Miguel A. Villamañán

Calorimetric investigation of the interactions between oxygen and hydroxyl groups in (alcohol+ether) at 298.15 K☆☆☆

Abstract Flow-calorimetric measurements of excess enthalpies at 298.15 K are reported for 17 mixtures of (an alcohol + an ether). The alcohol is methanol, ethanol, propan-1-ol, or heptan-1-ol; the ether is butyl ether, methyl butyl ether, diethylether, 3,6-dioxaoctane, or 2,5,8-trioxanonane. The results indicate that interactions between alcohol and ether which are a consequence of the interactions between the hydroxyl and the oxygen groups increase almost linearly with the surface fraction of oxygen in the ether molecule. These interactions are more important in the case of short-chain alcohols.

Excess thermodynamic functions for ternary systems containing fuel oxygenates and substitution hydrocarbons. 1. Total-pressure data and GE for methyl tert-butyl etherbenzenecyclohexane at 313.15 K

Abstract Experimental isothermal P–x–y data for the ternary system (methyl tert-butyl ether (MTBE)+n-heptane+1-hexene) and for its corresponding binaries at 313.15 K are reported. Data reduction by Barkers method provides correlations for GE using the Margules equation for the binary systems, the Wohl expansion for the ternary system and Wilson, NRTL and UNIQUAC models for both binary and the ternary mixtures.

Thermochemical behaviour of mixtures of n-alcohol + aliphatic ether: heat capacities and volumes at 298.15 K

Abstract Molar excess volumes VE at 298.15 K were obtained as a function of mole fraction for each of the binary mixtures formed from methyl n-butylether, 3,6-dioxaoctane, and 2,5,8-trioxanonane + methanol, and + ethanol, and also for 2,5,8-trioxanonane+1-propanol. In addition, a Picker flow calorimeter was used to determine molar excess heat capacities CPE at 298.15 K for the same mixtures. All the excess heat capacities are positive and the excess volumes are negative. Values of VE of mixtures with a given ether become less negative with increasing chain length of the alcohol.

Excess enthalpies of (n-alkanol + 2,5-dioxahexane) at 298.15 K

Abstract The excess molar enthalpy H m E has been determined as a function of mole fraction x at atmospheric pressure and 298.15 K for 9 binary liquid mixtures of an ( n -alkanol + 2,5-dioxahexane). The n -alkanols were methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, heptan-1-ol, octan-1-ol, and nonan-1-ol. All the mixtures show positive excess molar enthalpies which increase with increasing chain length n of the alkanol.

Phase equilibrium properties of binary and ternary systems containing tert-amylmethyl ether (TAME) as oxygenate additive and gasoline substitution hydrocarbons at 313.15 K

Abstract Experimental isothermal P – x – y data for the binary systems ( tert -amylmethyl ether (TAME)+the hydrocarbons n -heptane, cyclohexane, benzene and 1-hexene) and the ternary system ( tert -amylmethyl ether (TAME)+1-hexene+cyclohexane) at 313.15 K are reported. Data reduction by Barkers method provides correlations for G E using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems presented here and they have been used for predicting the behaviour of the other ternary systems involving TAME+hydrocarbon+hydrocarbon, where the four types of substitution hydrocarbons have been used.

Isothermal vapor-liquid equilibria of binary mixtures containing methyl tert-butyl ether (MTBE) and / or substitution hydrocarbons

Abstract Isothermal P-x-y data are reported for the binary systems methyl tert-butyl ether (MTBE) + 1-hexene, n-hexane + 1-hexene, benzene + n-heptane at 313.15 K, and the latter also at 298.15 K. Data reduction by Barkers method provides correlations for GE using the Margules equation.

Experimental investigation of the vapor–liquid equilibrium at 313.15 K of the ternary system tert-amylmethyl ether (TAME)+n-heptane+methanol

Abstract Experimental isothermal P–x data at 313.15 K for the ternary system (tert-amylmethyl ether (TAME)+n-heptane+methanol) and for one of the unmeasured constituent binary systems, (tert-amylmethyl ether (TAME)+methanol) are reported. Data reduction by Barkers method provides correlations for gE using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems. The presence of azeotropes in the ternary system and constituent binaries are studied as well as the presence of immiscible zones.

Thermodynamics of 1-alkanol + N-ether mixtures

Abstract Recent vapor-liquid equilibrium data for four 1-alkanol+n-polyether mixtures are examined on the basis of DISQUAC model -an extension of the surface-interaction version of the quasichemical group contribution theory, to correlate and predict excess enthalpies and excess Gibbs energies for such mixtures at 298.15 K. Using the new data, revised interaction parameters are proposed, which provide a fairly consistent description of the properties of the mixtures as functions of composition.

Role of alcohol in microemulsions. III. Volumes and heat capacities in the continuous phase water-n-butanol-toluene of reverse micelles

Abstract Roux-Desgranges, G., Grolier, J-P.E., Villamanan, M.A. and Casanova, C., 1986. Role of alcohol in microemulsions. III. Volumes and heat capacities in the continuous phase water- n -butanol-toluene of reverse micelles. Fluid Phase Equilibria , 25: 209-230. Densities and volumetric heat capacities of the ternary system water (1) + n -butanol (2)+toluene (3) were determined in the homogeneous single phase region of the diagram. From these quantities the apparent molar volumes V φ i and heat capacities C φ i of species i are calculated. An analysis of the variation of these apparent molar quantities as a function of concentration is carried out taking either water, n -butanol or toluene as a molecular probe of the structural behavior of the medium. In particular, apparent molar properties of n -butanol, V φ2 and C φ2 , in the binary n -butanol + toluene and even more the apparent molar properties of water at infinite dilution, V θ φ1 and C θ φ1 , in the ternary water + n -butanol + toluene show sharp changes in the toluene rich domain of the diagram. These changes are due to the self-association of n -butanol in the binary; the self-association being most likely enhanced by water in the ternary. This kind of behavior confirms the ‘detergentless microemulsion’ nature of such ternary systems where alcohol acts as both a surfactant and a cosurfactant. Communicated in part at the 3rd International Conference on Thermodynamics of Solutions of Non Electrolytes - Universite de Clermont-Ferrand 2, Abuiere, France, 2–6 July 1984, the proceedings of which were published in Volume 20 of this journal.

Progress towards an acoustic determination of the Boltzmann constant at CEM-UVa

An acoustic gas thermometer was used to achieve a determination of the Boltzmann constant, kB, using a misaligned stainless steel (316L) spherical cavity with an internal volume of approximately 268 cm3. Measurements of the speed of sound while the cavity is filled with argon at the temperature of the triple point of water, 273.16 K, and at different pressures between 78.2 kPa and 0.9 MPa, were used to extrapolate the value of the speed of sound in argon at zero pressure. The internal volume of the resonator was accurately determined by measuring microwave resonance frequencies at the same temperature and pressure conditions as for the acoustic measurements. The measurements were taken at pressures from 78.2 kPa up to 901.3 kPa, and at 273.16 K. As the results of the measurements, we determined kB = (1.380 644 1   ±   0.000 022 1)  ×  10−23 J K−1 which means a relative standard uncertainty of 16 parts in 106.