Study on diffusion and flow of benzene, n-hexane and CCl4 in activated carbon by a differential permeation method

Bae, J. S. and Do, D. D. (2002) Study on diffusion and flow of benzene, n-hexane and CCl4 in activated carbon by a differential permeation method. Chemical Engineering Science, 57 15: 3013-3024. doi:10.1016/S0009-2509(02)00190-2


Author Bae, J. S.
Do, D. D.
Title Study on diffusion and flow of benzene, n-hexane and CCl4 in activated carbon by a differential permeation method
Journal name Chemical Engineering Science   Check publisher's open access policy
ISSN 0009-2509
Publication date 2002-01-01
Sub-type Article (original research)
DOI 10.1016/S0009-2509(02)00190-2
Volume 57
Issue 15
Start page 3013
End page 3024
Total pages 12
Place of publication Oxford
Publisher Pergamon-elsevier Science Ltd
Language eng
Subject C1
250103 Colloid and Surface Chemistry
780102 Physical sciences
Abstract In this paper the diffusion and flow of carbon tetrachloride, benzene and n-hexane through a commercial activated carbon is studied by a differential permeation method. The range of pressure is covered from very low pressure to a pressure range where significant capillary condensation occurs. Helium as a non-adsorbing gas is used to determine the characteristics of the porous medium. For adsorbing gases and vapors, the motion of adsorbed molecules in small pores gives rise to a sharp increase in permeability at very low pressures. The interplay between a decreasing behavior in permeability due to the saturation of small pores with adsorbed molecules and an increasing behavior due to viscous flow in larger pores with pressure could lead to a minimum in the plot of total permeability versus pressure. This phenomenon is observed for n-hexane at 30degreesC. At relative pressure of 0.1-0.8 where the gaseous viscous flow dominates, the permeability is a linear function of pressure. Since activated carbon has a wide pore size distribution, the mobility mechanism of these adsorbed molecules is different from pore to pore. In very small pores where adsorbate molecules fill the pore the permeability decreases with an increase in pressure, while in intermediate pores the permeability of such transport increases with pressure due to the increasing build-up of layers of adsorbed molecules. For even larger pores, the transport is mostly due to diffusion and flow of free molecules, which gives rise to linear permeability with respect to pressure. (C) 2002 Elsevier Science Ltd. All rights reserved.
Keyword Engineering, Chemical
Surface Diffusion
Differential Permeation
Activated Carbon
Adsorption
Diffusion
Capillary Condensation
Condensable Vapors
Surface-diffusion
Mesoporous Media
Adsorbed Gases
Permeability
Transport
Membrane
Model
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Chemical Engineering Publications
 
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Created: Wed, 15 Aug 2007, 04:40:14 EST