Decomposition rate of ozone in water with ultraviolet radiation

Abstract

The combination of ozone and UV radiation is useful in removing refractory compounds dissolved in water. In this paper, the decomposition of ozone with UV radiation was investigated by using a rectangular flow reactor equipped with transparent quartz walls. The decomposition rate of ozone in water was proportional to the UV irradiance and the ozone concentration. The dependence on OH_ ion concentration was very weak compared to decomposition without UV radiation. Data were correlated with an experimental equation which was applicable in the pH range of 2–9. A simulation of ozone utilization in a model reactor indicates that unnecessarily intensive UV radiation destroys ozone in the gas phase before it is transferred into the liquid phase. This loss decreases the amount of ozone decomposed in the liquid phase and hence hinders the ozonation of dissolved pollutants. Ozone absorption and UV radiation have to be carried out in different parts of the reactor. © 1987, The Society of Chemical Engineers, Japan. All rights reserved.