Plasma deposition of tetraethoxysilane onto polycarbonate membrane for Pervaporation of aqueous tetrafluoropropanol mixture
| Autor: | Chia-Hao Lo, 羅嘉豪 |
|---|---|
| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 93 The production of highly storage memory, DVD-R, was increases resulted from the insufficient storage capacity of CD-R for the expansion of information. The tetrafluoropropanol（TFP）was necessary to disperse the dyestuff in the fabricated procedure of DVD. While the water content in the China’s made TFP was too high（20~50%）to use for the fabrication of DVD（the water content should be lower than 0.5 wt%）. Moreover, large amount of TFP waste gas can be created in the process of DVD fabrication, which can be condensed and reused. The utilization of pervaporation to purify and reuse the TFP can reduce the production costs and environmental pollution. In this study, the pervaporation membranes, SiOxCyHz/ polycarbonate（PC） composite membranes, were fabricated by using the plasma enhanced chemical vapor deposition（PECVD）method to deposit the tetraethoxysilane (TEOS) on the surface of PC membrane to investigate the effects of plasma power and deposition time on the deposition layer thickness and chemical structure of SiOxCyHz and hope to obtain highly free volume SiOxCyHz layer with excellent pervaporation performances for the separation of aqueous TFP solution. The results show that the deposition rate decreases with increasing the RF power and deposition time due to the enhancement of ion bombardment and etching effect results from the increasing temperature of substrate surface. The XPS and FT-IR data reveal that the C/Si ratio of composite membrane decreases while the O/Si ratio increases with increasing the RF power and deposition time and lead the property of membrane can be changed from organic property to inorganic property. It means that the packing density of SiOxCyHz layer increases with decreasing the C/Si ratio. Nevertheless, the change of deposition layer thickness at higher RF power would drop off as increasing the deposition time. It also can be proved that the packing density of SiOxCyHz layer increases with increasing RF power and deposition time. An optimum pervaporation results, permeation rate of 442 g/m2hr and 99.4 wt% water concentration in permeate, was obtained with the SiOxCyHz/PC composite membrane prepared by 50W plasma power and 3 hr deposition time. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|