M. Iglesias

Mixing properties of (methanol, ethanol, or 1-propanol) with (n-pentane, n-hexane, n-heptane and n-octane) at 298.15 K

In this work, we present experimental values of the density, refractive index, speed of sound, and dynamic viscosity of the binary mixtures (methanol, ethanol or 1-propanol) with (n-pentane, n-hexane, n-heptane, and n-octane) at 298.15 K and atmospheric pressure, as a function of the molar fraction. From the experimental values, the corresponding excess and deviation values were computed (excess molar volumes, changes of refractive index on mixing, changes of isentropic compressibility and dynamic viscosity deviations), variable-degree polynomials being fitted to the results. Different methods were applied in order to estimate values of these physical properties, in good agreement with experiment. The binodal tie lines for each methanol + alkane binary mixture at different temperatures were determined by the measurement of physical properties and application of the corresponding fitting polynomials. UNIFAC-Dortmund group contribution method was applied to predict these liquid-liquid equilibria.

Refractive indices, densities and excess properties on mixing of the systems acetone + methanol + water and acetone + methanol + 1-butanol at 298.15 K

Abstract Refractive indices and densities of acetone + methanol + water, acetone + methanol + 1-butanol and of the binary mixtures acetone + water, acetone + 1-butanol, methanol + water, and methanol + 1-butanol have been determined experimentally over the entire range of composition at the temperature 298.15 K and at atmospheric pressure. Derived excess properties were determined, variable-degree polynomials being fitted to the results. Methods for predicting ternary excess properties from the values of the corresponding three binary mixtures involved are tested and compared. An estimation of excess volumes is also evaluated using a modified Heller equation (Heller, 1965) which depends on the refractive indices of the mixture. Comparison of the predictions by different methods with the experimental values of the physical properties is made.

Thermodynamic properties of the mixture benzene + cyclohexane + 2-methyl-2-butanol at the temperature 298.15 K: excess molar volumes prediction by application of cubic equations of state

Abstract Excess molar volumes, changes of refractive indices, and changes of isentropic compressibilities of the ternary mixture benzene (1)+cyclohexane (2)+2-methyl-2-butanol (3), and the corresponding binary mixtures benzene (1)+2-methyl-2-butanol (3), and cyclohexane (2)+2-methyl-2-butanol (3) have been evaluated from density, refractive index, and speed of sound measurements at 298.15 K, and atmosphere. These derived properties of binary, and ternary mixtures were fitted to Redlich–Kister, and Nagata equations, respectively, the correlation parameters being gathered. In spite of the high non-ideality observed, the excess molar volumes were satisfactorily predicted by means of cubic equations of state with simple mixing rules.

Thermodynamic behaviour of mixtures containing methyl acetate, methanol, and 1-butanol at 298.15 K: application of the ERAS model

Abstract Excess molar volumes, and changes of refractive indices, of the ternary mixture methyl acetate+methanol+1-butanol, and the binary mixtures methyl acetate+1-butanol, and methanol+1-butanol have been evaluated from density, and refractive indices measurements at 298.15 K, and 1 atm. These derived properties of binary, and ternary mixtures were fitted to Redlich–Kister, and Cibulka type equations, respectively. The ERAS model interaction parameters of the binary systems contained in the ternary mixture were computed, the obtained results showing good accuracy. The high polar/associative behaviour of the mixtures should be the cause of high deviations in ternary excess prediction. The obtained results suggest the convenience of extending the model to multicomponent polar/associative mixtures in order to take into account all binary polar effects, and higher order polar effects in the mixtures.

Derived Properties of Binary Mixtures Containing (Acetone or Methanol) + Hydroxil Compounds

Abstract This work reports values of the density, refractive index and speed of sound of the binary mixtures acetone or methanol with (2-methyl, 1-propanol, 3-methyl, 1-butanol, 1,2-ethanediol, 1,2-propanediol and 1,3-propanediol) at 298.15 K and atmosphere, as a function of the mole fraction. From the experimental values, the corresponding excess and derived magnitudes were computed (excess molar volumes, changes of refractive index on mixing and changes of isentropic compressibility on mixing), variable-degree polynomials being fitted to the results. Only expansive trend was observed for those mixtures enclosing branched alcohols. The influence of the hydroxil group in the nonideal behaviour of these mixtures were analyzed in terms of the partial molar excess volumes.

