VOCs (acetone, toluene, and n-hexane) adsorption equilibria on mesoporous silica (MCM-41) over a wide range of supercritical carbon dioxide conditions: Experimental and theoretical approach by the Dubinin-Astakhov equation

Adsorption equilibria of three volatile organic compounds (VOCs) (acetone, toluene, and n-hexane) on mesoporous silica (MCM-41) were investigated over a wide range of supercritical and pressurized carbon dioxide conditions. Measurements of the adsorption equilibria were performed with a fixed bed method at temperatures from 313 to 353K and pressures from 4.2 to 15.0MPa. The measured adsorption equilibria strongly depended on properties of VOCs, which could be explained by the affinity between the adsorbent and adsorbate. The Dubinin-Astakhov equation demonstrated satisfactory correlations of the adsorption equilibria within 10% of average relative deviation. Two fitting parameters determined with the equation provided quantitative information on adsorption phenomena in considerations of the VOCs affinity to the adsorbents, CO₂ density, and pore structure of adsorbents.