Abstract
Hydroxyl radicals are formed upon the hydroxide-ion catalyzed decomposition of ozone in water as is shown by the relative rates with which organic substrates compete with each other for consuming the oxidative intermediates. The yield of the decarboxylation of 14C-labelled benzoic acid indicates that up to 0.55 ± 0.08 mol of hydroxyl radicals may be produced from 1 mol ozone at pH 10.5. Published data on hydroxyl radical-reactions can now be applied to describe oxidations initiated by ozonation. Parameters influencing the prior ozone decomposition and protective effects of radical scavengers, such as carbonates, have to be accounted for when optimizing the processes. The solutes present in water influence appreciably the rate of the chain reaction leading to the decomposition of ozone.