本研究藉由薄膜結構設計製備具雙連續結構之聚醯亞胺(Polyimide, PI)管式薄膜(tubular membrane),進一步利用界面聚合反應,製備聚醯胺(Polyamide)/聚醯亞胺管式薄膜,應用在奈米過濾操作程序。 研究中探討不同分子量之聚乙烯吡咯烷酮(Poly(vinyl pyrrolidone), PVP)造孔劑對於PI管狀薄膜結構型態之影響。實驗結果顯示,隨著PVP分子量之上升,鑄膜液黏度亦隨之提升,可降低薄膜相轉換速率,因而產生較連通之薄膜表面。此外,PVP之造孔效應可提升PI管式薄膜之純水通量達30 L/m2h (LMH),為未添加PVP之PI管膜的2倍。研究中同時探討相轉換系統中非溶劑醋酸(Acetic acid, AA)之添加對於PI管狀薄膜結構型態之影響。由於AA與PVP、NMP之間產生氫鍵作用力,使鑄膜液黏度升高而導致相轉換速率降低,因此薄膜表面生成較大孔洞且截面開始形成雙連續結構,而雙連續結構之厚度隨著鑄膜液黏度上升而上升,在鑄膜液中添加10 wt.% 醋酸時,經相轉換後,PI管狀薄膜屬於整體雙連續之結構型態,其水通量在4 bar下可達80.90 LMH。研究中同時發現,在雙連續結構下PI管狀膜之厚度變化幾乎不影響薄膜結構而可提升透過效能。 為提升PI管狀薄膜之奈米過濾效能,研究中將 (15 wt.% PI+4 wt.% PVP360k+10 wt.%AA)/NMP鑄膜液所製備具雙連續結構型態之PI管狀薄膜利用Piperazine (PIP)以及Trimesoyl chloride (TMC)進行界面聚合反應,製備聚醯胺/聚醯亞胺管狀複合薄膜之選擇層,應用於奈米過濾程序中,其對Na2SO4以及NaCl分別具有80%以及20%之阻擋率,而對Brilliant Blue R染料之阻擋率則為98%,顯示此聚醯胺/聚醯亞胺管狀複合薄膜在染料純化之應用上具有良好之潛力。
In this study, a novel polyimide (PI) tubular membrane with bi-continuous morphology was fabricated by membrane morphology design. The polyamide (PA) / PI composite tubular membrane then was prepared by interfacial polymerization for nanofiltration. The effects of poly (vinyl pyrrolidone) (PVP) pore-forming agents on the morphology of PI tubular membranes were investigated. The results show that with the increase of the molecular weight of PVP, the viscosity of the casting solution also increases, and the membrane formation rate can be reduced, resulting in a surface with more pores. In addition, the pore-forming effect of PVP can increase the pure water flux of PI tubular membrane to 30 L/m2h, which is 2 times that of PI tubular membrane without PVP. The effects of acetic acid (AA) addition on the morphology of PI tubular membranes were also investigated. Because of the hydrogen bond between AA and PVP/NMP, the formation rate of membrane decreases due to the increase of the viscosity of the casting solution, thereby the surface pore of the membrane is bigger and forms bi-continuous morphology in the cross section of PI tubular membrane. When 10 wt.% acetic acid was added to the casting solution, the PI tubular membrane was an entire bi-continuous morphology with a water flux of 80.90 LMH at 4 bar. It was also found that the thickness of the PI tubular membrane almost did not affect the membrane morphology but could improve the rejection. In order to enhance the nanofiltration performances of PI tubular membrane, the PI tubular membrane with bi-continuous morphology which was fabricated by using (15 wt.% PI + 4 wt.% PVP360k + 10 wt.% AA) / NMP casting solution was used to prepare PA/PI composite tubular nanofiltration membrane via interfacial polymerization by using piperazine (PIP) and trimesoyl chloride (TMC) as the monomers. The resulted PA / PI composite tubular membrane had a rejection of 80% and 20% for Na2SO4 solution and NaCl solution, respectively, while the rejection for Brilliant Blue R dye solution was 98%, indicating that the PA/PI composite tubular membrane had a good potential in the application of dye purification.