Ferric phosphate

Hydrogenis prevented from forming a passivating layer on the surface by an oxidant additive which also oxidizes ferrous iron to ferric iron. Ferric phosphate then precipitates as sludge away from the metal surface. Depending on bath parameters, tertiary iron phosphate may also deposit and ferrous iron can be incorporated into the crystal lattice. When other metals are included in the bath, these are also incorporated at distinct levels to generate species that can be written as Zn2Me(P0 2> where Me can represent Ni, Mn, Ca, Mg, or Fe. 

Phosphates and siUcates of metals often react with phosgene at elevated temperatures and yield the metal chloride and phosphoms oxychloride or sihcon dioxide. The reaction with ferric phosphate at 300—350°C has been proposed as a synthetic method for phosphoms oxychloride, POCl. ... 

Variable results have been reported with this pigment and an examination of its inhibitive action has led to the conclusion that under rural and marine conditions, where the pH of the rain-water is above 5, it behaves as an inert pigment owing to its limited solubility. However, in industrial and urban areas, where the pH of the rain-water may be in the region of 4 or lower, it is converted into the more soluble monohydrogen phosphate. This reacts in the presence of oxygen, with the steel surface to form a mixture of tribasic zinc and ferric phosphates, which being insoluble protects the steel from further attack. 

The presence of nitrate as acelerator has a pronounced effect on the amount and composition of gas evolved from the work being treated (Table 15.8). It will be observed that hydrogen evolution drops to a very low figure with the zinc/nitrate baths. The formation of nitrite arises from decomposition of nitrate by reaction with primary ferrous phosphate to form ferric phosphate ... 

Determination of the Solubility of Ferric Phosphate in Phosphating Solutions Using Radioiron , US Department of Commerce, Office of Technical Services, Rep. No. PB 111, 399 (1953)... 

Early studies on oxide films stripped from iron showed the presence of chromium after inhibition in chromate solutionand of crystals of ferric phosphate after inhibition in phosphate solutions. More recently, radio-tracer studies using labelled anions have provided more detailed information on the uptake of anions. These measurements of irreversible uptake have shown that some inhibitive anions, e.g. chromateand phosphate are taken up to a considerable extent on the oxide film. However, other equally effective inhibitive anions, e.g. benzoate" pertechnetate and azelate , are taken up to a comparatively small extent. Anions may be adsorbed on the oxide surface by interactions similar to those described above in connection with adsorption on oxide-free metal surfaces. On the oxide surface there is the additional possibility that the adsorbed anions may undergo a process of ion exchange whereby... 

Ferric phosphate FeP04 Found in low temperature passivation film with hematite. 

Na3P04 sodium phosphate FeP04 iron(III) phosphate or ferric phosphate... 

Iron is stored in these proteins in the ferric form, but is taken up as Fe2+, which is oxidized by ferroxidase sites (a more detailed account of iron incorporation into ferritins is given later in this chapter). As we point out in Chapter 13, ferritins are members of the much larger diiron protein family. After oxidation, the Fe3+ migrates to the interior cavity of the protein to form an amorphous ferric phosphate core. Whereas the ferritins in bacteria appear to fulfil the classical role of iron-storage proteins, the physiological role of bacterioferritins is less clear. In E. coli it seems unlikely that bacterioferritin plays a major role in iron storage. 

Patented proposals have been made to heat sodium chloride with phosphoric acid (A. Delhaye) zinc or lead pyrophosphate (L. J. F. Margueritte) or ferric phosphate (A. R. Arrott). The resulting soluble sodium phosphate is decomposed by boiling with lime to form sodium hydroxide, which, if needed, can be converted into carbonate by a current of carbon dioxide. These methods are quite impracticable. In 1809, J. L. Gay Lussac and L. J. Thenard proposed to make soda by the action of steam on a mixture of sodium chloride and silica If these two compounds are melted together there is very little action, for the salt volatilizes before anything but a superficial combination takes place, and the action of salt in the glazing of pottery is probably made possible by the aq. vapour in the furnace gases. The sodium silicate formed by the joint action of sodium and... 

J. T. Way, and T. Twynam heated Thomas slag with soda, and extracted the alkali phosphate with M ater. N. A, Helouis and M. Rychonnet, L. Imperatori, and F. Jean calcined a mixture of the phosphate with sodium sulphate and carbon C. Schwarz, and M. Boblique heated the mineral with iron so as to make ferric phosphate, which was then heated with sodium sulphate and carbon. In each of these cases the alkali phosphate was leached from the mass. M. Drevermann treated the iron phosphate with sodium sulphide, C. Clemm with potassium sulphide. 

Iron. Excess iron in wines causes cloudiness, interferes with the color, and can impair flavor. The mechanism of ferric phosphate precipitation has been intensively studied, and numerous colorimetric methods have been developed. For routine purposes the color developed with thiocyanate is adequate (6,9), but many enologists prefer the orthophenanthro-line procedures (3, 4, 6, 22). Meredith et al. (Ill) obtained essentially the same results for iron using 2,4,6-tripyridyl-s-triazine (TPTZ) to develop the color. Atomic absorption spectrophotometry can be used but, as with copper, corrections for reducing sugar and ethanol are necessary (51). 

Iron buildup in the bath is objectionable in the iron-removal equations above, it is seen that dissolved Fe+ can he removed by oxidation, slowly in air or more rapidly by peroxides or nitrite, as shown in the final equation. The irnn removed becomes ferric phosphate, while iron in the coating is ferrous phosphate. 

In the alkylation of ethylbenzene with ethylene, with conventional acid catalysts under usual conditions,. veobutyl benzene is a byproduct. rec-Butylbenzene was detected when the reaction was carried out over catalysts such as supported phosphoric acid,189 ferric phosphate,189 or AICI3—NiO—Si02-190 When Nafion-H or AICI3 are used, no such byproduct is detected, probably due to fast dealkylation of sec-butylbenzene under the more acidic conditions. 

The next stages of mineralization differ according to species. In some species, the remaining matrix framework is filled with an amorphous hydrous ferric phosphate [12], In most species the process is more complex. Fepidocrocite (y-FeO(OH)) forms in a thin layer just beneath the magnetite layer [23, 24] and... 

By a similar reaction ferric phosphate is decomposed by carbonyl chloride at 800° to 400° C.1 ... 

The precipitates obtained with magnesia mixture (magnesium chloride in ammoniacal solution), or ferric chloride in an acid solution to which sodium acetate has been added, are often used as tests for phosphate (see p. 180), and in the latter case the phosphate is removed from solution as ferric phosphate. Another common test is the formation of yellow ammonium phosphomolybdate when, a nitric acid solution of ammonium molybdate is added to phosphate solution (see pp. 180, 181). 

The phosphates of iron and aluminium form gelatinous precipitates which are insoluble in weak acids, or in hydrolysed acid phosphates or sulphates. Ferric phosphate may be decomposed, using up more sulphuric acid, as in the equation... 

Ferric Phosphate occurs as a yellow-white to buff colored powder. It contains from one to four molecules of water of hydration. It is insoluble in water and in glacial acetic acid, but is soluble in mineral acids. 

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