碳量子點/聚醚碸中空纖維薄膜製備與油水分離效能之研究

Study on the preparation and oil/water separation performance of carbon quantum dots/polyethersulfone hollow fiber membrane

李品賢(Pin-Hsien Li)

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(2020年)

https://doi.org/10.6840/cycu202000626

摘要

本研究使用一步法製備碳量子點(Carbon quantum dots, CQDs)/聚醚碸(Polyethersulfone, PES)混合基質中空纖維膜，應用於柴油/水乳化液之分離。研究中，將CQDs分散在2-吡咯烷酮(2-pyrrolidinone, 2P)中，而後加入PES高分子，配製成CQDs/PES鑄膜液，使用乾/濕式紡絲法製備CQDs/PES混合基質中空纖維膜，並且探討紡絲時芯液組成和氣距長度對薄膜結構和油水分離效能之影響。
藉由添加CQDs增加薄膜的親水性，研究結果顯示PES薄膜的水接觸角由未添加CQDs的62.02.7O下降至添加2,500 ppm CQDs的471.1O。PES中空纖維膜的柴油/水(1/99)乳化液透過通量，則由未添加CQDs的39.615.57 LMH上升至添加2,500 ppm CQDs的76.75.05 LMH，為未添加CQDs之PES中空纖維膜通量的兩倍。改變PES中空纖維膜紡絲參數研究發現，將芯液由蒸餾水置換成50 wt.% NMP/H2O和氣距調整為10 cm，使用SEM鑑定發現，中空纖維膜的內表面和外表面結構型態變為鬆散，外表面孔洞尺寸由99.62 nm增加至118.55 nm；而AFM的鑑定結果，中空纖維膜外表面的粗糙度由3.78 nm提高至5.75 nm，油水乳化液透過通量由76.75.05 LMH進一步提升至177.445.54 LMH，而對油的阻絕率仍然維持在99.9%。最後，本研究探討CQDs/PES中空纖維膜進行油水分離操作時的抗垢能力測試，未添加CQDs的PES中空纖維膜經過四個油水抗垢測試的循環，通量為初始通量的56.8%，而添加2,500 ppm CQDs的PES中空纖維膜經過兩個油水抗垢測試的循環，通量為初始通量的77.2%，研究結果顯示製備的CQDs/PES中空纖維膜具優異的通量回復率，適用於油水分離操作系統。

關鍵字

聚醚? ； 碳量子點 ； 油水分離

並列摘要

Carbon quantum dots (CQDs)/polyethersulfone (PES) mixed matrix hollow fiber membranes have been fabricated through a one-step dry/wet spinning method. The membranes were used to separate diesel/water (1:99) emulsion and to improve the oil-water separation performance by varying the CQDs concentration, bore liquid composition, and air gap distance.
The hydrophilicity of PES hollow fiber membranes increased by adding 2500 ppm CQDs which decreased its water contact angle from 62o to 47o and the oil-water flux increased from 39.615.57 LMH to 76.75.05 LMH. Moreover, the study on spinning parameters shows that the inner surface of hollow fiber membrane became loose. The pore size as observed from the FESEM images was found to be enlarged form 99.62 nm to 118.55 nm. The surface roughness of the hollow fiber membranes increased form 3.78 nm to 5.75 nm by using 50 wt.% NMP for bore liquid and 10 cm distance for air-gap as confirmed through AFM analysis. In diesel/water emulsions separation performance, the flux increased form 76.75.05LMH to 177.445.54LMH when the air-gap distance and bore fluid composition was changed and the oil rejection was maintained at 99.9%.
Lastly, the analysis on oil/water anti-fouling properties of CQDs/PES hollow fiber membrane showed that the flux of pristine PES hollow fiber membrane declined to 56.8% while the flux of CQDs/PES hollow fiber membrane only declined to 77.2% upon operating to 4 cycles of oil/water anti-fouling test. The results show that the one-step method to fabricate CQDs/PES mixed matrix hollow fiber membrane is suitable for operating the oil/water emulsion separation system.

並列關鍵字

polyethersulfone ； carbon quantum dot ； oil/water separation

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