界面聚合聚醯胺複合膜應用於滲透蒸發分離四氫呋喃水溶液之研究

Study on interfacially-polymerized polyamide composite membrane for pervaporative separation of aqueous tetrahydrofuran solution

李彥璋(Yan-Zhang Li)

中原大學/工學院/化學工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100628

摘要

為了提升聚醯胺薄膜滲透蒸發分離效能，本研究以化學結構相異的二胺單體(BATO、DOA與BAE)與醯氯單體(TMC、TPC及tNDBC)，在改質的聚丙烯腈(modified polyacrylonitrile，mPAN)非對稱基材膜表面進行界面聚合反應，製備一系列聚醯胺複合薄膜(polyamide/mPAN composite membrane)，應用於滲透蒸發分離程序分離四氫呋喃水溶液。研究中利用全反射式傅立葉轉換紅外線光譜儀(ATR-FTIR)與X射線光電子能譜儀(XPS)鑑定界面聚合層的化學結構與組成，利用掃描式電子顯微鏡(SEM)與原子力顯微鏡(AFM)分析聚醯胺複合薄膜表面與截面的結構型態，進一步更利用可變單一能量慢速正子束(Variable monoerergy slow positron beam，VMSPB)分析儀偵測聚醯胺複合薄膜不同層間的微結構變化，期望與滲透蒸發分離效能有良好的關聯性。
研究中發現化學結構相異的單體所造成的立體障礙效應，將導致單體間反應性與聚醯胺聚合層結構型態上的差異，另外，單體所具有的特殊官能基團，亦會對聚醯胺聚合層之結構型態與化學性質產生影響。由可變單一能量慢速正子束(Variable monoenergy slow positron beam，VMSPB)分析結果可知，化學結構相異的聚醯胺複合薄膜具有不同的層間自由體積變化，且此變化與複合薄膜之滲透蒸發分離效能有良好的關聯性。
研究中探討基材膜水解反應時間、單體結構與界面聚合條件，例如：水相與有機相溶液單體濃度、水相浸泡時間、聚合時間等效應，對滲透蒸發分離效能的影響。由滲透蒸發的實驗結果顯示，聚醯胺複合薄膜最適理想的製備條件為：以2M氫氧化鈉溶液水解反應時間10分鐘之mPAN為基材膜，其浸泡於2 wt% BAE的水相溶液中3分鐘，再與1 wt% TMC有機相溶液接觸，進行界面聚合反應30秒，此聚醯胺複合薄膜在操作溫度30oC下，應用於滲透蒸發程序分離90 wt%四氫呋喃水溶液，具有最理想的分離效能，其透過量約為1399 g/m2h，透過水濃度高於99 wt%。

關鍵字

滲透蒸發 ； 界面聚合 ； 聚醯胺 ； 四氫呋喃

並列摘要

To improve the pervaporation performance of polyamide membrane, a series of polyamide composite membranes were prepared by the interfacial polymerization of various diamine monomers (BATO,BAE and DOA) and acyl chloride monomers (tNDBC,　TPC and TMC) onto the surface of the asymmetric modified polyacrylonitrile (mPAN) membrane. These composite membrames were applied in the pervaporation separation of the aqueous tetrahydrofuran (THF) solution. Attenuated total reflection infrared spectroscopy (ATR-FTIR) and x-ray photoelectron spectroscopy (XPS) were used to characterize the chemical structures and compositions of the interfacially-polymerized layers of the composite membranes. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the surface and cross-sectional morphologies of the polyamide composite membranes. Further, the variable monoerergy slow positron beam (VMSPB) analyzer was used to examine the variations in the fine-structure in the different layer through the polyamide composite membrane. The data obtained from VMSPB analysis were expected to correlate well with the pervaporation performance
It was found the different chemical structures of the monomers, which caused different sterical stabilizations, leaded to the difference in the reactivities between the monomers and the variation in the chemical structures of the polyamide active layers, in addition, the special functional groups in the molecular chain of the monomer also could influence the chemical structures and the chemical properties of the polyamide active layers. From the result of the VMSPB measurement, the composite membranes, which owned the different chemical structures in their polyamide active layers, had the variations in the free volume in the different layers through the polyamide composite membrane. The above results that we mentioned were highly consistent with the pervaporation performance.
The effects of the hydrolysis time of the support membrane, the chemical structure of the monomer and the interfacial polymerization conditions, such as the monomer concentration of aqueous and organic solutions, the immersion time of aqueous diamine solution, the polymerization time, on the pervaporation performance were investigated. From the results of the pervaporation separation experiments, The most desirable conditions for the preparation of a polyamide composite membrane are as follows: The mPAN which is hydrolyzed using a 2M NaOH solution for 10 min is used as a support membrane. This support membrane is immersed in a 2 wt% aqueous BAE solution for 3 min. And then this membrane is contacted with a 1 wt% organic solution for 30 sec to carry out the interfacial polymerization. The resulting membrane is obtained and has the most desirable pervaporation performance of a 90 wt% aqueous THF solution, which is a permeation rate of about 1399 g/m2h and a water concentration in permeate higher than 99 wt%.

並列關鍵字

Interfacial polymerization ； Polyamide ； Pervaporation ； Tetrahydrofuran

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