ISSN:
1572-8757
Keywords:
hybrid isotherm
;
darken
;
surface diffusivity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Physics
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract The concentration dependence of the observed surface diffusivity for activated carbon due to the pore size distribution is theoretically investigated. The mathematical model is derived based on the assumption of a local hybrid adsorption isotherm (proposed recently by Shethna and Bhatia, 1994) and a local surface diffusive flux for a particular pore of half widthr. Using those local quantities and assuming a Gamma pore size distribution, the observed surface diffusivity is obtained. This observed surface diffusivity was found to increase rapidly with loading if the chemical potential is the driving force for surface flow. Furthermore, this observed surface diffusivity,D/D(0), was found to be the same as the Darken thermodynamic correction factor, using only the macroscopic isotherm information. This indicates that the thermodynamic correction factor contains information on the averaging of the surface heterogeneity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00707352
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