EN
Metal oxide particles in the submicron and nanometer range endow a wide
range of consumer products with unique properties. The widespread use
of such products raises concerns on potential toxicity of these materials to
man and the environment. Besides their size, the photo-catalytic properties
of metal oxide particles are of particular concern. By utilizing molecular
probes with tailored optical properties, we investigated the photo-catalytic
properties of seven TiO2 (anatase), ZnO and CeO2 manufactured particles in
environmental media. Controlled experiments confirmed that the particles
catalyzed photo-oxidation and photo-production of reactive oxygen
species (ROS), while no ROS generation was observed when the ionic
form of the materials was used in place of the particles. While affecting
their aggregation and sedimentation, the type of media was not found to
strongly influence the photo-catalytic behavior of the particles. Within the
size range that was investigated, ZnO particles resulted in the highest
production of ROS, while anatase particles possessed the highest oxidative
ability. Possible explanations of such behavior are suggested.