page_title: Charcoal
section_title: Purification and filtration
hierarchical_section_title: Charcoal / Uses / Purification and filtration
caption_attribution_description: English: Activated carbon both in powder and block form Deutsch: Aktivkohle in Pulver -und Blockform
context_page_description: Charcoal is a lightweight black carbon residue produced by strongly heating wood so as to drive off all water and other volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. Charcoal can also be produced by heating the material in a closed retort.
  This process also happens while burning wood, as in a fireplace or wood stove. The visible flame in that case is actually due to combustion of the volatiles given off as the wood turns into charcoal. The soot and smoke commonly given off by wood fire result from incomplete combustion of those volatiles. Charcoal itself burns at a higher temperature than wood, with hardly a visible flame, and gives off practically no smoke, soot, or unburnt volatiles.
context_section_description: Charcoal may be activated to increase its effectiveness as a filter. Activated charcoal readily adsorbs a wide range of organic compounds dissolved or suspended in gases and liquids. In certain industrial processes, such as the purification of sucrose from cane sugar, impurities cause an undesirable color, which can be removed with activated charcoal.
  It is also used to absorb odors and toxins in gases, such as air. Charcoal filters are also used in some types of gas masks. The medical use of activated charcoal is mainly the absorption of poisons. Activated charcoal is available without a prescription, so it is used for a variety of health-related applications. For example, it is often used to reduce discomfort and embarrassment due to excessive gas (flatulence) in the digestive tract.
  Animal charcoal or bone black is the carbonaceous residue obtained by the dry distillation of bones. It contains only about 10% carbon, the remaining being calcium and magnesium phosphates (80%) and other inorganic material originally present in the bones. It is generally manufactured from the residues obtained in the glue and gelatin industries. Its decolorizing power was applied in 1812 by Derosne to the clarification of the syrups obtained in sugar refining; but its use in this direction has now greatly diminished, owing to the introduction of more active and easily managed reagents. It is still used to some extent in laboratory practice. The decolorizing power is not permanent, becoming lost after using for some time; it may be revived, however, by washing and reheating. Wood charcoal also to some extent removes coloring material from solutions, but animal charcoal is generally more effective.
caption: Activated carbon
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