Molecular dynamics simulation study on the desorption mechanism of toluene from activated carbon under supercritical CO2

The desorption of activated carbon saturated with VOCs (volatile organic compounds) may not only prolong the life of activated carbon, but also promote environmental protection. Supercritical CO2 is considered to be a promising desorption method because it may avoid the inherent defects of traditional thermal methods. However, the desorption mechanism still remains unclear because the desorption process in the nanopores cannot be observed by the macro-experiments. In this paper, toluene is considered the representative of VOC; the diffusion of CO2, the interaction between CO2 and toluene, and the diffusion of toluene in the nanopore of activated carbon are studied using molecular dynamics simulation. The research results at the molecular level reveal that the strong diffusion of CO2, the interaction energy between CO2 and toluene, and CO2 greatly improving the mobility of toluene play decisive roles for the desorption mechanism. The research results of this paper may provide some beneficial guides for further studying the influence mechanism of VOC types and operating parameters on VOC desorption behavior under supercritical CO2.