A Modified Solution-Diffusion Model and Its Application in the Pervaporation Separation of Alkane/Thiophenes Mixtures with PDMS Membrane

A better understanding of the mass transfer in pervaporation membranes under different conditions is essential for both the design of improved membranes in various applications, and for the process design. In this article, a modified solution-diffusion model is proposed to account for the mass transport of penetrants in the polymer membrane. In the model, the group contribution method (the UNIFAC-ZM model) is first introduced to calculate the activity of penetrants in the polymer membrane, and a modified Fujita diffusion coefficient equation is developed to describe the diffusion behavior of the penetrants. The aim of this work is to establish a predictive solution-diffusion model. By refitting the group interaction parameters based on pervaperation data of penetrants-membrane systems, the model can be applied to predict the flux and separation factor of various polymer membrane systems. As an exemplary application of the model, the permeation fluxes and separation factors of alkane/thiophene and alkane/2-methyl-thiophene mixtures in polydimethylsiloxane (PDMS) membrane system have been predicted and showed to be in good agreement with experimental values. (c) 2008 Wiley Periodicals, Inc.