Multi wall carbon nanotube surface modification and adsorption performance of Cu~(2+)

摘要

Mixed acid processed Multi-walled carbon nanotubes (MWCNTs) were used as adsorbent to adsorb Cu~(2+) in artificial wastewater in this. In this study, the effect factors of Cu~(2+) adsorption capacity, such as initial concentration of Cu~(2+), absorbent contact time and dosage, etc were investigated respectively in the solution at neutral pH. The results show that population of -OH is increased on surface of mixed acid processed MWCNTs; and at condition of 30°C, pH 6, as the increase in concentration and contact time, there is an increase in adsorption capacity of two adsorbents(processed and unprocessed), and the Cu~(2+) adsorption rate increased with the increase in adsorbent dosage. In addition, the considered adsorption capacity change was obtained when processed MWCNTs was used. Carbon nanotubes, also called bucky tube, are fuller carbon system. The 1st carbon nanotubes were discovered by Iijima(PHD, Electron microscopy experts, NEC corp., Japan) through high resolution electron microscopy in 1991[1]. They are tube body made up of grapheme slices seamlessly and mid-hollowly, each tubular layer is made up of carbon hexagon structure, similarly with graphite structure. The carbon atom of sp~2 hybridization is given priority, the curvature of the pipe in some carbon atoms hybrid way as the sp~3 hybridization, its diameter in 1 ～ 30 nm. Special structure of carbon nanotubes attracted great concern from experts of physics, chemistry, materials, electronics, and other fields, and then a lot of research work followed up. Carbon nanotubes have hydrophobic surface, larger specific surface area, strong reaction activity and abundant pore structure, so they have good adsorption capacity to heavy metal ions[2-3]. Further study showed that the adsorption performance mainly depends on their surface functional group [4] or complex, and through a change of their surface structure, and then the adsorption capacity can be improved. At present, liquid phase oxidation method is commonly used to improve the adsorption capacity of carbon nanotubes to heavy metal ions by inserting active functional groups such as hydroxyl, etc to the carbon nanotube surface. In this experiment concentrated sulfuric acid and nitric acid were used to oxidize MWCNTs in liquid phase. The effect factors of Cu~(2+) adsorption capacity, such as initial concentration of Cu~(2+), absorbent contact time and dosage, etc, were discussed respectively in the solution at pH 6.