Degradation of organic molecules by streamer discharges in water: coupled electrical and chemical measurements

This paper presents an experimental study of pre-breakdown discharges in water (usually called 'corona' or 'streamer') used to degrade organic molecules for depollution purposes. Streamers in water are generated by high voltage pulses of short duration in order to minimize energy losses by Joule heating. Measurements of the electrical energy used to develop streamers can be taken only when losses due to the electrical conduction in the test cell becomes negligible, i.e. at high voltage. Coupled to electrical measurements, the formation of hydrogen peroxide and the degradation of organic compounds such as 4-chlorophenol and 4-nitrophenol is studied. Chemical effects are correlated with the amount of electrical energy released, which depends mainly on conductivity and applied voltage. On the other hand, the chemical yield of these processes, expressed in terms of mole/joule is independent of voltage and conductivity.