- 學位論文
ZIF-8/PPO混合基質複合薄膜用於滲透蒸發分離醋酸水溶液之研究
Pervaporation of acetic acid/water mixtures through a zeolitic imidazolate frameworks (ZIF-8)/poly(2,6-dimethyl-p-phenylene oxide) mixed matrix composite membranes
摘要
本研究係將疏水性高分子poly(2,6-dimethyl-p-phenylene oxide) (PPO)混合有機咪唑配體與二價鋅所合成的Zeolitic Imidazolate Framework-8 (ZIF-8) 刮於聚丙烯腈基材膜上製備成混合基質複合薄膜應用於醋酸水溶液的滲透蒸發脫水程序。通常在常溫操作下，醋酸跟水分子之間有很強的氫鍵作用力，在滲透蒸發程序中會產生Coupling的影響，使醋酸水溶液的脫水效能不佳，若要消除Coupling的影響必須將操作溫度提高，藉由提高分子動能降低分子之間的作用力，本研究利用疏水性PPO高分子進行分離醋酸水溶液，期望藉由PPO玻璃態的性質在高溫下依然具有分離能力，另添加ZIF-8期望分子篩的效應提升透過量與選擇性。研究中ZIF-8添加量改變及混合機質薄膜熱處理對滲透蒸發透過效能之影響被詳細探討，FESEM及SEM-EDX被用來觀察薄膜之結構型態及MOF在薄膜中的分布狀態，FTIR、DSC、TGA、接觸角量測則被用於鑑定ZIF-8/PPO複合薄膜之物、化特性。 研究結果發現添加ZIF-8會使透過量提高但透過水濃度下降，因此利用熱處理對混合基質複合薄膜進行後處理，實驗數據發現，熱處理溫度為100°C而熱處理時間為30分鐘時擁有最好的效能，其分離90wt%醋酸水溶液的透過量為112g/m2h而分離因子為1491。ZIF-8/PPO複合薄膜在高溫操作能同時提升透過量及透過水濃度，此結果證實高溫操作確實可降低醋酸跟水分子之Coupling效應。
並列摘要
In this study, ZIF-8 was added into a hydrophobic polymer, poly(2,6-dimethyl-p-phenylene oxide), and casted on PAN support membranes to form a mixed matrix composite membranes. The MMCMs was applied to separate 90wt% acetic acid aqueous solution. However, the pervaporation performance have limited by coupling effect between acetic acid and water at room temperature. This problem was solved by increasing operation temperature, because the kinetic energy of molecular was increased at high temperature that could decreased the interaction between water and acetic acid. On the other hand, the PPO polymer was a glassy polymer that the polymer chain cannot move easily at high temperature, so the pervaporation performance still good at high temperature. The pervaporation separation performance was studied by changing the amount of ZIF-8 and heat treatment. The dispersion of ZIF-8 in the PPO active layer was evaluated by FESEM and EDX images to characterize the structure and dispersible. The membrane structure was correlated with the pervaporation performance. In other ways, the physicochemical properties of ZIF-8/PPO mixed matrix composite membranes was characterized by FTIR、TGA、DSC、water contact angle. The pervaporation results show the performance is limited by coupling effect. In research, heat-treated ZIF-8/PPO mixed matrix composite membranes could improve the pervaporation performance. The flux is 112g/m2h and the separation factor is 1491 at best condition 100°C and 30minutes. The permeation rate and water concentration in permeat of ZIF-8/PPO mixed matrix composite membranes both increased with operation temperature increasing. It confirmed that coupling effect can be reduce by high temperature operation.