Luisa Segade

Thermophysical properties of four binary dimethyl carbonate + 1-alcohol systems at 288.15–313.15 K

Abstract Densities and kinematic viscosities for the dimethyl carbonate (DMC) + (ethanol, 1-propanol, 1-pentanol, 1-octanol) binary systems have been experimentally determined at 288.15, 293.15, 303.15 and 313.15xa0K and normal atmospheric pressure, over the entire mole fraction range. Moreover, the excess molar enthalpies for the present binary mixtures were determined at 303.15xa0K. Other mixing properties of interest such as the excess molar volumes, the viscosity deviations, the isobaric thermal expansion coefficients, the excess expansibilities, and the pressure coefficients of the molar excess enthalpy have been also obtained for each of the systems and temperatures. The obtained properties have been compared with those reported by other authors when available in the literature, and have been analyzed in terms of the molecular interactions present in this kind of mixtures. The composition–viscosity data were correlated with several specific equations to evaluate their feasibility for these systems.

Surface tensions, densities and refractive indexes of mixtures of dibutyl ether and 1-alkanol at T=298.15 K

Abstract The aim of our present work is to present measurements of the surface tension, density and refractive index for binary mixtures of dibutyl ether with eight 1-alcohols {C 4 H 9 OC 4 H 9 +C 3 H 7 OH,+C 4 H 9 OH,+C 5 H 11 OH,+C 6 H 13 OH,+C 7 H 15 OH,+C 8 H 17 OH,+C 9 H 19 OH and +C 10 H 21 OH} at the temperature of 298.15xa0K and atmospheric pressure. The experimental data are correlated by means of suitable empirical expressions, which relate the surface tension and refractive index of a mixture with its corresponding density. Also, calculated are the surface tension deviations and excess molar volumes from the measured data for all binary mixtures. The results of the study attending to the number of carbon atoms of the 1-alcohol are discussed.

Densities, viscosities, and refractive indexes for {C2H5CO2(CH2)2CH3+C6H13OH+C6H6} at T=308.15 K

Abstract In this work we present densities, kinematic viscosities, and refractive indexes of the ternary system {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH+C 6 H 6 } and the corresponding binary mixtures {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 6 }, {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH}, and {C 6 H 13 OH+C 6 H 6 }. All data have been measured at T =308.15xa0K and atmospheric pressure over the whole composition range. The excess molar volumes, dynamic viscosity deviations, and changes of the refractive index on mixing were calculated from experimental measurements. The results for binary mixtures were fitted to a polynomial relationship to estimate the coefficients and standard deviations. The Cibulka equation has been used to correlate the experimental values of ternary mixtures. Also, the experimental values obtained for the ternary mixture were used to test the empirical methods of Kohler, Jacob and Fitzner, Colinet, Tsao and Smith, Toop, Scatchard et al ., and Hillert. These methods predict excess properties of the ternary mixtures from those of the involved binary mixtures. The results obtained for dynamic viscosities of the binary mixtures were used to test the semi-empirical relations of Grunberg–Nissan, McAllister, Auslander, and Teja–Rice. Finally, the experimental refractive indexes were compared with the predicted results for the Lorentz–Lorenz, Gladstone–Dale, Wiener, Heller, and Arago–Biot equations. In all cases, we give the standard deviation between the experimental data and that calculated with the above named relations.

Vapor-liquid equilibria for the binary system hexan-1-ol + tert-butyl methyl ether (MTBE) at 298.15, 318.15, and 338.15 K

Abstract Vapor–liquid equilibrium (VLE) data are reported for the binary mixtures formed by hexan-1-ol and the branched ether tert -butyl methyl ether (MTBE). A Gibbs–van Ness type apparatus was used to obtain total vapor pressure measurements as a function of composition at 298.15, 318.15, and 338.15xa0K. The system shows positive deviations from Raoult’s law. VLE data are analyzed using the UNIQUAC equation and compared with predictions from the modified UNIFAC (Dortmund) model.

Excess molar volumes and enthalpies for the ternary system [butyl butyrate + 1-octanol + octane] at the temperature 308.15 K

Abstract In this work, we present in detail the excess magnitudes of volume and enthalpy of the ternary system: [butyl butyrate+1-octanol+octane] at the temperature 308.15xa0K and normal atmospheric pressure. The experimental values obtained were correlated with the Redlich–Kister equation in the case of the binary systems and the Cibulka equation for the ternary systems. Both magnitudes were also used to test several group contribution models and empirical methods.

Excess molar enthalpies for propyl propanoate + cyclohexane + benzene at 298.15 and 308.15 K

Abstract Excess molar enthalpies of the ternary system ( x 1 (propylpropanoate)+ x 2 (cyclohexane)+(1− x 1 − x 2 )benzene) and of their binary mixtures ( x 1 (propylpropanoate)+ x 2 (cyclohexane)) and ( x 1 (cyclohexane)+ x 2 (benzene)) have been determined at 298.15 and 308.15xa0K and atmospheric pressure, over the whole composition range. The excess molar enthalpies were measured using a Calvet microcalorimeter. The experimental values were compared with the results obtained with empirical expressions for estimating ternary properties from binary data. The group contribution model of UNIFAC in the version of Gmehling were also applied to predict excess molar enthalpies.

