DIFFUSION FLUX EQUATION WITHIN MEMBRANE COMBINED TO MODIFIED UNIFAC MODEL AND PERCOLATION-FRACTAL THEORY

摘要

The models describing transfer behavior of permeating molecules in dense membrane generally included sorption models, diffusion models and trans-membrane mass transfer models. It is more applied for UNIFAC model, free-volume theory and Maxwell-Stephan theory. Transfer behavior of small permeating molecules can be expounded in definite extent and degree by these models and theories, which can not be applied for anomalous diffusion phenomena within membrane. This anomalous diffusion phenomenon was expounded by many researchers in which Tiangang Shang et al. put forward percolation-fractal model that has definite meaning. Based on percolation-fractal model, introducing UNIFAC activity coefficient models, combined to Maxwell-Stephan theory and considering conception of charge density, diffusion flux calculating equation was achieved of small molecules in dense membrane in this article.