PREDICTION OF THE CONCENTRATION-DEPENDENCE OF MUTUAL DIFFUSION-COEFFICIENTS IN BINARY-LIQUID MIXTURES

Based on the absolute-rate theory and the two-liquid solution theory, a new equation is proposed to predict the dependence of the binary mut ual diffusivities on concentration. The equation, in terms of the diff usion coefficient at infinite dilution, the correction factor for ther modynamic nonideality, and the acentric factor, predicts the behavior of the diffusion coefficient generally well. Further, another new equa tion, in which only the diffusion coefficient at infinite dilution and some basic properties (acentric factor, critical pressure, molecular weight, and dipole moment) are needed, is proposed and tested to predi ct the mutual liquid diffusion coefficients for 38 different binary sy stems. The results of prediction shows that this new equation is more successful than either Vignes' equation or Asfour-Dullien's equation i n predicting the concentration dependence of the diffusion coefficient s as a whole, though it-does not require a correction factor for therm odynamic nonideality or viscosity data.