Effects of moisture on warming of activated carbon bed during VOC adsorption

Thermal waves resulting from the dynamic adsorption of organic vapor present in air on a granular activated carbon (GAC) filter were studied. An experimental design was carried out to determine the influential factors among the relative humidity of air (0-60%), the initial water content of the activated carbon (0-9.8%), and the volatile organic compound (VOC) concentration (0-50 g . m(-3), i.e;, 0-20,700 ppmv for acetone). The temperature increase is a function of the initial VOC concentration as well as the energy flux released. The warming of the adsorber is shown to be important for the adsorption of high VOC concentrations on a dry carbon bed, but the thermal amplitude is distinctly reduced when the GAC is initially wet because of water desorption. The moisture content of the air in the range of 0-95% is not found to be a prominent factor affecting both the adsorption capacity and the warming of the GAC bed for the high VOC concentration tested (20,700 ppmv of acetone). Temperature monitoring provides interesting information about the adsorption process, and the mechanisms involved are discussed.