yc|m where y = γ x1/{1 + x1(γ - 1)} and yc = γ x1c/{1 + x1c(γ - 1)}. Tc and x1c are the coordinates of the critical points fitted together with k, m and γ using a Marquardt algorithm. The critical exponents of the order parameter for the mixtures studied are calculated. Its mean value is 0.363.
  • Domanska, U; Gonzalez, JA; Thermodynamics of branched alcohols - II. Solid-liquid equilibria for systems containing tert-butanol and long-chain n-alkanes. Experimental results and comparison with DISQUAC predictions; Fluid Phase Equilibr, 147 (1-2) 1997 251-270
Solid-liquid equilibrium temperatures for tert-butanol + n-alkanes (C18, C19, C20, C21, C22, C23, C24, C25, C26, C28) systems have been measured by a dynamic method from 298.15 K to the melting point of the alkane. All the systems present an eutectic point at very low concentration of the alcohol. A first-order transition was observed for many of the n-alkanes considered. The experimental values are compared with those given by the DISQUAC model using the interaction parameters previously determined on the basis of vapor-liquid equilibria, VLE, and molar excess enthalpies, HE, of systems containing the lower n-alkanes (n-C-6, n-C-7). Calculations were developed taking into account the solid-solid transition of the alkanes. The mean relative standard deviation for the equilibrium temperatures is 0.0073. Differences between experimental data and calculated results for SLE and HE are analysed in terms of the Patterson effect. The possibility of improving predictions by modifying only the third dispersive interchange coefficient is discussed. Two values for this parameter are proposed depending on n, hereafter the number of C atoms in the n-alkane (n less than or equal to 8 and n greater than or equal to 9). In this way, the variation with the temperature of HE is better represented by the model for those systems including the longer n-alkanes. Predictions on SLE remain unchanged, because they depend essentially on the first interchange coefficients when the range of temperature considered, as in this case, is rather narrow.
  • Rubio, MA; Gonzalez, JA; de la Fuente, IG; Cobos, JC; Thermodynamic properties of n-alkoxyethanols plus organic solvent mixtures. IX. Liquid-liquid equilibria of systems containing 2-methoxyethanol or 2-ethoxyethanol and selected n-alkanes; J Chem Eng Data, 43 (5) 1998 811-814
Liquid-liquid equilibria (LLE) data are reported for 2-methoxyethanol + dodecane, and for 8-ethoxyethanol + dodecane, + tetradecane, or + hexadecane mixtures between 275.7 K and the upper critical solution temperatures (UCST). The solubility curve of pure solid hexadecane in liquid 2-ethoxyethanol is also presented in the range of 0 to 0.1833 of mole fraction in 2-ethoxyethanol. The coexistence curves were determined visually. For a given alkoxyethanol, the LLE curves are rather asymmetrical, with the asymmetry increasing with the size of the n-alkane. Moreover, the UCSTs increase almost linearly with the number of the carbon atoms of the n-alkane. The (x, T) data were fitted to the equation T = Tc + k|y-yc|m where y = γ x1/[1 + x1(γ - 1)] and yc = γ x1c/[1 + x1c(γ - 1)]. Tc and x1c are the coordinates of the critical points fitted together with k, m, and alpha using a Marquardt algorithm.



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