Application of the Elovich equation to the kinetics of occlusion. Part 3.—Heterogeneous microporosity
- 1 January 1982
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 78 (8) , 2329-2336
- https://doi.org/10.1039/f19827802329
Abstract
A model is considered in which occlusion takes place in parallel in an array of micropores with different coefficients of diffusion. The rate equation for occlusion in a pore is approximated by a parabolic or by an exponential equation, and the rate for the overall process is obtained by summing the rates in the pores. The plot of Vt/V∞ against ln t, where Vt and V∞ are the amounts sorbed at times t and infinity, respectively, is sigmoid and has an intermediate part with greatest slope. The slope of this intermediate part is related to the heterogeneity of the system. If vE(E) is constant, where E is the energy of activation for diffusion and vE the pore volume for an energy between E and E+ dE, the reciprocal of the slope is equal to the difference between the highest and lowest E divided by RT. If E is constant the slope is close to 0.2.Keywords
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