Influence mechanism of pressure on the toluene desorption from active carbon under supercritical CO2

Desorption of activated carbon saturated with VOCs (volatile organic compounds) under supercritical CO2 is considered to be a promising method, but the desorption ratio is greatly affected by operating parameters, and the influence mechanism is still ambiguous. In this paper, the influence mechanism of pressure which is the most important operating parameter on the desorption ratio is studied. Toluene is considered as the representative of VOC, the relationship between toluene desorption ratio and pressure is investigated by experimental methods, the diffusion of supercritical CO2 molecules in the nano pores of activated carbon and the interaction between CO2 molecules and toluene molecules are investigated by molecular dynamics simulation. The results show that increasing pressure enhances the interaction energy between CO2 and toluene, which enhances the desorption driving force of toluene. Meanwhile, increasing pressure also reduces the adsorption between activated carbon and toluene, this reduces the desorption resistance of toluene. Finally, the toluene desorption ratio increases as pressure increases.