Comparison of relative concentration of ozone and oh radical produced in discharge space with water droplets

We have studied a water treatment by spraying into a pulsed discharge space in air. OH radical produced by the discharge decomposes refractory organic compounds because of its high oxidizing power. The well-known process of OH radical production is dissociation of water molecule by electron collision. However, we expect almost all OH radicals are produced via reactions including ozone. To confirm it, relative concentrations of ozone and OH radical, reacting with organic compounds were measured using the indigo method and a florescence method using the disodium salt of terephthalic acid (NaTA), respectively. The measurements were carried out regarding pulsed discharge of repetition rate of 17 and 300 pulse per second. Concentrations of ozone and OH radical increased by higher repetition rate. However, energy yields for those production decreased by higher repetition rate. A possible reason is the increase of decayed ozone. This result shows the possibility that OH radical is produced by the reaction with ozone.