Black oxide, precipitated

Black magnetic oxide Black oxide, precipitated Black rouge. See Iron... 

Synonyms Black magnetic oxide Black oxide, precipitated Black rouge Cl 77499 Ethiops iron Ferric ferrous oxide Ferrosoferric oxide Iron oxide Iron (II, III) oxide Iron (III) oxide Iron (II) oxide, black Iron (II, III) oxide, black Iron oxide magnetic Iron oxides (FesOJ Magnetite Pigment black 11 Triiron tetraoxide Classification Syn. iron oxide Empirical FejO,... 

Black oxide, precipitated. See Iron oxide black Black Pearls 120, Black Pearls 13Q, Black Pearls 160, Black Pearls 170, Black Pearls 280, Black Pearls 410, Black Pearls 420, Black Pearls 430, Black Pearls 450 Black Pearls 460, Black Pearls 470, Black Pearls 480, Black Pearls 490, Black Pearls 520, Black Pearls 570, Black Pearls 700] Black Pearls 800] Black Pearls 880] Black Pearls 900] Black Pearls 1000] Black Pearls 1100] Black Pearls 1300] Black Pearls 1400, Black Pearls 2000] Black Pearls 3700] Black Pearls 6100] Black Pearls L See Carbon. black... 

Addition of an alkali metal hydroxide solution to an aqueous solution of a nickel(II) salt precipitates a finely-divided green powder. nickel(II) hydroxide NilOHfj on heating this gives the black oxide. NiO. which is also obtained by heating nickel(II) carbonate or the hydrated nitrate. Black nickel(II) sulphide, NiS, is obtained by passing hydrogen sulphide into a solution of a nickel(II) salt. 

It is readily dehydrated on warming, to give the black oxide CuO. It dissolves in excess of concentrated alkali to form blue hydroxo-cuprate(II) ions, of variable composition it is therefore slightly amphoteric. If aqueous ammonia is used to precipitate the hydroxide, the latter dissolves in excess ammonia to give the deep blue ammino complexes, for example [Cu(NH3)4(H20)2] ... 

Iron Oxide Reds. From a chemical point of view, red iron oxides are based on the stmcture of hematite, a-Fe202, and can be prepared in various shades, from orange through pure red to violet. Different shades are controlled primarily by the oxide s particle si2e, shape, and surface properties. Production. Four methods are commercially used in the preparation of iron oxide reds two-stage calcination of FeS047H2 O precipitation from an aqueous solution thermal dehydration of yellow goethite, a-FeO(OH) and oxidation of synthetic black oxide, Fe O. ... 

Brown oxides are manufactured either by blending mixtures of the red, yellow, and black oxides or by precipitation of an iron salt with alkaU followed by partial oxidation of the precipitate. The result is a mixture of red Fe202 [1309-37-1] and black Fe O [1309-38-2] FeO Fe202-... 

The black oxides are prepared by the controlled precipitation of Fe O (treat FeSO -7H2 O with NaOH and O2) to form a mixture of ferrous and ferric oxides. 

An example for chemical preparation that can be carried out within seconds in a beaker is this Dissolve pyrrole in dilute sulfuric acid. Add ferric chloride as an aqueous solution and watch the black polypyrrole precipitate. The oxidizing Fe ions are reduced to Fe, imparting one +-charge and donating their now excessive Cr ion as dopant ion to the polymer. 

If impure hydroquinone is used, a black, sticky precipitate will usually appear after the addition of the sulfuric acid to the hydroquinone solution. This should be removed, before the oxidation is started, by filtration without suction through a fluted filter. 

Figure 15. Illustration of possible variations in isotopic fractionation between Fe(III),q and ferric oxide/ hydroxide precipitate (Aje(,n),q.Fenicppt) and precipitation rate. Skulan et al. (2002) noted that the kinetic AF (ni)aq-Feiricppt fractionation produced during precipitation of hematite from Fe(III), was linearly related to precipitation rate, which is shown in the dashed curve (precipitation rate plotted on log scale). The most rapid precipitation rate measured by Skulan et al. (2002) is shown in the black circle. The equilibrium Fe(III),-hematite fractionation is near zero at 98°C, and this is plotted (black square) to the left of the break in scale for precipitation rate. Also shown for comparison is the calculated Fe(III),q-ferrihydrite fractionation from the experiments of Bullen et al. (2001) (grey diamond), as discussed in the previous chapter (Chapter lOA Beard and Johnson 2004). The average oxidation-precipitation rates for the APIO experiments of Croal et al. (2004) are also noted, where the overall process is limited by the rate constant ki. As discussed in the text, if the proportion of Fe(III),q is small relative to total aqueous Fe, the rate constant for the precipitation of ferrihydrite from Fe(III), (Ai) will be higher, assuming first-order rate laws, although its value is unknown.

