Abstract
Silicalite of a high hydrophobicity and large surface area, is naturally viewed as a good adsorbent in organic selective pervaporation. In this thesis, nanocomposite membranes of PDMS containing well dispersed micron-size or nano-size silicalite particles are successfully prepared. Experimental data show that under the same operation conditions, nanocomposite membranes have better performance in pervaporation of acetic acid/water solutions, mainly because that nano-size silicalite particles have higher sorption ratio of acetic acid to water than the micron-sized ones. They also have better thermal stability according to the TG analyses. Thickness is the major factor for pervaporation performance in both separation factor and permeation flux. The next factor is particle size, which exhibits more influence than silicalite loading. When the thickness of the nanocomposite membrane is 50um, silicalite loading is 40 wt%, operation temperature is 45oC and feed concentration is 20 wt%, we can have a separation factor of 2.45 and permeation flux of 220 g/m2-hr. The separation factor is almost the same as the pure silicalite membrane shown by Sano et al. (1994), and the permeation flux is much higher than that of Sano et al. The separation factor of Sano et al. was 2.6 and the flux was 38 g/m2-hr, under the conditions of 35oC, 15 vol% feed concentration and 400mm thickness.