Effects of adsorbed water vapor on the adsorption rate constant and the kinetic adsorption capacity of the wheeler kinetic kodel.
Hall-T; Breysse-P; Corn-M; Jonas-LA
Am Ind Hyg Assoc J 1988 Sep; 49(9):461-465
The effect of adsorbed water vapor on the kinetic adsorption parameters of the Wheeler equation was investigated in order improve understanding of the effect of adsorbed water vapor on the effectiveness of respiratory protective devices used on the job. The adsorbates used were carbon-tetrachloride (56235) and triple distilled water; the adsorbent was activated-carbon. The Wheeler- Dubinin model was developed from a mass balance analysis of contaminant laden air passing through an adsorbent bed. The model rests on the assumption that a pseudo first order kinetic reaction occurs between the adsorbing molecules, the adsorbent and an unoccupied adsorption space. The water vapor-carbon isotherm derived indicated a significant hysteresis effect suggesting that once water vapor has been adsorbed onto the adsorbent, it is not desorbed readily. As the concentration of water vapor in the system was increased, the adsorption capacity decreased in a linear fashion when plotted against relative humidity. As the ability of the Wheeler-Dubinin Model to predict service life of a respirator cartridge is dependent on the accuracy of the Wheeler equation, it is significant to know that the adsorbed moisture had a profound effect on the parameters of this equation. The findings of this study indicate that when the relative humidity ranges from 60 to over 80 percent due to environmental conditions, the adsorbent bed is nearly saturated and maximum reductions in bed capacity should be anticipated.
NIOSH-Publication; NIOSH-Grant; Respirators; Respiratory-protective-equipment; Personal-protective-equipment; Air-contamination; Adsorbents; Mathematical-models
Environmental Health Sciences Johns Hopkins University 615 North Wolfe Street Baltimore, MD 21205
American Industrial Hygiene Association Journal
Johns Hopkins University, Baltimore, Maryland