DIFFUSION OF POLAR AND NONPOLAR MOLECULES IN WATER AND ETHANOL

Interdiffusion coefficients of 1,2-butanediol, 1,4-butanediol, meso-erythritol, xylitol, mannitol, and myo-inositol in water, and of 1-butanol, 1,2-ethanediol, 1,2-butanediol, 1,4-butanediol, 1,2,3-propanetriol, water, and benzene in ethanol have been measured at concentrations close to infinite dilution and temperatures between 278 and 373 K. In water, activation energies are not sensitive to the solutes, decrease with increasing temperature, and are close to that for the self-diffusion of pure water. In ethanol the activation energy is largest for water and smallest for benzene. The quantity Dη/T (D, η, and T are diffusivity, viscosity, and absolute temperature, respectively) is not sensitive to temperature in water, but shows strong dependence on the temperature for benzene and water in ethanol. Using the corrected Stokes-Einstein equation, the effective radii of the solutes were obtained in ethanol. Some differences in diffusion behavior in ethanol and water are discussed.