Thermodynamic Analysis of 2-Pentanone Adsorption on Activated Carbon under Supercritical CO ₂ Conditions at <i>P</i> = (10.0 to 20.0) MPa and <i>T</i> = (313 to 353) K

Volatile organic compounds (VOCs), such as ketones, are widely used in industry, yet their release raises environmental concerns, underscoring the need for efficient separation and recovery methods. Supercritical CO2 offers attractive properties for adsorption processes including tunable density, low viscosity, and environmental compatibility. In this study, the equilibrium adsorption of 2-pentanone on activated carbon in supercritical CO2 was investigated at P = (10.0 to 20.0) MPa and T = (313 to 353) K. Adsorption isotherms were analyzed using the Dubinin–Astakhov (DA) equation. The adsorption capacity decreased with increasing pressure due to stronger competition from CO2 and a reduced 2-pentanone fugacity, whereas at lower pressures the adsorption increased with temperature because a lower CO2 density alleviated competitive pore filling by CO2. Comparisons with other ketone VOCs showed that 2-pentanone exhibited the highest affinity for activated carbon, consistent with its lower volatility and stronger dispersion interactions. Analysis of the DA parameters further revealed that the characteristic adsorption energy correlates with molecular size, while the saturated adsorption capacity inversely correlates with VOC volatility. These findings demonstrate that both affinity and volatility jointly control VOC adsorption equilibria in supercritical CO2 and provide thermodynamic insight useful for designing efficient separation processes for ketone-type VOCs.