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activated charcoal[′ak·tə‚vād·əd ′char‚kōl]
or active carbon, obtained from fossil or wood carbon by the removal of resinous substances and the creation of a branching network of pores. With its highly developed surface, activated charcoal adsorbs many different substances. (Hydrocarbons and their derivatives are readily adsorbed; alcohol, ammonia, water, and other polar substances less readily.) Very fine-pored activated charcoal is obtained through thermal decomposition (carbonization without available air) of certain polymers. Pore diameter varies from 10 Å(with specific surface up to 1,000 m2/g) to 1,000 Å (specific surface of about 1 m2/g). Fine-pored activated charcoals adsorb readily, even in the presence of low concentrations and low partial vapor pressures. The phenomenon of capillary condensation is characteristic of large-pored activated charcoals.
Activated charcoals are used in antigas equipment as adsorbents and carriers of catalytic and chemisorption-active additives, in industry for the recovery of valuable organic solvents and for the removal of organic impurities from water, in high-vacuum technology to create sorption pumps, and in medicine for the absorption of harmful substances from the gastrointestinal tract, especially in connection with dyspepsia, meteorism, food poisoning, and poisoning by alkaloids and salts of the heavy metals. (For the latter purpose, activated charcoal is also prepared in the form of “Karbolen” tablets.)
REFERENCESDubinin, M. M. Fiziko-khimicheskie osnovy sorbtsionnoi tekhniki, 2nd ed. Moscow-Leningrad, 1935.
Metody issledovaniia struktury vysokodispersnykh i poristykh tel, books 1–2. Moscow, 1953–58.
Aref’ev, S. V., and S. P. Maksimov. Zhurnal fizicheskoi khimii, vol. 41, 1967. Page 1565.
V. I. SHIMULIS