Surface tensions of binary mixtures:2-propanol+dichloromethane and n-pentane+methylacetate at 298.15 K

Densities and surface tensions of 2-propanol+dichloromethane and n-pentane+methylacetate mixtures were determined over the whole composition range at 298.15 K, by the maximum bubble pressure method. Positive excess surface tensions were observed in the first mixture and negative excess surface tensions were observed in the second mixture. Different equations existing in the literature were applied and calculated values were compared with the experimental ones. Hoar and Melford's equations were the best.     

New thermal diffusion coefficient measurements for hydrocarbon binary mixtures: viscosity and composition dependency

New thermal diffusion coefficients of binary mixtures are measured for n-decane-n-alkanes and 1-methylnaphthalene-n-alkanes with 25 and 75 wt % at 25 degrees C and 1 atm using the thermogravitational column technique. The alkanes range from n-pentane to n-eicosane. The new results confirm the recently observed nonmonotonic behavior of thermal diffusion coefficients with molecular weight for binary mixtures of n-decane- n-alkanes at the compositions studied. In this work, the mobility and disparity effects on thermal diffusion coefficients are quantified for binary mixtures. We also show for the binary mixtures studied that the thermal diffusion coefficients and mixture viscosity, both nonequilibrium properties, are closely related.     

Effect of Molecular Size of Solutes on Their Partial Molar Volumes in Supercritical n-Pentane

Supercritical fluids (SCFs) have many unique properties1. However, nearly all of the features are related with the aggregation or clustering of the molecules in the fluids. Some researchers have reported that the partial molar volumes (PMVs) of the solutes in dilute supercritical (SC) solutions are large negative values1-4, which is different from common liquid solutions. Negative PMV of a solute in SC solution results from the fact that the local density of the solvent surrounding the so…     

Enthalpies of mixing of binary and ternary mixtures containing diisopropylether,benzene and cyclohexane at 303.15 K

Enthalpies of mixing H have been measured for liquid binary mixtures of diisopropylether (DIPE)+benzene or cyclohexane and for liquid ternary mixtures diisopropylether+benzene+cyclohexane at 303.15 K and constant pressure using a C80 calorimeter. A Redlich-Kister type equation was used to correlate experimental results.     

Thermodynamic Properties of Multicomponent Liquid Mixtures

Considering a ternary liquid mixture to be made up of three binary mixtures, by means of cell model using Sutherland type potential function for pair interaction between molecules, a statistical theory for binary liquid mixtures has been extended for ternary systems. In the light of above extension, excess volume ( V E ), excess energy ( E E ) and excess entropy ( TS E ) have been computed for three binary (benzene + cyclohexane, benzene + chlorobenzene and cyclohexane + chlorobenzene) and the resultant ternary system (benzene + cyclohexane + chlorobenzene) at 298.15 K. All the above mentioned excess properties have been computed from the data of ultrasonic velocity and density only.     

Solubility of 2,5-dimethylphenol and 3,4-dimethylphenol in binary solvent mixtures containing alcohols

Solubilities are reported for 3,4-dimethylphenol and 2,5-dimethylphenol in binary mixtures of ethyl acetate with alcohols (methanol, 1-butanol, 1-hexanol), as well as for 2,5-dimethylphenol in binary mixtures of hexane with 1-butanol. The results of these measurements are compared to those obtained from the predictions by the Wilson equation for the excess Gibbs free energy of mixing (G^E). Parameters in binary solute—solvent systems were regressed from solid—liquid equilibrium data, whereas for binary mixed solvents they were taken from literature data of vapour—liquid equilibrium as well as from solid—liquid equilibrium data in ternary mixtures for equimolar compositions of binary solvents. The systems containing 3,4-dimethylphenol—ethyl acetate+alcohol mixed solvents were found to exhibit a small synergistic effect of solubility.     

Molecular simulation of the high-pressure phase equilibria of binary atomic fluid mixtures using the exponential-6 intermolecular potential

Molecular simulation results using the exponential-6 intermolecular potential are reported for the phase behaviour of the atomic binary mixtures of neon+xenon, helium+neon, helium+argon and helium+xenon. These binary mixtures exhibit both vapour–liquid and liquid–liquid phase equilibria up to very high pressures. Comparison with experiment indicates good overall agreement. The results indicate that the exponential-6 intermolecular potential is a useful generic potential for molecular simulation.     

