SUMMARY OF RUNS D-77 THROUGH D-93. RATE OF OXIDATION OF CHROMIUM(III) IN DILUTE URANYL SULFATE SOLUTION IN THE PRESENCE OF RUTHENIUM

The rate of oxidation of chromium(III) to chromium(VI), catalyzed by ruthenium, was determined at various temperatures and oxygen concentrations. The rate at 300 deg C was too rapid for measurement by aliquot sampling. In the temperature range of 225 to 275 deg C, oxidation was rapid and the rate increased with oxygen concentration. A linear dependence of initial oxidation rate on the reciprocal of chromium(VI) concentration suggested that a rate-controlling step in the reaction mechanism may be desorption of chromium(VI) from the ruthenium catalyst. The activation energy calculated for the reaction is 19 kcal/mole. (auth