高分子複合膜應用於有機溶劑脫水程序

Polymer composite membrane applied to organic solvent dehydration process

何登貴(Deng-Gui He)

指導教授 ： 游勝傑 ； 李魁然

中原大學/工學院/環境工程學系/碩士(2020年)

https://doi.org/10.6840/cycu202000712

摘要

蒸餾程序不僅耗能，且無法有效分離共沸混合物，另外，緻密薄膜具有低透過通量的缺點。因此，本研究利用界面聚合反應製備具超薄選擇層的複合膜，應用於滲透蒸發進行有機溶劑脫水程序。本研究利用化學結構相異的二醯氯單體(succinyl chloride (SCC)、trans-5-norbornene-2,3-dicarbonyl chloride (tNBDC)及isophthaloyl chloride (IPC))與胺類單體diethylenetriamine (DETA)，於改質的非對稱多孔隙聚丙烯腈（modified polyacrylonitrile，mPAN）基材膜表面進行界面聚合反應，製備一系列聚醯胺（polyamide，PA）複合膜，應用於滲透蒸發分離醇類水溶液。研究中探討二醯氯單體化學結構變化、界面聚合反應參數與滲透蒸發操作條件對聚醯胺複合膜分離效能之影響。本研究亦利用全反射式傅立葉轉換紅外線光譜（Attenuated total reflectance-Fourier transform infrared spectroscopy，ATR-FTIR）分析聚合層的化學結構，以掃描式電子顯微鏡（scanning electron microscope，SEM）觀察複合膜的表面與截面型態，利用原子力顯微鏡(atomic force microscope，AFM)偵測複合膜的表面粗糙度，對水接觸角量測實驗被用來分析複合膜的親水性。
本研究發現不同單體化學結構所造成立體障礙效應的差異，會導致聚合層在化學結構及型態上有所差異，進而影響複合膜滲透蒸發分離效能，本研究理想的單體組合為胺類單體DETA及二醯氯單體IPC。由滲透蒸發實驗的結果得知，mPAN基材膜浸泡於1.5 wt%的DETA水溶液3.0分鐘，再與0.5 wt%的IPC有機溶液接觸，進行界面聚合反應1.5分鐘，並在50oC下進行熱處理30 min，製得最佳化的聚醯胺複合膜。此複合膜在操作溫度70oC下，應用於滲透蒸發分離70 wt%異丙醇水溶液，可獲得最理想的分離效能，其透過通量約為4750 g/m2 h，透過物水濃度高於99 wt%。經由上述結果可知，本研究所發展之DETA-IPC聚醯胺複合膜能抵抗進料有機溶液的膨潤效應，且具備高溫操作穩定性，未來將可實際應用於滲透蒸發程序的實務操作。

關鍵字

有機溶劑脫水 ； 聚醯胺 ； 複合膜

並列摘要

Distillation process not only consumes energy but also can not separate the azeotropic mixture effectively. Dense membranes have the disadvantage of low permeation flux. Therefore, in this study, the composite membranes with ultra-thin selective layer were prepared through the interfacial polymerization and were applied to the pervaporation for organic solvent dehydration. A series of polyamide (PA) composite membranes were prepared by using the interfacial polymerization of various acyl dichloride monomers (succinyl chloride (SCC), trans-5-norbornene-2,3-dicarbonyl chloride (tNBDC) and isophthaloyl chloride (IPC)) and amine monomer diethylenetriamine (DETA) on the surface of the modified asymmetric porous polyacrylonitrile (mPAN) support membrane. These composite membranes were applied to the pervaporation separation of alcohol aqueous solutions. Effects of acyl dichloride chemical structure, interfacial polymerization reaction parameter, and pervaporation operation condition on the separation performance of polyamide composite membranes were investigated. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to analyze the chemical structure of polymerized layer. Scanning electron microscope (SEM) was used to observe the surface and cross-sectional morphologies. Atomic force microscope (AFM) was used to probe the surface roughness of composite membrane. The water contact angle measurement was used to analyze the hydrophilicity of composite membrane.
It was found that the monomers with different chemical structures, which caused a difference in the sterical stabilization, resulted in a difference in the chemical structure and morphology of polymerized layer and affected the pervaporation performance of composite membrane. The optimal monomers for interfacial polymerization were the amine DETA and the acyl dichloride IPC. From the results of pervaporation experiments, the optimal polyamide composite membrane was prepared by immersing mPAN into 1.5 wt% DETA aqueous solution for 3.0 min, and then contacting it with 0.5 wt% IPC in toluene organic solution for 1.5 min. The resulting composite membrane had the most desirable pervaporation performance of 70 wt% isopropanol aqueous solution at the operating temperature of 70oC, which was a permeation flux of 4750 g/m2 h and a water concentration in permeate high than 99 wt%. From the above results, DETA-IPC polyamide composite membrane developed in this study can resist the swelling effect of feed organic solution and has the stability for high-temperature operation. It will be applicable to the practical operation of pervaporation process in the future.

並列關鍵字

organic solvent dehydration ； polyamide ； composite membranes

參考文獻

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