Generation of active entities by the pulsed arc electrohydraulic discharge system and application to removal of atrazine.

Reactions induced by the pulsed arc electrohydraulic discharge (PAED) system in aqueous solutions were studied. PAED was generated by a spark gap type power supply (0.5 kJ/pulse) with rod-to-rod type electrodes in water. The measurements of physical parameters showed that the discharge is characterized by a sudden drop of the voltage while a peak of current occurs. The pressure waveform is composed of a positive pressure wave (shock wave) followed by negative pressure waves (expansion waves with a multiple wall reflection wave). The optical emission arc spectrum covers the UV-B, UV-A and visible zone with a maximum intensity in the range 380-425 nm. Peaks were representative of OH() radicals and atomic hydrogen emission lines. The identification of typical by-products from the removal of selected compounds in aqueous solution showed that PAED is the origin of photolysis, oxidation and reduction reactions. The impact of scavengers for OH() radicals or solvated electrons on the removal of atrazine and the concentration of the by-product deethylatrazine allowed the study of the combined and separate effects of the active entities. The energy efficiency of the PAED system can be improved by varying the gap of the electrodes in water.