An experimental study of gas adsorption on fractal surfaces

Matthew J. Watt-Smith, Karen J. Edler, Sean P. Rigby

Research output: Contribution to journalArticle

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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 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.
Original languageEnglish
Pages (from-to)2281-2292
Number of pages12
JournalLangmuir
Volume21
Issue number6
DOIs
Publication statusPublished - 2005

Fingerprint

Gas adsorption
Fractals
fractals
Fractal dimension
Adsorption
adsorption
Nitrogen
gases
nitrogen
Butane
Silicon Dioxide
butanes
Silica
silicon dioxide
Adsorption isotherms
isotherms
Molecules
deviation

Keywords

  • Fractals
  • Physisorption (adsorption of nitrogen and butane on fractal silica surface)
  • Adsorption (isotherm
  • adsorption isotherm physisorption nitrogen butane fractal silica surface
  • adsorption of nitrogen and butane on fractal silica surface)

Cite this

An experimental study of gas adsorption on fractal surfaces. / Watt-Smith, Matthew J.; Edler, Karen J.; Rigby, Sean P.

In: Langmuir, Vol. 21, No. 6, 2005, p. 2281-2292.

Research output: Contribution to journalArticle

Watt-Smith, Matthew J. ; Edler, Karen J. ; Rigby, Sean P. / An experimental study of gas adsorption on fractal surfaces. In: Langmuir. 2005 ; Vol. 21, No. 6. pp. 2281-2292.
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