Radon adsorption on activated charcoal in the presence of indoor pollutants

A number of recent studies have reported that activated charcoals can adsorb significant amounts of volatile organic compounds at concentration levels generally encountered indoors. In this study, a fundamental understanding of radon adsorption on activated charcoal in the presence of water vapor and various indoor volatile organic compounds has been presented.; A dynamic adsorption system was designed and constructed to study adsorption of radon both as a pure component (when present alone in a gas mixture with nitrogen) and in the presence of water vapor and some selected indoor air pollutants. The air pollutants investigated in this study include carbon dioxide, formaldehyde, toluene and 1,1,1-trichloroethane. The experimental data were obtained in the form of breakthrough curves. The data were used to verify several existing models for both pure component radon adsorption and its adsorption from binary mixtures.; As expected, radon adsorption capacity by charcoal decreased in the presence of water vapor. However, a decrease of about 9% was observed when the relative humidity of the nitrogen stream was below 40%. A sharp decrease in the adsorption capacity, about 40%, was noted if the relative humidity was above 50%. The adsorption capacity for radon decreased by 10% to 20% in the presence of toluene and 1,1,1-trichloroethane. The decrease was about 2% to 6% when carbon dioxide or formaldehyde was present in the gas mixture. The capacity for radon also decreased by about 40% during adsorption from the multicomponent mixtures. However, this reduction in the capacity was due mainly to the water vapor. Therefore it may be concluded that radon measurements would be affected significantly in the presence of various indoor pollutants.; The models used in this study provided excellent agreement with the experimental data for both pure radon (when present alone in the nitrogen stream) and when present in binary mixtures with water vapor and other indoor pollutants.