| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 87 === The objective of this study is to synthesize nano-pore zirconia membranes using Zr alkoxide via sol-gel route. Unlike the traditional technique, the hydrolyzing water is provided by the esterification of butanol and acetic acid. In addition, acetic acid also serves as chelating agent to stabilize the hydrolysis-condensation process so that the agglomeration of zirconia is minimized. Esterification is verified by the product, butyl acetate, determined by a GC/Mass. The chelating complex is evidenced from FTIR spectrum. The peptization is performed either adding HNO3 or H2O resulting two different sols with pH values, ~1 and ~ 5.5, respectively. Such sols are spin-coated on Whatman anodic discs, dried in controlled temperature and humidity, then calcined at 500℃ to remove organic compounds. Zirconia is transformed to the mixture of tetragonal and cubic forms which is confirmed by XRD pattern.
SEM micrograph shows a uniform layer on disc which using sol peptized by HNO3. The flow average pore size of membrane is estimated 3.63 nm by nitrogen gas permeation. The pore size distribution of un-supported zirconia ranges from 1.5 to 3.5 nm measured by nitrogen adsorption.The rejection of soybean oil / hexane mixture reaches 37% which is much better than that of bare disc. TEM shows that average particle size is near 5~10 nm. Gelation occurs in the sol peptized by H2O when setting for a period of time. Membrane prepared from H2O peptized sol can develop a few cracks, which cause the destruction of disc resulting anomalous gas permeation and the negative rejection of soybean oil / hexane.
|
|---|
