- 學位論文
添加劑對熱穩定化聚丙烯腈中空纖維滲透蒸發膜之影響
The effect of additive on the pervaporation performances of stabilized PAN hollow fiber membranes
摘要
本研究係以乾/濕式紡絲方式（Dry/wet spinning process）製備非對稱性聚丙烯腈中空纖維膜（Asymmetric PAN hollow fiber membranes），探討紡絲條件(例如氣距長度、添加劑含量)以及熱處理溫度等對PAN中空纖維膜之薄膜結構型態與滲透蒸發操作程序分離乙醇水溶液之分離效能影響。 研究結果發現，未經熱處理之PAN中空纖維膜隨添加劑PEG10000含量增加，透過量有隨之增加而透過水濃度下降的趨勢。紡製有氣距條件之中空纖維膜過程，由於存在重力拉伸誘導高分子鏈順向排列以及水氣誘導相分離兩種競爭機制，使得透過水濃度有先上升後下降的趨勢。 將PAN中空纖維膜經12小時之不同溫度熱處理後發現，隨熱處理溫度增加中空纖維膜結構趨於緻密化。由正子入射能量對S參數的影響，發現隨熱處理溫度提升，S參數(自由體積)有下降的趨勢；且從FTIR-ATR圖譜發現，在熱處理溫度為210℃時， PAN中空纖維膜在2940cm-1(-CH2-)與2240cm-1(-CN)兩個特性吸收峰消失。且從TA-MS圖譜亦可發現，升溫至300℃過程中，在14 amu處發現有peak存在。推斷在熱處理過程中，N或是CH2被移除，證實在此溫度下熱處理PAN高分子會有除氫與環化反應產生。 藉由PEG10000之添加有助於滲透蒸發性能提升，主要PEG10000於熱處理穩定化過程中逐漸被裂解燒除，因而增加進料透過路徑，由S參數圖譜亦可間接證明當熱處理溫達210℃時，PAN高分子會由有機轉變為無機，此亦有助於透過性能的提升。 本研究以22wt.% PAN+PEG10000(8:2)/DMF為紡絲液，在氣距長度為30cm下所製備之PAN/PEG 10000混掺中空纖維膜於210 ℃下熱處理12小時後在25℃進行90 wt.% EtOH 水溶液之滲透蒸發分離操作程序可得最佳之分離效能，其透過量約為427 g/m2h，透過水濃度為98.7 %。
並列摘要
In this study, stabilized polyacrylonitrile (PAN) hollow fiber membranes were fabricated by heat-treating dry/wet spun asymmetric PAN/Poly(ethylene glycol) (PEG) 10k blended hollow fiber membranes for 12 hours with various temperature. The effects of spinning conditions (such as air gap, amount of PEG 10k) as well as heat-treatment temperature on the morphology of PAN hollow fiber membrane and pervaporation performances of 90 wt.% aqueous ethanol solution through hollow fiber membrane were investigated. The results show that the permeation rate increased while water concentration in permeate decreased with increasing PEG 10k content in the dope for the heat-treated free PAN/PEG 10k blended hollow fiber membranes. The water concentration in permeate was increased and then was decreased as increased the air gap. These phenomena might be due to the effects of gravity induced the orientation of PAN polymer chain and vapor induced phase separation. By comparing with the heat-treated free PAN hollow fiber membranes, the morphology became denser after heat-treated the PAN hollow fiber membrane for 12 hours. Moreover, FTIR-ATR spectrum shows the peak in the wavenumber of 2940 cm-1 and 2240 cm-1 were disappeared and the TA-MS peak in 14 amu was appeared. It can be evidenced that the dehydrogenation and cyclization reaction have occurred during the heat-treatment process. The optimum pervaporation performances for 90 wt.% aqueous ethanol solution at 25 ℃ can be gotten through the 210 ℃, 12 hours stabilized 22 wt.% PAN/PEG 10k (8/2) blended hollow fiber membrane. The permeation rate and water concentration in permeate were 427 g/m2h and 98.7 wt.%, respectively.