碳纳米管径向尺寸对碳纳米管自支撑膜孔隙结构及通量的影响

为了探索碳纳米材料膜在水处理中应用的可能性,本实验选取4种径向尺寸的碳纳米管(Carbon Nanotubes, CNTs),采用压力辅助过滤技术制备CNTs自支撑膜.通过对CNTs自支撑膜的平均孔径、孔径分布及截留分子量(Molecular weight Cut-Off,MWCO)等进行分析,研究了CNTs径向尺寸变化对CNTs自支撑膜孔隙结构的影响.结果表明,CNTs的径向尺寸越小,制备得到的CNTs自支撑膜越趋向于形成小孔径的膜孔,且孔径分布更加均匀,孔隙面积比越高,膜的MWCO越小.单壁碳纳米管(Single-walled carbon nanotube, SWNT)与多壁碳纳米管(Multi-walled carbon nanotube, MWNT)相比,前者更容易形成膜平均孔径更小且孔径分布更均匀的CNTs自支撑膜.膜通量测定结果表明,研究制备的CNTs自支撑膜的通量属于低压膜范围,通量在230～347 L·m~(-2)·h~(-1)·bar~(-1)之间.其中,虽然由径向尺寸较小的CNTs所制备的CNTs自支撑膜的平均孔径更小,但由于其具有更高的孔隙面积比和更小的膜厚度,其纯水通量相对高于由大径向尺寸CNTs制备的CNTs自支撑膜.

Effect of radial diameter on pore structure and water flux of CNT self-supporting membrane

In order to explore the possible application of carbon nanotubes (CNTs) self-supporting membranes in water treatment, CNTs membranes were prepared by pressure-assisted membrane filtration technology with CNTs of four different radial diameters. The mean pore size, pore size distribution and molecular weight cut-off (MWCO) of the four types of CNTs self-supporting membranes were analyzed, and the influence of radial diameter changes on the pore structure of CNTs self-supporting membranes was investigated. The results showed that the smaller the radial diameter of CNTs was, the greater the tendency for CNTs to form membranes with small pore size. Besides, the pore size distribution of CNTs membranes was more uniform and the pore area ratio was relatively higher, which caused a denser nano-network structure and smaller MWCO of CNTs self-supporting membranes. Compared with multi-walled carbon nanotubes (MWNT), it was easier for single-walled carbon nanotubes (SWNT) to form the CNTs self-supporting membranes with an excellent membrane pore structure. The results of membrane flux revealed that the CNTs self-supporting membranes prepared in this study belonged to the range of low-pressure membrane, and their membrane fluxes were between 230~347 L·m^-2·h^-1·bar^-1. Although the average pore size of CNTs self-supporting membranes prepared by CNTs with smaller radial diameter decreased, their pure water fluxes were relatively higher due to their higher pore area ratio and smaller membrane thickness.