薄膜表面自組裝塗布聚乙二醇共聚高分子之抗污改質及其水處理應用

在過濾程序中，薄膜污塞現象是目前無法避免的情形，一旦薄膜發生污塞，污塞物會導致薄膜操作效能降低，並且縮短薄膜使用的壽命。然而，造成污塞的原因大多為疏水性的膜材表面所引起，因此許多學者近年來從事薄膜相關改質研究，透過膜面親水性的改質來降低污塞的問題。為了改善薄膜的親水性，分子鏈段中含有醚基的聚乙二醇衍生高分子為理想使用的抗污塞材料。本研究中，將商業疏水性聚偏二氟乙烯（Poly(vinylidene fluoride), PVDF）薄膜進行表面改質，透過物理性塗布法將共聚高分子PSx-b-PEGMAy塗布於膜面上。首先，使用單體苯乙烯（styrene）和聚（乙二醇）甲醚甲基丙烯酸酯（poly(ethylene glycol) methyl ether methacrylate, PEGMA），利用原子轉移自由基聚合法進行不同PS/PEGMA莫耳比例之共聚高分子合成，並在核磁共振光譜儀的鑑定結果顯示，共聚高分子成功地進行製備。接著，將共聚高分子以不同濃度塗布於PVDF表面上，發現塗布密度和表面接觸角會隨著分子量的上升而下降。針對PVDF塗布後的抗污特性，將塗布膜依序進行靜態蛋白質吸附和細菌沾黏實驗。在靜態蛋白質吸附中，使用牛血清蛋白（bovine serum albumin, BSA）和溶菌酶（lysozyme, LY）當作測試蛋白質，結果發現當PS/PEGMA莫耳比例為1.86（PS55-b-PEGMA30）時有最佳的蛋白質吸附阻力，與PVDF相較之下，BSA和LY的蛋白質相對吸附量分別下降75%和85%。另外，在細菌沾黏實驗中，使用表皮葡萄球菌（Staphylococcus epidermidis, S. epidermidis）和大腸桿菌（Escherichia coli, E. Coli）當作測試細菌，利用掃描式電子顯微鏡拍攝細菌沾黏的結果，發現PS55-b-PEGMA30塗布膜有效抵抗細菌的沾黏，並且在塗布濃度為0.5 mg/mL時，膜表面上沒有發現細菌沾黏的情形，達到100%的抗菌沾黏效果。最後，將PS55-b-PEGMA30塗布膜進行掃流過濾和薄膜生物反應槽（Membrane bioreactor, MBR）操作，從掃流過濾結果發現在BSA溶液過濾清洗後，PVDF的純水通量回復率（flux recovery ratio, FRR）會逐次降低，並分別為60%、30%和25%；然而，塗布膜的FRR從第1循環的77%降至第2循環的67%後，即沒有繼續下降的情形。在MBR操作過程中，塗布膜與PVDF和商業親水膜比較下，塗布膜在各循環過濾後，由透膜壓（transmembrane pressure, TMP）可知膜面上的污塞物都可以完全清洗去除，並且可以達到較長時間的操作。

關鍵字

聚乙二醇；抗污塞；薄膜生物反應器；掃流過濾；薄膜塗布

並列摘要

The fouling phenomenon during membrane filtration is unavoidable circumstances. Once the membrane fouling occurred, the foulant on the membrane surface will result in reducing the operational effectiveness and shorting the life time of membrane usage. However, most fouling problems were induced by hydrophobic surface. The membrane surface was modified to be hydrophilic so as to reduce the fouling problem effectively. Hence, ether group in poly(ethylene glycol) (PEG)-based materials are the useful method of surface functional moiety with anti-fouling characteristics. Purposes of this study were emphasized the commercial hydrophobic PVDF membrane surface modified with PSx-b-PEGMAy diblock copolymer via dip coating processes. Results showed that the coating density and surface contact angle would be decreased with increasing molecular weight. The best protein resistant membrane named PS55-b-PEGMA30 was coated with the molar ratio of 1.86 (PS/ PEGMA). Compared to the virgin PVDF, the relative protein adsorption of BSA and LY were decreased 75% and 85%, respectively. In addition, there were no barteria on the membrane surface with coated concentration about 0.5 mg/mL. The PS55-b-PEGMA30-coated membrane owned better anti-fouling properties for the cross-flow filtration and MBR systems even if the long-time operation.

並列關鍵字

cross-flow filtration ； membrane bioreactor ； dip coating ； PEG ； antifouling

參考文獻

Abuchpwski, A., T. van Es, N. C. Palczuk and F. F. David, “Alteration of Immunological Properties of Bovine Serum Albumin by Covalent Attachment of Polyethylene Glycol,” Biol. Chem, 252, 3578-3591 (1977).

Ahmad, A. L. and N. A. H. Hairul, “The effect of protein–membrane interactions on filtration behavior in forced-flow electrophoresis of protein solutions,” Sep. Purif. Technol., 61, 384-390 (2008).

Ang, W. S. and M. Elimelech, “Protein (BSA) fouling of reverse osmosis membranes: Implications for wastewater reclamation,” J. Membr. Sci., 296, 83-92 (2007).

Babu, P. R. and V.G. Gaikar, “Membrane characteristics as determinant in fouling of UF membranes,” Sep. Purif. Technol., 24, 23-34 (2001).

Chan, R. and V. Chen, “The effects of electrolyte concentration and pH on protein aggregation and deposition: critical flux and constant flux membrane filtration,” J. Membr. Sci., 185, 177-192 (2001).

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薄膜表面自組裝塗布聚乙二醇共聚高分子之抗污改質及其水處理應用

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