Most engineers do not realise, that multicomponent mixtures have properties quite different from those of binary mixtures. For example, that it is possible for diffusion in a multicomponent mixture to run against a concentration gradient. Many mass transfer processes are driven by forces other than those due to concentration gradients. In electrolysis and electrodialysis, transfer is due to gradients of the electrical field. The centrifugal field dominates gas separations by ultracentrifugation.
Pressure gradients are important in many membrane processes and in heterogeneous catalysis.
It is not possible to include these driving forces in a proper way in the traditional description of mass transfer. In this course, you will learn a method which is applicable to all mass transfer processes. The species are taken to move with respect to each other due to their potential gradients. Their rate of movement is restricted by friction between the species. The method links thermodynamics and transport phenomena in a way which is easily understood by engineers.