Generation of chemically active species by electrical discharges in water

Pulse positive streamer corona discharges in water solution with a different conductivity have been investigated in reactors with the needle-plate and coaxial electrode geometry. A special composite anode was used in the coaxial geometry. With such an anode hundreds of streamers were generated at each voltage pulse. Production of H, O and OH radicals by the discharge was proved by emission spectroscopy and formation of H2O2 and degradation of phenol was demonstrated by chemical methods. Assuming that the broadening of the H alpha line profile was caused by the dynamic Stark effect, plasma with an electron density over 10(18) cm(-3) was generated during the initial phase of voltage pulse in the both reactors in spite of the very different electrode geometry and wave-forms of voltage pulses.. Production of OH radicals was most effective at solution conductivity below 100 mu S cm(-1).