Strategy of Development on Zeolite Membrane for Forward Osmosis Operation; Effects of Structural Parameter of Support Layer and Si/Al Ratio of ZSM-5 Layer on Water Flux

The strategy of development on zeolite membrane for forward osmosis was investigated. Defect-less MFI membranes with almost the same thickness were successfully prepared on five kinds of α-Al2O3 tubular supports having different structural parameters. The water flux through these membranes could be expressed as a function of the structural parameter of support. Moreover, the effect of the Si/Al ratio in zeolite layer, which serves as an index of hydrophilicity, was examined. As a result, a membrane with a relatively hydrophilic character, having Si/Al ratio = 18.6, showed a higher water flux. Conversely, both water and salt hardly penetrated through a hydrophobic membrane (Si/Al = ∞). Reducing the structural parameter in the support layer and improving the hydrophilicity of the active layer is crucial to achieving high water-permeability of zeolite FO membrane.