REMOVAL OF VOCS FROM HUMIDIFIED GAS STREAMS USING ACTIVATED CARBON CLOTH

This research investigates the effects of relative humidity (RH) on th e adsorption of soluble (acetone) and insoluble (benzene) volatile org anic compounds (VOCs) with activated carbon cloths (ACC). A gravimetri c balance was used in conjunction with a gas chromatograph/mass spectr ophotometer to determine the individual amounts of water and VOC adsor bed on an ACC sample. RH values from 0 to 90% and organic concentratio ns from 350 to 1000 ppmv were examined. The presence of water vapor in the gas-stream along with acetone (350 and 500 ppmv) had little effec t on the adsorption capacity of acetone even at 90% RH. Water vapor in the gas stream had little effect on: the adsorption capacity of benze ne (500 ppmv) until about 65% RH, when a rapid decrease resulted in th e adsorption capacity of benzene with increasing RH. This RH was also about where capillary condensation of water vapor occurs within ACC po res. Water vapor condenses within the ACC pores, making them unavailab le for benzene adsorption. Increasing benzene concentration can have a significant effect on the amount of water vapor adsorbed. At 86% RH a nd 500 ppmv, 284 mg/g water was: adsorbed, while at 86% RH and 1000 pp mv, only 165 mg/g water was adsorbed. Water vapor was more inhibitory for benzene adsorption as benzene concentration in the gas stream decr eased. Copyright (C) 1996 Elsevier Science Ltd