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Activated Charcoal

Definition

Activated charcoal or activated carbon is an amorphous form of carbon. This means that it has no regular atomic structure, unlike the other forms (allotropes) of elemental carbon: diamond, graphite, fullerenes or nanotubes.

Activated charcoal differs from the familiar charcoal that is used in barbecue grills. Common charcoal contains other organic residues, is much less porous, and has a lower surface area.

Trade names for activated carbon include Norit and Ultracarbon.

Additional Info

Charcoal is obtained by burning wood, nutshells, coconut husks, animal bones, and/or other carbonaceous (carbon-containing) materials. Charcoal becomes activated by heating it with steam to approximately 1000 ^oC in the absence of oxygen (O₂). This treatment removes residual non-carbon elements and produces a porous internal microstructure having an extremely high surface area. A single gram of such material can have 400 to 1,200 square meters of surface area, 98% of it internal!

The chemical nature of amorphous carbon, combined with a high surface area and porosity, makes it an ideal medium for the adsorption and absorption of organic chemicals. Adsorption means that the chemical has an interaction with the surface of the material; absorption is incorporation into a host structure through pores (interstices). To avoid confusion, we can refer to the incorporated material as "sorbed". Activated carbon can remove organic materials from gas streams or solutions. The amount of material removed depends on the capacity of the activated carbon as well as the affinity of the material for the carbon. Typical uses are to remove odors and volatile organic compounds (VOC's). Laboratory chemists often use activated carbon to remove colored impurities from crude organic reaction products. Typically, one dissolves the material in a solvent (if it is not already a liquid), adds activated carbon, and then filters the mixture to remove the carbon. This technique works well for colorless or lightly colored materials; in general, colored impurities tend to have molecular structures that make them bind preferentially to the charcoal. Activated charcoals impregnated with other materials are also effective industrial and laboratory catalysts for chemical reactions. For example, vegetable oils may be hydrogenated by exposing them to a hydrogen atmosphere in the presence of a carbon-supported palladium catalyst.

Need to filter something? We have all kinds of filtration apparatus like this one from Safety Emporium.

MSDS Relevance

Supplied air respirator systems do not depend on charcoal canisters and provide superior respiratory protection.

Activated charcoal can appear in several ways on an MSDS: It may be specified as a gas or vapor adsorbent in air-purifying respirators. These are commonly provided as screw-on cartridges. Keep in mind that charcoal canisters or filters have a finite capacity for organic materials and that one can generally not tell when this limit has been reached. Regularly replace filters according to the manufacturer's recommendations. It may be specified as a spill adsorbent or to purify contaminated solutions. It may be utilized as a solid adsorbent in air sampling and monitoring. Many OSHA air-monitoring protocols involve drawing an air sample through an activated carbon column followed by chemical analysis of the adsorbed material. It is commonly given as an antidote to certain ingested poisons. Every home with small children should have a container of activated charocal for use in accidental poisonings, but administration as an antidote should only be done after contacting a poison control center or other medical professional. Activated charcol is good at preventing the absorption of many poisons from the gastointestinal tract, however, it does a poor job with alcohols, hydrocarbons, cyanides, iron, boron, lithium, other metals, corrosives and organo-phosphates (certain nerve agents or pesticides). NEVER attempt to use regular charcoal briquettes (the kind you buy at a store for a barbecue grill) as a substitute for activated charcoal.

Further Reading

• American Association of Poison Control Centers or call (800) 222-1222.
• Activated Carbon (see the nav links on the left side) at Norit, a major activated carbon producer.
• Activated carbon filtration at North Dakota State University (good info).
• Use of Activated Charcoal for poisonings at the Illinois Emergency Medical Services for Children.
• How Stuff Works What is activated charcoal and why is it used in filters?
• What is Activated Charcoal? and additional info at Carbon Resources.

See also: antidote, catharsis, emetic, poison, respirator, smoke.

Additional definitions from Google and Onelook.

Disclaimer: The information contained herein is believed to be true and accurate, however ILPI makes no guarantees concerning the veracity of any statement. Use of any information on this page is at the reader's own risk. ILPI strongly encourages the reader to consult the appropriate local, state and federal agencies concerning the matters discussed herein.