A carbon nanotube filter, a use for a carbon nanotube filter and a method of forming a carbon nanotube filter. The method including (a) providing a carbon source and a carbon nanotube catalyst; (b) growing carbon nanotubes by reacting the carbon source with the nanotube catalyst; (c) forming chemically active carbon nanotubes by forming a chemically active layer on the carbon nanotubes or forming chemically reactive groups on sidewalls of the carbon nanotubes; and (d) placing the chemically active nanotubes in a filter housing.