A Preliminary Study of Pulsed Streamer Corona Discharge for the Degradation of Phenol in Aqueous Solutions

Abstract

Pulsed corona discharges are shown in this investigation to be effective at breaking down phenol in aqueous solutions in an isothermal batch reactor and in a semi-batch reactor with the continuous addition of oxygen. In the experiments where no oxygen was bubbled through the reactor the phenol breakdown was independent of pH, thus indicating significant hydroxyl radical formation directly from the corona discharge. The addition of iron was found to significantly enhance phenol degradation; this may be due to Fenton's reaction arising from hydrogen peroxide formed directly by the corona discharge. In experiments where oxygen was fed to the reactor, it appeared that two simultaneous reaction pathways contributed to phenol degradation. The first pathway consisted of corona-induced aqueous phase reactions. The second pathway arose from ozone production in the gas phase with subsequent mass transfer into the liquid phase followed by liquid phase ozone reactions. The presence of phosphate and borate buffers decreased the rate and magnitude of phenol breakdown at low and high pH, respectively, due to radical quenching.