Determination of Operating Conditions for Hydrogen Peroxide and Hydroxyl Radical Production in Electro-peroxone Process

Electro-peroxone (EPO) process is an enhanced ozonation process with a simple installation of electro-oxidation apparatus into the ozone reactor. It enables the use of excess oxygen gas caused by inefficient ozone generation by ozone generators. The sparged oxygen is reduced to form hydrogen peroxide (H2O2) on the cathode surface and then the electrogenerated H2O2 reacts with ozone to form hydroxyl radical (OH•). Thus, the highly oxidative species such as OH• and H2O2,are produced in the bulk solution. In this study, the effects of operating conditions such as reaction time, ozone flow rate and the applied current on the production of oxidant species were discussed. Response Surface Methodology (RSM) was used for the modeling of reaction conditions. The models employed were both significant for the production of OH• and H2O2. Reaction time is the most important factor in the production of oxidants. While the reaction time and ozone flow rate had a synergistic effect on OH• production, the interaction of the applied flow and the ozone flow rate affected H2O2 production. Optimum operating conditions were determined maximizing the OH• concentration. The short reaction time of the process may be preferred because OH• is inhibited by the electrogenerated H2O2 at advancing reaction times.