The photocatalytic oxidation of nitrite to nitrate in aqueous solutions containing different semiconducting metallic oxides of environmental concern was investigated. From the results obtained, TiO2 and ZnO have been shown to be the most photoactive photocatalysts for nitrite photo-oxidation. For ZnO slurries, photogenerated H2O2 was detected (larger amounts in the presence of nitrite than in its absence). In addition, in the presence of nitrite the photochemical instability of ZnO in aqueous suspensions was increased. From an analysis of the results it is concluded that the nitrite is oxidized by photogenerated OH radicals in the adsorption layer of the semiconductor particles following Langmuir-Hinshelwood kinetics. © 1993.
|Journal||Journal of Photochemistry and Photobiology, A: Chemistry|
|Publication status||Published - 1 May 1993|