Volumes of mixing and theP * effect: Part II. Mixtures of alkanes with liquids of different internal pressures

Novel Binary Mixtures of Alkanolamine Based Deep Eutectic Solvents with Water—Thermodynamic Calculation and Correlation of Crucial Physicochemical Properties

This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 ‒ 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperature-dependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components.

Excess compressibility in binary liquid mixtures

Brillouin scattering experiments have been carried out on some mixtures of molecular liquids. From the measurement of the hypersonic velocities we have evaluated the adiabatic compressibility as a function of the volume fraction. We show how the quadratic form of the excess compressibility dependence on the solute volume fraction can be derived by simple statistical effects and does not imply any interaction among the components of the system other than excluded volume effects. This idea is supported by the comparison of the experimental results with a well-established prototype model, consisting of a binary mixture of hard spheres with a nonadditive interaction potential. This naive model turns out to be able to produce a very wide spectrum of structural and thermodynamic features depending on values of its parameters. An attempt has made to understand what kind of structural information can be gained through the analysis of the volume fraction dependence of the compressibility.

Excess density in oilfield water—crude oil dispersions

Extensive density measurements were performed with mixtures of 12 degassed (dead) crude oils with respective oilfield brines (formation waters). All unprocessed samples were collected directly from wellheads and contained only indigenous surfactants, such as asphaltenes and fine solids. Nonzero excess densities and excess thermal expansions (evaluated on the assumption of quasi-binary water-oil mixtures) were observed for water cuts in the range from X=0.4 to 0.6 at all studied temperatures T=5-50 degrees C. We suggest that these results are due to the formation of a dense asphaltene-mediated "middle phase" in the studied w/o dispersions. This suggestion is substantiated by plotting T-X phase diagrams which topologically strongly resemble those conventionally observed in some standard Winsor III-type systems. The formation of a complexly structured "middle phase" has been directly verified by preliminary visual/microscopic studies of a phase separation in a crude oil-water mixture.

Excess molar volumes and viscosities of binary mixtures of triethylene glycol dimethyl ether (triglyme) with chloroalkanes at 298.15 K

Excess molar volumes (VEm) and viscosities (η) for mixtures of triethylene glycol dimethyl ether + dichloromethane, + trichloromethane, and + tetrachloromethane have been determined at 298.15 K and atmospheric pressure over the whole concentration range. From the experimental results, deviations in viscosities (Δ ln η) have been calculated. These properties were fitted to the polynomial relations to obtain the coefficients and the standard deviations. The results have been analysed in terms of molecular interactions between components.Key words: experiments, data, excess volume, viscosity deviation, binary mixtures.

Dependence upon temperature of the excess molar volumes of tetrahydropyran + n-alkane mixtures

Excess molar volumes VE, at 288.15 and 308.15 K and normal atmospheric pressure, are reported for the binary mixtures tetrahydropyran + n-alkanes (C7–C9). From the results, the differential coefficient (∂VE/∂T)p was estimated over the entire range of mole fractions. The Prigogine–Flory–Patterson theory and its applicability in predicting VE is tested. Keywords: Excess molar volumes, digital densimeter, tetrahydropyran, n-heptane, n-octane, n-nonane, Prigogine–Flory–Patterson theory.