Mixing Properties of the Binary Mixtures of Acetone, Methanol, Ethanol, and 2-Butanone at 298.15 K

Abstract Speeds of sound, densities and refractive indices of the binary mixtures containing acetone, methanol, ethanol, or 2-butanone have been measured at 298.15 K and atmospheric pressure, in the whole composition diagram, the derived excess values being determined. Parameters of analytical expressions which represent the composition dependences of excess and variation of properties are reported. Values of physical properties were compared with the results obtained by different prediction methods. The excess volumes were estimated using different applications of the Heller equation, which are depending on the refractive indices of the mixtures. A good agreement between the experimental and theoretical values both in magnitude and sign were obtained by these methods.

Temperature influence on refractive indices and isentropic compressibilities of alcohol (C2–C4)+olive oil mixtures

This paper presents isentropic compressibilities and refractive indices on mixing of mixtures enclosing short aliphatic alkanols (ethanol, 1-propanol, 2-propanol and 1-butanol) with olive oil that have been measured in the temperature range from 283.15 to 298.15 K and atmospheric pressure. The values of these properties were calculated in all range of homogeneous composition, phase splitting appearing in the mixtures (ethanol or 2-propanol) with olive oil. From the mentioned properties, derived properties such as compressibility solvation numbers, isentropic apparent molar compressibility and changes of magnitudes were calculated. The enhanced packing efficiency of alcohols at low molar fractions is strongly affected by steric hindrance of aliphatic residues, although dimers or rings of alcohol molecules are formed at high concentrations when residue end of alkanol is small. Different mixing rules for refractive indices on mixing were applied, as well as the collision factor theory (CFT) formulation for isentropic compressibilities. The thermal pressure coefficients of these solvents were analysed as a function of the temperature, their shape and trend being commented upon.

Influence of temperature on ultrasonic velocity measurements of ethanol + water + ethyl acetate mixtures

The ultrasonic velocity of the ternary mixtures ethanol + water + ethyl acetate at the range 288.15–323.15 K and atmospheric pressure, has been measured over the whole concentration range. The corresponding change of isentropic compressibility was computed from the experimental data. The results were fitted by means of a temperature-dependent equation, the parameters of which have been gathered in this experiment. The experimental ultrasonic velocities have been analyzed in terms of different theoretical models, an adequate agreement between the experimental and predicted values both in magnitude and sign being obtained, despite the high non-ideal trend of the studied mixture. The obtained experimental values indicate varying extent of interstitial accommodation among unlike molecules as a function of steric hindrance attending to ethyl acetate composition as key component and as a function of hydrogen bond and temperature attending to ethanol composition as key component.

Thermodynamics of binary mixtures of aliphatic linear alkanes (C6–C12) at 298.15 K

This article reports experimental values of speeds of sound, densities and refractive indices on mixing of the binary mixtures n-hexane + (n-heptane, n-octane, n-nonane, n-decane, n-undecane, or n-dodecane) at 298.15 K and atmospheric pressure, over the whole concentration range. The corresponding excess and derived properties were computed from the experimental data. The results were fitted by means of the Redlich–Kister equation, such parameters being gathered. Different estimation methods (equations of state, mixing rules, Collision Factor and Free Length Theory) were applied, qualitative agreement between the experimental and theoretical values both in magnitude and sign being obtained.

Liquid phase behaviour and thermodynamics of acetone+methanol+n-alkane (C9–C12) mixtures

Abstract This paper reports the results of a new experimental study of two-liquid phases equilibria as a function of temperature and one-liquid phase thermodynamic magnitudes (densities, refractive indices and speeds of sound), covering the composition diagrams for the mixtures acetone+methanol+n-alkane (C9–C12). The obtained coexistence curves were very asymmetrical with respect to equimolar alcohol+n-alkane composition, such effect increasing with the length of the aliphatic chain and temperature. A comparative analysis was performed by application of different methods to predict experimental liquid–liquid equilibria (LLE) behaviour and thermodynamics of these ternary mixtures. The obtained experimental results let us know the potential role of the linear aliphatic alkanes as separation agents for heterogeneous modified distillation of the azeotrope acetone+methanol.