Viscosity of ternary liquid mixtures

Viscosities of ternary liquid mixtures containing benzene + cyclohexane + carbon tetrachloride and the three possible binary combinations were measured at 25°C, and the excess viscosities were computed. Theoretical expressions for viscosity were developed on the basis of the Flory theory, the significant structure theory and a theory based on a method of estimating the properties of multi-component systems from those of binary systems. Reasonable agreement between experimental and theoretical viscosities is found.     

Thermal diffusion and molecular diffusion values for some alkane mixtures: a comparison between thermogravitational column and thermal diffusion forced rayleigh scattering

In the present work we studied the thermal diffusion behavior of n-decane in various alkanes by thermogravitational column (TC) technique and the thermal diffusion forced Rayleigh scattering (TDFRS) method. The investigated lighter alkanes compared to n-decane are n-pentane, n-hexane, n-heptane, n-octane, and the heavier ones are n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and n-eicosane. The binary mixture n-decane/ n-pentane we investigated at several different concentrations; all other mixtures were only investigated at a mass fraction of 50%. Even for the volatile n-pentane/ n-decane mixture the deviations between the thermal diffusion coefficients determined by the different methods agreed within the error bars. Typically the agreement between the two methods was in the order of 5%. In comparison to recently published TC and TDFRS data we found deviations in the order of 30% up to 40%. We analyze and discuss the possible reasons for the discrepancies for the present and the past publications.     

Isothermal vapor–liquid equilibria and excess molar volumes for the ternary mixtures containing 2-methyl pyrazine

Isothermal vapor–liquid equilibrium (VLE) data at 353.15 K and excess molar volumes (V^E) at 298.15 K are reported for the binary systems of ethyl acetate (EA)+cyclohexane and EA+n-hexane and also for the ternary systems of EA+cyclohexane+2-methyl pyrazine (2MP) and EA+n-hexane+2MP. The experimental binary VLE data were correlated with common g^E model equations. The correlated Wilson parameters of the constituent binary systems were used to calculate the phase behavior of the ternary mixtures. The calculated ternary VLE data using Wilson parameters were compared with experimental ternary data. The experimental excess molar volumes were correlated with the Redlich–Kister equation for the binary mixtures, and Cibulka’s equation for the ternary mixtures.     

Properties of ionic liquid HMIMPF6 with carbonates,ketones and alkyl acetates

The densities and refractive indices of the pure ionic liquid (IL) HMIMPF₆ were determined at temperature range from T =(278.15 to 318.15) K for density and from T = (288.15 to 318.15) K for refractive index. The coefficient of thermal expansion of HMIMPF₆ was calculated from the experimental values of density. The densities and refractive indices of binary mixtures involving dimethyl carbonate (DMC), diethyl carbonate (DEC), acetone, 2-butanone, 2-pentanone, methylacetate, ethylacetate, and butylacetate + HMIMPF₆ (1-hexyl-3-methylimidazolium hexafluorophosphate) have been measured at T = 298.15 K and atmospheric pressure. Excess molar volumes and changes of refractive index on mixing for the binary systems were calculated. The miscibility of IL with different organic solvents and (liquid + liquid) equilibrium (LLE) data of binary mixture HMIMPF₆ + DEC have been determined experimentally.     

Cloud point measurements of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate with alcohols

Mutual solubility data of imidazolium-based ionic liquid, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([bmmim][BF₄]) with the alcohols, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, and 1-hexanol were obtained by a cloud point method. The upper critical solution temperatures of the ionic liquid and alcohol mixtures were determined from the mutual solubility data. The upper critical solution temperature of the binary mixtures gradually increased as the chain length of the alcohol increased. The mutual solubility data of binary systems ([bmmim][BF₄] + alcohols) have been correlated by the original UNIQUAC model as well as the extended and modified form of the UNIQUAC model. The temperature dependence of the mutual solubility data could be represented in terms of the temperature dependence of the binary energy parameters obtained from the correlation. Additionally the influence of water contamination on the ionic liquid mixture was shown experimentally by adding pure water into the binary mixture ([bmmim][BF₄] + 1-butanol).     

