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An experimental study of gas adsorption on fractal surfaces

Watt-Smith, Matthew J. ; Edler, Karen J. LU orcid and Rigby, Sean P. (2005) In Langmuir 21(6). p.2281-2292
Abstract

The validity of the fractal versions of the FHH and BET theories for describing the adsorption of butane and nitrogen on a variety of partially dehydroxylated silica surfaces has been tested. The fractal dimensions obtained from adsorption data have been compared with those obtained completely independently using SAXS. It was found that the fractal dimensions obtained from butane adsorption isotherms, using both the fractal FHH and fractal BET theories, agreed well with the corresponding values obtained from SAXS over overlapping length scales. However, in general, a systematic deviation between the fractal dimension obtained from nitrogen adsorption and that obtained from SAXS was observed. The fractal dimensions obtained from nitrogen... (More)

The validity of the fractal versions of the FHH and BET theories for describing the adsorption of butane and nitrogen on a variety of partially dehydroxylated silica surfaces has been tested. The fractal dimensions obtained from adsorption data have been compared with those obtained completely independently using SAXS. It was found that the fractal dimensions obtained from butane adsorption isotherms, using both the fractal FHH and fractal BET theories, agreed well with the corresponding values obtained from SAXS over overlapping length scales. However, in general, a systematic deviation between the fractal dimension obtained from nitrogen adsorption and that obtained from SAXS was observed. The fractal dimensions obtained from nitrogen adsorption were consistently larger than those obtained from SAXS, which is the opposite of what has often been found in the literature. It has been suggested that the differences in the suitability of the adsorption theories tested to describe butane and nitrogen adsorption is due to the significant difference between the interaction strengths of these two different molecules with silica surfaces. A modified theory that can account for the discrepancy between the fractal dimensions obtained from nitrogen adsorption and SAXS has been proposed. The implications of the new theory for the accuracy of nitrogen adsorption BET surface areas for silicas are discussed.

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author
; and
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type
Contribution to journal
publication status
published
in
Langmuir
volume
21
issue
6
pages
12 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:15844394132
ISSN
0743-7463
DOI
10.1021/la048186t
language
English
LU publication?
no
id
cf9f2847-873d-4a60-b3b5-da3700d09b6b
date added to LUP
2023-05-04 18:14:50
date last changed
2023-06-13 09:30:41
@article{cf9f2847-873d-4a60-b3b5-da3700d09b6b,
  abstract     = {{<p>The validity of the fractal versions of the FHH and BET theories for describing the adsorption of butane and nitrogen on a variety of partially dehydroxylated silica surfaces has been tested. The fractal dimensions obtained from adsorption data have been compared with those obtained completely independently using SAXS. It was found that the fractal dimensions obtained from butane adsorption isotherms, using both the fractal FHH and fractal BET theories, agreed well with the corresponding values obtained from SAXS over overlapping length scales. However, in general, a systematic deviation between the fractal dimension obtained from nitrogen adsorption and that obtained from SAXS was observed. The fractal dimensions obtained from nitrogen adsorption were consistently larger than those obtained from SAXS, which is the opposite of what has often been found in the literature. It has been suggested that the differences in the suitability of the adsorption theories tested to describe butane and nitrogen adsorption is due to the significant difference between the interaction strengths of these two different molecules with silica surfaces. A modified theory that can account for the discrepancy between the fractal dimensions obtained from nitrogen adsorption and SAXS has been proposed. The implications of the new theory for the accuracy of nitrogen adsorption BET surface areas for silicas are discussed.</p>}},
  author       = {{Watt-Smith, Matthew J. and Edler, Karen J. and Rigby, Sean P.}},
  issn         = {{0743-7463}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{6}},
  pages        = {{2281--2292}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Langmuir}},
  title        = {{An experimental study of gas adsorption on fractal surfaces}},
  url          = {{http://dx.doi.org/10.1021/la048186t}},
  doi          = {{10.1021/la048186t}},
  volume       = {{21}},
  year         = {{2005}},
}