單寧酸-鐵離子/聚丙烯腈中空纖維膜應用在含油乳化液分離之研究

Study on the separation of oil in water emulsion through tannic acid - iron ion/ polyacrylonitrile hollow fiber membrane

徐偉倫(Wei-Lun Hsu)

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(2018年)

https://doi.org/10.6840/cycu201800351

摘要

本研究使用聚丙烯腈(Polyacrylonitrile, PAN)做為紡絲高分子，添加不同含量聚乙烯吡咯烷酮（Polyvinylpyrrolidone, PVP）於鑄膜液內，探討成膜機制改變製備雙連續之PAN中空纖維膜，並藉由調控抽絲參數、次氯酸鈉後處理以改善膜之通量。爾後，製備親水性之單寧酸(Tannic acid)-鐵離子(Iron ion)於膜上，提升膜之通量並改善膜之抗垢能力，製備出單寧酸-鐵離子/聚丙烯腈中空纖維膜，應用於分離水包柴油乳化液程序。
首先探討不同含量PVP添加對於膜結構之影響，由實驗結果發現，紡絲液黏度大幅上升，導致成膜速率大幅下降，薄膜結構型態也從手指狀結構轉變成雙連續結構並帶有內外厚皮層。再藉由調控抽絲參數，氣距以及芯液組成來消除內外厚皮層，提升膜之純水通量以及油水通量。製備成膜後藉由表面後處理的方式來改善薄膜性能，首先利用次氯酸鈉將膜表面之PVP降解析出達到提升通量之效果，再製備單寧酸-鐵離子於中空纖維膜上，單寧酸-鐵離子之製備可有效提升膜之親水性，親水性上升也改善膜之抗垢能力，進而提升膜之油水通量。
研究中利用FESEM、流變儀、光穿透實驗驗證成膜機制對於結構型態改變之影響，FTIR、XPS、接觸角量測儀鑑定膜表面化學結構變化對於膜之親水性影響，以及利用強力試驗機、總有機碳量測儀量測膜之機械強度和分離效能。實驗結果發現，在聚丙烯腈中空纖維膜上製備單寧酸-鐵離子層，應用於分離水包柴油之乳化液程序上，具有良好之分離效能，膜之選擇性可高達98 %以上，純水通量為87.7 LMH，一小時操作下之油水通量為66.8 LMH，且相較於未改質之膜，其抗垢能力也有明顯提升。

關鍵字

單寧酸 ； 聚丙烯腈 ； 中空纖維膜 ； 乳化液

並列摘要

In this study, polyacrylonitrile (PAN) was used as the spinning polymer, and different amounts of polyacrylonitrile (PVP) were added into the dope solution to investigate the mechanism of membrane formation to prepare bi-continuous PAN hollow fiber membranes. By adjusting spinning parameters and sodium hypochlorite post-treatment can improve the permeation flux of membrane. After that, in order to enhance the permeation flux and improve antifouling ability of prepared membrane, tannic acid (TA)-iron ion (FeIII)/PAN hollow fiber membrane was prepared and applied to separate the diesel -in- water emulsions.
Firstly, the effect of PVP content on the morphology of PAN hollow fiber membrane was investigated. The results showed that as increasing the PVP content, the viscosity of the spinning solution increased significantly, resulting in a significant decrease in the membrane formation rate. The morphology of the membrae was changed from finger-like structure into bi-continuous structure with internal and external thick skin layer. By adjusting the spinning parameters such as air gap and bore liquid composition, the inner and outer thick skin layers can be eliminated and the pure water flux and oil-water flux of the membrane can be improved. The prepared PVP added PAN hollow fiber membrane then was post-treated by using sodium hypochlorite aqueous solution to degrade PVP in the membrane surface to increase the permeation flux. Furthermore, TA–FeIII layer then was coated on the outer surface of sodium hypochlorite treated PAN hollow fiber membrane. The prepared TA–FeIII layer can effectively improve the hydrophilicity and antifouling ability of the membrane, thereby improving the oil-water flux of the membrane.
In this study, FESEM, rheometer and light transmission experiment were used to confirm the influence of the membrane formation mechanism on the change of the morphology. FTIR, XPS and contact angle measurement instruments were used to identify the influence of changes in the chemical structure on the hydrophilicity of the membrane. Instron and total organic carbon (TOC) instrument were used to measure the mechanical strength and separation efficiency. The results show that the prepared TA-FeIII/PAN hollow fiber membranes can be applied to separate diesel-in-water emulsion with good performance. The selectivity can be as high as 98%, pure water flux was 87.7 LMH and the emulsion flux was 66.8 LMH under one hour of operation. The antifouling ability of TA-FeIII/PAN hollow fiber membrane was also significantly improved compared to the unmodified membrane.

並列關鍵字

Tannic acid ； Polyacrylnitrile ； Hollow fiber membrane ； Emulsion

參考文獻

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