The report gives results of a study of the rate of oxidation (low pH catalyzed oxidation and high pH uncatalyzed oxidation) of SO2 in a 1 liter semi-batch reactor. Low pH experiment results included: (1) both MgSO4- and MnSO4-catalyzed liquid-phase oxidation of SO2 at low pH are zero order in SO2 concentration; (2) while Mn is a very effective catalyst even at concentrations as low as 3 ppm, Mg shows little catalytic action even at concentrations as high as 20,000 ppm; (3) energy of activation for the Mn-catalyzed reaction was 18.7 kcal/mole; (4) low pH oxidation of SO2, catalyzed by MnSO4, is independent of pH between 1 and 4, while at pH values above 4, the reaction speeds up due to the presence of sulfite ions; (5) ionic strength did not appear to affect the reaction rate significantly (additional tests at higher ionic strengths should be performed to check this effect); and (6) sulfate ions inhibit the reaction significantly. The primary result of the high pH study was a first order rate constant of 0.0053 per second; during the experiments, oxidation was kinetically controlled with a constant oxidation concentration of 0.0013 M. Results applied to conditions in a SO2 scrubber indicated that the catalyst effect, even at ppm concentration, is very significant. The effect of catalysts in high pH scrubbing systems subject to oxidation is much greater than in low pH systems.

"The University of Illinois." "January 1979." Includes bibliographical references (pages 67-69). "Grant no. R800303, program element no. EHE624."