Characteristics of Narrow Gap Strong Ionization Dielectric Barrier Discharge and Its Application

In general, the discharge gap of plasma reactor is larger than 1 mm, which leads to weak ionization degree of gas and less oxygen active particles. For the purpose of improving the intensity of ionized gas in plasma reactor and obtain high concentration of oxygen active particles, a coaxial plasma reactor with discharge gap less than 0.3 mm is designed by using quartz as the barrier dielectric. The characteristics of narrow gap strong ionization dielectric barrier discharge and its application are researched in this paper. Taking the amount of O3 produced by discharge as the evaluation index, the effects of different voltage and gas types on the discharge of plasma reactor have been studied. Furthermore, the effects of different discharge power and aerated stone on the degradation of methylene blue wastewater are discussed. The results show that the narrow gap plasma reactor can achieve stable strong ionization discharge and the discharge electric field strength is 33.5 kV/mm. The optimal discharge voltage (peak-to-peak voltage) is 14.2 kV for producing high concentration oxygen active particles by narrow gap plasma reactor. The concentration of O3 produced by ionizing air is above 500 ppm, the concentration of O3 produced by ionizing O2 is above 2300 ppm. Moreover, the optimal discharge power is 19.6 W for decolorization of methylene blue. Under aeration condition and treatment time for 3 min, the decolorization ratio of methylene blue can reach 99.48 %, its concentration is degraded from initial 50 mg/L to 0.26 mg/L. The narrow gap plasma reactor can greatly improve the discharge electric field strength and discharge performance. It is expected to provide a new idea for the development of efficient and green degradation technology of organic wastewater in industry.