- 學位論文
聚醯胺/聚丙烯腈複合中空纖維膜製備及 其滲透蒸發效能之研究
The Study on the preparation and pervaporation performance of PA/PAN composite hollow fiber membranes
摘要
本研究主要目的是以聚丙烯腈(Polyacrylonitrile, PAN)中空纖維膜為基材，並在其上以Triethylenetetramine（TETA）以及Trimesoyl chloride（TMC）為單體進行界面聚合反應，以製備聚醯胺（Polyamide, PA）/PAN複合中空纖維薄膜，並應用於滲透蒸發操作程序，分離醇類水溶液，期望製備出具高透過量，同時擁有高選擇性之滲透蒸發用中空纖維模組。研究中探討PAN中空纖維基材膜之紡絲條件（例如鑄膜液擠出壓力、芯液流速以及芯液組成）、氫氧化鈉水溶液的水解條件以及界面聚合條件等，對所製備之PAN中空纖維膜以及PA/PAN複合中空纖維膜之結構型態與滲透蒸發分離效能之影響。 研究結果顯示，於紡製PAN中空纖維膜時，當改變芯液流速，則只對成膜後之中空纖維厚度有影響，而厚度的不同則會造成滲透蒸發通量之不同。中空纖維紡製時芯液組成對中空纖維膜內表面結構型態有顯著的影響，由SEM分析顯示，使用芯液組成為DMF/water、比例為9:1時，其PAN中空纖維膜之截面結構型態為由外表面貫穿到內表面之巨型孔洞，而內表面則是由較大的孔洞以及雙連續結構組成。當芯液中DMF/water比例為8:2時，截面之巨型孔洞結構則沒有貫穿到內表面，而內表面則是由雙連續結構組成。當比例為7:3時，內表面結構則趨於緻密化。為提升PAN中空纖維膜之親水特性以利於界面聚合反應，研究中將所紡製之PAN中空纖維膜於50℃下以2M NaOH水溶液進行水解30分鐘。由水解實驗結果發現，經過水解後之聚丙烯腈中空纖維膜之表面物理及化學性質均會改變。由ATR-FTIR分析可以知道，經過水解後之聚丙烯腈中空纖維膜其表面CN官能基鍵結轉變為CONH2或COOH鍵結。由接觸角實驗可以得到聚丙烯腈中空纖維膜經過30 min水解後其對水接觸角值大幅下降，若持續增加水解時間，則接觸角值將無明顯變化。將以界面聚合方式所製備之PA/PAN複合中空纖維膜進行進行醇類水溶液之滲透蒸發分離效能測試，由實驗結果發現，界面聚合前基材之含水量會影響所製備複合中空纖維膜的滲透蒸發分離效能。由25℃時進行90wt%乙醇水溶液之滲透蒸發分離實驗可以得知，本研究製備之PA/PAN 複合中空纖維膜其最佳界面聚合條件為：基材乾燥時間20min、TETA水相單體濃度1wt%、單體浸泡時間2min、水相單體溶液浸泡後纖維的垂流時間5min、TMC油相單體濃度0.5wt%、單體浸泡反應時間0.5min。其透過量與透過水濃度分別為570 g/m2h 以及 96wt%。研究中同時改變滲透蒸發操作時進料醇類水溶液之種類，分別為異丙醇與第三丁醇。由實驗可以得知，本研究所製備之PA/PAN複合中空纖維膜進行異丙醇與第三丁醇水溶液之分離時同樣具有良好之分離效能。
並列摘要
In this study, Polyamide (PA)/Polyacrylonitrile (PAN) composite hollow fiber membranes were fabricated from Triethylenetetramine (TETA) and Trimesoyl chloride (TMC) through interfacial polymerization onto the surface of PAN hollow fiber membranes for preparation the high permeation rate and selectivity pervaporation hollow fiber modules for aqueous alcohol solution. The effects of spinning process (such as dope extrusion rate, bore liquid flow rate and composition), NaOH aqueous solution hydrolysis condition as well as interfacial polymerization conditions on the morphology and pervaporation performances of PAN hollow fiber membrane and PA/PAN composite hollow fiber membrane were investigated. The results show that the thickness of PAN hollow fiber membrane can be affected by changing bore liquid flow rate resulted in the difference of permeation rate. As for the bore liquid composition, the macrovoids were passed through the entire cross section and large pore with bicontinueous morphology was found in the inner surface of PAN hollow fiber membrane by using 9/1 of DMF/water as the bore liquid composition. The macrovoids was found can not pass through the entire cross section while bicontinueous morphology can be found in the inner surface as using 8/2 of DMF/water as the bore liquid. Moreover, the inner surface was become denser in the case of 7/3 of DMF/water as the bore liquid. To enhance the hydrophilic property of PAN hollow fiber membrane for interfacial polymerization, PAN hollow fiber membranes were hydrolyzed with 2M NaOH at 50℃ for 30 mins. The results show that the physic and chemical properties were affected by hydrolysis. From the analysis of ATR-FTIR, the –CN group in the surface of PAN hollow fiber membranes were converted to CONH2 or COOH groups. The water contact angle was drastically decreased after hydrolyzed for 30 mins. The interfacial polymerized PA/PAN composite hollow fiber membrane was used to investigate the pervaporation performances of aqueous alcohol solution. The data reveal that the pervaporation performances can be affect by water content of PAN substrate hollow fiber membrane before polymerization. In this study, the best interfacial polymerization conditions for the pervaporation of 90 wt% aqueous ethanol solution through PA/PAN composite hollow fiber membranes at 25 ℃ were shown below: the dry time for PAN substrate hollow fiber membrane was 20 min. the concentration and immersion time of TETA solution were 1 wt% and 2 min, respectively. The hang time of TETA immersed PAN hollow fiber membrane was 5 min. The concentration of TMC and reaction time were 0.5 wt% and 0.5min, respectively. The permeation rate and water concentration in permeate of PA/PAN composite hollow fiber membranes were 570 g/m2h and 96 wt%, respectively. Moreover, the pervaporation performances of aqueous isopropanol solution and aqueous tert-butanol solution through PA/PAN composite hollow fiber membranes were also investigated. It also shows good separation performances as aqueous isopropanol solution one.