Measurement of diffusivity of volatile organic compounds into activated carbon fibers using zero length column chromatography
- Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering
The Clean Air Act Amendments of 1990 mandate reductions in emissions of a wide range of volatile organic compounds (VOCs) to the atmosphere. These regulations have encouraged the development of new technologies to capture and recover VOCs from gas streams. A laboratory-scale activated carbon fiber cloth (ACFC) adsorber coupled with a cryogenic condenser has been developed to capture and recover VOCs from gas streams. Design of the fixed bed that contains ACFC requires knowledge of the effective diffusivity of VOCs into the ACFC adsorbent. Once the diffusivity of VOCs is known for realistic conditions, the fixed-bed design can be optimized to capture and recover VOCs. In this research, effective diffusional time constants for acetone are extracted from adsorption and desorption curves using Zero Length Column chromatography (ZLC). The experimental apparatus is also used to obtain adsorption capacity data over much shorter time scales than conventional packed-bed studies. Compressed gas cylinders and mass flow controllers are used to generate the gas stream of known concentration and flow rate. The gas stream then passes through the ZLC in a carefully controlled temperature environment. Heat and gas phase film and axial (secondary) mass transfer resistances are reduced to negligible values. Select inorganic carrier gases such as N{sub 2} and He are used as a check for the consistency of negligible secondary resistances. A flame ionization detector (FID) is then used to detect the VOCs. The effective diffusivities of acetone are measured between 25 degrees C and 65 degrees C and at concentrations of 30 ppmv to 60 ppmv. The results are being integrated with Crank`s solution for diffusion to fibers to describe diffusivity of acetone into ACFC adsorbents as a function of adsorbate concentration and temperature. These results will then be used to better design the fixed bed of ACC.
- OSTI ID:
- 682216
- Report Number(s):
- CONF-980632-; TRN: IM9942%%201
- Resource Relation:
- Conference: 91. annual meeting and exhibition of the Air and Waste Management Association, San Diego, CA (United States), 14-18 Jun 1998; Other Information: PBD: 1998; Related Information: Is Part Of Proceedings of the 91. annual meeting and exhibition. Bridging international boundaries: Clean production for environmental stewardship; PB: [5000] p.
- Country of Publication:
- United States
- Language:
- English
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