Iron phosphorus containing

Fluorapatite is the only significant phosphorus-containing mineral in the Earth s crust and schreibersite has been found in iron meteorites. The only organic species to be found containing phosphorus in meteorites are the alkyl phosphonic acids. These are at least promising even if they do not contain the P-O-P phosphoester bond unit. 

Phosphorus-containing iron ores are sometimes used in the steel industry, so an investigation of the Fe-P-O system at 800-1000 C has been made. Some of the new compounds discovered in this work contain mixed iron valencies. 

Organic constituents that may be found in ppb levels in WP/F smoke include methane, ethylene, carbonyl sulfide, acetylene, 1,4-dicyanobenzene, 1,3-dicyanobenzene, 1,2-dicyanobenzene, acetonitrile, and acrylonitrile (Tolle et al. 1988). Since white phosphorus contains boron, silicon, calcium, aluminum, iron, and arsenic in excess of 10 ppm as impurities (Berkowitz et al. 1981), WP/F smoke also contains these elements and possibly their oxidation products. The physical properties of a few major compounds that may be important for determining the fate of WP/F smoke in the environment are given in Table 3-3. 

Steel is the name given to iron which contains 0.04 to 1.7% carbon, small percentages of manganese, and only very small amounts of impurities such as sulfur and phosphorus, and which is capable of being hardened by quenching (i.e., rapid cooling by immersion in water, oil, or other suitable liquid). The carbon content of steel must be kept below... 

Iron always contains a small amount of carbon and other impurities unless it is specially prepared, say for spectroscopic purposes. The impurities are dissolved during production, phosphorus and sulphur from the ore, silicon and carbon from the limestone and coke. Silicon and carbon do not greatly reduce the corrosion resistance of iron when present in small quantities. Sulphur, however, may increase corrosion rates if allowed to precipitate as FeS. Crystals of FeS have a fairly high conductivity and can act as local cathodes. Additions of small amounts of manganese to the melt will cause the formation of MnS rather than FeS, the former being a poor conductor. 

Magnetochemical measurements for the solid phosphorus-containing zinc, iron, nickel, and cobalt tris-diiminates showed that the first two are diamagnetic and low-spin complexes. The cobalt and nickel(II) complexes proved to be high-spin clathrochelates with magnetic moments of 4.91BM (S=3/2) and 3.11BM (S=l), respectively [92, 93]. 

Blast furnace production of iron allows the hot, newly reduced product to trickle through the bed of heated coke to the hearth. Since carbon is somewhat soluble in molten iron, pig iron usually contains from 3 to 4.5% carbon. It also contains smaller percentages of other reduced elements such as silicon, phosphorus, manganese, etc., generated by the same reducing processes that yielded the iron (Table 14.3). Primarily from the effect of the high-carbon content on the iron crystal structure, the blast furnace product is brittle, hard, and possesses relatively low-tensile strength. Hence the crude pig iron product of the blast furnace is not much used in this form. 

Effects of Phosphorus-Containing Compounds on Iron and Zinc Utilization... 

A number of investigators have studied the relative bioavailability of iron from various compounds that contained both iron and phosphorus. Three such salts that have been studied extensively are ferric phosphate, ferric pyrophosphate, and sodium-iron pyrophosphate. All three have been listed as Generally Recognized as Safe (GRAS) in the Code of Federal Regulations and have been added to foods in the United States as iron supplements (1). However, only small amounts of two of these phosphorus-containing salts, ferric pyrophosphate and sodium iron... 

The bioavailability of iron from several organic phosphorus-containing compounds appears to be good. The iron in ferripoly-phosphate protein powder (13) and ferric glycerol phosphate Q, 6) was found to be 92-100% as bioavailable as ferrous sulfate in heme repletion assays with anemic rats and chicks. Morris and Ellis (14) have reported that the iron in monoferric phytate was utilized by rats as well as the iron in ferrous ammonium sulfate. While Lipschitz, et al. (15) have reported that dogs absorbed radio-labelled iron from a small dose (1.5 mg iron) of monoferric phytate one-half as well as they absorbed iron from ferrous sulfate. 

On the basis of the iron content these investigators identified their ovotyrine jS2 with the vitellinic acid of Levene and Alsberg. Moreover, they emphasized that the high content of serine in ovotyrine (82 (i-c., vitellinic acid) indicated that the phosphorus-containing unit of vitellin was phos-phoserine. As discussed earlier this suggestion then led to the isolation of 0-phosphorylserine from vitellinic acid (44). 

Ferritin consists of a shell of protein subunits surrounding a core of ferric hydroxyphosphate. For some time the inorganic component of ferritin was thought to be attached to the surface of the protein (65). However, the demonstration that ferritin and apoferritin have the same electrophoretic mobilities and are precipitated equally well with horse ferritin antibody (66) together with electron microscopic evidence (67) clearly showed that the iron is concentrated in the middle of the apoferritin protein shell. The iron micelle has a diameter of 70—75 A whilst the protein shell has a diameter of the order of 120 A (67—70, 62). Somewhat lower values are found in dried preparations (71, 72). The micelle contains ferric iron, predominantly as (FeO.OH) but also with some 1—1.5% phosphate (4,50) and it seems that the iron phosphorus ratio is constant for ferritins of different iron content (52). The composition (FeO.OH) g. (FeO.OPOgHg) has been suggested (73, 74). The percentage of iron in the micelle on this basis is 57%. 

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