Hydrated ferric oxide mixtures

If a soap is added to a lead hydrogen arsenate-hydrated ferric oxide mixture considerable damage and leaf drop is caused, especially if the soap contains a strong base, as in the case of commercial potash fish-oil soap or potassium oleate. Laboratory tests show that more soluble arsenic is formed than with a soap of a weak base such as triethanolamine oleate.7 The addition of cryolite to an arsenate inhibits the formation of soluble arsenic 8 fluosilicates cause decomposition. These fluorine... 

Synonyms umber sienna hydrated ferric oxide mixtures calcined (burnt ocher) yOctalactone... 

For steel, passivation is achieved by the surface formation of a tough, adherent mixture of oxides. The passive film is primarily gamma-magnetite (y-Fe203) but also contains gamma-hydrated ferric oxide (y-FeOOH). The film thickness is perhaps 15 A to 30 A (angstrom units). 

Both humic acids and fulvic acids have a strong affinity for particulate and crystalline substances possessing oxygen atoms at their surfaces and they have been reported to bring about the dissolution of iron phosphate, calcium phosphate (61), uranium dioxide (65), hydrated magnesium alumino-silicates (66) and limonite, a complex mixture of hydrated ferric oxides (67). 

An artificial pigment analogous to the ochres is Mars yellow, consisting of a mixture of hydrated ferric oxide with calcium sulphate, alumina or zinc oxide of analogous composition are the pigments derived from it by more or less pronounced heating (Mars orange, red, brown, violet, purple). 

The most common ores of iron are hematite, or ferric oxide (Fe203) limonite, or hydrated ferric oxide magnetite, or iron oxide (Fe304) and siderite, or iron carbonate (FeC03). An increasingly important source of iron is taconite. Taconite is a mixture of hematite and silica (sand). It contains about 25 percent iron. 

Hydrated ferric oxide is also a coagulant. Aluminium sulphate made from bauxite rich in iron contains a considerable quantity of ferric sulphate and this mixture is known as aluminoferric. Hydrated silica, prepared by the addition of an acid or sodium bicarbonate to sodium silicate solution is also effective as a coagulant. It can be used alone or with aluminium hydroxide. 

We now consider Fe hydrolysis. The hexaaquaflFerric cation[Fe(H20)e] is more acid than hexaaquaferrous cation [Fe(H20)g]. The equilibrium constant of hydrolysis is approximately one order lower than that in phosphoric acid, whereas the equilibrium constant of the hydrolysis of Fe " is approximately one order higher than that in boric add. During the hydrolysis the following essentially mononuclear complexes are produced [FeOH] ", [Fe(OH)2]" , [Fe(OH)3(aq)]° and [Fe(OH)4]. By other reactions a series of polynuclear complexes is formed, for example, [Fe2(OH)2], [Fe3(OH)4] , [Fe4(OH)g] , etc. (for simplicity, the coordinated water molecules are omitted). First, colloid hydroxo complexes are formed and finally there is a precipitate of hydrated ferric oxide which is in fact a mixture of different polynuclear complexes. The distribution of polynudear complexes depends not only on pH, but also on the initial concentration of iron. In diluted solutions of ferric salts a precipitate of hydrated Fe203 is separated only at a higher pH. The equilibrium between particular polynuclear complexes is established only very slowly. 

A rather complex mixture is that constituted by the Italian tuffs [8, 53, 54], which contain various hydrated phases, namely three zeolites (phillipsite, chabazite and analcime, Table 1), unreacted glass (pumice, glass fragments, scoriae), hydrated ferric oxides and an X ray amorphous gel-like alumino-silicate, in addition to some non-hydrated phases, such as sanidine and biotite crystals. The most concentrated phases are phillipsite and chabazite, the total content of which usually amounts to 50% or more. Since Italian tuffs, simply because of the elevated contents of the above zeolites, are gaining a pre-eminent position in many industrial, agricultural and environmental applications, it is of great interest to have a rapid and reliable method available for evaluating zeolite content in the rock. 

By this method the carbon dioxide is not absorbed, and a nuxe efficacious plan is to use a mixture of equal parts of ferrous sulpbat or green vitriol and sawdust, with half the weight of risked lima A mixture containing slaked lime, hydrated ferric oxide, and sulphate of lime is thus obtained, made porous with sawdust, and this acts as an excellent absorbent. The spentmixture... 

Historiad Background. The first installations utilized a simple form of the iron oxide (or dry-box) process. In this form of the process, hydrogen sulfide was removed completely by reaction with hydrated ferric oxide, resulting in the formation of ferric sulfide. After removal from the box and exposure to atmospheric oxygen, the ferric sulfide oxidized to elemental sulfur and ferric oxide. The oxidized mixture was reloaded into the box and used to react with additional hydrogen sulfide. The cycle could be repeated several times before the material lost activity due to the presence of excessive amounts of elemental sulfur. 

The mechanism by which chromate passivates steel has been studied extensively, and it appears hkely that protection is afforded by a combination of adsorption and oxide formation on the steel surface. Adsorption helps to polarize the anode to sufficient potentials to form very thin hydrated ferric oxides that protect the steel. Because the oxide film is invisible on steel, articles protected by chromate remain bright in otherwise aggressive environments. The oxide film is a mixture of ferric and chromic oxides and is kept in good repair by adsorption and oxidation, with very little loss of metal as long as sufficient chromate remains in solution. 

Portland cement is made from limestone or other natural sources of calcium carbonate, clay (a source of silica), alumina, ferric oxide, and minor impurities. After grinding, the mixture is fired in a kiln at approximately 2500°F/1137°C. The final product is ground to a fineness of about 10 pm, and mixed with gypsum to control setting. When mixed with water, the portland cement forms a hydrated phase and hardens. As the cement hardens, chemical reactions take place. The two most important reactions are the generation of calcium hydroxide and of tricalcium silicate hydrate. The calcium hydroxide generated could theoretically... 

Different compounds can be found within this group. Some examples are described below. Among others, we can find iron oxides, which offer excellent stability and are the most widely mineral pigments in make-up. There are three basic shades of iron oxides yellow (which corresponds to hydrated ferrous oxide, i.e. FeO nH20), red (which is attributed to ferric oxide, i.e. Fe203) and black (which is a mixture of both iron oxides). 

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