Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Activated is sometimes substituted with active. Due to its high degree of microporosity, one gram of activated carbon has a surface area in excess of 3,000 m2 (32,000 sq ft) as determined by gas adsorption. An activation level sufficient for useful applications may be obtained solely from the high surface area. Further chemical treatment often enhances adsorption properties. Activated carbon is usually derived from charcoal. When derived from coal it is referred to as activated coal. Activated coke is derived from coke.
Activated carbon is used in methane and hydrogen storage, air purification, solvent recovery, decaffeination, gold purification, metal extraction, water purification, medicine, sewage treatment, air filters in gas masks and respirators, filters in compressed air, teeth whitening, production of hydrogen chloride in dark and many other applications.
Activated carbon is used to treat poisonings and overdoses following oral ingestion. Tablets or capsules of activated carbon are used in many countries as an over-the-counter drug to treat diarrhea, indigestion, and flatulence. However, activated charcoal shows no effect on intestinal gas and diarrhea, and is, ordinarily, medically ineffective if poisoning resulted from ingestion of corrosive agents such as alkalis and strong acids, iron, boric acid, lithium, petroleum products, or alcohol. Activated carbon will not prevent these chemicals from being absorbed into the human body. It is on the World Health Organization’s List of Essential Medicines, the safest and most effective medicines needed in a health system.