On the Effective Permeability of Mixed Matrix Membranes

Mixed matrix membranes (MMMs) are attracting significant interest for pervaporation and gas separation applications. To better comprehend the impact of filler particles within polymer matrices, the species permeation mass transport was theoretically studied by numerical simulation using finite differences. The Fick’s second law of diffusion was solved for a three-dimensional MMM to obtain the concentration profile within the membrane and consequently the steady-state permeation flux of the species. The effective permeability of MMMs was then calculated using the steady-state permeation flux of the permeants. The effects of various structural parameters such as the filler volume fraction, particle size, shape and orientation, the ratio of permeability coefficients in the dispersed and continuous phases (Pd/Pc), membrane thickness and particle sorption isotherms were investigated. Results revealed that the effective permeability of MMMs strongly depends on the permeability ratio of the dispersed phase to the continuous phase and the volume fraction of the filler material. Moreover, the shape and size of the particles had no influence on the effective permeability of MMMs for filler volume fractions that are less than 0.4. For numerical simulations performed with different particle sorption isotherms, results showed that the effective permeability of the membrane depends on the type and parameters of the isotherm as well as the feed concentration.