“枝干”形貌多尺度、多层次非织造复合材料对超细颗粒过滤性能研究

Nonwoven filter materials have received a great deal of attention in air filtration field due to its advantages, such as low cost, good filtering effect. However, filtering mechanism based on sieving always results in the contradiction between the trapping efficiency of ultrafine particles and the gas flux. To achieve high filtering efficiency for ultrafine particles (less-than 0.1μm) and high air permeability, we plan to build multi-scale, multi-level composite filter materials. We will prepare the functionalized multi-walled carbon nanotubes-chitosan (f-MWCNTs-CS) nanofiber membranes with branch-like structure via using high-pressure assisted spraying or electrospraying method as the function layer, and polypropylene (PP) melt-blown nonwoven fabrics will be taken as support layer. In this project, we will study the coupling between the parameters of spraying method and the morphology of f-MWCNTs-CS function layer, probe the effects of the morphology of f-MWCNTs-CS/PP filter materials on the filtering performance for ultrafine particles, master the method of controlling the composite morphology, and reveal the filtration mechanisms of composite filter materials. This project will provide the theoretical and experimental foundation of fabricating the nonwoven filter materials, and have great value in theory and practical significance to promote the development of efficient, low-cost and environmentally-friendly air pollution treatment technology.

非织造过滤材料以其成本低、过滤效果好等优势在空气过滤领域引起了广泛关注，但其基于筛分为主的过滤机制容易造成“对超细颗粒拦截效率与气体通量相互制约”的问题。本项目拟通过静电纺丝-同步喷射技术制备具有“枝干”形貌的超薄碳纳米管-壳聚糖(f-MWCNTs-CS)复合膜作为功能层，以聚丙烯(PP)熔喷非织造材料为支撑层，构建多尺度、多层次的复合过滤材料，实现针对超细颗粒(粒径＜0.1μm)的高过滤效率与高透气量的协同设计。研究静电纺丝-同步喷射技术的工艺条件与f-MWCNTs-CS功能层结构、形貌的耦合关系，探索f-MWCNTs-CS/PP复合过滤材料的结构、形貌对超细颗粒过滤性能的影响规律，掌握复合过滤材料结构、形貌的调控方法，并揭示其对超细颗粒的过滤机制。项目将丰富非织造复合过滤材料结构设计的理论依据和实验基础，对于促进高效、低成本及环境友好的大气污染治理技术发展具有重要的理论价值和现实意义。

针对纳米纤维膜作为过滤材料存在的过滤精度低和通量受限的问题，本项目分别采用亲水性材料涂覆、无机纳米颗粒表面修饰以及碳纳米管表面嵌入组装等方式提高了纤维膜过滤材料的过滤和渗透性能。研究了在亲水改性的聚丙烯腈（PAN）纳米纤维膜表面引入不同浓度壳聚糖(CS)的过渡层后，PAN/CS复合膜性能的演化规律及其复合膜分离、渗透性能的增强机制；探索并优化半包覆结构的二氧化钛/介孔碳纳米纤维复合膜的制备工艺，分析了复合膜对有机染料（罗丹明B）的高效催化特性。在上述研究成果的基础上，分别采用三种不同方法（静电喷涂、高压喷枪以及直接共混）将具有高比表面积的羧基化多壁碳纳米管(f-MWCNTs)引入电纺CS纳米纤维膜中，构建出一种兼具高通量及高过滤效率的“枝干”结构f-MWCNTs/CS复合膜，并探究了其对有机染料及固体颗粒物的过滤性能及其影响机理。