Activated Charcoal

ACTIVATED CHARCOAL. Charcoal has long been used both in technology and in medicine for the absorption of various gases, as well as for the isolation of certain substances (especially from solutions). In technology, this is widely used for the purification of alcohol, sugar syrup, etc. However, the absorption capacity, based on the adsorption properties of charcoal, quickly disappears. To restore it, the charcoal is roasted and treated with steam at a temperature of 800–1,100° to remove hydrocarbons formed during the carbonization of wood. This process is called activation. Activated charcoal is also distinguished by its catalytic properties (decomposition of phosgene by moist air, the reaction of its formation from chlorine and carbon monoxide, etc.). The absorbing surface of activated charcoal is extremely large—1 kg of coke charcoal has an adsorption surface of approx. 20 sq. km. E. Urbain in France recently proposed a new method for activating charcoal, namely, obtaining it from peat mixed with phosphoric acid; the phosphoric anhydride formed during heating to 1,200° absorbs all accidental impurities and hydrogen-containing substances. The resulting activated charcoal is then washed with HCl and dried. This super-activated charcoal is used in particular in medicine under the name carbonada, to combat gases formed in the intestines. Activated charcoal is also used in technology for the purification of illuminating gas, for the absorption of volatile petroleum oils, etc. Animal or bone charcoal possesses the best absorption capacity, but for a number of purposes, especially when using the Urbain method of activation, ordinary wood charcoal is also applicable. Activated charcoal finds wide application in the protection against harmful gases, both military and industrial. During the imperialist war, birch activated charcoal was proposed for military gas masks by the Russian Prof. Zelinsky and found wide application in the Kummant-Zelinsky gas masks (see). After the war, military masks began to be widely redesigned into industrial gas masks, and in the canisters of the latter, usually, regardless of various other absorbents, activated charcoal also finds wide application. Recently, the question has been raised about the use of activated charcoal for the absorption of various gases released during work processes in the atmosphere surrounding workers. Wide prospects are also opening up for the use of activated charcoal in industrial ventilation for the purpose of absorbing various harmful gases and purifying air currents from them.