Mutual diffusion coefficients of ethanol + isooctane and n-butanol + isooctane mixtures and tests of a new local-composition prediction model for diffusion in binary liquids

The mutual diffusion coefficients of ethanol + isooctane and n-butanol + isooctane mixtures were measured by digital holographic interferometry. The measurements were performed at atmospheric pressure with temperatures ranging from 288.15 K to 318.15 K and mass fractions ranging from 0.05 to 0.95, and the effects of changes in temperature and composition were discussed. Based on the local composition theory, a new model is proposed for predicting mutual diffusion coefficients. Modified from the Vignes model, this model can be used to predict the mutual diffusion coefficient in ideal or non-ideal mixtures within a given deviation range. A comparison of the prediction results for the new model and five other models shows that the new model is far superior to the Darken model and Vignes model, and also has some advantages over the other models.