CNT-PVDF复合中空纤维膜的制备及其电辅助抗膜污染性能

Preparation of CNT-PVDF composite hollow fiber membrane and its antifouling performance with electro-assistance

电辅助膜过滤是减缓膜污染的有效方法,但是受限于缺乏稳定性好、机械强度高、制备工艺简单的导电膜。通过在PVDF膜表面真空抽滤CNT制备得到了导电的碳纳米管-聚偏氟乙烯(CNT-PVDF)复合中空纤维膜,然后利用酸化CNT表面羧基与聚乙烯醇的羟基发生交联反应来固定CNT,以提高导电功能层的稳定性。抗污染实验结果表明:单纯膜过滤在5个运行周期内的膜通量衰减72%,反冲洗再生后膜通量为初始通量的58%;而在电辅助下(2 V电压,膜作为阴极),静电排斥作用可以有效降低膜通量衰减速度,减缓膜污染程度,5个运行周期内的膜通量衰减均小于10%,反冲洗再生时能完全恢复膜初始通量。以上研究结果可为推进电辅助缓解膜污染技术的实际应用提供参考。

Electro-assisted membrane filtration is an effective method to mitigate membrane fouling, but it is limited by the lack of conductive membrane which possesses high stability, high mechanical strength and simple preparation process. In this study, the conductive carbon nanotube-polyvinylidene fluoride(CNT-PVDF)composite hollow fiber membrane was prepared by vacuum-filtrating CNT on the PVDF support layer. Then a crosslink reaction occurred between the carboxyl groups on the surface of acidified CNT and the hydroxyl group of crosslinking agent PVA to enhance the stability of the conductive functional layer. The result of antifouling experiment showed that the flux of single membrane filtration decreased by 72% during five operation cycles,and the membrane flux after regeneration only recovered 58% of the initial flux. However, the electrostatic repulsion could effectively slow down the decline speed of membrane flux and mitigate the membrane fouling under the condition of-2 V electro-assistance. The flux decline was less than 10% during five operation cycles.And the membrane flux could be completely recovered after backwash regeneration. The above results provide reference for the practical application of electric-assisted anti-fouling technology.