Process for the production of Berlin blue
AssigneeDeutsche Gold- und Silber-Scheideanstalt vormals Roessler
InventorsHelmut Reinhardt, Karl Trebinger, Gottfried Kallrath
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Abstract
Berlin blue is produced by converting (a) calcium ferrocyanide, sodium ferrocyanide or magnesium ferrocyanide with (b) an iron II salt at a pH below 7 to an acidic iron II salt of ferrocyanic acid FeH.sub.2 [Fe(CN).sub.6 ]. The calcium or sodium ions can be washed out of the precipitate of the ferrocyanic salt. The precipitate is treated with (c) an inorganic or organic potassium salt to form Berlin white and then oxidized to Berlin blue. Alternatively, (a), (b) and (c) can be reacted together at a temperature of 20.degree. to 60.degree.C. to form Berlin white directly.
Claims12
A process comprising reacting in water (a) a member of the group consisting of calcium ferrocyanide, sodium ferrocyanide and magnesium ferrocyanide with (b) a water soluble iron II salt which does not form a water insoluble salt with calcium, magnesium or sodium and (c) with a water soluble potassium salt at a pH below 7 to form Berlin white, said process being carried out in one step in which the reaction of (a), (b) and (c) is carried out simultaneously at a temperature commencing between 20 and 60.degree.C.
Dependencies are inferred from the claim text.