兩性離子碳量子點/醋酸纖維素/熱塑性聚氨酯 管狀膜製備與應用於螯合超過濾之研究

工業革命使人類文明快速地發展，隨之而來的是資源短缺以及水資源的匱乏。人們開始反思永續發展的重要性，並對有著節約能源與循環再利用特質的技術進行研究，在此當中，薄膜分離程序是一項足以承載此重任的技術。薄膜分離技術即以薄膜為核心，在本研究中採用高分子混摻的方式製備管狀膜，應用於螯合超過濾(chelating ultrafiltration)，進行含重金屬廢水處理。將醋酸纖維素(cellulose acetate, CA)以及熱塑性聚氨酯(thermoplastic polyurethane, TPU)混摻後，改變製備薄膜時的成膜機制，進而控制薄膜結構，使薄膜效能得以提升。而後添加不同碳量子點進行效能的比較，最終目的為製備具有高效能且高穩定性的管狀膜。本研究首先探討CA與TPU混摻比例對薄膜成膜機制之影響，研究結果發現，隨著CA/TPU中TPU混摻比例的提升，成膜動力學以及成膜熱力學皆顯示，混摻TPU有助於薄膜巨型孔洞結構出現與成長，巨型孔洞的出現使薄膜質傳阻力下降，導致薄膜通量提升。在CA混摻TPU時，由於分子間氫鍵的產生，使CA不易受到鹼性環境的影響，並在其中透過CA/TPU混摻比例的變化，選擇出具有最佳穩定性的薄膜。研究發現，CA/TPU以80/20 (w/w%)混摻(80CA20TPU)，配置成13 wt%鑄膜液，紡製成之管膜具最適性質。由於碳量子點(carbon quantum dots, CQDs)上有許多可反應性官能基，透過1-(3-二甲基氨基丙基)-3-乙基碳二亞胺鹽酸鹽(1-(3-Dimethyl aminopropyl)-3-ethylcarbodiimide hydrochloride, EDC)，將EDC接枝於碳量子點，形成帶有三級胺基團的改質碳量子點(tertiary amine quantum dots, TQDs)。並透過1,4-丁烷磺內酯(1,4-Butanesultone, 1,4-BS)開環，使三級胺結構兩性離子化，形成更親水的兩性離子碳量子點(zwitterionic carbon quantum dots, ZQDs)，而後將不同量子點加入鑄膜液中進行CA/TPU管狀膜改質。在螯合複合超過濾的銅離子測試中發現，添加不同量子點的薄膜其通量皆高於未改質之薄膜並且截留率與未改質薄膜保持一致。未改質管膜(80CA20TPU)的通量與螯合銅截留率為437.536.9 LMH與95.31.3%，添加ZQDs的管膜通量與螯合銅截留率則分別為622.727.3 LMH與95.51.6%，主要原因為多孔的表面以及親水性造成通量的提升。於大腸桿菌(Escherichia coli, E.coli)貼附實驗與牛血清蛋白(Bovine serum albumin, BSA)靜態吸附測試中，添加兩性離子碳量子點之薄膜(ZQDs-M)，藉由親水性的提升，使薄膜具有抗沾黏以及抗菌效能。由BSA動態測試中能觀察到，ZQDs-M與未改質薄膜(80CA20TPU)相比之下，由於親水性的提升，ZQDs-M具有88.84%的通量回復率以及77.86%的可逆結垢率，而不可逆結垢率則較小，僅有11.16%。證明ZQDs-M具有抗沾黏以及抗菌效能外，在BSA動態測試中也具有較好的穩定性。將本研究所製備的ZQDs-M管狀膜與其他重金屬分離研究文獻比較，保持著一定的截留率且有著最高的通量外，此研究所需添加劑含量與其他需要添加劑的處理程序相比，是當中所需含量最低的，顯示出管狀膜具有高效的重金屬水處理的分離效能。

