The working of active carbon is based on a very large surface area with a fine microstructure and a large number of very fine pores. Commercially available types of activated carbon have an internal surface area of 500 to 2000 m² / g. The activated carbon particles (carbon atoms) exert an attraction to gaseous or liquid particles (molecules) that surround the active carbon or flow through. The strength of this attraction force, is determined by a number of factors, for example, by the shape and mass of the molecules that are in contact with the activated carbon. Because not all molecules are as strongly attracted and retained (adsorbed) by the activated carbon, it is possible to remove one or more unwanted substances from air, gas or liquids.