Method For Preparing Aqueous Solutions Of Sodium Borohydride Of High Concentration

[loki396]

Sodium borohydride is extracted from an aqueous solution containing from about 5 to about 12.9 percent sodium borohydride and from about 35 to about 47 percent sodium hydroxide by weight by countercurrent extraction with a solvent for sodium borohydride, such as isopropylamine. The solvent is removed from the extract by distillation leaving an aqueous solution of high sodium borohydride content.
From the latter, crystals of sodium borohydride dihydrate are separated leaving an aqueous mother liquor containing about 32 percent sodium borohydride and about 5 percent The mother liquor is diluted with sodium hydroxide or an aqueous solution of high sodium hydroxide content and relatively low sodium borohydride content to obtain an aqueous solution of from about 13 to 30 percent sodium borohydride. The sodium borohydride dihydrate is dried to obtain solid sodium borohydride.

[cphorns]

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[walter24]

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