4-異丙基酚/酚基共聚合磷氮高分子薄膜 於滲透蒸發程序之應用

Copolymerization of poly[(phenoxy) (4-isopropylphenoxy) phosphazene] membranes：Perparation and its application in pervaporation

林昇柏

指導教授 ： 孫一明

元智大學/工程學院/化學工程與材料科學學系/碩士(1998年)

摘要

本研究探討4-異丙基酚/酚基共聚合磷氮高分子(4-ISOPOP)於滲透蒸發程序上對於醇類水溶液去除水份之應用。由滲透蒸發實驗的結果知膜材對水具較佳的選擇性，且隨著進料溶液中醇類含量的增加總透過量會隨之降低；提高進料溫度時，醇與水在滲透側的通量均會增加，膜材對水的選擇性則會降低。在此，運用偏差係數(deviation coefficient, ε)和滲透比(permeation ratio, θ)的觀念闡述偶合效應，並且藉由滲透物種對膜材的塑化效應及滲透分子本身或和膜材間的交互作用力，解釋偶合輸送現象對滲透通量的影響。
在低醇類進料濃度時，由實驗的結果推論醇與水會因彼此之間的交互作用力形成類似於結合分子的形式，水的滲透行為會加速醇的滲透速率；相反的，此時的作用力卻是水分子擴散通過膜材的阻力，會降低水的滲透通量與分離係數。當高醇類進料濃度時，膜材因吸附醇類分子而膨潤，高分子鏈的移動性增加，以及團聚效應的減弱，提升了水的滲透通量與選擇性；然而醇的滲透通量則因為醇類分子受膜材吸附現象的影響，而呈現平穩的現象，其中以乙醇和異丙醇的趨勢較為明顯。比較ε和θ值時，觀察得ε值較能表現成份的滲透通量與選擇性受不同進料組成造成的影響。
4-ISOPOP膜材的改質可經由1H的NMR光譜中異丙基上的氫原子消失獲得證實。在固定濃度與溫度的滲透蒸發條件下，膜材改質前對醇類的滲透活化能由大至小的順序分別是異丙醇＞二丁醇＞乙醇＞甲醇；水分子在不同進料系統中的滲透活化能依次則為：異丙醇＞甲醇＞乙醇＞二丁醇。UV改質實驗中，因氧氣的存在或膜材膨潤時所用的溶劑，造成4-ISOPO膜材表面極性變化的現象，是使得膜材選擇性降低的主因。而膜材上仍擁有相似結構的異丙基集團，應是異丙醇/水混合物的選擇性並未降低的原因。

關鍵字

滲透蒸發 ； 偏差係數 ； 滲透比 ； 偶合效應 ； 結合分子 ； 團聚效應

並列摘要

The pervaporation for dehydration of aqueous alcohol solution by using of poly[(4-isopropyl-phenoxy)-co-(phenoxy)phosphazene] (4-ISOPOP) membranes was investigated. The pervaporation results showed that the membrane was selective to water. The total permeation flux decreased and the separation factor increased with increase the alcohol concentration in feed. In this article, the deviation coefficientεand permeation ratioθ were applied to describe the effect of coupling effect. These phenomena were explained by the plasticizing effect of the permeates and the interaction among the permeates and the polymer membrane or themself.
At low alcohol concentration, the interaction between alcohol and water molecules may form associated molecules and the permeation of water accelerate the permeation of alcohol. Conversely, the interaction inhibited water molecules transport through the membrane so that water permeation rate and selectivity was reduced. At high alcohol concentration, membrane dissolve or adsorb more alcohol molecules and polymer chain in the swollen region become more flexible, the clustering effect of water is also minimized, the permeation of water and separation factor were enhanced. Because the swelling effect inhibited by the interaction between permeates and membranes, the permeation flux of alcohol exhibits an steadily curve, especially of ethanol and isoproanol. In comparison of the deviation coefficient and permeation ratio, the former can better indicate the composition effect on permeation flux and selectivity.
The modification of 4-ISOPOP membranes was confirmed by the disappear of hydrogen atom on isopropyl group by 1H NMR spectrum. On the same operation condition of pervaporation, the sec-butanol aqueous solution showed the best separation factor before the modification and the permeation activation energy of alcohol follows the order of 2-propanol＞sec-butanol＞ethanol＞methanol, and the permeation activation energy of water in various feed mixtures follows the order of 2-propanol＞methanol＞ethanol＞sec-butanol. Isopropanol aqueous solution showed the best separation factor after the modification. When 4-ISOPOP membranes were exposed to UV radiation, molecular oxygen or the solvent for membrane swelling resulted in a remarkable degradation of the polyphosphazene. Consequently, the membrane selectivity decrease. The approximate of separation factor for isopropanol aqueous mixtures would be the similarly structure on the polymer backbone.

並列關鍵字

pervaporation ； deviation coefficient ； permeation ratio ； coupling effect ； associated molecules ； clustering effect

參考文獻

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