The Effect of Nitrogen- and Oxygen-Containing Functional Groups on C2H6/SO2/NO Adsorption: A Density Functional Theory Study

Abstract

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.