Insoluble Prussian blue

Apart from these cyanide complexes, there are also mixed and bridged cyanide complexes (Barnes etal. 2000). A commonly occurring double salt is the Tumball or Prussian blue insoluble complex (Na or K)Fe4[Fe(CN)6]3. In acidic soils, precipitation and dissolution of Prussian blue dominates iron cyanide speciation (Meeussen etal. 1994). 

K+ is generally used as the reversibly intercalating ion since it leads to insoluble compounds for all the forms. In the mixed-valence Prussian Blue compound, Fe is in the high-spin state and coordinated octahedrally with the N ends of the cyaiudes, whereas Fe is low-spin and octahedrally coordinated with the C ends of the... 

The industrial production of Prussian blue is based on the reaction in aqueous solution of sodium hexacyanoferrate(n), Na4Fe(CN)6, with iron(n) sulfate, FeS04-7H20 in the presence of an ammonium salt, which results initially in the formation of the colourless insoluble iron(n) hexa-cyanoferrate(n) (Berlin white). Prussian blue is generated by subsequent oxidation with a dichromate or chlorate. 

For cases in which the NPs are not soluble in the supporting electrolyte in which they will be examined, it is possible to solvent-cast a thin film of the NPs on the electrode surface followed by evaporation [44] or to directly apply an insoluble gel containing the NPs [45]. In a related approach, films of anionic Prussian Blue NPs that had been synthesized in a solution containing chitosan (a cationic glucosamine polymer) were drop-cast onto glassy carbon surfaces, giving very stable... 

Thompson DF, Called ED Soluble or insoluble Prussian blue for radiocesium and thallium poisoning Ann Pharmacother 2004 38 1509. [PMID 15252192]... 

The insoluble prussian blue is found in lumps more... 

The term iron blue pigments as defined in ISO 2495 has largely replaced a great number of older names (e.g., Paris blue, Prussian blue, Berlin blue, Milori blue, Turnbull s blue, toning blue, and nonbronze blue). These names usually stood for insoluble pigments based on microcrystalline Fe(II)Fe(III) cyano complexes many were associated with specific hues. A standardized naming system has been demanded by users and welcomed by manufacturers, and has led to a reduction in the number of varieties [3.177],... 

FeCl3, dark blue precipitate—Prussian blue, Fe4 Fe(CN)6 3, insoluble in HO, soluble in oxalic acid. 

Alkali or alkaline-earth salts of both complexes are soluble in water (except for Ba2[Fe(CN)6]) but are insoluble in alcohol. The salts of hexakiscyanoferrate(4—) are yellow and those of hexakiscyanoferrate(3—) are mby red. A large variety of complexes arise when one or more cations of the alkali or alkaline-earth salts is replaced by a complex cation, a representative metal, or a transition metal. Many salts have commercial applications, although the majority of industrial production of iron cyanide complexes is of iron blues such as Prussian Blue, used as pigments (see PIGMENTS, inorganic). Many transition-metal salts of [Fe(CN) J4"" have characteristic colors. Addition of [Fe(CN)6]4 to an unknown metal salt solution has been used as a qualitative test for those transition metals. 

All of the [Fe(CN) J4- salts may be considered salts of ferrocyanic acid or tetrahydrogen hexakiscyanoferrate [17126-47-5], H4[Fe(CN)J, a strongly acidic, air-sensitive compound. It is soluble in water and alcohol but is insoluble in ether. It can be prepared by precipitation of an etherate by adding ether to a solution of [Fe(CN) J4"" that was acidified with concentrated sulfuric acid. Removal of the ether of solvation affords a white powder which is stable when dry but slowly turns blue in moist air because of Prussian Blue formation. 

