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Pattern of adsorption isotherms in Ono-Kondo coordinates
Panita Sumanatrakul1, Sarah Abaza, Gregory L Aranovich
1Department of Chemical Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Journal of Colloid and Interface Science
|November 30, 2011
Summary
This study reveals distinct adsorbate-adsorbate interactions in supercritical fluids using the Ono-Kondo lattice density functional theory. Attractions dominate at low coverages, while repulsions occur at high coverages, indicating adsorption compression.
Area of Science:
- Physical Chemistry
- Surface Science
- Computational Chemistry
Background:
- Ono-Kondo lattice density functional theory previously analyzed subcritical adsorbed phases.
- Prior work focused on adsorbate-adsorbate repulsions during adsorption compression.
Purpose of the Study:
- To present the general pattern of adsorption isotherms in Ono-Kondo coordinates for supercritical systems.
- To analyze adsorbate-adsorbate interactions in supercritical fluids.
Main Methods:
- Plotting experimental adsorption isotherms for supercritical fluids (N2, CH4, CO2) in Ono-Kondo coordinates.
- Performing Grand Canonical Monte Carlo simulations for Lennard-Jones molecules.
- Analyzing adsorption isotherms in Ono-Kondo coordinates.
Main Results:
- A consistent pattern of adsorption isotherms in Ono-Kondo coordinates was observed.
- Regimes of adsorbate-adsorbate attractions at low surface coverage and repulsions at high surface coverage were identified.
- The slope of isotherms varied from positive (low pressure) to negative (high pressure), indicating adsorption compression.
Conclusions:
- The generalized Ono-Kondo model effectively describes adsorbate-adsorbate interactions across a wide pressure range.
- Negative slopes in linear sections of Ono-Kondo plots signify adsorption compression.
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