<unk> <unk> , also called<unk>  charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed<unk>  to have small, low-volume pores that increase the surface area available for adsorption (which is not the same as absorption) or chemical reactions. Activation is analogous to making popcorn from dried corn kernels: popcorn is light, fluffy, and has a surface area that is much larger than the kernels.<unk>  is sometimes replaced by active. Due to its high degree of microporosity, one gram of<unk>  has a surface area in excess of as determined by gas adsorption. Charcoal, before activation, has a specific surface area in the range of 2.0 - 5.0 m2/g. An activation level sufficient for useful application may be obtained solely from high surface area. Further chemical treatment often enhances adsorption properties.<unk>  is usually derived from waste products such as coconut husks; waste from paper mills has been studied as a source. These bulk sources are converted into charcoal before being<unk> '. When derived from coal it is referred to as<unk>  coal.<unk>  coke is derived from coke.
Activated carbon
Caphosol
Dissolvable tobacco
Chlorofluorocarbon
Mustard gas
Bioactive glass
Podophyllum resin
Carbonated water