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John L. Falconer and Richard D. Noble
Transient Isotope Pervaporation

We developed a new method to characterize the transport properties of zeolite membranes using isotope labeling and transient permeation. This method has been applied to pervaporation, where the feed is a liquid and the permeate under vacuum. The contributions of adsorption and diffusion to separations can be distinguished by directly measuring the times for molecules to diffuse through a zeolite layer. This method is effective for comparing different molecules that might have the same flux but different coverages and diffusivities. It is also useful for comparing membranes of different thicknesses. We have shown directly for some binary mixtures that a slower diffusing molecule slows down a faster diffusing molecule, and a faster diffusing molecule speeds up a slower one. For some mixtures both molecules diffuse slower than either of the pure molecules. These measurement allow us to understand competitive adsorption in mixtures and why mixtures selectivities are different from ideal selectivities.

Sample Publications

M. Yu, J. Wyss, R.D. Noble, J.L. Falconer, “Transient Isotope Permeation of

     Acetone Mixtures through MFI Zeolite Membranes” (2008).

Bowen, T.C., Wyss, J.C., Noble, R.D., and Falconer, J.L, “Measurements of

     Diffusion through a Zeolite Membrane using Isotopic-Transient

     Pervaporation”, Microporous Mesoporous Materials 71, 199-210 (2004)

Bowen, T.C., Wyss, J.C., Noble, R.D., and Falconer, J.L., "Inhibition during

     Multicomponent Diffusion through ZSM-5 Zeolite", Ind. Eng. Chem.

     Research 43, 2598-2601 (2004)

Bowen, T.C., Wyss, J.C., Noble, R.D., and Falconer, J.L, "Measurements of Diffusion through a Zeolite Membrane using Isotopic-Transient Pervaporation", Microporous Mesoporous Materials 71, 199-210 (2004)

Tanaka, K., H. Kita, K.-I. Okamoto, R.D. Noble, and J.L. Falconer, "Isotopic-Transient Permeation Measurements in Steady-State Pervaporation through Polymeric Membranes", J. Membrane Science 197, 173-183 (2002).