Method for producing sodium dithionite

Details Method for producing sodium dithionite Method for producing sodium dithionite

2011-06-28

2011-06-28

Mayes, Melvin C (Department: 1732)

Chemistry of inorganic compounds

Sulfur or compound thereof

Oxygen containing

Reexamination Certificate

active

07968076

ABSTRACT:
The invention relates to a process for the preparation of sodium dithionite, comprising the steps(a) provision of a synthesis batch comprising sodium formate, sulfur dioxide and an alkaline sodium compound in aqueous methanolic solution with formation of a sodium dithionite mother liquor,(b) isolation of sodium dithionite from the sodium dithionite mother liquor, a residual mother liquor being obtained,(c) separation of methanol from the residual mother liquor,(d) separation of the residual mother liquor into a thiosulfate-rich first part-stream and a thiosulfate-poor, formate-containing second part-stream by means of nanofiltration,(e) concentration of sodium formate in the second part-stream and(f) recycling of the concentrated second part-stream to process step (a).

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