Study of Polysiloxaneimide Pervaporation Membrane in Alcoholic Aqueous Separation Process
| Autor: | Li,Shao-Hua, 李韶華 |
|---|---|
| Rok vydání: | 1993 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 81 The separation of ethanol from water by pervaporation was carried out using polysiloxaneimide(PSI) membranes. Polyimide/ polydimethylsiloxane (PI/PDMS) segmented copolymer with various PDMS contents in the main chain were prepared by polycondensation of oligomers of amine-terminated poly( dimethylsiloxane) with or without oxydianiline (ODA) and 3,3',4,4'- benzophenone tetracarboxylic dianhydride (BTDA) followed by thermal dehydration. Upper curing temperature of 300℃ were used to insure complete imidization. All the membranes, PI/PDMS segmented copolymer with and without ODA, were affinity to water around room temperature. Interestingly, the separation factor toward water decreased to unity with increasing feed temperature to a specific temperature (Tci). Thereafter, the membrane were affinity to ethanol. The separation factor toward ethanol increased to a maximum when kept the feed temperature increasingto Tmax. Such a special phenomenon which was due to the increasing feed temperature will be discussed in detail. As a result, we were able to obtain a desired separation factor toward water or ethanol via a carefully controlled feed temperature. A separation factor toward ethanol of 3.9 and a permeation rate of 325 gram per square meter per hour with 72.5℃ feed temperature can be obtained. In addition, a separation factor toward water of 7.5 and a permeation rate of 207 gram per square meter per hour with 20℃ feed temperature were also available. The PSI membranes without ODA had lower permeation rates and higher separation factor toward ethanol than that containing ODA. The PSI membrane had a maximum separation factor toward ethanol at a feed concentration of 30wt% ethanol. In addition, the membranes permeated alcohols preferentially except for the methanol. The properties and structures of PSI copolymer were characterized by FT-IR、contact angle、X-ray、DSC and TGA. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|