Role of fly ash in catalytic oxidation of sulfur(IV) slurries

The rate of catalytic oxidation of S(IV) in aqueous fly ash slurries has been examined by monitoring loss of SO{sub 3}{sup 2-} and O{sub 2}, and SO{sub 4}{sup 2-} formation. Evidence from both filtering and extraction studies indicates that dissolved iron which has been leached from the ash is the chief catalyst. This homogeneous reaction dominates any catalytic effect of the ash surface.