Removal of Heavy Metal Ions from Wastewater by Carbon Nanotubes (CNTs)

Advent of nanotechnology has introduced us with new generation of adsorbents such as carbon nanotubes (CNTs) which have aroused widespread attention due to their outstanding ability for the removal of various inorganic and organic pollutants from large volumes of water. This article reviews the practical feasibility of various kinds of raw and surface modified carbon nanotubes for adsorption of heavy metal ions from wastewater. Further, properties of CNTs (adsorption sites), characterization of CNTs (pore volume, BET surface area, surface total acidity, surface total basicity) and solution properties (ionic strength, effect of pH) are explained very well. The adsorption mechanisms are mainly attributable to chemical interactions between metal ions and surface functional groups of the CNTs. The adsorption capacity increases to greater extend after functionalization i.e. surface oxidation of CNTs. Future work on developing cost effective ways of production of CNTs and analyzing its toxicity are recommended.