Investigation of the radiation stimulated oxidation of sulfite by molecular oxygen in aqueous solutions

The principles of the radiation-stimulated oxidation of sulfite by molecular oxygen in the range of pH 11.0-14.6 were investigated. It was established that with increasing sulfite concentration, the kinetic order of the reaction with respect to sulfite falls from 1 to 0, and with respect to oxygen it increases from 0 to 1. This is explained by the fact that at low sulfite concentrations the rate-determining step of the process is the reaction SO5- (HSO5) + SO32- → SO4- (HSO4) + SO42-, while at high concentrations it is the reaction SO3 + O2 → SO5-. The influence of the pH is explained on the assumption of the existence of two forms of the peroxomonosulfate radical, the more reactive of which is the acid. A number of ratios of reaction rate constants were determined