Fick Diffusion Coefficients in Binary Liquid Mixtures Containing Alkanes, Aromatics, Alcohols, or Acetone by Using Dynamic Light Scattering

This work reports Fick diffusion coefficients D11 and thermal diffusivities a in binary
liquid mixtures containing cyclohexane, n-decane, n-heptane, toluene, isobutylbenzene, 1-methylnaphthalene,
methanol, ethanol, or acetone. The mixtures are investigated by dynamic
light scattering at temperatures T = 298, 348, and
423 K close to saturation conditions. Besides equimolar composition,
toluene-based binary mixtures with methanol, ethanol, or cyclohexane
are investigated at toluene mole fractions between 0.1 and 0.9. The
average relative expanded experimental uncertainties (k = 2) for D11 and a are
5.3 and 8.3%. For the studied systems, the influence of molecular
characteristics on the diffusivities as a function of T and composition is discussed. While D11 clearly depends on the molecular structure of the mixture components,
i.e., alkane chain length, aliphatic or aromatic rings, or hydroxyl
and carbonyl functional groups, such relationships were not resolvable
for a within the experimental uncertainties. For
mixtures containing the polar species methanol, ethanol, or acetone,
an influence of hydrogen bonding on D11 was found. In general, the identified structure–property
relationships agree with those reported in the literature for similar
systems. Furthermore, a comparison of the present D11 and a data with corresponding literature
data is performed.