Performance evaluation of activated carbon with different pore sizes and functional groups for VOC adsorption by molecular simulation

Abstract

Volatile organic compounds (VOCs) are growing pollutants now that cause air pollution and threaten human health. In this paper, the Grand Canonical Monte Carlo was used to simulate the adsorption performance of activated carbon on VOCs (benzene, toluene, acetone and methanol). After simulating different pore sizes (0.902 nm,1.997 nm,3 nm and 4 nm) adsorption performances of activated carbon, activated carbon with a pore size of 1.997 nm was selected to further study the influence of functional groups (carboxyl, amino, hydroxyl and hydrogen), and the capillary condensation was explained by the Kelvin equation. Furthermore, effects of functional groups under saturated vapor pressure (P0) of VOCs that range from 0 to 0.1 P0 were explained by the accessible volume and intermolecular interaction potential, respectively. Under pressure range of 0–0.1 P0, at the beginning of adsorption of acetone and methanol, carboxyl and amino groups could reduce the threshold pressure while hydroxyl and hydrogen have the opposite effect. For benzene and toluene, all functional groups have little effect on the threshold pressure, and they reduce the adsorption capacity instead. It could be concluded that the activated carbon could achieve the best adsorption effect on acetone and methanol, on the contrary, the addition of functional groups on benzene and toluene will weaken their adsorption performance.