Metal oxide nanomaterials such as TiO2 and CeO2 as well
as carbon nanotubes have been studied as catalysts in heterogeneous
catalytic ozonation processes that provide fast
and comparatively complete degradation of organic pollutants.
Both radical-mediated and non-radical-mediated reaction
pathways have been proposed 
. The adsorption of ozone and/or pollutants
on the catalyst surface plays a critical role in both mechanisms.
Nanomaterials have large specific surface area and an
easily accessible surface, leading to high catalytic activity.
Some nanomaterials were also reported to promote decomposition
of ozone into hydroxyl radicals, facilitating degradation
process through radical-mediated routes (Orge et al.,