Compositions – Reductive bleachant – deoxidant – reductant – or generative – Sulfur containing reductant – bleachant – deoxidant – or...
Patent
1980-06-05
1981-08-11
Cooper, Jack
Compositions
Reductive bleachant, deoxidant, reductant, or generative
Sulfur containing reductant, bleachant, deoxidant, or...
423265, 423515, C01B 1766
Patent
active
042833035
ABSTRACT:
Substantially stable slurries containing 30-35% by weight of sodium dithionite are manufactured by evaporating sodium dithionite solutions while maintaining the heating medium at 220.degree.-250.degree. F. and the solution and slurry at 110.degree.-155.degree. F. under a vacuum of at least 25 inches Hg and by promptly cooling the resultant slurry while agitating it. The vacuum is preferably 26.5-27.5 in. Hg. At 4-5% by weight of the sodium dithionite and preferably at 4.3% by weight, NaOH is preferably added to the solution or alternatively to the slurry, immediately after evaporation. A chelator is preferably added to the solution to prevent metal contamination thereof. Zinc-derived sodiation liquor is the preferred sodium dithionite solution.
REFERENCES:
patent: 2226576 (1940-12-01), Park et al.
patent: 3804944 (1974-04-01), Kise et al.
patent: 3839218 (1974-10-01), Owen et al.
patent: 3985674 (1976-10-01), Ellis et al.
patent: 4100098 (1978-07-01), Magan
Dulepov et al. "Zhurmal Prikladnoi Khimii," vol. 49, No. 5, pp. 1135-1137, May, 1976.
Cooper Jack
Virginia Chemicals Inc.
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