聚醯胺/醋酸纖維素複合中空纖維膜應用於正滲透

The preparation of polyamide/cellulose acetate thin film composite hollow fiber membrane for forward osmosis

方俞運(Yu-Yun Fang)

指導教授 ： 賴君義 ； 李魁然

中原大學/工學院/化學工程研究所/碩士(2019年)

https://doi.org/10.6840/cycu201900560

摘要

正滲透(Forward osmosis, FO)操作程序在廢水處理及海水淡化有許多的研究及應用，本研究在醋酸纖維素(Cellulose acetate, CA)中空纖維薄膜的內表面，以界面聚合方式製備超薄聚醯胺(Polyamide, PA)層，形成聚醯胺/醋酸纖維素超薄複合(Thin-film composite, TFC)中空纖維膜，探討界面聚合條件對所製備之聚醯胺/醋酸纖維素超薄複合中空纖維膜，應用於正滲透操作程序之分離效能影響。
研究中利m-phenylenediamine (MPD)胺單體與不同有機相醯氯單體，trimesoyl chloride (TMC)、isophthaloyl chloride (IPC)、terephthaloyl chloride (TPC)、succinyl chloride (SCC)和有機相溶劑如toluene、xylene、heptane、octane、hexane等進行界面聚合反應，製備聚醯胺層，並探討不同有機相單體與溶劑，對於聚醯胺/醋酸纖維素超薄複合中空纖維膜正滲透效能的影響。此外，界面聚合時水相及有機相溶液於醋酸纖維素中空纖維膜內腔的流速變化，對於聚醯胺/醋酸纖維素超薄複合中空纖維膜正滲透效能的影響亦進行探討。結果顯示，在水相溶液中使用單體MPD及溶劑為水，流速使用1 ml/min與有機相中使用單體為TMC及溶劑為toluene，流速使用5 ml/min時具有最佳正滲透效能，水通量為27.98±0.89 LMH，鹽逆擴散通量為1.08±0.25 gMH。
接著將聚醯胺/醋酸纖維素超薄複合中空纖維膜內腔，以1,3-diamino-2-propanol (DAPL)水溶液流通，利用DAPL具有OH基團與界面聚合殘餘之醯氯基團進行反應，使DAPL接枝在聚醯胺層上。從FE-SEM鑑定分析顯示，DAPL的接枝對於聚醯胺層的厚度並沒有影響。由AFM、XPS、WCA鑑定分析顯示，隨著DAPL濃度增加，聚醯胺/醋酸纖維素超薄複合中空纖維膜內表面變得較平滑，粗糙度降低；由於OH基團增加，薄膜表面親水性增加。使用DI water作為進料液、2M NaCl作為汲取液，在PRO mode下進行FO操作測試，結果以0.2 wt% DAPL改質的聚醯胺/醋酸纖維素超薄複合中空纖維膜，具有最高的水通量(30.6±1.60 LMH)，以及低的鹽逆擴散通量(1.02±0.49 LMH)。此外，使用3.5 wt% NaCl作為進料液，2M NaCl作為汲取液的海水淡化測試中，此改質中空纖維薄膜具有6.31±1.20 LMH之水通量。使用界面聚合法製備聚醯胺層並利用DAPL接枝，可以有效地降低內部濃度極化(Internal Concentration Polarization, ICP)效應，使薄膜具有高的水通量及低的鹽逆擴散通量，因此，本篇薄膜應用在廢水處理或海水淡化上是具有潛力的。

關鍵字

醋酸纖維素 ； 中空纖維膜 ； 正滲透 ； 界面聚合

並列摘要

Forward osmosis (FO) receives intensive studies for various potential applications such as wastewater treatment and seawater desalination. In this study, polyamide (PA)/cellulose acetate (CA) thin-film composite (TFC) hollow fiber (HF) membranes were fabricated for the FO process.
This study used m-phenylenediamine (MPD) with different organic phase acyl chloride monomers such as trimesoyl chloride (TMC), isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), succinyl chloride (SCC) and organic phase solvents such as toluene, xylene. heptane, octane, hexane, etc. were interfacial polymerization to prepare PA layer, and the effects of organic phase monomers and solvents on the FO performance of PA/CA TFC HF membrane were investigated. In addition, the effects of the aqueous solution and organic phase solution flow rate in the lumen of the CA HF membrane during the interfacial polymerization on the FO performances of the prepared PA/CA TFC HF membrane were also discussed. The results showed that the flow rate of the aqueous phase solution was 1 ml/min and the organic monomer solution of TMC/toluene with the flow rate of 5 ml/min had the best FO performance, and the water flux and reverse salt flux were 27.98±0.89 LMH and 1.08 ± 0.25 gMH, respectively. Next, the lumen of the PA/CA TFC HF membrane was modified by using 1, 3-diamino-2-propanol (DAPL) aqueous solution. FE-SEM analysis showed that the grafting of DAPL had no effect on the thickness of the PA layer. The identification analysis by AFM, XPS and WCA showed that as the DAPL concentration increased, the inner surface of the PA/CA HF membrane became smoother, roughness decreased, and surface hydrophilicity increased.
Using DI water as a feed solution and 2M NaCl as a draw solution, the FO operation test was carried out in PRO mode. As a result, the PA/CA HF membrane modified with 0.2 wt% DAPL had the highest water flux (30.6 ± 1.60 LMH) and low reverse salt flux (1.02 ± 0.49 LMH). In addition, the modified hollow fiber membrane had a water flux of 6.31 ± 1.20 LMH in a seawater desalination test using 3.5 wt% NaCl as a feed solution and 2 M NaCl as a draw solution.
Preparation of PA layer by interfacial polymerization and grafting with DAPL can effectively reduce the internal concentration polarization (ICP), so that the membrane has high water flux and low reverse salt flux. The membrane prepared in this study has potential in wastewater treatment or desalination.

並列關鍵字

cellulose acetate ； hollow fiber membranes ； forward osmosis ； interfacial polymerization

參考文獻

[1] N.L. Le, S.P. Nunes, Materials and membrane technologies for water and energy sustainability, Sustainable Mater. Technol., 7 (2016) 1-28.

[2] M. Mulder, Basic principles of membrane technology, Springer Science & Business Media, The Netherlands, 2012.

[3] N. Sperelakis, Cell physiology source book: essentials of membrane biophysics, Elsevier, 2012.

[4] G.T. Gray, J.R. McCutcheon, M. Elimelech, Internal concentration polarization in forward osmosis: role of membrane orientation, Desalination, 197 (2006) 1-8.

[5] S. Phuntsho, H.K. Shon, S. Hong, S. Lee, S. Vigneswaran, J. Kandasamy, Fertiliser drawn forward osmosis desalination: the concept, performance and limitations for fertigation, Rev. Environ. Sci. Bio/Technol., 11 (2012) 147-168.