The uptake if iron often requires Fe(II) as the bioavailable form, and uptake from soils containing insoluble Fe(III) is accomplished by phenolic compounds which are exuded by certain plants (Chaney and Bell, 1987). A particular use of staining has been in the study of the sites if iron reduction in plants, using Prussian blue stain (PB) (Ambler et al., 1971 Brown and Ambler, 1974). The method consists of placing the roots in a nutrient solution containing Fe(III) and ferricyanide. Since PB can be produced both from Fe(III) and Fe(CN)64 and from Fe(II) and Fe(CN)63, reduction of either source of iron in the presence of the roots will produce PB at the sites of... 

The widespread occurrence of iron ores, coupled with the relative ease of extraction of the metal, has led to its extensive use as a constructional material with the result that the analysis of steels by both classic wet and instrumental methods has been pursued with vigour over many years.3 Iron complexes are themselves widely used as the basis of convenient analytical methods for the detection and estimation of iron down to parts per million. Familiar tests for iron(III) in aqueous solution include the formation of Prussian blue as a result of reaction with [Fe(CN)6]4, and the formation of the intensely red-coloured [Fe(H20)5SCN]2+ on reaction with thiocyanate ion.4 Iron(II) forms particularly stable red tris chelates with a,a -diimines such as 1,10-phenanthroline or 2,2 -bipyridine that have been used extensively in spectrophotometric determinations of iron and in the estimation of various anions.5 In gravimetric estimations, iron(III) can be precipitated as the insoluble 8-hydroxyquinoline or a-nitroso-jS-naphthol complex which is then ignited to Fe203.6 In many situations the levels of free [Fe(H20)6]3+ may be controlled through complex formation by addition of edta. 

Fe(OH)3+3HNOs Fe(N03)3+3H20 is disturbed, owing to removal of ferric nitrate as insoluble Prussian blue.3... 

Ferrocyanic acid is also obtained when a solution of insoluble Prussian blue in hot, concentrated hydrochloric acid is allowed to stand (see p. 227). 

The test is done by boiling a portion of the alkaline solution from the solution fusion with iron(II) sulfate and then acidifying. Sodium cyanide reacts with iron(II) sulfate to produce ferrocyanide, which combines with iron(III) salts, inevitably formed by air oxidation in the alkaline solution, to give insoluble Prussian Blue, NaFe[Fe(CN)J. Iron(II) and iron(III) hydroxide precipitate along with the blue pigment but dissolve on acidification. 

An early X-ray study of Prussian blue and some related compounds showed that in ferric ferricyanide (Berlin green), FeFe(CN)6, Prussian blue, KFeFe(CN)6. and the white insoluble K2FeFe(CN)6. there is the same arrangement of Fe atoms on a cubic face-centred lattice. In Fig. 22.5 ferrous atoms are distinguished as shaded and ferric as open circles. In (a) all the iron atoms are in the ferric state in (b) one-half the atoms are Fe and the others Fe, and alkali atoms maintain electrical neutrality. These are at the centres of alternate small cubes, and it was supposed that in hydrated compounds water molecules could also be accommodated in the interstices of the main framework. Lithium and caesium, forming... 

If the normal hydrate bo dried in vacuo it is converted into (Fe, ).jH,0, and this, when boiled for some hours with H,0, is converted into the colloid, or modified hydrate (Fe,)H,0, ( ), which brick-red in color almost insoluble in HNO, and HCl ves no Prussian blue reaction, and forms a turbid solution with acetic acid. If recently precipitated ferric hydrate be dissolved in solution of ferric chloride or acetate, and subjected to dialysis, almost all the acid passes out, leaving in the dialyzer a dark-red solution, which probably contains this colloid hydrate, and which is instantly coagulated by a trace of H,SO, by alkalies, many salts, and by heat dialyzed iron). 

Prussian blue is a chelating agent. It insolubly binds radioactive and nonradioactive cesium and thallium in the GI tract by ion-exchange, adsorption, and mechanical trapping within the crystal structure. It is indicated in the treatment of patients with known or suspected internal contamination with radioactive cesium and/or radioactive or nonradioactive thallium to increase the rate of their elimination. 

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