The production of radical species during aqueous ozonation of illuminated titanium dioxide suspensions

Abstract

The combination of aqueous ozone, suspended titanium dioxide, and ultraviolet light with predominant wavelength of 254 nm was tested against other pairs of these three variables to determine if more radical species were produced. The addition of suspended and illuminated titanium dioxide did not affect the total or instantaneous transfer at the 95 percent confidence level measured in this research. Radical generation was suggested by the increased dissolved ozone decomposition with increased semiconductor concentration at pH 7.2 and the increase in ozone decomposition rate upon addition of 3.0 g/l TiO₂ to water pH 3.1. The presence of hydrogen peroxide in the suspensions may have assisted in the production of radicals by reacting with the semiconductor. The increased decomposition of glucose with 3.0 g/l TiO₂ also provided evidence that O₃/UV/TiO₂ led to the generation of more radical species.