(656f) Efficient Electrochemical Generation of Ozone from Water with a Novel Electrode Material

Ozone is conventionally generated in air by the high voltage corona discharge method, which is energy intensive and may generate NOx byproducts. For high purity ozone, a pure-oxygen feed is required. An attractive alternative to generate ozone from water via electrolysis has been investigated in the past, but current efficiency has been low since oxygen electrolysis is the thermodynamically preferred reaction. Our recent investigations on a doped tin dioxide material show very promising results. With a voltage of less than 3.0 V, high dissolved ozone concentration of 34 mg/l and over 30% current efficiency can be achieved in acid electrolytes [1,2]. The electrochemical ozone generator can also operate with a pure water medium when a proton exchange solid electrolyte is used [3]. The electrochemical cell is an assembly of an air cathode, a doped tin oxide anode mesh, and a solid polymer electrolyte. With this membrane electrode assembly (MEA), oxygen from air is reduced at the air cathode while ozone is generated in pure water. Protons are produced at the anode and consumed at the cathode. There is no net consumption of water and the overall reaction is oxygen converting to ozone. The gaseous ozone concentration can reach over 15%, without the need of a pure oxygen supply. The operation of a hand-held prototype demo unit powered by two small batteries will be demonstrated in the presentation. The electrode area is 4 cm x 6 cm in the demo cell and the results of the performance data are also based on this area.

We report the latest developments of this electrochemical technology with a multiple cell stack designed to produce ozone > 0.1 g /hr per MEA. The effects of flow rate, operating voltage, and current on current efficiency, concentrations of dissolved and gaseous ozone will be reported. Using the novel electrode material, the electrochemical route to generate ozone appears to be an attractive alternative to the conventional corona discharge method.