Activated Charcoal & Activated Carbon: Definition, Production, and Use
Activated charcoal (also called activated carbon) is a type of processed carbon. Unlike ordinary charcoal (for example, that which is used in barbeques), activated charcoal is extremely porous and contains no organic residues. Because it is so porous, activated carbon has a very large internal surface area. Its porosity makes it very absorbent, therefore it is widely used in air and water filtration systems, as an antidote to poisons ingested by people and animals, in laboratory purification and testing processes, and it has industrial applications as well.
Charcoal is created by burning organic, carbon-containing materials, such as bone, wood, or other plant matter. It becomes activated charcoal by being burned in an oxygen-free environment at a temperature between 600 and 900 degrees Celsius, by being heated with carbon dioxide, oxygen, or steam to approximately 1,000 degrees Celsius, or by a combination of these two processes. These processes remove any non-carbon residue and produce the porous internal microstructure. One gram of activated carbon can have up to 1,200 square feet of internal surface area. Activated carbon is effective as a filter for organic chemicals because it is an excellent medium for both adsorption (where the chemical interacts with the surface of the carbon) and absorption (where the chemical is incorporated into the carbon’s surface structure).
Some everyday uses of activated charcoal are in air and water filtration systems. A replaceable activated carbon filter removes toxic organic chemicals and compounds and is changed regularly when the pores become full. Activated carbon is also used regularly in hospitals on patients who have ingested certain poisons because it binds with the toxins and prevents their absorption into the patient’s bloodstream. While in the 19th century activated carbon was sold (with dubious benefit) to relieve flatulence and indigestion, today it has nearly replaced the use of emetics and stomach pumping for emergency treatment of poisoning.
Activated charcoal is quite useful in laboratory and industrial settings. In a laboratory, activated carbon can be used to remove impurities from crude organic reaction products. Additionally, it may be impregnated with other materials for use as catalysts for chemical reactions. Activated charcoal that has been used as a filter may be tested to see which residues are present. This last laboratory application is also used by environmental protection agencies to test for pollutants that may be present in air and water samples. One of the most widespread industrial uses of activated carbon is in metal finishing, where it is used to purify electroplating solutions. It is also commonly used to purify distilled alcoholic beverages, and it is an effective tool for removing mercury from coal-burning power station and incinerator emissions.
