The primary reaction in the decomposition of ozone in acidic aqueous solutions

The primary step in the thermal decomposition of acidic aqueous ozone solutions is the dissociation reaction: O3 is O + O2, This reaction is supported by the retarding effect of O2 on the decomposition rate, by our activation energy measurements, EA = 79.5 ± 8.0 kJ mol−1, and by isotopic exchange experiments with 18, 18O2. The rates of ozone decomposition were measured at pHs 0–4, at temperatures 0–46 °C, and at O2 concentrations 10−5–10−3 M. The O atom formed in the dissociation reaction is postulated to be the precursor for OH and HO2 formation. The ionization of the HO2 free radical (pK = 4.8) accounts for the increase in rate with rising pH. The mechanistic implications of O3 decomposition in acid solution are briefly discussed.