ABSTRACT
A possible fourth type of reaction could be some sort of nucleophilic addition, although this reaction has only been confirmed in nonaqueous systems.1
In some cases, free radicals are formed from these reactions. These free radicals propagate themselves through mechanisms of elementary steps to yield hydroxyl radicals. These hydroxyl radicals are extremely reactive with any organic (and some inorganic) matter present in water.2 For this reason, ozone reactions in water can be classified as direct and indirect reactions. Direct reactions are the true ozone reactions, that is, the reactions the ozone molecule undergoes with any other type of chemical species (molecular products, free radicals, etc.). Indirect reactions are those between the hydroxyl radical, formed from the decomposition of ozone or from other direct ozone reactions, with compounds present in water. It can be said that a direct ozone reaction is the initiation step leading to an indirect reaction.
