Abstract
Currently, contamination of water resources due to the discharge of heavy metals is a serious concern worldwide. The challenge to remedy toxic metal-containing waste streams from present or former mining operations, industrial sites, and groundwater is immense. Adsorption is a simple, economical and widely used method which plays an important role in wastewater treatment. It is based on the physical interaction between metal ions and sorbents. Various types of natural and chemically modified sorbents have been applied over the years for the elimination of metal ions in industrial wastewaters. With the development of nanotechnology, nanomaterials are used as the sorbents in wastewater treatment; several researches have proved that nanomaterials are new and effective sorbents for the removal of heavy metal ions from wastewater due to their unique structure properties. The discovery of carbon nanotubes (CNTs) as sorbents and the anticipation of developing novel carbon-based nanomaterials have attracted researchers worldwide. Carbon nanotubes (CNTs) and modified CNTs with chemical treatment are relatively new sorbents due to their unique properties such as chemical stability, mechanical and thermal stability, and the high surface area that have proven very efficient for treating many kinds of trace pollutants specially heavy metal ions. CNTs show high selectivity, regeneration and adsorption capacity for heavy metal ions. This chapter presents a summary of the recent information obtained using batch and column studies (preconcentration factor and limits, sorption capacity, detection limit and kinetics model) and deals with the mechanisms involved during adsorption.