OXIDATION OF AQUEOUS SULFUR-DIOXIDE IN SUSPENSIONS OF MAGNESIUM-OXIDE - REMOVAL OF SO2 FROM FLUE-GASES

The kinetics of oxidation of aqueous SO2 in acetate buffered suspensions of MgO obeys rate law (i) R(obs) = k{MgO][S(IV)2[H+]-1 ...(i) and the main oxidation product is sulphate. The suggested mechanism involves the formation of surficial complexes between hydroxylated magnesium and S(IV). There exists a close parallelism between R(obs) and pH of zero point charge, pH(ZPC), for CdO, MgO and SiO2. The results suggest that in wet-scrubbers, which utilize the slurries of MgO for removal of SO2 fro the flue gases, the sulphite formed as a result of SO2 absorption will be oxidized by atmospheric oxygen to sulphate, the extent of which will increase with increase in pH, temperature, slurry density and absorbed SO2.