This paper investigates the mechanism of nitrogen- and oxygen-containing functional groups in the collaborative adsorption of harmful gases by activated carbon through numerical simulation. The aim is to provide theoretical guidance for the industrial production of high-performance and universally applicable activated carbon. By employing density functional theory, we explore the impact of pyridine, pyrrole, carboxyl, and carbonyl groups on the co-adsorption of C₂H₆/SO₂/NO by activated carbon through analyzing surface electrostatic potential (ESP), physical adsorption energy, and non-covalent interaction. The findings demonstrate that the presence of nitrogen- and oxygen-containing functional groups within activated carbon surfaces enhances their polarity, while simultaneously forming strong non-covalent interactions with C₂H₆ and SO₂. The N-atom of NO can form a strong C-N ionic bond with the C-atom of the benzene ring. The adsorption site of NO is influenced by the nitrogen- and oxygen-containing functional groups. On an activated carbon model containing a pyrrole functional group, NO exhibits meta-adsorption behavior, while on activated carbon with pyridine, carboxyl, and carbonyl groups, it shows ortho-adsorption characteristics. The interaction between C₂H₆ and SO₂, as well as NO, primarily involves the H-bond, whereas the interaction between SO₂ and NO is predominantly driven by dipole–dipole interactions. These intermolecular forces significantly contribute to the mutual adsorption of these molecules.

In this paper, the physical adsorption of volatile organic compounds (VOCs) such as methyl chloride (CH₃Cl), carbon disulfide (CS₂), dimethyl sulfide (C₂H₆S), and benzene (C₆H₆) by three models of activated carbon (without a functional group, with a pyridine-containing functional group, and with a pyrrole-containing functional group) was simulated. The surface electrostatic potential (ESP), physical adsorption energy, and non-covalent interaction between activated carbon and VOC molecules were analyzed based on the density functional theory (DFT). The effect mechanism of nitrogen-containing functional groups on VOC adsorption by activated carbon was determined. Our simulations showed that nitrogen-containing functional groups can change the surface ESP and polarity of activated carbon. The pyrrole functional group is conducive to CH₃Cl and CS₂ adsorption on the activated carbon plane, while the pyridine functional group is relatively small or even unfavorable for CH₃Cl and CS₂ adsorption on the activated carbon plane. The promotional effect of the pyrrole functional group on the adsorption of C₂H₆S is more significant than that of the pyridine functional group. The adsorption of C₆H₆ on activated carbon occurs through parallel-displaced π–π stacking interactions, in which functional groups have little influence on it. The adsorption energy of VOCs on the activated carbon plane is higher than that at the edge, so VOCs are more likely to be adsorbed on the activated carbon plane.