process for the preparation of aqueous solutions of sodium hexacyanoferrate (iii) - and hexacyano of sodiumet potassium ferrate

摘要

1377133 Na and Na/K ferricyanides DEUTSCHE GOLD-UND SILBER-SCHIEDEANSTALT 13 March 1972 [3 May 1971] 11575/72 Addition to 1338274 Heading C1A [Also in Division C7] Na 3 Fe(CN) 6 or NaK 2 Fe(CN) 6 is formed by oxidizing an aqueous solution of Na 4 Fe(CN) 6 or a mixture of Na 4 Fe(CN) 6 and K 4 Fe(CN) 6 , in the presence of added H 4 Fe(CN) 6 or H 3 Fe(CN) 6 . The oxidation may be effected electrolytically or with O 2 , air, or H 2 O 2 . The acid may be obtained by reacting the Ba salt with H 2 SO 4 or the alkali metal salt with HCl or with a cation exchange resin in the H form. A solid product may be obtained by crystallization or spray drying.