關鍵字

兩性離子碳量子點；管狀膜；螯合超過濾；抗沾黏

並列摘要

Industrial revolution has made the rapid development of human civilization, but it caused shortage of resources and water. Human have begun to reflect on the importance of sustainable development and focused on research of possible ways to save energy, in which the membrane separation process is proven to carry out the task. Membrane separation is a technology that primarily uses a membrane. In this study, tubular membranes are prepared through polymer blending and used in chelating ultrafiltration to treat wastewater containing copper heavy metal. By blending cellulose acetate (CA) and thermoplastic polyurethane (TPU), the membrane formation was regulated to control the morphology and improve the membrane performance. Then, different quantum dots were added to the membrane and compared their performance to achieve the goal of preparing tubular membrane with high efficiency and stability. This study first discusses the effect CA and TPU blending ratio on membrane formation and the results of showed that as the TPU blending ratio is increased, the kinetics and thermodynamics behavior showed that blended TPU would let the formation and growth of macrovoids morphology. The macrovoids morphology decreases the membrane mass transfer resistance, which lead to the enhancement of membrane pure water flux. Moreover, the CA membrane blended with TPU improved its stability in alkaline environment due to the intermolecular hydrogen bonding, and the 80CA20TPU membrane have shown to have the optimized stability. Carbon quantum dots (CQDs) was modified through reacting 1-(3-dimethylaminopropyl)-3-ethylcarbondiimide hydrochloride (EDC) with carboxylic groups of CQDs, forming the modified CQDs with tertiary amine groups (TQDs). Then, zwitterionic carbon quantum dots (ZQDs) were prepared by ring-opening reaction of 1,4-butane sultone (1,4-BS) with the tertiary amine groups of TQDs. The three different quantum dots were added into the casting solution to modify the 80CA20TPU tubular membranes. It was found that the flux of membranes modified with three different quantum dots is higher than unmodified membrane, while the chelated copper rejection is at the same level. Specifically, the pure water flux and chelated copper rejection of the unmodified membrane (80CA20TPU) were 437.5 ± 36.9 LMH and 95.3 ± 1.3%, respectively and ZQDs-M were 622.7 ± 27.3 LMH and 95.5 ± 1.6%, respectively. The improvement in performance can be attributed to more porous surface and increased surface hydrophilicity. In the adsorption test using Escherichia coli (E. coli) and bovine serum albumin (BSA), ZQDs-M membrane have highest antifouling and antibacterial property due to the improved surface hydrophilicity. According to dynamic ultrafiltration experiment using BSA, the flux recovery ratio of ZQDS-M is 88.84%, the reversible fouling ratio is 77.86%, and the irreversible fouling ratio is only 11.16%, which is due to the improvement of membrane surface hydrophilicity. It showed that ZQDS-M had good antifouling and antibacterial performance and had good flux recovery efficiency. The separation performance of ZQDs-M was compared to other reported in literature in separating copper heavy metal. It shows that ZQDs-M have similar rejection and have the highest flux compared with other, indicating that the ZQDs-M have high efficiency in heavy metals wastewater treatment.

並列關鍵字

zwitterion carbon quantum dots ； tubular membrane ； chelating ultrafiltration ； anti-fouling

參考文獻

[1] B. Sivakumar, Water crisis: from conflict to cooperation—an overview,Hydrological Sciences Journal 56 (2011) 531-552.

Google Scholar

[2] M. Ait-Kadi, Water for development and development for water: realizing the sustainable development goals (SDGs) vision, Aquatic Procedia 6 (2016) 106-110.

Google Scholar

[3] M. Mulder, J. Mulder, Basic principles of membrane technology, Springer Science & Business Media, 1996.

Google Scholar

[4] S.K. Hubadillah, M.H.D. Othman, T. Matsuura, A.F. Ismail, M.A. Rahman,Z. Harun J. Jaafar, M. Nomura, Fabrications and applications of low cost ceramic membrane from kaolin: A comprehensive review, Ceramics International 44 (2018) 4538-4560.

Google Scholar

[5] F. Liu , N.A. Hashim, Y. Liu, M.R.M. Abed, K. Li, Progress in the production and modification of PVDF membranes, Journal of Membrane Science 375 (2011) 1–27.

Google Scholar

主題瀏覽