DE534365C - Process for the production of potassium ferricyanide - Google Patents

Description

Process for the production of potassium ferricyanide The production of Potassium ferricyanide has hitherto generally been carried out by oxidation of potassium ferrocyanide. The potassium ferrocyanide required for this had to be obtained from the poorly soluble double salt potassium calcium ferrocyanide can be obtained by reacting with potash. Except for a suggestion, the conversion to be carried out with potassium chloride in the presence of gaseous chlorine, all attempts are to replace the potash with the more accessible and cheaper potassium salts, failed so far.

According to the invention, the use of potassium carbonate in the Wise avoided that the sodium ferrocyanide started out from the raw materials can be obtained by means of cheaper means than the corresponding potash salt. This salt is first oxidized to sodium ferricyanide. The sodium ferricyanide is then with a potassium salt, which favors the salting out of the potassium ferricyanide, implemented. Potassium chloride is particularly suitable for this. Due to the different Solubilities of the sodium and potassium salts of ferricyanidic acid separate then the potassium ferricyanide äus. The crude potassium ferricyanide is = in one fresh amount of the sodium ferricyanide salt solution obtained by oxidation of the sodium ferrocyanide solution recrystallized. This way of working is the cleaning of what comes first Crude salt is practically possible at no cost, since the process of excretion of the crude salt adhering salts, such as. B. potassium chloride, recovered in the recrystallization by reacting this potassium chloride in turn with the sodium ferricyanide. From the mother liquor, which is obtained in the second pure crystallization, leaves By adding potassium chloride, raw potassium ferricyanide is then restored, as just now bdwritten, weed out.

Example In the anode compartment of an electrolyzer were 3 l at 60 ° C saturated ferrocyanide solution with about 5oo g of yellow soda per liter and introduced electrolytically oxidized. In the course of the electrolysis, 4209 yellow soda crystals were formed added until there was no more ferrocyanide next to ferricyanide.

The following were applied: 3.25 l of solution (I) with 386 g of red soda per liter.

a) 2,251 of this solution were heated and 61o g of potassium chloride were added with constant stirring. After cooling, it was filtered. The following were applied: 880 g of crude salt with 80% Kje (CN) s, 14 "/. KCl and 6% moisture; furthermore 2050 ccm of solution (II) with 183 g of sodium chloride and 92.6 g of cotnatron according to Littr.

b) The raw salt was recrystallized into the remainder of the solution - @ I} - after heating. The following were obtained: 885 g Kg Fe (CN) β of 99.5 ° A purity. The mother liquor (Solution III), as described under a, mixed with potassium chloride, and 1 56 g 8o ° / oiges crude salt were erhalten-.

c) The remaining solution (IV) was combined with solution (II) and reduced to yellow sodium in the cathode compartment of the electrolysis. In this case, 380 g Gelbnatronkristalle were obtained and 3 1 end liquor having 1 5 g per liter Gelbnatron which possibly can be precipitated with iron salts. Trial balance Brought in: 1. 3000 cc with 500 9 Yellow soda liters .... = 1500 g yellow soda 2. 420 g yellow soda crystals. . . . . . . . . . - 4209 - 192o g of yellow soda through reduction again won ........ 38o g - .remaining ... 1540 g of yellow soda -Deployed: 1. 885 g red potash (99.5% oig). . . . . . . . 1300 g of yellow soda = 84.5% 2.156 g (80% raw salt) . . . . . . . . . . . . . 183 g of yellow soda = I2.0 0/0 1483.g yellow soda = 96.5%

Claims (2)

PATENT CLAIMS: i. Process for the production of potassium ferricyanide, characterized in that sodium ferrocyanide is initially applied to any known Way is oxidized to sodium ferricyanide, whereupon this with different from potassium carbonate Potassium salts, preferably potassium chloride, reacted and the resulting potassium ferricyanide is deposited in the usual way by crystallization. 2. The method according to claim i, characterized in that the purification of the crude potassium ferricyanide salt by Recrystallization in a further amount of sodium ferricyanide liquor obtained in the process itself he follows.