Isothermal vapor–liquid equilibria for mixtures composed of 1,2-dimethoxybenzene, 2-methoxyphenol,and diphenylmethane

Diphenylmethane was found to be a potential entrainer for separating the closely boiling mixtures of 2-methoxyphenol+1,2-dimethoxybenzene via extractive distillation. To gain insight into the capability of this auxiliary agent, isothermal vapor–liquid equilibrium data were measured for the binary and the ternary mixtures containing 2-methoxyphenol, 1,2-dimethoxybenzene, and diphenylmethane at temperatures from 433.15 to 463.15 K. All the binary data passed thermodynamic consistency tests. However, there exhibits a large discrepancy between the experimental values and the predicted results from the UNIFAC model. The new data were correlated with the Wilson, the NRTL, and the UNIQUAC models, respectively. The model parameters determined from the binary data were applied to predict the phase equilibrium behavior of the ternary system.     

Isobaric vapour–liquid equilibria for binary mixtures of n-heptane with bromobenzene,chlorobenzene and fluorobenzene at atmospheric pressure

Vapour–liquid equilibria at atmospheric pressure for binary mixtures of n-heptane + bromobenzene, +chlorobenzene and +fluorobenzene have been determined. These have been shown to be thermodynamically consistent.     

Isobaric vapour–liquid equilibria for binary mixtures of 1,2-dibromoethane with 1,2-dichloroethane,trichloromethane, and 1,1,2,2-tetrachloroethane at atmospheric pressure

Vapour–liquid equilibria at atmospheric pressure have been determined for binary mixtures of 1,2-dibromoethane + 1,2-dichloroethane, +trichloromethane, and +1,1,2,2-tetrachloroethane. These have been shown to be thermodynamically consistent.     

Enthalpy of solution of 1,4-naphthoquinone in CO2 + n-pentane in the critical region of the binary mixture: mechanism of solubility enhancement

The enthalpy of solution (Delta(solv)H(m)) and solubility of 1,4-naphthoquinone in CO(2) + n-pentane were measured at 308.15 K in the critical region of the binary fluid. In order to study the effect of phase behavior of the mixed solvent on Delta(solv)H(m), the experiments were carried out in the supercritical (SC) and subcritical region of the binary solvent. The density of the mixed solvent in different conditions was determined. The isothermal compressibility (K(T)) of the mixed solvent, and the partial molar volume (V(n-pentane)) of n-pentane in the solution were calculated. It was demonstrated that the Delta(solv)H(m) was negative in all conditions. Delta(solv)H(m) is nearly independent of pressure or density in all the solvents in a high-density region, in which compressibility of the solvent is very small; this indicates that the intermolecular interaction between the solvent and the solute is similar to that for liquid solutions. It is very interesting that Delta(solv)H(m) in the mixed SC fluid differs from the Delta(solv)H(m) in mixed subcritical fluids. The absolute value of Delta(solv)H(m) in the mixed SC fluid is close to that in pure SC CO(2) in the high-density region, and is much lower than that in pure SC CO(2) in the low-density region. In the mixed subcritical fluids, the Delta(solv)H(m) is also close to that in the pure CO(2) in the high-density region. However, at the same density, the absolute value of Delta(solv)H(m) in the binary subcritical fluid is larger than that in pure CO(2) in the high-compressible region of the mixed solvent. The main reason for this is that the degree of clustering in the SC solutions is small at the density in which the degree of clustering is large in the subcritical solutions. It can be concluded that solubility enhancement by n-pentane in the mixed SC fluid is entropy driven. In contrast, the solubility enhancement by n-pentane in subcritical fluids is enthalpy driven. The intermolecular interaction in the SC solutions and subcritical solutions can be significantly different even if their densities are the same.     

Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg

Arce, A., Blanco, A. and Tojo, J., 1986. Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg. Fluid Phase Equilibria, 26: 69–81.Vapour—liquid equilibrium data for the mixture benzene + cyclohexane + 1-propanol at a constant pressure of 760 mm Hg have been determined experimentally and predicted using the group contribution methods UNIFAC and ASOG and the NRTL, UNIQUAC and Wilson equations (with correlation parameters obtained from data for the corresponding binary mixtures). The various predictions are compared and evaluated in the light of the experimental results.     

Phase equilibria in binary mixtures of propane + acenaphthene

In the near-critical region of propane, phase equilibria of binary mixtures of propane + acenaphthene have been investigated experimentally. Apart from the three-phase equilibrium solid acenaphthene + liquid + vapour, two-phase boundaries liquid + vapour and solid acenaphthene + liquid have been investigated over the entire mole fraction range. The measurements were performed in the temperature region 350–420 K with pressures up to 10 MPa.