- 學位論文
矽烷偶聯劑改質之薄膜蒸餾技術應用之研究
Study on surface modification by n-alkylsilane grafting applied in Membrane Distillation
摘要
本研究主要目的是透過結合電漿和接枝等兩種改質方法，來提高聚醚碸（PES）薄膜的疏水性，然後研究應用改質膜於薄膜蒸餾(MD)系統中之性能。 PES 薄膜以氧電漿進行改質後，再以四種烷基矽烷化學物質進行接枝：已基三氯矽烷、辛基三氯矽烷、癸基三氯矽烷和十二烷基三氯矽烷。研究經由孔徑、孔隙率、水接觸角 (WCA)、掃描電子顯微鏡 (SEM)、衰減式全反射傅立葉轉換紅外光譜儀 (ATR-FTIR) 和原子力顯微鏡 (AFM)、X 射線光電子能譜儀（XPS）對改質膜進行特性分析。本研究評估了接枝劑化學結構中碳鏈長度和電漿處理對薄膜表面疏水性的影響。研究於空氣間隙式薄膜蒸餾 (AGMD) 系統中分析應用改質薄膜之效果，進料溶液為 4% wt/wt氯化鈉合成廢水，透過脫鹽率和水流通量等兩個參數，評估改質膜之適用性，在AGMD操作期間並持續監測電導度變化，以確保薄膜沒有破裂現象。 研究結果顯示辛基改質膜（1次接枝）（辛基-1）、辛基改質膜（2次接枝）（辛基-2）和癸基改質膜（2次接枝）(癸基-2)具有較高的除鹽效率，其去除率分別為 99.36%、99.06% 和 99.79%。此外，辛基-1改質膜的水流通量為 9.3 kg/m2h，接近聚四氟乙烯/聚丙烯(PTFE/PP) 靜電紡絲和聚偏二氟乙烯(PVDF)商用薄膜的水流通量。對於辛基-2和癸基-2改質膜，水流通量值則分別為 4.27 和 4.61 kg/m2h，低於一般商業薄膜。原因是辛基-2和癸基-2改質膜通過 2 次連續的矽烷接枝反應進行改質，導致這兩種膜會比辛基-1改質膜厚，因此降低通量。三種改質膜在操作8小時內電導度值均低於0.2 mS/cm，可證明在AGMD操作過程中所有改質膜都沒有破裂的情形。
並列摘要
The main purpose of the report is to improve the hydrophobicity of the polyethersulfone (PES) membrane by combining two membrane modification methods such as plasma and grafting and then investigate the performance of the modified membrane in the MD system. The PES membrane was modified with oxygen plasma and then grafted with four chemicals of alkylsilane: hexyl trichlorosilane, octyl trichlorosilane, decyl trichlorosilane, and dodecyl trichlorosilane. The modified membranes were characterized by pore sizes, porosity, water contact angle (WCA), scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR), and atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS). The influence of the carbon chain length in the chemical structures of the grafted agent and the plasma treatment on the hydrophobic properties of the membrane surface was evaluated in this study. Modified membranes were investigated in the air gap membrane distillation (AGMD) system, with the feed solution being 4wt% NaCl synthetic wastewater. The applicability of modified membranes was evaluated by two parameters: salt rejection and permeability flux. The conductivity was also checked during MD operations to make sure the membrane was not broken. The research results showed high salt removal efficiency for the following membranes: octyl modified membrane (1-time grafting) (Octyl – 1), octyl modified membrane (2 times grafting) (octyl – 2), and decyl modified membrane (2 times grafting) (Decyl – 2). More specifically, the efficiency values were 99.36%, 99.06%, and 99.79% for Octyl – 1, Octyl – 2, and Decyl – 2, respectively. Besides, the water flux of Octyl – 1 was 9.3 kg/m2.h, which was close to the water flux of PTFE/PP electrospun and PVDF commercial membranes. For Octyl – 2 and Decyl – 2 membranes, the water flux values were 4.27 and 4.61 kg/m2.h, respectively, which were lower than those of commercial membranes. The reason is that Octyl – 2 and Decyl – 2 membranes are modified with 2 consecutive silane grafting reactions, resulting in these two membranes being thicker than Octyl – 1 membrane. The conductivity values of three modified membranes were lower than 0.2 mS/cm during 8 hours of operation, which prove that modified membranes are not broken during MD operation.