- 學位論文
PVA-石墨烯衍生物混成薄膜滲透蒸發效能之研究
Investigation on the pervaporation performance of PVA/Graphene derivative hybrid membrane
摘要
親水性的氧化石墨烯(GO)常用於與有機高分子共混形成複合材料，但合成GO的過程使用大量的強酸與強氧化劑，導致對於環境的嚴重污染，因此本研究擬透過多巴胺改質石墨烯(mGr)的方式製備環境友善的複合材料，應用於乙醇脫水程序，我們將mGr加於聚乙烯醇(PVA)中，製備PVA-mGr混成薄膜，以滲透蒸發分離程序探討薄膜透過效能，並利用全反射式傅立葉轉換紅外線光譜儀(ATR-FTIR)、表面接觸角量測儀(Water contact angle)、場發式電子顯微鏡(FESEM)及X-ray繞射儀(XRD)對薄膜化學結構、親水性及物理結構形貌進行鑑定。 無機相在有機相中的分散狀態會對混成薄膜的物理化學性質與分離效能造成很大的影響。由實驗結果顯示，本研究以多巴胺改質之mGr相較於石墨烯(Gr)，其親水性的提升有助於增加其在高分子基質中的分散性，並改善Gr在高添加量狀態下的由於凡德瓦爾力作用所產生之團聚現象。 探討不同添加量的石墨烯衍生物對薄膜滲透蒸發效能結果指出，相較於PVA-Gr薄膜，改質後的PVA-mGr薄膜展現優異的乙醇水分離效能，在mGr添加量為3wt%時，於25℃的進料溫度下分離90wt%乙醇水溶液展現最佳之分離效能，透過量及透過端水濃度分別為359 (g/m2 h)與98.4 wt%。 本研究進一步探討滲透蒸發操作條件對於分離效能之影響，包含進料溫度、進料濃度以及薄膜長時間穩定性測試。相較於PVA薄膜，混成薄膜能有效抑制薄膜膨潤現象，提升薄膜長時間操作穩定性。在高溫70℃進料環境下進行滲透蒸發操作，PVA-3mGr之透過端水濃度高於PVA-3Gr與PVA薄膜，其透過端水濃度為83 wt%，且透過量為982 (g/m2 h)；混成薄膜對滲透蒸發分離90 wt%乙醇水溶液長時間穩定性的影響，經過22天測試，PVA-3mGr與PVA-3Gr之透過端水濃度分別維持在97 wt%與93 wt%，且其透過量分別為537 (g/m2 h)與356 (g/m2 h)。
並列摘要
The hydrophilic graphene oxide (GO) is generally used to be nanocomposite materials by mixing it with polymer. But large amounts of strong acid and oxidants during GO synthesis produces environmental pollutants. In this study, we prepared an environmentally friendly nanocomposite materials through modified graphene(mGr) with dopamine for dehydration process of ethanol. PVA-mGr hybrid membranes were fabricated for pervaporation application by adding mGr in the PVA solution. The physicochemical properties, structure, and hydrophilicity of the fabricated membranes were characterized by attenuated total reflection - Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle measurement, field-emission scanning electron microscope (FE-SEM) and x-ray diffraction techniques (XRD). The improvement of the physicochemical properties and pervaporation performance of the hybrid membranes are presumably due to the effect of nanoscale structure and the interaction between polymer and inorganic material. Graphene agglomerates because of Van der Waals forces between graphene layers. The mGr does not agglomerates since the hydrophilicity was increased because of the Gr modification with dopamine. The effect of the content of graphene derivatives on pervaporation performance were investigated. The results showed that PVA-mGr hybrid membranes had excellent performance when added with 3 wt% mGr in the separation of 90 wt% aqueous ethanol solution at 25 ℃. The permeation flux and water concentration in permeate side of PVA-mGr membranes were 359 g/m2-h and 98.4 wt%, respectively. This study also investigated the effects of pervaporation conditions, including feed temperature, feed concentration, and durability test on pervaporation separation. Compared with PVA membrane, the hybrid membrane could effectively suppress swelling and enhance the stability of membranes. At a high feed temperature of 70℃, the water concentration in permeate side was 83 wt%, and the permeation flux was 982 g/m2 h. The membrane life of pervaporation process through the durability test for 90 wt% aqueous ethanol solution. After 22 days, the water concentration in permeate side and permeation flux of PVA-3mGr and PVA-3Gr membranes were remained at 97 wt%, 93 wt% and 537 (g/m2 h), 356 (g/m2 h) respectively.
參考文獻
延伸閱讀
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