This paper presents the function and application of carbon nanotubes and its derivatives (functionalized carbon nanotubes) in various fields. Carbon nanotubes applications in oil-spill, dye-adsorption, pesticides remediation, heavy and toxic metals absorptions, cancer diagnosis therapy, removal of toxic by-products and hydrogen storage are major fields of research. Extraordinary properties of carbon nanotubes make it a useful material for all of the above applications. The adsorption properties of carbon nanotubes make it a commendable material in surface chemistry. Thus, carbon nanotubes based materials provide a huge thrust to the pollutant absorbent industry and semiconductor devices. Based on the application of carbon nanotubes in controlling different pollutants by utilizing its adsorbent properties, this paper stresses upon the useful applications of carbon nanotubes in the context of adsorption of pesticides, herbicides, dyes, oil spill, toxic metals, hydrogen storage and cancer diagnosis.