Production characteristics of reactive oxygen/nitrogen species in water using atmospheric pressure discharge plasmas

A pulsed discharge, a DC corona discharge, and a plasma jet are separately generated above a water surface, and reactive oxygen species and reactive nitrogen species (ROS/RNS) in the water are investigated. ROS/RNS in water after the sparging of the off-gas of a packed-bed dielectric barrier discharge (PB-DBD) are also investigated. H2O2, NO2-, and NO3- are detected after plasma exposure and only NO3- after off-gas sparging. Short-lifetime species in plasma are found to play an important role in H2O2 and NO2- production and long-lifetime species in NO3- production. NOx may inhibit H2O2 production through OH consumption to produce HNO2 and HNO3. O-3 does not contribute to ROS/RNS production. The pulsed plasma exposure is found to be effective for the production of H2O2 and NO2-, and the off-gas sparging of the PB-DBD for the production of NO3-. (C) 2016 The Japan Society of Applied Physics