Preparation of hydrophilic silicalite-1 nanocrystal-layered membrane for separation of water from water–acetone solution by pervaporation

Hydrophilic silicalite-1 nanocrystal-layered membrane was successfully prepared on an alumina ceramic filter. The silicalite-1 nanocrystals were layered on the outer surface of cylindrical alumina ceramic filters, followed by a hydrothermal synthesis to form a silicalite-1 layer (protection layer) on the nanocrystal layer. In order to achieve high hydrophilic properties of the membrane with the remaining silanol group, the liquid phase oxidation technique was applied to remove the template. From the SEM observation, the nanocrystal layer and the protection layer were clearly observed, and the silicalite-1 protection layer was uniformly formed on the nanocrystal-layer. Pervaporation experiments to separate water from water–acetone solution (acetone: 90 wt%) were conducted using the silicalite-1 nanocrystal-layered membrane. The membrane exhibited the selective permeation as well as the high flux of water. In the nanocrystal-layered membrane, water–silanol networks were formed on the non-zeolitic pores surface among the nanocrystals, which were the main channels for water permeation. The increase in the number of pores among the silicalite-1 crystals leads to a high flux of water through the membrane.