Preparation and characterization of Silicalite‐1/PDMS surface sieving pervaporation membrane for separation of ethanol/water mixture

Abstract

To improve the pervaporation performance of Silicalite-1/PDMS composite membrane by adding a small amount of Silicalite-1 zeolite, novel Silicalite-1/PDMS surface sieving membranes (SSMs) were prepared by attaching Silicalite-1 particles on the PDMS membrane surface. The obtained membranes and traditional mixed-matrix membranes (MMMs) were characterized by SEM, XRD, TGA, FT-IR, and pervaporation separation of ethanol-water mixture. Effects of Silicalite-1 particles content, feed temperatures, and feed compositions on the separation performance were discussed. From the cross-section view SEM images of SSMs, a two-layer structure was observed. The thickness of the Silicalite-1 layer was about 300 nm to 2 lm. The TGA analysis indicates that the zeolite concentration in 3 wt % SSM is lower than 10 wt % MMMs. In the ethanol/water pervaporation experiment, the separation factor of Silicalite-1/PDMS SSMs increased considerably compared with pure PDMS membrane. When the suspensions concentrations of Silicalite-1 particles reached 3 wt %, the separation factor was about 217% increase over pure PDMS membrane and 52.9% increase over 10 wt % Silicalite-1/PDMS MMMs. As the ethanol concentration in the feed increases, the separation factor of SSMs increases, whereas permeation flux decreases. At the same time, with increasing operating temperature, the permeation flux of SSMs increased. The stability of SSMs at high temperature is better than the traditional MMMs.

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