Molecular dynamics simulation of dielectric barrier discharge–photocatalyst synergistic treatment of volatile organic compounds

Dielectric barrier discharge (DBD) is an effective method for treating volatile organic compounds (VOCs). In the presence of a photocatalyst, photocatalytic technology can be used to generate a variety of reactive oxygen species (ROS). Numerous experiments have demonstrated that DBD–photocatalyst synergism is superior to the use of either approach individually. In this study, the degradation mechanism of VOCs under the DBD–photocatalyst system was investigated via the ReaxFF reaction molecular dynamics method. Acetaldehyde, toluene, 1,2,4-trimethylbenzene, cresol, and phenol were selected as representative VOCs and · O, · OH, HO2, and H2O2 were chosen as representative ROS to construct the DBD and DBD–photocatalyst reaction systems. A concentration control group and a component control group were established. Comparison of the various ROS revealed that · O and · OH possess higher activities and are more conducive to cracking VOC molecules. Among the various VOCs, the reaction rate was faster for highly reductive reactants. The carbon conversion rate was only dependent on the molecular complexity and was higher for simpler structures. To simulate the DBD–photocatalyst synergistic conditions, we established concentration control simulation systems. When · OH is used as the ROS, a large number of oxidative adsorption and hydrogen abstraction processes can occur. Increasing the · OH concentration promotes the VOC removal reactions to afford complete cracking of the VOCs into the small-molecule product CO2.