Prediction of viscosities of liquid mixtures by a group contribution method

Abstract A group contribution method for mixture viscosity predictions, requiring only pure component viscosities, is presented. It is based on the Eyring viscosity model for pure components. For mixtures, the free energy of activation for the rate process is considered to be equal to the molar average of the free energies of activation of the pure components, plus an excess free energy of activation. The latter is taken to be related to the excess Gibbs free energy of mixing. Using the UNIFAC model for excess Gibbs free energy of mixing and the group interaction parameters from regression of experimental viscosity data, predictions with good accuracy were obtained. Interaction parameters were obtained from regression using viscosity data of more than 80 binary systems, containing water, hydrocarbons, esters, alcohols, ketones, aromatics and chlorinated hydrocarbons.