Iron manganese

By reference to the outline periodic table shown on p. (i) we see that the metals and non-metals occupy fairly distinct regions of the table. The metals can be further sub-divided into (a) soft metals, which are easily deformed and commonly used in moulding, for example, aluminium, lead, mercury, (b) the engineering metals, for example iron, manganese and chromium, many of which are transition elements, and (c) the light metals which have low densities and are found in Groups lA and IIA. 

The amount of iron and manganese in an alloy can be determined by precipitating the metals with 8-hydroxyquinoline, C9H7NO. After weighing the mixed precipitate, the precipitate is dissolved and the amount of 8-hydroxyquinoline determined by another method. In a typical analysis, a 127.3-mg sample of an alloy containing iron, manganese, and other metals was dissolved in acid and... 

Cobalt, copper, molybdenum, iodine, iron, manganese, nickel, selenium, and zinc are sometimes provided to mminants. Mineral deficiency or toxicity in sheep, especially copper and selenium, is a common example of dietary mineral imbalance (21). Other elements may be required for optimal mminant performance (22). ExceUent reviews of trace elements are available (5,22). 

Micronutrients. Attention to meeting the micronutrient needs of crops has greatiy increased as evidenced in an analysis undertaken by TVA and the Soil Science Society in 1972 (99). The micronutrient elements most often found wanting in soil—crop situations are boron, copper, iron, manganese, molybdenum, and zinc. Some of these essential micronutrients can be harmful to plants when used in excess. 

In addition to its presence in fmits, S(—)-malic acid has been found in cultures of a variety of microorganisms including the aspergiUi, yeasts, species of Sekrotinia, and Penicillium brevicompactum. Yields of levorotatory malic acid as high as 74% of theoretical have been reported. Iron, manganese, chromium, or aluminum ions reportedly enhance malic acid production. S(—)-Mahc acid is involved in two respiratory metaboHc cycles the Krebs tricarboxylic acid... 

Analogous reactions form sodiummethyldithiocarbamate [137-42-8] from methylamine, and disodiumethylenebis(dithiocarbamate) [142-59-6] from ethylenediamine. Iron, manganese, and 2iac salts can be prepared from the sodium salts heavy metals form characteristically colored compounds with dithio c arb amate s. 

In some reports Gallionella have been associated with manganese and iron deposits that also contain chloride. It has been postulated that deep undercut pits on stainless steels (especially at welds) containing such deposits are indirectly caused by these bacteria, since the iron-manganese deposition can be accelerated by Gallionella. In spite of numerous literature citings, however, evidence for stainless steel... 

At present, chlorine dioxide is primarily used as a bleaching chemical in the pulp and paper industry. It is also used in large amounts by the textile industry, as well as for the aching of flour, fats, oils, and waxes. In treating drinking water, chlorine dioxide is used in this country for taste and odor control, decolorization, disinfection, provision of residual disinfectant in water distribution systems, and oxidation of iron, manganese, and organics. The principal use of chlorine dioxide in the United States is for the removal of taste and odor caused by phenolic compounds in raw water supplies. 

Uranium Short-term tests indicate that the practical upper limit for niobium as a container material for uranium is about 1 400°C . Niobium is dissolved in a uranium-bismuth alloy in less than lOOh at a temperature of 800°C". Uranium eutectics with iron, manganese or nickel, corroded niobium at 800°C and 1 000°C It is significantly attacked by uranium-chromium at 1 000°C . 

All conventional phosphate coating processes are based on dilute phosphoric acid solutions of iron, manganese and zinc primary phosphates either separately or in combination. The free phosphoric acid in these solutions reacts with the iron surface undergoing treatment in the following manner ... 

The relation between free phosphoric acid content and total phosphate content in a processing bath, whether based on iron, manganese or zinc, is very important this relation is generally referred to as the acid ratio. An excess of free acid will retard the dissociation of the primary and secondary phosphates and hinder the deposition of the tertiary phosphate coating sometimes excessive loss of metal takes place and the coating is loose and powdery. When the free acid content is too low, dissociation of phosphates (equations 15.2, 15.3 and 15.4) takes place in the solution as well as at the metal/solution interface and leads to precipitation of insoluble phosphates as sludge. The free acid content is usually determined by titrating with sodium... 

Manganese phosphate coatings heated in the absence of air lose their corrosion resistance at between 200 and 218°C. At these temperatures, between 75 and 80% of the water of hydration is lost and it is assumed that this results in a volume decrease of the coating which causes voids and thereby lowers the corrosion resistance. Fig. 15.4 shows the loss of water of hydration from zinc, iron and iron-manganese phosphate coatings. 

Fig. 15.4 Effecl of heating on phosphate coatings for 16 h at various temperatures, showing loss of water of hydration. Curve A zinc phosphate, B iron phosphate and C iron manganese phosphate (courtesy y./.S./., 170, II (1952))...

Mention has been made of the necessity for controlling the acid ratio of phosphating baths, particularly those of iron, manganese and zinc operating... 

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