Abstract
Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical composition and structure. Extremely high aspect ratios, molecularly smooth hydrophobic graphitic walls, and nanoscale inner diameters of CNTs give rise to the peculiar adsorption properties. This review provides an overview on CNTs functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems. A summary of recent information obtained using batch studies and deals with mechanisms involved during the adsorption have been reported. Adsorption capacity of CNTs has been observed by numerous investigators to increase substantially after functionalization/treatment with oxidizing agents such as NaOCl, HNO3, H2SO4, KMnO4, and other oxidizing agents. However, the selectivity of CNTs toward metal ions depends on both the route used for their synthesis and reagent employed for purification. The recovery of metal ions and the regeneration of CNTs have minimal impact on their performance. Desorption of metal ions from saturated adsorbent can be achieved using acid/base elution.