Influence of pressure and temperature on the toluene desorption from activated carbon under supercritical CO2

Abstract

Desorption of activated carbon saturated with VOCs (volatile organic compounds) under supercritical CO2 is greatly affected by pressure and temperature, and the influence mechanism remains ambiguous. In this paper, toluene is considered as the representative of VOC, influence of pressure and temperature on the toluene desorption ratio is investigated by experimental and molecular dynamic simulation methods. The experimental results show that the toluene desorption ratio increases as pressure increases, but the influence of temperature on the toluene desorption ratio is affected by pressure. The desorption ratio decreases with increasing temperature at lower pressure, while the desorption ratio increases at the beginning but then decreases with increasing temperature at higher pressure. The mechanism analysis presents that the influence of pressure is governed by “density effect”, the influence of temperature is governed by “density effect” and “diffusion effect” together, the final result is determined by the competition between the two effects.