Tracer diffusion of aromatic hydrocarbons in liquid cyclohexane up to its critical temperature

Tracer diffusion coefficients in liquid cyclohexane of benzene, toluene, p‐xylene, mesitylene, naphthalene, and phenanthrene have been determined from 298.2 to 523.2 K (TR = 0.54 ∼ 0.95) using the Taylor dispersion method. Positive deviations from the Arrhenius relationship are observed as the critical temperature is approached, but a rough‐hard‐sphere theory is found to be adequate for describing the data across the entire temperature range. On the basis of the computer simulation results for hard‐sphere fluids, correlations involving solute and solvent critical volumes and their molecular weights have also been developed for practical applications. Tracer diffusivities in supercritical carbon dioxide are also adequately represented by the proposed correlation, as the fluid density is not far removed from that of liquid carbon dioxide.