Diffusivities in 1-Alcohols Containing Dissolved H₂, He, N₂, CO, or CO₂ Close to Infinite Dilution

Abstract

The influence of the strength of intermolecular interactions on mass diffusive processes remains poorly understood for mixtures of associative liquids with dissolved gases. For contributing to a fundamental understanding of the interplay between liquid structures and mass diffusivities in such systems, dynamic light scattering, Raman spectroscopy, and molecular dynamics simulations were used in this work. As model systems, binary mixtures consisting of the gases hydrogen, helium, nitrogen, carbon monoxide, or carbon dioxide dissolved in ethanol, 1-hexanol, or 1-decanol were selected. Experiments and simulations were performed at macroscopic thermodynamic equilibrium close to infinite dilution of solute for temperatures between 303 and 423 K. The Fick diffusion coefficients and self-diffusivities of the gas solutes increase with increasing temperature, decreasing alkyl chain length of the 1-alcohols, and decreasing molar mass of the solutes except for helium and hydrogen showing the opposite behavior. The analysis of the liquid structure of the mixtures showed that the fraction of hydrogen-bonded alcohol molecules decreases with increasing alkyl chain length and temperature. From the obtained structure–property relationships, a new correlation was developed to predict mass diffusivities in binary mixtures consisting of n-alkanes or 1-alcohols with dissolved gases close to infinite dilution within 10% on average.

Effective Thermal Conductivity of Nanofluids: Measurement and Prediction

“…For the characterization of particle size and its distribution as well as the dispersion stability of the nanofluids in the same fluid state as it is investigated in connection with the effective thermal conductivity, the diffusion coefficients were obtained by dynamic light scattering (DLS). For details on the principles of the technique [52] and its application for the determination of several thermophysical properties of various types of fluids [53][54][55][56] and dispersed systems [57][58][59], the reader is referred to the respective literature. In the following, only the information relevant for the present investigations is given.…”

Diffusion coefficients at infinite dilution of carbon dioxide and methane in water, ethanol, cyclohexane, toluene, methanol, and acetone: A PFG-NMR and MD simulation study

“…For (CO 2 + water), abundant data for the diffusion coefficient at infinite dilution are available [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34]. Fewer data are available for CO 2 in ethanol [35,10,11,36,37,29,38], cyclohexane [39], toluene [10,40,41], methanol [35,10,11,19,31,42], and acetone [10]. For CH 4 , diffusion coefficients have been investigated before in water [8,43,9,44,…”

“…The methods that were used in the literature for studying the diffusion coefficient can be categorized as follows: diaphragm cells [8], wetted surface absorbers [13,17], laminar jets [20], capillary cells [29], Taylor dispersion [50,51], and dynamic light scattering (DLS) [38]. In a diaphragm cell, two solutions of different composition are brought into contact by a diaphragm.…”

Three-dimensional convective dissolution of carbon dioxide into brine

“…Fick diffusion coefficient, solute self-diffusivity, and solute tracer diffusion coefficient are equal in the infinite dilution regime 40 . For that reason, diffusivity data collected from the literature are at different pressures along the vapor-liquid equilibrium.…”

“…For the present systems, the occurrence of convection is insensitive to the pressure dependence of D and η 39 . This is because the concentration of CO 2 dissolved in brine or pure water remains small enough over the complete pressure range 33 such that D and η can be assumed constant 40,41 . Above a threshold critical value Ra * s , the system undergoes a symmetry-breaking mechanism leading to the appearance of a convective instability characterized by the formation of density patterns (Fig.…”