Single-component gas phase adsorption and desorption studies using a tapered element oscillating microbalance

Adsorption equilibrium data, usually obtained using volumetric or gravimetric methods, are important for the proper design of adsorption systems. In this work, a tapered element oscillating microbalance (TEOM(R) series 1500 pulse mass analyzer) was used to characterize the hydrophobicity of some microporous materials, and to obtain adsorption isotherms of some chlorinated volatile organic compounds (CVOCs) on those materials. The sorption capacities of samples of silicalite-1, dealuminated zeolite Y (DAY), and activated carbon for trichloroethylene, chloroform, and water vapor were determined. A "hydrophobicity index" also was determined by monitoring water desorption at elevated temperatures. The adsorption of pure component CVOCs showed that a DAY sample had a higher limiting adsorption capacity than the silicalite-1 sample. The opposite behavior was observed when the CVOC adsorption was in the presence of water. These data supported the conclusion that water interferes with the adsorption of CVOCs in these materials, even though they exhibit significant hydrophobic character. (C) 2002 Elsevier Science Inc. All rights reserved.