Carbon nanotubes in environmental remediation - A global perspective

Carbon nanotubes have been identified as potential sorbents for the remediation of various organic and inorganic pollutants over the years. These materials have even demonstrated a superior adsorption capability to that of activated carbon. This chapter highlights some of the key observations made in the use of carbon nanotubes for the extraction of contaminants from aqueous solution over the past decade. The studies conducted to date are critically reviewed where both the advantages and shortcomings of using carbon nanotubes in environmental remediation are examined. Contradictions in the literature are discussed. Some case studies where carbon nanotubes have been used for the removal of key pollutants such as Cr(VI) and Hg(II) are highlighted. Modifications to the nanotube surface for the selective extraction of a target pollutant also features as a key topic in this chapter. In the regard, the effect of functional groups and the introduction of various heteroatoms is discussed. Other modifications such as the effect of acid and base treatment and the dopant concentrations are also examined. The impact of the studies conducted to date on the large-scale industrial usuage of carbon nanotubes in water treatment is critically discussed. Lastly, the chapter concludes with a discussion on aspects that are lacking in the use of carbon nanotubes for environmental remediation and future research perspectives are discussed.