PFG-NMR and MD Simulation Study of Self-Diffusion Coefficients of Binary and Ternary Mixtures Containing Cyclohexane, Ethanol, Acetone, and Toluene

Abstract

Recently, Guevara-Carrion et al. published a comprehensive molecular dynamics (MD) study on the thermodynamic properties of binary mixtures containing methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride which also includes results on self-diusion coecients. However, for the mixtures acetone/cyclohexane, acetone/ethanol, acetone/toluene, cyclohexane/ethanol, and toluene/ethanol, no experimental data on self-diusion coecients were available for comparison. Therefore, in the present work, self-diusion coecients in these mixtures were measured by 1 H NMR spectroscopy using pulsed eld gradients (PFGs) at 298.15 K and ambient pressure. The experimental data were compared to the simulations of Guevara-Carrion et al. Good agreement was observed for all mixtures that do not contain ethanol, whereas, for ethanol-containing mixtures, the deviations were larger. This nding is attributed to deciencies of the molecular model in describing the hydrogen-bonding of ethanol. Furthermore, self-diusion data for the ternary mixture acetone/toluene/cyclohexane were 1 measured and compared to molecular simulation data from the present work. Good agreement was observed.

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 the systems with CO 2 , good predictions are achieved for water, toluene, and acetone, but not for the two alcohols methanol and ethanol, or for cyclohexane. Poor predictions of diffusion coefficients in systems with alcohols in molecular simulations with the models that were used here (as well as with similar models) have been observed before [4,83,84,70].…”

“…This equation was modified to compensate for gradient non-linearity as well as the application of bipolar gradient pulses, resulting in Eq. ( 2); details are reported elsewhere [4].…”

“…In contrast, nuclear magnetic resonance spectroscopy using pulsed field gradients (PFG-NMR) yields information on the self-diffusion coefficient from equilibrium measurements, which greatly facilitates the study. With the PFG-NMR method, diffusion coefficients can be measured with high accuracy [4]. While the method is well established in chemistry and physics, it is still not widely adopted in engineering.…”

Mass transfer through vapour–liquid interfaces: a molecular dynamics simulation study

“…[90] using the Green-Kubo formalism as in previous work of our group [91][92][93][94][95]. Simulation details are reported in the Supplementary Material.…”

Accurate measurements of self‐diffusion coefficients with benchtop NMR using a QM model‐based approach

“…Therein, is a correction constant that accounts for the use of bipolar gradients. The probe specific calibration factors and were adopted from Bellaire et al [ 3 ] and account for the non‐linearity of the gradient. A graphical view of the pulse sequence can be found in the supporting information.…”