Carbon Nanotubes in the Removal of Heavy Metal Ions from Aqueous Solution

Carbon nanotubes possess excellent electrical and mechanical properties. These excellent properties make CNTs promising materials for many applications. Because of their large surface areas and the ability to establish p-p electrostatic interactions, CNTs have become a new type of adsorbent due to their outstanding ability to remove various inorganic and organic pollutants from water. Moreover, aft er acid functionalization, the surface functional groups and hydrophobic surfaces of CNTs show strong interactions with both heavy metal ions and organic compounds. Studies have shown that CNTs possess great potential for removing heavy metal ions such as Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, Zn²⁺, etc. The adsorption of heavy metal ions from solution on CNTs has been proven mainly due to the surface functional groups on CNTs, and it is also strongly dependent on the pH of the solution. This chapter focuses on the adsorption capacity of carbon nanotubes. Factors that aff ect the adsorption process of Cd(II), Cr(II), Cu(II), Ni(II), Pb(II) and Zn(II) are reviewed.