Adsorption equilibria of volatile organic compounds on various adsorbents in supercritical carbon dioxide: Measurement and analysis by the Dubinin-Astakhov equation

• Adsorption equilibria of VOCs on various adsorbent in supercritical carbon dioxide was studied.
• Measured adsorption isotherm strongly depended on adsorbates, adsorbents and CO2 density.
• Measured data could be correlated with the Dubinin-Astakhov equation.
• The Dubinin-Astakhov parameters provided quantitative information on adsorption phenomena.

Adsorption equilibria of VOCs (toluene, acetone, n-hexane) on various adsorbents (activated carbon, mesoporous carbon, mesoporous silica, and zeolite) in supercritical carbon dioxide were studied. The amount of adsorbed VOC on the adsorbents in supercritical carbon dioxide was measured by a fixed bed method at temperatures from 313 to 353 K and pressures from 4.2 to 15.0 MPa. The measured adsorption equilibria were strongly dependent on VOC species, adsorbent properties and CO2 density, and could be correlated by using the DA (Dubinin-Astakhov) equation. Two fitting parameters determined with the equation provided quantitative information on adsorption phenomena of VOCs on the adsorbents in considerations of the VOCs affinity to the adsorbents, CO2 density, and properties of the adsorbents.

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