Vapor–liquid equilibria of propan-1-ol + 1,1-dimethylethyl methyl ether (MTBE) mixtures. Experimental results and modeling

Vapour–liquid equilibrium (VLE) data are reported for the binary mixtures formed by propan-1-ol and the branched ether 1,1-dimethylethyl methyl ether (tert-butyl methyl ether or MTBE). A Gibbs–van Ness type apparatus was used to obtain total vapour pressure measurements as a function of composition at 298.15, 318.15 and 338.15 K. The system shows positive and relatively large deviations from Raoults law. The UNIQUAC, ERAS and modified UNIFAC (Dortmund) models are used to analyse these VLE data together with the VLE data at 313.15 K, the negative excess volume data at 298.15 K and the endothermic excess enthalpy data at 298.15 and 313.15 K previously reported for propan-1-ol+MTBE mixtures.

The ternary system propyl propanoate+ hexane+chlorobenzene at 298.15 k

Excess molar enthalpies for the ternary mixture {propyl propanoate + hexane + chlorobenzene} and the binary mixtures {propyl propanoate + chlorobenzene} and {hexane + chlorobenzene} were determined at the temperature 298.15 K and normal atmospheric pressure. The experimental values were measured using a Calvet microcalorimeter. Excess molar enthalpies obtained were also used to test empirical expressions for estimating ternary properties from binary results.

Mesostructure and physical properties of aqueous mixtures of the ionic liquid 1-ethyl-3-methyl imidazolium octyl sulfate doped with divalent sulfate salts in the liquid and the mesomorphic states

This paper extends the study of the induced temperature change in the mesostructure and in the physical properties occurring in aqueous mixtures of the ionic liquid 1-ethyl-3-methyl imidazolium octyl-sulfate [EMIm][OSO4]. For some compositions, these mixtures undergo a phase transition between the liquid (isotropic in the mesoscale) and the mesomorphic state (lyotropic liquid crystalline) at about room temperature. The behavior of mixtures doped with a divalent metal sulfate was investigated in order to observe their applicability as electrolytes. Calcium sulfate salt is almost insoluble even in the 20 wt% water mixture. The magnesium salt, in contrast, can be dissolved up to concentrations of 730 ppm in the same mixture and it has a profound impact on its properties. Six aqueous mixtures (with water content from 10 wt% to 33 wt%) of [EMIm][OSO4] were saturated with magnesium sulfate salt, producing the ternary mixture [EMIm][OSO4] + H2O + MgSO4. Viscosity, density and ionic conductivity for these samples were measured from 10 °C to 90 °C. In addition, SAXS, FTIR, diffussion NMR and Raman spectroscopy of the most interesting samples have been performed, and structural data indicate a transition between a hexagonal lyotropic liquid crystalline phase below and an isotropic solution phase above room temperature. The octyl sulfate anions of the cylindrical micelles in the hexagonal phase are coordinated with water molecules through H-bonds (about four per sulfate anion), while the [EMIm] cations seem to be poorly coordinated and so free to move. Inorganic salt addition reinforces that network, increasing the phase transition temperature.

Physical Properties of Binary Mixtures of ILs with Water and Ethanol. A Review.

The interest on ionic liquids (ILs) began in the present century, because these compounds have many physico-chemical interesting properties to be one of the most promising new materials family for the development of the novel Green Chemical industry, where generated pollution would be negligible (Rogers & Seddon, 2002; Rogers et al., 2002). To develop the novel green processes in the chemical industry using ILs it is necessary to know and to understand the physical properties of the fluids to be used, both pure ILs as mixed with other solvents (Rogers & Seddon, 2005; Danek, 2006). This last is particularly important to develop one of the most promising uses of the ILs, as electrolytes for lithium batteries, dye-sensitized solar cells (DSSC) and electrochemical processes (as deposition or metal recovery) (Ohno, 2005; Brennecke et al., 2007). Electrolytes are materials with free ions, which can move transporting electrical charge. They can be solid, liquid or even gaseous, but the most interesting for the chemical industries are liquid or gel. The use of a pure liquid as electrolyte is not very common, because the optimum efficiency in the charge transport process is given by a mixture of different substances, as it is well known for molten salt electrolytes (Danek, 2006). Furthermor, pure ILs have the problem of being very viscous at room temperature, and hence its electrical conductivity is relatively low. If we heat the IL those problems are minimized, because viscosity reduces and electrical conductivity increases, both exponentially. Usually pure ILs have a boiling temperature high enough to allow warming, although decomposition temperature is usually much lower (not higher than 400 K) (Rogers & Seddon, 2002). A much cheaper alternative to decrease viscosity and to increase electrical conductivity of the ionic liquid is to make a solution using a solvent. Thus, while viscosity decreases exponentially with the solvent molar fraction, electrical conductivity increases more than 10 times for a given IL + solvent concentration (Seddon et al., 2000). This last behaviour have been observed in aqueous solutions of metal salts, as aluminium halogen ones (Vila et al., 2005) and indicates that the increase of mobility of the IL ions is higher than the decrease of ion concentration when solvent is added, up to an optimum content. In spite of its interest, the measurement of the physical properties of IL mixtures begins in the present decade, and before 2005 the amount of papers published about it was scarce (Marsh et al., 2004). From that year the publication rhythm increased a lot, as can be