Experimental Aspects of Mechanistic Studies on Aqueous Ozone Decomposition in Alkaline Solution

Abstract

Ozone decomposition in aqueous solution was studied by the stopped - flow method over the pH 10.4 - 13.2 range at 25 ± 0.1 °C and I = 0.5 M NaClO4. At 260 nm the molar absorptivity of aqueous ozone was determined to be 3135 ± 22 M−1cm−1. It was shown that various experimental factors may significantly alter the course of the reaction. Even small amounts of H2O2 absorbed by the plastic parts of the stopped-flow instrumént can affect the kinetic features of the reaction for an extended period of time. Under strictly controlled experimental conditions sufficiently reproducible data could be obtained for the decomposition. The data were evaluated by comparing experimental and simulated kinetic traces. A detailed kinetic model was developed which is able to predict the decay and life-time of ozone as well as the formation and decomposition of the ozonide ion radical (O3 −) over the pH 10.4 - 13.2 range.