ON THE COUPLING EFFECT IN PERVAPORATION

Coupled transport often takes place in pervaporation of multicomponent mixtures due to strong interaction between membrane and penetrants. In this paper, the ideal separation factor alpha(i/j)I, deviation coefficient epsilon, and molar normalized permeation rate J(n) are introduced to describe the coupling effect. epsilon > 1 indicates enhanced transport and conversely epsilon < 1 indicates inhibited transport. The sorption of penetrant components in membranes and the orientation of the dissolved penetrant molecules change the configuration of the microvoids between the polymer chains and cause the facilitation or inhibition of transport of the other component through the membrane. Experimental data from literature and our work are expressed as alpha(i/j)I, epsilon and/or j(n) to analyze binary mixture pervaporation, showing that the new concepts are in agreement with actual permeation.