Oxidation of sulfur dioxide by oxygen and ozone in aqueous solution: A kinetic study with significance to atmospheric rate processes

On the discrepancy between reported studies of the uncaialysed aqueous oxidation of SO2by O2

“…1. The results of Fuller and Crist (3), Larson et al (18), Schroeter (9), and Clarke and Radojevic (21) over this pH range show that k = [H + F. This is also in agreement with the pH dependence observed by Reinders and Vies (2) at pH < 8.4 (18,35). Schroeter's experimental results may be expressed in terms of the equation quoted in Table 1, which reduced to:…”

“…However, Yagi and Inoue (6) observed that the rate was first-order in 0 2 concentration at pH 8 to 9, while Larson et al (18) report an oxygen dependence at higher pH (> 9.5). O'Brien and Birkner (17) report an 0 2 dependence for the reaction, however they did not study sulphite oxidation directly but inferred the rate law from experiments into sulphide oxidation.…”

“…Other techniques have involved manometric or polarographic measurement of 0 2 consumption by sulphite solutions. In some of the bulk solution studies the reaction was followed almost to completion, for more than 80% of its course (3,9,18) while other workers generally followed the reaction for less than half its course (15,19,21).…”

“…The oxidation of sulphite by 0 2 is extremely sensitive to trace impurities of catalysts and inhibitors, even at levels present in standard laboratory waters and reagents. Some authors have therefore gone to great lengths to purify the reagents, the water, and the air or oxygen used in their experiments (3,9,18). However, certain of these "purification" procedures may have themselves resulted in contamination of solutions by traces of extraneous agents.…”

“…However, certain of these "purification" procedures may have themselves resulted in contamination of solutions by traces of extraneous agents. For example, Larson et al (18) purified distilled-deionised water by adding H 2 0 2 to the water and irradiating with intense UV radiation for several hours. This was intended to remove organic contaminants and they report that some 5 x 10" 7 M H 2 0 2 survived the irradiation.…”