Kinetics of ozone photolysis in aqueous solution

The kinetics of ozone photolysis were investigated experimentally in well-characterized aqueous solution and by a conceptual kinetic and mechanistic model developed based on possible reaction pathways. The primary quantum yield of ozone photolysis at 254-nm wavelength was measured at 20 degrees C as 0.48 +/- 0.6. The rate of ozone photolysis increased with ina easing light intensity, ozone concentration and pH, and decreased with increasing inorganic carbon concentration in water. The model was able to predict the experimentally observed rare of ozone photolysis quite well for various combinations of UV light intensity, initial ozone concentration and water characteristics. In the mechanistic model, the formation of the hydroxyl radical, which is the primary oxidant in the O-3/UV process, was tied to the decomposition of ozone; therefore, the model can now be extended to predict the oxidation rates of water contaminants by the hydroxyl radical generated in the O-3/UV process.