Evaluation of the Distribution Function of Adsorption Site Energies Based on the Fermi–Dirac's Law in a Monolayer
✍ Scribed by Soo-Jin Park; Jean-Baptiste Donnet
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 122 KB
- Volume
- 200
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
Even though the experimental adsorption isotherm can be A model is proposed for physical adsorption of gases on homogedoubtless transformed into an adsorption site energy term neous solid surfaces on the basis of the Fermi-Dirac's distribution (11), it is difficult to find a correlation in a simple analytical function. The carbon fibers before and after anodic surface treatexpression between infinite dilution (or Henry's region) and ment are employed in this study conducted by the technique of finite dilution (or concentration region) of the solute over inverse gas chromatography (IGC) at finite dilution. This distributhe solid surface with respect to the physical adsorption. In tion function leads to the probability of a given state of site energy addition, the useful values of the physical adsorption oband then the potential of the molecules (or the adsorption energy tained at the infinite dilution, for neglecting adsorbate-adlevel), determining their tendency to move at a gas sold interface.
sorbate interaction, may be largely shown to equal the sum When evaluating the distribution function with the amount adsorbed, we propose, for the starting adsorption value, a method of the van der Waals attraction and hydrogen bonding having using values measured by IGC at infinite dilution, instead of Hobthe order of magnitude of 27-45 kJ mol 01 (generally equal son's or Adamson's method. It is found that the adsorption energy to heat of vaporization of the adsorbate) at ambient temperalevel measured with n-hexane and ethyl acetate on carbon fibers tures (12, 13); it is also difficult to find in periodicals or is increased by the anodic surface treatment. In particular, the monographs.
results given by ethyl acetate, which is able to display the polar
In this work, we propose an analytical method leading to force on the carbon fibers treated, showed a significant increase the correlation between infinite dilution and finite dilution when compared to nonpolar probes ( n-hexane). This is probably in an adsorbate-adsorbent interaction system. And we report due to the effect of surface chemical polar groups on adsorption the results of the experimental adsorption isotherm calcuenergetics.