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Effect of surface heterogeneity on surface diffusion in microporous solids
Author(s) -
Horiguchi Y.,
Hudgins R. R.,
Silveston P. L.
Publication year - 1971
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450490115
Subject(s) - diffusion , microporous material , surface diffusion , homogeneous , surface (topology) , thermodynamics , chemical physics , materials science , surface roughness , helium , effective diffusion coefficient , chemistry , adsorption , physics , organic chemistry , mathematics , geometry , composite material , medicine , radiology , magnetic resonance imaging
An experimental investigation of the effect of surface energetic heterogeneity on surface diffusion using Vycor and Graphon and as gases ethane, propylene, nitrogen, and helium confirms published reports that surface diffusion proceeds more rapidly on the energetically homogeneous Graphon surfaces. Activation energies for diffusion are found to be about the same for Vycor and Graphon; thus, it is postulated that a major factor in the difference is surface roughness. A comparison of surface diffusion models shows that Fick's Law correlated results about as well as a hydrodynamic model. Both models fail to allow adequately for surface coverage. A comprehensive form of Fick's Law for surface diffusion is proposed.