“疏松”复合纳滤膜的构筑及其结构与性能调控

复合纳滤膜的渗透通量和截留率的“Trade-off”效应是制约其广泛应用的瓶颈，目前同时提高复合纳滤膜的渗透通量和截留率仍是一项技术挑战。本项目拟通过纳米纤维支撑的具有“疏松”结构的超薄亲水荷电功能阻隔层提供高渗透性；利用复合膜的荷电表面阻隔层组装聚电解质达到饱和时的孔径缩小以及同种电荷排斥作用（唐南效应），提高复合膜的截留率，减少膜污染。这种双层结构协同作用，能够使复合膜的渗透通量和截留率都保持在较高水平。通过膜材料的设计及功能阻隔层的微孔构筑制备“疏松”复合纳滤膜，系统地研究功能阻隔层微结构形成机制，探索表面功能阻隔层微观结构-筛分尺寸-过滤性能之间相互关系及调控方法，探讨双层结构协同作用和相应的有机污染物去除机制以及抗膜污染机制，为高性能新型高分子分离膜的研究提供理论依据和技术支持。

The wide application of composite nanofiltration membrane is greatly restricted by the “Trade-off” effect between the rejection rate and permeate flux, and it is still a challenge to enhance both permeability and selectivity performance of nanofiltration membranes at the same time. In this project an ultrathin charged barrier layer will be constructed on nanofibrous substrate to provide high permeability of the composite membrane; The donnan effect, repulsive interaction of like charges when the adsorption of charged barrier layer to polyelectrolyte reaches saturation, is taken advantage of to increase the rejection ratio and decrease the membrane fouling due to the decreased pore size and enhanced “Donnan Effect”. Based on the point, two-tier thin film nanofibrous composite membrane with “loose” structure was constructed for wastewater treatment by taking advantage of membrane fouling in this project. The bother of conventional composite membranes suffering from severe membrane fouling and low permeability can be solved by the two-tier structure coordinated effect. Herein, the material design and the formation mechanism of microstructure during the nanofibrous composite membrane preparation will be studied systematically. The rules and the control methods of the relationship between the microstructure, the sieving pore size and filtration performance of the composite membranes will be explored through the design and adjustment of the microstructure of the composite membranes. The coordinated effect of two-tier structure, the separation and antifouling mechanism to wastewater will also be investigated. It is firmly believed that the study will provide important theoretical basis and technical support for the development of high performance novel polymer separation membranes.