HAZARDOUS WASTE & HAZARDOUS MATERIALS Volume 10, Number 2, 1993 Mary Ann Liebert, Inc., Publishers A Preliminary Study of Pulsed Streamer Corona Discharge for the Degradation of Phenol in Aqueous Solutions A.K. SHARMA, B.R. LOCKE, P. ARCE, and W.C. FINNEY Department of Chemical Engineering FAMU/FSU College of Engineering Tallahassee, FL 32316-2175 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. INTRODUCTION A number of alternative processes have been considered and studied for the degradation of organic contaminants in aqueous solutions (1). These include oxidation processes such as UV photolysis, direct ozonation (2), photo-catalysis (3,4), electron beams (5), and various combinations of these methods. Other processes may include microwave plasma reduction (6), ultrasonication (7), and radiation-initiated processes such as gamma radiation from cobalt sources (8,9). Despite advances in the above techniques, there still remains a need to develop more efficient, practical, and robust methods to treat the vast quantities of organic waste released to the environment from a wide variety of processes. It is also crucial to develop a fundamental understanding of the chemical reaction pathways involved in the breakdown of organic species in order to design and operate reactors for waste treatment. The present study emerges from previous work on the use of pulsed streamer corona discharges for treating gas-phase pollutants (10). In the gas phase, pulsed streamer corona was found to be much more effective at promoting the reactions leading to desulfurization and denitrification than, for 209