Ferrous dithionate

Dithionic Acid, H2S2O0, is obtained only in aqueous solution. If sulphur dioxide is passed into an aqueous suspension of ferric hydroxide at 0° C., a red solution of ferric sulphite is first produced, which then changes to a pale green solution of ferrous sulphite and ferrous dithionate 4... 

Ferrous dithionate, FeS206, is readily obtained by double decomposition of solutions of the barium salt and ferrous sulphate. The dithionate is also formed by dissolving ferric hydroxide in sulphurous... 

On passing sulphur dioxide into cold solutions of ferric sulphate, ferrous dithionate is formed.3 With a 2 per cent, solution of ferric sulphate, 80 per cent, of the sulphate is converted into dithionate at 0° C., but this amount diminishes as the temperature rises, none being formed at 95 ° C. The equilibrium may be represented by the equation —... 

Ferric dithionate has not been isolated, as its solution decomposes yielding ferric sulphate, ferrous dithionate, sulphurous and sulphuric acids. 

In the case of the reduction of ferric salts by sulphur dioxide it has been suggested 9 that the reduction most probably proceeds in stages, a red ferric ferrisulphite, Fe[Fe(S03)3], being first formed, which on warming yields the ferrous salt and the dithionate, thus ... 

The improvement over the existing Japanese processes can be made by developing a more efficient ferrous chelate such that it can provide better absorption efficiency for NO, faster reaction rates between NO and S02> and better stability for the ferrous chelate toward oxidation, compared to Fe +(EDTA) or Fe +(NTA) employed in Japanese processes. The development of an efficient and cost-effective method for the reduction of ferric chelate to ferrous chelate without producing dithionate ions could make the process attractive. In addition to these areas, the study of several alternative approaches and novel ideas could develop into a much more efficient and cost-effective scrubber system employing metal chelate additives. 

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