新型超薄滲透蒸發複合膜之研究

Study on the novel ultra-thin composite membrane for pervaporation

謝昀穎(YUN-YING HSIEH)

指導教授 ： 李魁然 ； 賴君義

中原大學/工學院/化學工程學系/碩士(2008年)

https://doi.org/10.6840/cycu200900543

摘要

為了克服一般緻密性薄膜低透過量的缺點，本研究利用不同結構的二胺單體2,2'-Dimethylbenzidine hydrochloride (m-tolidine-H)及1,4-bis(4-aminophenoxy)-2-tert-butylbenzene (BATB)與醯氯單體1,3,5-苯三醯氯(trimesoyl chloride, TMC)，於改質的聚丙烯腈(modified polyacrylonitrile, mPAN)非對稱基材膜的表面上進行界面聚合反應，製備超薄聚醯胺複合薄膜(m-tolidine-H-TMC/mPAN與BATB-TMC/mPAN)，應用於滲透蒸發程序分離乙醇水溶液。研究中利用全反射式傅立葉轉換紅外線光譜儀(ATR-FTIR)與掃瞄式電子顯微鏡(SEM)來鑑定聚醯胺聚合層的化學結構與型態，並探討二胺單體結構與製備條件，例如：水相與有機相單體溶液濃度、水相處理時間、聚合時間等效應對滲透蒸發分離效能的影響。亦探討滲透蒸發操作條件，例如：進料溶液組成及溫度等效應對滲透蒸發分離效能的影響。為進一步了解聚醯胺複合膜其聚合層結構的變化，利用正子湮滅光譜分析技術(Positron annihilation spectroscopy, PAS)結合可變單一能量慢速正子束(Variable monoenergy slow positron beam, VMSPB)分析儀來偵測聚醯胺複合膜其聚合層自由體積與結構變化，並期望與滲透蒸發分離效能有良好的關聯性。研究發現，經由界面聚合所形成之聚合層在靠近基材位置處有較為緻密的結構，而遠離基材之聚合層結構則較為鬆散。利用m-tolidine-H與TMC進行界面聚合所製備之聚醯胺複合薄膜(m-tolidine-H-TMC/mPAN)，隨著水相處理時間、有機相溶液濃度及聚合時間增加，滲透蒸發操作透過量呈現下降趨勢，推估由於聚合層厚度增厚，造成透過阻力增加所導致。另外，由都卜勒展寬能量光譜(Doppler-broadened energy spectrum, DBES)及正子湮滅時間光譜(Positron annihilation lifetime spectroscopy, PALS) 探討有機相溶液濃度及聚合時間對聚醯胺複合薄膜其自由體積與聚合層結構的影響發現：隨著有機相溶液濃度及聚合時間增加，聚合層自由體積數量（I3）增加。研究中發現：mPAN基材膜在1.5wt% m-tolidine-H水溶液中浸漬10秒，再於0.05wt% TMC有機溶液聚合10秒，所製得之複合薄膜於25℃下進行90wt%乙醇水溶液之滲透蒸發操作有最佳之分離效能，其透過量為2191g/m2h而透過水濃度為99.5wt%以上。

關鍵字

複合膜

並列摘要

In order to improve the permeation rate of the dense pervaporation membrane, a series of the polyamide thin-film composite membranes are prepared by interfacial polymerization of two different amines, 2,2'-Dimethylbenzidine hydrochloride (m-tolidine-H), 1,4-bis(4-aminophenoxy)-2-tert-butylbenzene (BATB) and trimesoyl chloride (TMC) on the surfaces of the modified polyacrylonitrile (mPAN) membranes. The polyamide/mPAN composite membranes were used to separate the aqueous ethanol mixtures by pervaporation. Attenuated total reflection infrared spectroscopy (ATR-FTIR) and scanning electron microscope (SEM) are used to characterize the chemical structures and morphologies of the polyamide active layers of the composite membranes. The effects of the chemical structure of the amines and the thin-film composite membrane preparation conditions during interfacial polymerization, such as the monomer concentration of aqueous and organic solutions, immersion time of aqueous solution and polymerization time etc., on the pervaporation performance are investigated. In addition, the effects of the operation conditions of the pervaporation process such as the composition and temperature of the feed solutions on the pervaporation performance are also studied. In order to further realize the polyamide active layer structure variation of the polyamide thin-film composite membrane, the Positron annihilation spectroscopy (PAS) coupled with a variable monoenergy slow positron beam (VMSPB) is utilized to detect the depth profile of the free volume and multilayer structure through the polyamide/mPAN composite membrane to correlate with the pervaporation performance. It is found that the structure of the polyamide active layer prepared by interfacial polymerization near the support was denser, and that far away from the support was looser. For the m-tolidine-H-TMC/mPAN composite membrane, the entire thickness of active layer increases and permeation rate decreases with increasing the immersion time of aqueous solution, concentration of organic TMC solution and polymerization time, as resulted in increasing the permeation resistance. Besides, according to the results of the effects of organic TMC solution concentration and polymerization time on the depth profile of the free volume and multilayer structure characterized by Doppler-broadened energy spectrum (DBES) and Positron annihilation lifetime spectroscopy (PALS), it is found that the o-Ps annihilation intensity (I3) increases with increasing the concentration of organic TMC solution and polymerization time for the m-tolidine-H-TMC/mPAN composite membrane. The m-tolidine-H-TMC/mPAN thin-film composite membranes prepared by immersing mPAN into 1.5wt% aqueous m-tolidine-H solution for 10s and then contacting with 0.05wt% organic TMC solution for 10s have the best pervaporation performance. For pervaporation separation of 90wt% aqueous ethanol solution at 25℃, that is, the permeation rate and water concentration in permeate are 2191g/m2h and above 99.5wt%, respectively.

並列關鍵字

m-tolidine-H-TMC/mPAN

參考文獻

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