Oxidative degradation of dimethylsulfoxide by locally concentrated hydroxyl radicals in streamer corona discharge process

This study systematically investigates the characteristic degradation behaviors of dimethylsulfoxide (DMSO) by the streamer corona discharge process (SCDP) in water. The analysis of the oxidized intermediates of DMSO shows that hydroxyl radical (radical dotOH) is the main oxidant responsible for the degradation of DMSO in the SCDP. The various experiments on the degradation and mineralization of DMSO, and the effect of the radical dotOH scavenger suggest that the SCDP produces locally concentrated radical dotOHs in and around the plasma channel. This explanation was also supported by the formation of H2O2 and the effect of the radical dotOH scavenger on the H2O2 production rate in the SCDP. Based on the kinetic data for the degradation of DMSO and the production of H2O2 in the SCDP, the volume of the active region in which the radical dotOHs are concentrated, and the effective concentration of radical dotOH in that region were estimated to be 0.21 μl and 5.0 × 10−3 M, respectively. This level of radical dotOH concentration in the SCDP is approximately 107–109 times higher than that generated in ordinary advanced oxidation processes using radical dotOH. The ramifications of the results obtained in this study on successful water treatment using the SCDP are also discussed.