Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

Abstract

This work contributes to the characterization of three binary liquid hydrocarbon-based mixtures via the determination of density, viscosity, and interfacial tension over the entire concentration range up to temperatures of 573.15 K. The oscillating-tube method, surface light scattering (SLS), and equilibrium molecular dynamics (EMD) simulations are applied to analyze the influences of chain length, branching, and hydroxylation on the aforementioned thermophysical properties. For probing these effects, the three binary systems of n-hexadecane (1) with n-octacosane (2), 1-hexadecanol (2), or 2,2,4,4,6,8,8-heptamethylnonane (2), each with mole fraction of x 1 = 0.25, 0.5, or 0.75, are investigated in macroscopic thermodynamic equilibrium at or close to saturation conditions at temperatures between 298.15 and 573.15 K. Based on the experimental results for the liquid densities, liquid viscosities, and interfacial tensions with average expanded uncertainties (k = 2) of 0.10, 2.0, and 1.8%, respectively, our previously published modification to the optimized potentials for the liquid simulations (OPLS) force field for long hydrocarbons (L-OPLS) is evaluated for its transferability to liquid mixtures in EMD simulations. Considering all simulation results, the average absolute relative deviations for the density, viscosity, and interfacial tension are 0.74, 27, and 14%, respectively. Experimental results are also applied for the evaluation of simple prediction models based on pure-component properties. Especially at high temperatures, such simple mixing rules perform well. At lower temperatures, however, nonidealities like surface enrichment or the formation of molecule clusters in the mixture are more likely to dominate fluid behavior, leading to a failure of the simple mixing rules. To explain this observation, partial-density profiles and radial distribution functions from simulations, giving access to the fluid structure on a microscopic level, are evaluated.

Development and Thermophysical Profile of Cetyl Alcohol-in-Water Nanoemulsions for Thermal Management

“…Figure 7b compares the α p values of water and the buffer solution with those of four representative C 16 OH/W and C 16 OH + C 20 OH/W emulsions. As can be observed, the isobaric thermal expansivity increases with the content of dispersed fatty alcohol, which agrees with the fact that cetyl alcohol has a higher expansivity (α p = 7-8•10 −4 K −1 at 343 K [81,91]) than water.…”

Thermophysical properties of $n$-hexadecane: Combined Molecular Dynamics and experimental investigations

“…MD techniques have been used to investigate the hexadecane in several works. It has already been shown that the temperature behavior of viscosity, density, and interfacial tension estimated with MD [29] for hexadecane correlates well with recent data [18,24]. Nonetheless, improving the efficiency of PCMs-based heat capacitors necessitates knowledge of the systems' thermal physical features.…”

Mutual and Thermal Diffusivities in Mixtures of Cyclohexane, n-Hexadecane, n-Octacosane, or n-Hexanoic Acid with Carbon Dioxide Obtained by Dynamic Light Scattering and Molecular Dynamics Simulations

“…On average, the deviations between EMD and DLS are 17% at x co 2 < 0.5 and 9.8% at larger x CO2 , not including D 11,EMD at x CO2 = 0.71 and T = 303 K. Further details are provided in the Supporting Information. For T = 303 K and x CO2 < 0.35, the calculation of D 11,EMD was not possible due to solidification of the mixture in the simulation box. , …”