Mechanisms of Active Substances in a Dielectric Barrier Discharge Reactor: Species Determination, Interaction Analysis, and Contribution to Chlorobenzene Removal

Several typical active substances ((NO)-N-center dot, (NO2)-N-center dot, H2O2, O-3, (OH)-O-center dot, and O-2(-center dot)), directly or indirectly play dominant roles during dielectric barrier discharge (DBD) reaction. This study measured these active substances and removed them by using radical scavengers, such as catalase, superoxide dismutase, carboxy-PTIO (c-PTIO), tert-butanol (TBA), and MnO2 in different reaction atmospheres (air, N-2, and O-2). The mechanism for chlorobenzene (CB) removal by plasma in air atmosphere was also investigated. The production of O=NOO-center dot generated by (NO)-N-center dot took around 75% of the total production of O=NOO-center dot. Removing (NO)-N-center dot increased the O-3 amount by about 80% likely because of the mutual inhibition between O-3 and reactive nitrogen species in or out of the discharge area. The quantitative comparison of center dot OH and H2O2 revealed that the formation of center dot OH was 3.06-4.65 times that of H2O2 in these reaction atmospheres. Calculation results showed that approximately 1.61% of H2O was used for O3 generation. Ionization patterns affected the form of solid deposits during the removal of CB in N-2 and O-2 atmospheres caused by Penning ionization and thermal radiation tendencies, respectively. Correlation analysis results suggested the macroscopic synergistic or inhibitory effects happened among these active substances. A zero-dimensional reaction kinetics model was adopted to analyze the reactions during the formation of active substances in DBD, and the results showed good consistency with experiments. The interactions of each active substance were clarified. Finally, a response surface method model was developed to predict CB removal by the DBD plasma process. Stepwise regression analysis results showed that CB removal was affected by the contents of different active substances in air, N-2 atmosphere, and O-2 atmosphere, respectively: O-2(-center dot), (OH)-O-center dot, and O-3; H2O2, O.NOO-center dot, and O-3; (OH)-O-center dot and O-3.

Automated summary

This study investigated the production and mechanism of active substances in dielectric barrier discharge reactions in different reaction atmospheres. The interactions between different active substances were found to have synergistic or inhibitory effects. Experiments showed that the removal of chlorobenzene by plasma in air atmosphere was affected by the presence of various active substances.