Some Aspects on Sodium Sulfite Oxidation in Aqueous Solution

Abstract

The effects of the partial pressure of oxygen and the pH value on the rate of oxidation of sodium sulfite with oxygen in an aqueous solution catalyzed by cobaltous ion were investigated by a gas absorption method at 25°C. Measurements were made on the solution of 0.3 mol/l of sodium sulfite with 10⁻⁶ mol/l of cobaltous ion in the region of the pH values from 6 to 13, and in the region of the oxygen partial pressures from 0.1 to 1 atm. The order of reaction with respect to oxygen was found to be unity when the oxygen partial pressure was higher than 0.17 atm, and two when the oxygen partial pressure was lower than 0.17 atm. The rate of reaction was very sensitive to the pH value of the solution. The relation between them is very complicated. Hence, it is difficult to find a simple expression to correlate them.