(123a) Preparation and Characterization of Vinyltrimethoxysilane (VTMS)-Modified Silicalite-1 Filled Polydimethylsiloxane (PDMS) Composite Pervaporation Membrane and Application in Butanol Separation From Aqueous Solution

Composite membranes comprising ultrafiltration (UF) membranes of poly[acrylonitrile] and poly(ether sulfone) (PES) as support and vinyltrimethoxysilane (VTMS)-silicalite-1 filled polydimethylsiloxane (PDMS) as selective top layer were prepared. Two criteria for the successful preparation of composite membranes were studied: (a) effect of supporting layer and (b) pre-polymerization of coating solution. The resultant membranes were characterized by scanning electron microscopy (SEM) and water contact angle analysis, while the separation performance of the composite membrane was characterized by flux and selectivity for pervaporative separation of butanol from aqueous solution. The experimental results showed that hydrophilic support was favorable for preparation of high performance silicalite-1/PDMS composite membranes and the PAN ultrafiltration membrane was more suitable for preparing the composite membrane. Pre-polymerization of the coating solution using “platinum cure” could serve as a useful and promising method for preparation of high performance composite membranes, and with this method the VTMS-modified silicalite-1/PDMS composite membranes with an active layer thickness of 5-6 μm could be prepared. Using the composite membranes prepared with 65 % silicalite-1 loading and PAN ultrafiltration membrane as a support, a selectivity of 70 and a flux of 1353 g/m²h were obtained in separating butanol from 1.0 wt% aqueous solution at 343 K. With the composite membranes, the effects of operating parameters such as temperature and feed butanol concentration on the pervaporation performance were also investigated in detail.