with ozone are relatively slow and selective. Therefore, if the ozonation
reaction is not satisfactorily fast, radical processes have to
be implemented. Ozone decomposition in water is strongly pH
dependent and occurs faster with an increase of pH. Reactions of
radicals with organic and inorganic molecules are, as opposed to
direct molecular ozone reactions, fast and non-selective. Recombination
of hydroxyl radicals might also take place and might lead as a
result to inactive moieties. Termination of the radical chain reaction
leads to a decrease of ozone oxidative power. In contrast to ozonation
alone, catalytic ozonation allows for the effective formation of
hydroxyl radicals also at a low pH. Catalytic ozonation utilises catalysts
in order to achieve controlled decomposition of ozone and
hydroxyl radicals’ formation. Therefore catalytic ozonation can be
placed in the group of methods called advanced oxidation processes,
although there are some exceptions observed. Catalytic
ozonation should provide fast degradation of organic pollutants
and also more effective mineralization of both micropollutants and
natural organic matter