Influence of ozone on the photocatalytic oxidation of organic compounds

Heterogeneous photocatalytic oxidation processes using titanium oxide as a photocatalyst are widely discussed topics in research for water and waste water treatment. Oxygen fed into the systems is normally used as oxidizing agent. However few investigations exist concerning the use of ozone as an additional oxidant. In this work the influence of ozone on the photocatalytic degradation of organic compounds are described. The results are compared with those by using ozone, UV/O-3 and UV/TiO2/O-2. The oxidation reactions were performed at pH 3 and 7. In this research compounds of the different classes were used: glyoxal, pyrrole-2-carboxylic acid, p-toluenesulfonic acid and naphthalene-1,5-disulfonic acid. Depending on the classes of compounds in some cases the elimination rates of the initial compounds is enhanced by using UV/TiO2/O-3 compared to UV/O-3 or 03 alone. But in all cases greatest DOC elimination is achieved by using UV/TiO2/O-3.