Effect of growing CNTs onto bamboo charcoals on adsorption of copper ions in aqueous solution.

One kind of novel hierarchical carbon nanotubes/bamboo charcoal (CNTs/BC) was prepared by CVD growth of CNTs on low-cost bamboo charcoal (BC). The obtained CNTs/BC composites were characterized by SEM and TEM observations. Adsorption of copper ions by CNTs/BC in aqueous solution was investigated. The adsorbed copper species were analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the CNTs/BC composites exhibited higher adsorption capacities toward aqueous copper ions than the pristine BCs and commercial activated bamboo charcoals (ABCs) with a specific surface area of over 1000 m(2) g(-1). The adsorption capacity increases with nanotube growth time. Moreover, nitric acid treatment was used for the oxidation of the carbon surface. The surface functional groups of carbon samples were analyzed by Fourier transform infrared spectroscopy (FT-IR), Boehm's titration method, and zeta potential analysis. It was found that nitric acid treatment for CNTs/BC produced more oxygen-containing functional groups, leading to a higher copper ion adsorption capability than conventional carbon adsorbents under the same treatment condition.