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

Abstract

Several typical active substances (•NO, •NO2, H2O2, O3, •OH, and O2 –•), 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, N2, and O2). The mechanism for chlorobenzene (CB) removal by plasma in air atmosphere was also investigated. The production of ONOO–• generated by •NO took around 75% of the total production of ONOO–•. Removing •NO increased the O3 amount by about 80% likely because of the mutual inhibition between O3 and reactive nitrogen species in or out of the discharge area. The quantitative comparison of •OH and H2O2 revealed that the formation of •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 N2 and O2 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, N2 atmosphere, and O2 atmosphere, respectively: O2 –•, •OH, and O3; H2O2, ONOO–•, and O3; •OH and O3.

Volatile organic compound removal by post plasma-catalysis over porous TiO2 with enriched oxygen vacancies in a dielectric barrier discharge reactor

“…In NTP reactors, electrons are accelerated by applied electric fields to gain significant kinetic energy; these high-energy electrons (e*) can break the chemical bonds of organic molecules or collide with background gas molecules (N 2 , O 2 and H 2 O) to generate active radicals (˙O, ˙OH, O 2+ , H 3 O + , O 2− and O 3 ), thus eliminating toxic gases. 8–10 However, the wide variety of reactive species results in a wide spectrum of reaction pathways and by-products. Therefore, the large-scale industrial application of NTP is restricted by low energy utilization efficiency and inferior CO 2 selectivity.…”