The effects of humidity on the absorption of organic vapors by activated charcoal

Includes bibliographical references (page 25)Activated charcoal is used for determining the concentration of organic vapors in industrial atmospheres. It has been stated by several authors that humidity has no effect on the adsorption of organic compounds by activated charcoal. McBain proved that water vapor is adsorbed by activated charcoal. Burnett showed that charcoal sampling tubes adsorbed water to a significant degree, but did not test the effect of humidity on the adsorption of organic compounds. It has been shown that high humidity decreases the break through time for activated charcoal respirator cartridges. Test atmospheres of known humidity and solvent concentration were produced with a dynamic injection system. The sampling efficiency of activated charcoal for m-xylene, toluene, cyclohexane and vinyl toluene at various concentrations and relative humidities was determined. It was found that relative humidity (20-80%) had no significant effect on the adsorption of organic vapors by activated charcoal. This implied that the affinity of activated charcoal is much greater for organic vapors than for water vapor. This means that water vapor even in relatively high concentrations cannot effectively compete with organic vapors for the available sites on the activated charcoal