SCRUBBING OF SULFUR-DIOXIDE USING A CERIUM(IV)-CONTAINING ACIDIC SOLUTION - A KINETIC INVESTIGATION

The paper describes kinetic investigations related to the development of a wet scrubbing process for SO2 abatement from industrial waste gas es: the oxidation of sulfur dioxide by tetravalent cerium in a sulfuri c medium. Experiments carried out using two gas/liquid contactors and their interpretation could highlight the reaction schemes; rate consta nts could also be deduced from experimental data at 25 degrees C. Firs t, tetravalent cerium oxidizes sulfur dioxide into dithionate and sulf uric acid: increasing the concentration of sulfuric acid up to 5 M red uces the importance of dithionate species and the rate constants. The oxidation by Ce(TV) is a first-order process with respect to both reac tants, and the global rate constant of SO2 consumption decreases from 2 to 0.05 m(3) mol(-1) s(-1) when the concentration of sulfuric acid i s varied from 0.5 to 5 M. Besides, sulfur dioxide can also be oxidized by air oxygen through a catalytic process: both Ce(III) and Ce(TV) sp ecies were shown to have significant catalytic effect.