The multi-walled carbon nanotubes (MWNTs) were purified by immersing in a 3:1 mixture of concentrated H2SO4 and HNO3, and then were treated with ammonia and citric acid (CA), respectively. The structure and image of MWNTs were measured by Infrared spectrum and electron microscopes. Furthermore, their dispersion properties in aqueous solution were studied. The spectrum results showed that there are many oxygenated functional groups on the surface of the MWNTs, and the amidocyanogen and CA molecules were introduced onto the surface of MWNTs. The results of dispersion experiment illuminated that ...
