中微孔洞材料/幾丁聚醣複合薄膜之製備及其滲透蒸發分離乙醇/水混合物效能之研究

Meso-microporous materials/Chitosan mixed-matrix membranes with improved separation performance of water/ethanol mixtures

康朝翔(Chao-Hsiang Kang)

指導教授 ： 林義峯 ； 童國倫

中原大學/工學院/化學工程研究所/博士(2013年)

https://doi.org/10.6840/cycu201300343

摘要

本研究藉由不同方式添加ZIF-7（zeolitic imidazolate framework-7）粒子於CS（chitosan）高分子內，其中包含micro-scale、nano-scale和直接式的合成，均展現良好的相容性，主要來自於本身也具備有機鏈段，另外，添加ZIF-7之後的CS薄膜，改善了原本較低的選擇比。在micro-scale ZIF-7添加的部分，對於90 wt% 乙醇水溶液滲透蒸發分離，其中選擇比效能為純CS薄膜的19倍，而利用室溫合成法製備出小於50nm的ZIF-7粒子，並添加此nano-scale 的ZIF-7粒子在CS高分子內，結果顯示，當添加量小於20 wt% 時，選擇比與通量具有最佳值，但當添加量增加後，粒子團聚發生時會造成選擇比下降。另外，成功地於CS高分子溶液中直接合成出ZIF-7粒子，不需藉由其它溶劑法合成法先製備出粒子，省去多餘的粒子製備時間，結果方面，ZIF-7與CS高分子間的氫鍵作用力可有效增加薄膜的緻密程度，使選擇性提高，但通量卻不理想，在PSI值（pervaporation separation index）比較方面，以粒子添加方式所製備的20 wt% n-ZIF/CS MMM，其PSI值為 One Step合成方式所製備的dir-ZIF/CS-2 MMM的2.5倍。PB（prussian blue）粒子所提供的孔洞可增加通量提升，另外，外部附著的PVP（Polyvinylpyrrolidone）高分子鏈段，對於水分子有良好的親和性，可藉此增加水分子的選擇比，而最佳值為通量635 g/m2h，選擇比2297。
綜合以上結果，本研究針對操作溫度25oC下進行90 wt%乙醇水溶液滲透蒸發程序，整體而言，粒子添加有助於提升高分子薄膜整效能，且粒子與薄膜間具備有機鏈段或氫鍵作用力等，則可有效增加異質間的相容性，減少選擇比的下降。當異質加入高分子後，通量均有明顯提升，因此，與先前文獻相比無所不同，但對於分離的混合物來說，選擇比則相對重要，所以在添加粒子的選擇中，ZIF類型的孔洞材料極具潛力，同時達到材料的相容性與分子篩特性，以利作為無機-有機複合薄膜之製備與應用。

關鍵字

金屬有機配位沸石 ； 滲透蒸發 ； 複合薄膜 ； 咪唑類配位沸石

並列摘要

In this study, microporous ZIF-7 (zeolitic imidazolate framework-7) and meso-micro PB (Prussian Blue) particles were successfully incorporated into chitosan (CS) membranes to form mixed-matrix membranes (MMMs). The as-prepared MMMs were used to separate mixtures of water/ethanol at 25oC in the pervaporation process. In the first, the separation efficiency of MMMs with 5 wt % ZIF-7 incorporation showed 19 times higher than that of the pristine CS membranes, because of the rigidified polymer chain of the MMMs.
The other nano-scale ZIF-7 particles with particle size of 50 nm were successfully synthesized at room temperature and used to incorporate into CS membranes for separation of mixtures of water/ethanol. It was showed that the loading content with 20 wt% has the optimum value. Furthermore, the MMMs were utilized one step method to directly synthesize the ZIF-7 in the CS membrane. It was also displayed that higher separation factor like MMMs incorporation of micro-scale ZIF-7 particles. From the point view of PSI value, the 20 wt% n-ZIF/CS MMM showed 2.5 times higher than the dir-ZIF/CS-2 MMM. Regardless of which methods, the ZIF-7 crystal particles exhibited good interfaces with the CS polymer because of the nature of their organic linkers and hydrogen bonding. From the other MMMs incorporation of PB particles, it was clearly showed higher flux due to the large pore size of PB particles.
The separation factor and the flux of the as-prepared membranes clearly exceed the upper limit of the previously reported CS based membranes and MMMs. The present work demonstrates better pervaporation performance of the ZIF-7 particles incorporated CS membrane for the separation of water and ethanol and the feasibility of using this system for pervaporation.

並列關鍵字

metal-organic frameworks ； pervaparation ； zeolitic imidazolate frameworks ； mixed-matrix membrane

參考文獻

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