Generation of chemically active species by electrical discharges in water

TLDR

The authors investigated pulse positive streamer corona discharges in water of varying conductivity using needle‑plate and coaxial reactors, the latter equipped with a special composite anode. Each voltage pulse produced hundreds of streamers that generated H, O, and OH radicals (verified by emission spectroscopy), formed H₂O₂, degraded phenol, and yielded electron densities >10¹⁸ cm⁻³ via dynamic Stark effect, with OH production maximized at low solution conductivity.

Abstract

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 line profile was caused by the dynamic Stark effect, plasma with an electron density over 1018 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 .