基于纳米协同效应的高效光催化抗污染纳米复合膜材料的制备及性能研究

The tendency of aggregation, serious leaching and single antifouling property are three of the most challenging issues of the traditional nanocomposite membranes. In order to address the challenge, the preparation and the performance of novel antifouling nanocomposite membranes will be investigated in the project. Titanium dioxide (TiO2) is a special semiconductor with desirable hydrophilicity and photocatalytic properties. Silver nanoparticle (Ag) is an excellent biocide. In the present study, TiO2 is modified by silver nanoparticles in different ratios and methods to obtain series of TiO2-Ag nanocomposites with improved performance. Also the TiO2-Ag nanocomposites will be introduced into various membrane materials to fabricate antifouling membranes. The effects of different morphologies of TiO2-Ag nanocomposites on the microstructure, chemical composition, filtration and comprehensive antifouling performances will be systematically investigated. Also, the morphology observation and the silver leaching tests will be carried out to study the dispersion, stability and durability of nanocomposite membranes. By the study of these scientific questions, we will clarify the relationship between antibacterial, photocatalytic property and antifouling performance. This proposal will provide a new idea for the development of nanocomposite materials and novel high performance antifouling membranes.

针对传统的纳米复合膜存在纳米粒子易团聚、释放流失严重及抗污染效果单一的问题，本项目提出新型抗污染纳米复合膜的研制及其性能研究。纳米二氧化钛具有良好的亲水性和光催化性能，而纳米银是优异的杀菌剂。将纳米银以不同的比例、不同的方式对二氧化钛进行修饰和负载制备高性能二氧化钛载银系列纳米复合物，并以此为添加剂制备抗污染膜材料。剖析不同结构的纳米复合粒子在膜材料中的分散效果，对复合膜表面微观形态及化学结构、过滤及综合抗污染性能的影响。研究纳米粒子的负载和组合对其释放行为的影响。通过这些科学问题的研究，阐明新型抗污染纳米复合膜材料抗菌性、光催化效应和抗污染性能之间的构效关系，为纳米复合材料及新型高性能抗污染膜材料的研制提供新的思路。

耐温性差和膜污染一直是膜分离技术大规模应用过程中面临的瓶颈。本研究以提高有机膜热稳定性和膜污染控制为出发点，利用光还原法制备新型石墨相氮化碳（g-C3N4）载银系列纳米复合材料，并通过相转化法将其引入到有机聚醚砜中，构建g-C3N4/Ag/PES纳米复合膜。研究表明，光还原法在不改变g-C3N4晶型的情况下可以有效地将纳米银负载在石墨相氮化碳（g-C3N4）表面，减少了纳米银的团聚。纳米银的掺杂有效抑制光生电子(e-) 和空穴(h+)的复合，提高g-C3N4在可见光下光催化降解染料性能的同时赋予其优异的抗菌性。相转化法制备石墨相氮化碳/聚醚砜（g-C3N4/PES）纳米复合膜，g-C3N4的添加在一定时间和温度内显著改善复合膜的耐热性能，同时在光催化作用下提高了复合膜的抗污染性能。共混相转化制备石墨相氮化碳载银/聚醚砜（g-C3N4/Ag/PES）纳米复合膜，g-C3N4/Ag的添加提高了复合膜表面亲水性和孔隙率，改善了断面指状孔结构的贯通性，促进海绵层大孔的形成。在不影响蛋白质截留率的情况下使膜的纯水通量提高至268 L m-2 h-1；可见光照射下，纳米复合膜光催化染料降解率随着g-C3N4/Ag添加量的增加而提高；抑菌环和CFU计数实验表明纳米银的负载掺杂使g-C3N4/Ag/PES纳米复合膜展现出优异的抗菌性；蛋白质模拟污染物过滤实验、通量恢复率（FRR）和过滤阻力参数的计算均说明，复合膜的光催化性能可以有效降解吸附在膜孔中的污染物，促进污染物从膜表面脱落，提高了复合膜的综合抗污染性能。本课题具有开发新型纳米复合材料，解决膜技术应用难题的重要意义，能为社会带来显著的经济和环境生态效益，具有广泛的应用前景。