Research on methylene blue degradation based on multineedle-to-plane liquid dielectric barrier discharge mode

Abstract

Advanced oxidation processes (AOPs) focusing on non-thermal plasma induced by dielectric barrier discharge (DBD) are adequate sources of diverse reactive oxygen species beneficial for water and wastewater treatment. The degradation of methylene blue (MB) was investigated using plasma liquid dielectric barrier discharge with a multineedle-to-plane reactor. MB at 20 mg/L concentration was almost completely degraded after 40 min of treatment. In this study, several important parameters, such as input voltage, initial concentration, initial pH, discharge gap, tip radius of curvature, and presence of radical, were evaluated, and their effects on MB degradation rate were investigated. The degradation rate of MB increased with initial pH. By contrast, the degradation rate showed a downward trend with increasing initial concentration, discharge distance, and tip curvature radius. O3 and H2O2 produced during the degradation process considerably influenced the entire degradation process, especially when the quenching agents of HO⋅, O2·- and e− were added, and the degradation efficiency was obviously reduced. According to the measured spectrum, the possible process of the discharge process was analyzed, and the COMSOL finite element simulation is performed to obtain the visualization of the discharge model. This work can provide exploratory platforms for comprehensively understanding and enhancing MB degradation in DBD plasma technology.