Fluorocarbon aerosol propellants IX: adsorption on activated charcoal

The adsorption of three commonly used fluorocarbons, trichloromonofluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane, on activated charcoal was studied at 25 degrees. The adsorption versus pressure plots are consistent with the Brunauer, Emmett, and Teller (BET) type II and type IV isotherms, which can be explained as the condensation of the gaseous molecules in a wide range of pores in the activated charcoal. The monolayer capacity derived from the BET equation is discussed and used to estimate the volume of micropores present in the activated charcoal. Below the relative pressure of 0.01, the adsorption deviated from the BET plot. The deviation revealed that the adsorption capacity and adsorption potential at these lower pressures are greater than the extrapolated values. It is concluded that activated charcoal can be used effectively to remove propellants from the air in pollution control.