Ferrocyanide treatment

Metatartaric acid is added after fining, as there is a risk of partial elimination due to flocculation. It is particularly affected by bentonite and potassium ferrocyanide treatments. Although there... 

Potassium ferrocyanide treatment is restricted to white and rose wines, at least in France. Excess iron is eliminated from red wines using calcium phytate. 

The most efficient process for eliminating excess copper is potassium ferrocyanide treatment (Section 4.6.5), which produces an insoluble complex with the following formula Fe(CNe)Cu2. This treatment generally brings the copper content down to 0.1 or 0.2 mg/1. Copper is present in much less complex forms than iron, so it precipitates faster. When small qnantities of ferrocyanide are added to wines with high copper and low iron concentrations, the precipitate is sometimes reddish instead of bine. 

Put 20 g. of potassium ferrocyanide in a 250-cc. Erlenmeyer flask, adding 30 cc. of water. Place the flask on the water bath and heat till the ferrocyanide dissolves. Add 35 cc. of nitric acid (sp. gr., 1.24) and continue heating until a test portion shows no blue color but a dark green precipitate when treated with ferrous sulfate. Let stand for a day or two and filter off the tarry impurities. Now neutralize with sodium carbonate, taking care that no excess is added. Warm and, when cool, add from one to two times the volume of alcohol (ethyl). Set the flask in a dry place for a day or two, after which the impurities (chiefly crystals of potassium nitrate) may be filtered off, and the nitro-prusside crystallized out. Sometimes two or three treatments with alcohol are necessary. In order to expedite the operation of evaporating down to crystallization, the solution may be evaporated by heating in a suction flask under reduced pressure. Quick crystallization increases the yield. The yield should be above 75 per cent. 

Fe4[Fe(CN)6] can bind caesium therefore iron blue pigments are used in clinical practice as an antidote for the treatment of humans contaminated with radioactive caesium (see also Section 3.6.4). Clinical use of iron(III) ferrocyanide in doses up to 20 g/d for decontaminations of persons exposed to radio caesium has not been associated with any reported toxicity [3.209]. 

Ferrocyanide process a regenerative chemical treatment for mercaptan removal using caustic-sodium ferrocyanide reagent. 

A number of pentacyano complexes are known, containing in addition to five cyano groups, an additional ligand (for example, H20. NH3, CO, or NO ). The nitro derivative, Fe(CN)5NOj4, prepared by treatment of ferrocyanide with nitrite ion, is of interest because it reacts with acid to yield the important nitroprussidc ion ... 

The crude coal gas is washed with ferrous sulphate solution, whereby the latter is converted into a suspension of ferrous sulphide in ammonium sulphate solution. This reacts with the ammonium cyanide, yielding ferrous ferrocyanide, Fe2[Fe(CN)6], or ammonium ferrous ferrocyanide, (NH4)2Fe[Fe(CN)6], according to circumstances. Potassium ferrocyanide may be obtained from these by treatment with lime, as m the spent oxide process. By repeatedly dissolving in water and precipitating with alcohol, the salt can be obtained in a very pure state.1... 

The dihydroxide crystallises in hair-fine, white needles, and is isolated by boiling the bromide with silver oxide in 80 per cent, alcohol for twenty hours. Treatment of the hydi oxide in 50 per cent, alcohol with sulphuric acid precipitates the siilj hute as microscopic white needles, suddenly blackening above 150 C. The dibrornide with silver nitrate gives tlie dinitrate, from which the dichloride is prepared. It crystallises in white needles, >Lpt. C. The following compounds are also mentioned oxalate, succinate, ferrocyanide, white precipitates, and the azelate, w hite scales. 

The above reaction occurs rapidly at pH levels below 3. Because the acidic properties of ferrous sulfate are low at high dilutions, acid must be added for pH adjustment. The ferrous sulfate reducing process generates large volumes of sludge and thus its use is rare in large-scale treatment facilities. In addition, the use of ferrous sulfate to treat chromate wastes containing cyanide results in the formation of very stable ferrocyanide complexes, which prevent subsequent effective cyanide treatment. 

For acute toxicity, emesis is recommended. Treatment is symptomatic. A combination of BAL (British AntiLewisite 2,3-dimercaptopropanol) and calcium-ethylene diamine tetraacetic acid has been used successfully in a poisoned infant. Penicillamine has also been used. Recently, oral administration of 2,3-dime-rcaptol-propane sulfonate was found to be effective in experimental rodents. Electrolyte balance must be maintained when gastric lavage is indicated. Potassium ferrocyanide should be added to precipitate the copper. 

Gerken, Dekker, Schlodder and Witt S utilized the same protocols that were used for isolating the AA(Qa -Qa) difference spectrum to indirectly obtain the difference spectrum just for the oxidation of the secondary donor Y, i.e., AA[Yz -YzJ. To isolate the difference spectrum, AA(Qa -Qa)5 electron transfer in the PS-II complex was blocked between Yz and P680 by Tris treatment and after Qa by DCMU. A ferri-/ferro-cyanide couple was added to the reaction mixture to intervene with oxidized Yz and reduced Qa following photo-excitation. Then, after a certain time after the flash, say, at 800 ms, the oxidized Yz would have been completely re-reduced by ferrocyanide rather than by the Mn-cluster, but Qa re-oxida-tion by ferricyanide would have occurred to a slight extent due to slower kinetics. When the absorbance... 

Treating wines with potassium ferrocyanide or fining blue (Figure 4.1) was recommended in Germany as long ago as 1923. In France, this treatment was authorized for white and rose wines, including sparkling wines, in 1962. It is also permitted for vins doux naturels. 

---