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Calculation of the performance of activated carbon at high relative humidities.
Am Ind Hyg Assoc J 1987 Nov; 48(11):909-913
A simple mathematical model for the effect of relative humidity on the adsorption of water immiscible compounds by activated charcoal was developed. The ideas of Polanyi, Dubinin and Radushkevich, and Manes were used. The basic concept of the Polanyi potential theory was that an adsorbent could be characterized by an attractive force field over the microporous surfaces of the adsorbent. Dubinin and Radushkevich noted that the relationship between the adsorption potential and the adsorbate was Gaussian. Manes showed how, by simple geometric constructions, the Polanyi adsorption potential could be extended to water immiscible adsorbates in the presence of water vapor. Rather than depending on graphical analysis, the author developed an equation that permitted rapid calculation of the effect of water vapor on the adsorption of water immiscible organic compounds. The equation permitted the adsorptive capacity of activated charcoal in a respirator cartridge to be estimated for any combination of temperature, relative humidity, and contaminant concentration. Two parameters were introduced, one which gave the maximum effect of adsorbed water on the adsorption of the immiscible compound, and the other which described the increase in adsorption of the immiscible compound as the partial pressure of the water vapor was reduced. Values of the parameters were determined using experimental data of Werner. The mathematical model was consistent with the data in showing that below a certain value the relative humidity had little effect on the uptake of adsorbate, and that the effect of humidity, when observed, was more severe for lower than for higher contaminant concentrations.
NIOSH-Publication; NIOSH-Grant; Respiratory-equipment; Chemical-cartridge-respirators; Air-quality; Mathematical-models; Adsorbents; Air-purifying-respirators; Analytical-models; Air-treatment
Industrial Environ Health Scis University of Pittsburgh 130 Desoto Street Pittsburgh, Penn 15261
Issue of Publication
American Industrial Hygiene Association Journal
University of Pittsburgh at Pittsburgh, Pittsburgh, Pennsylvania
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division