OZONE PRODUCTION IN THE REACTION OF T2 AND O2 GAS - A COMPARISON OF EXPERIMENTAL RESULTS AND MODEL PREDICTIONS

Ozone, predicted to be an important intermediate species in T2 oxidation, was monitored in situ by UV absorption spectroscopy for 0.01-1.0 mol % T2 in O2 (1 atm, 298 K). These are the first measurements of a tritium oxidation reaction intermediate. The experimental results were compared with the predictions of our comprehensive model of tritium oxidation. The experimentally determined temporal variation in ozone concentration is qualitatively reproduced by the model. As predicted, the measured initial rate of ozone production varied linearly with the initial T2 concentration ([T2]0), but with a value one-third of that predicted. The steady-state ozone concentration ([O3]SS) was predicted to be dependent on [T2]0(0.3), but measured values showed a [T2]0(0.6) dependence, resulting in [O3]SS a factor of 4 larger than predicted for a 1.0% T2-O2 mixture. Addition of H-2 to the T2-O2 mixture, to differentiate between the radiolytic and chemical behavior of the tritium, produced a decrease in [O3]SS which was larger than predicted. Changing the reaction cell surface-to-volume ratio showed indications of minor surface removal of ozone. No reasonable variation in model input parameters brought both the predicted initial ozone production rates and steady-state concentrations of ozone into agreement with the experimental results. Though qualitative agreement was achieved, further studies, with emphasis on surface effects, are necessary to explain quantitative differences and gain a greater understanding of the oxidation mechanism.