- 學位論文
熱處理程序對聚丙烯腈管狀薄膜應用於滲透蒸發對極性溶劑脫水之研究
Study on the heat treatment process of PAN tubular membranes for polar solvent dehydration by pervaporation
摘要
本研究係將聚丙烯腈(PAN)鑄膜液塗佈於玻璃纖維管狀基材上，並對此管狀薄膜進行適當的熱處理程序，使其熱穩定化後得到具有抗極性溶劑之環化結構，並應用於極性溶劑之滲透蒸發脫水程序。為了提昇滲透蒸發效能，研究中以Polyvinyl-pyrrolidone (PVP)為造孔劑，並探討PVP添加量及分子量對滲透蒸發效能之影響。 研究結果發現，當高分子濃度為20wt%、熱處理溫度為210℃時，以此管狀薄膜進行滲透蒸發分離95wt% N-methyl-2-pyrrolidone (NMP)水溶液，在操作溫度為25℃之下，其透過量及透過端水濃度分別為104g/m2h及99.9wt%。此外，亦發現滲透蒸發分離效能會隨著進料端含水濃度的增加以及操作溫度的上升而提昇。 為進一步提昇滲透蒸發效能，在本研究中採用添加造孔劑的方式，製備PAN管狀薄膜，分別添加不同含量(1、3、5、7wt%)以及不同分子量(40kDa、360kDa、1300kDa)之PVP，並使用次氯酸鈉水溶液對管狀薄膜進行後處理。研究結果發現，以次氯酸鈉對含有造孔劑PVP之管狀薄膜進行後處理之後，可移除部分的PVP，並在管狀薄膜表面達到造孔之效果，因此，透過量有顯著提昇，且不喪失選擇性。在PVP分子量為360kDa且添加量為5wt%之下，管狀薄膜具有最佳之滲透蒸發效能，當進料為95wt% NMP水溶液、操作溫度為25℃時，透過量與透過端水濃度分別為254g/m2h與99.9wt%。
並列摘要
In this study, a tubular membrane for polar solvent dehydration by pervaporation process was prepared. Polyacrylonitrile (PAN) dope solution was casting on a glass fiber tubular substrate, then cyclized and dehydrogenated by heat treatment process to get a stabilized tubular membrane. In order to improve the pervaporation performance, the polyvinyl-pyrrolidone (PVP) was used to a pore forming agent. The effects of the concentration and molecular weight of PVP on pervaporation performance were also investigated. From the experimental results, we found that the tubular membrane, which prepared by 20wt% PAN dope solution and 210oC heat treatment temperature, could against the polar solvent due to its suitable mechanical strength. The permeation flux and water concentration in permeate of this tubular membrane for separating 95wt% N-methyl-2-pyrrolidone (NMP) solution at 25oC were 104g/m2h and 99.9wt%. The pervaporation performance would be enhanced by the increase of water concentration in the feed solution. To improve the permeation flux of the tubular membrane, the PVP was adding into the PAN dope solution, to be a pore forming agent. Different concentration and molecular weight of PVP was adding into the PAN dope solution. The PVP/PAN tubular membrane was treated by NaOCl aqueous solution, before heat treatment. The results show that some of PVP could be removed by NaOCl treatment of PVP/PAN tubular membrane, resulting in the pore formation on the surface of tubular membrane. When the molecular weight of PVP was 360kDa with 5wt% concentration in the PAN dope solution, the tubular membrane had best pervaporation performance. The permeation flux and water concentration in permeate were 254g/m2h and 99.9wt%, respectively, for separating 95wt% NMP aqueous solution at 25oC.