水相單體溶液共溶劑變化對界面聚合中空纖維複合膜結構與滲透蒸發效能之影響

Effect of co-solvent in aqueous monomer solution on pervaporation performance of interfacial polymerization PA/PVDF hollow fiber membranes

高敬凱(Jing-Kai Kao)

指導教授 ： 李魁然 ； 蔡惠安

中原大學/工學院/化學工程研究所/碩士(2015年)

https://doi.org/10.6840/cycu201500782

摘要

本論文主要目的是探討界面聚合程序中，水相單體溶液中不同共溶劑之添加對於界面聚合反應性的影響，並觀察聚合層的結構型態對滲透蒸發效能的影響。在紡絲的過程中，利用改變芯液組成，使PVDF中空纖維膜的內截面結構從巨型孔洞結構轉變為海綿狀結構，藉以提高薄膜的機械強度。
光穿透度實驗、SEM、 XPS、XRD 實驗結果顯示，因水相單體會與不同水相共溶劑產生交互作用力的影響，界面聚合反應速率也會發生改變，進而影響聚合層的交聯程度，結晶度與厚度。EDS與膨潤實驗發現，添加的水相共溶劑與PVDF中空纖維膜之間的親和性較佳，可使PVDF中空纖維薄膜吸附更多水相單體溶液，使聚合層更加完整。
為了解析單體結構對PA/PVDF中空纖維膜分離效能之影響，選用不同結構的二胺與醯氯單體進行界面聚合反應，水相單體m-phenylenediamine (MPD)、m-Xylylenediamine (XDA)與4-Methyl-m-phenylenediamine (TDA) 與油相單體trimesoyl chloride(TMC), Suberoyl chloride (SC) 被用來製備一系列PA/PVDF中空纖維複合薄膜。實驗結果顯示，水相單體立體障礙越小時，越能形成較緻密的聚合層；油相單體具有較多醯氯官能基時，所製備之中空纖維複合膜展現較較優異的滲透蒸發效能。由XPS鑑定結果得知，水相單體立體障礙越小，能形成交聯程度較高的聚合層；油相單體醯氯官能基數越多時，其形成的聚合層較為緻密。經由光穿透實驗也發現當水相單體立體障礙越小時，free standing薄膜之界面聚合反應速率越快。
經由界面聚合最適化條件所製備之PA/PVDF中空纖維膜，於25°C滲透蒸發分離70wt%異丙醇水溶液，透過量為550g/m2h，透過端水濃度為94.3wt%。

關鍵字

滲透蒸發 ； 界面聚合

並列摘要

In this study, PVDF hollow fiber with high mechanical property was fabricated by changing the bore liquid components. The structure of PVDF hollow fiber was transformed from macrovoid to sponge-like resulting to an increase in its mechanical property. Interfacial polymerization was performed to provide selective layer on the PVDF surface and the effect of co-solvent addition in aqueous solvent was investigated. We found from the results of light transmittance, SEM, XPS and XRD that there was an interaction between the aqueous monomer and aqueous co-solvent. The rate of interfacial polymerization was affected by the degree of cross-linking, crystallinity and thickness of selective layer. The degree of swelling results showed high affinity between PVDF and aqueous co-solvent and through EDX it was observed to have more aqueous monomer adsorbed on PVDF surface that enhanced the reactivity of interfacial polymerization.
PA/PVDF composite hollow fiber membranes on pervaporation performance and the morphology of selective layer were fabricated from several water-soluble amine monomers (e.g., m-phenylenediamine (MPD), m-Xylylenediamine (XDA), and 4-Methyl-m-phenylenediamine (TPD) and oil-soluble (e.g., trimesoyl chloride (TMC) and Suberoyl chloride (SC)) to investigate the effect of steric hindrance. PA/PVDF composite hollow fiber membranes showed better pervaporation performance and increased cross-linking degree with water-soluble amine monomers that has lower steric hindrance and more reactive sites of oil-soluble monomers based on XPS results . The light transmittance results revealed that the interfacial polymerization rate of free-standing polyamide was increased with water-soluble monomers that havelower steric hindrance.
Therefore, the ideal interfacial polymerization conditions was found when soaked in 2 wt% MPD for 2 min and reacted with 0.5 wt% TMC for 2 min. t The permeation flux was 550 g/m2hr with 94.3 wt% water permeate based on the pervaporation performance test for separating 70 wt% IPA at 25°C.

並列關鍵字

pervaporation ； interfacial polymerization

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