Effect of mass transport resistances in multicomponent membrane extractionon the overall mass fluxes

An effect is studied of all the individual mass transport mechanisms on the overall mass fluxes during membrane extraction, i.e. for the process that is both energy efficient and easy to operate. In multicomponent systems eac h of the constituent mechanisms is defined by an appropriate matrix of mass transfer coefficients. The method developed to assess the relative importa nce of the individual transport mechanisms is validated using multicomponen t extraction, studied experimentally by Kubaczka, Burghardt and Mokrosz (19 98, Membrane-based solvent extraction in multicomponent systems. Chemical E ngineering Science, 53, 899-917), as a test case. If resistances to mass tr ansfer, identified by the method as insignificant, are omitted from the sim ulations, the agreement between numerical predictions and experiment is not impaired. It is also demonstrated that the accuracy of calculating mass fl uxes in membrane extractors became worse when the variation of diffusivitie s with concentration along the diffusion path is neglected, and also, when the effect of the membrane on interrelationships between the mass fluxes (r eferred to the stationary system of coordinates) is not taken into account. (C) 2000 Elsevier Science Ltd. All rights reserved.