Thallous halides do not absorb ammonia at ordinary temperature, but in liquid ammonia these salts form triannnino-thallous halides of composition [T1(NH3)3]C1, [Tl(NH3)3]Br.1 The triammino-deriva-tives formed are somewhat soluble in liquid ammonia, and the solubility increases with rise of temperature and increase in atomic weight of the halogens. No lower ammino-derivatives are known. Tliallic halides absorb ammonia gas readily. If ammonia gas is passed into an alcoholic solution of thallic chloride, or if dry ammonia gas is passed over dry thallic chloride, the gas is absorbed and a white crystalline substance is formed of composition [T1(NH3)3]C13. The crystals may be washed with alcohol containing ammonia and then with absolute alcohol, and finally dried in vacuo. On coming in contact with water the triammine is decomposed with precipitation of violet-black oxide thus ... 

A solution of 0.5 M ferrous chloride (FeCI2) and 0.25 M ferric chloride (FeCI3) (200 ml) was mixed with 5 M sodium hydroxide (200 ml) at 60°C by pouring both solutions to 100 ml of distilled water. The mixture was stirred for 2 min during which time a black, magnetic precipitate formed. After settling, the volume of the settled precipitate was approximately 175 ml. The concentration of iron oxide in the precipitate was about 60 mg/ml. The precipitate was then washed with water until a pH of 6-8 was reached. 

The precipitated slurry, containing CaO. 2MnOa, called the Weldon mud was then used instead of black oxide of manganese fer the oxidation of hydrochloric acid. This reaction which was carried out in sandstone containers with steam fed into the reaction mixture proceeded according to the equation ... 

After filtration, addition of sodium sulphide to the clear solution effects the precipitation of the three metals, cobalt, nickel, and manganese, as sulphides. Digestion with the calculated quantity of ferric chloride oxidises the manganese sulphide to sulphate, which passes into solution. The residue consists of cobalt and nickel sulphides, which are washed and converted into their soluble sulphates by roasting. The sulphates are extracted with water, and converted into chlorides by addition of calcium chloride solution. Their separation is effected g.s follows The requisite fraction of the chloride solution is precipitated with milk of lime, and the insoluble hydroxides of nickel and cobalt thus obtained are oxidised to the black hydroxides by treatment with chlorine. The. washed precipitate is then introduced into the remainder of the chloride solution, and the whole is well stirred and heated, when the black hydrated oxide of nickel passes, into solution, displacing tlm Remainder of. the cobalt from the solution, into. the precipitate.. The final product is thus a suspension of hydrated peroxide.of cobalt,in p. solution of nickel chloride, from which idle cobalt precipitate is removed by filtration, washed, and ignited, to the black oxide. 

In the copper slurry formulations described below, we have attempted to maximize the solubility and dissolution rate of the copper in the slurry, and therefore dissolution of the abraded material is expected to be the dominant removal mechanism. However, the removal of the abraded material may occur as a combination of several of the above mechanisms. For example, the abraded material may initially fall into the pad undissolved, where it then dissolves. Such a scenario was described in Section 4.6.2 where it was observed that when the concentration of polish by products in the pad is high, the slurry initially turns black, indicating incomplete dissolution and the formation of copper oxide precipitates. With time, however, the slurry turns blue, indicating dissolution and the formation of the Cu(NH3)2 complex. Thus, the optimum polishing conditions may provide for a combination of removal mechanisms. 

Certain precipitated hydroxides are easily converted to oxide, Tl(OH)3 even in boiling water, but others, for instance Cu(OII)2, which gives a hydrated black oxide, cannot be completely dehydrated. Au(OH)3 clianged only to AiiO(OH) after prolonged standing over P2O5. 

The goods are treated with manganese chloride, and then passed through an alkaline bath whereby manganous oxide is precipitated on the fibre. A subsequent oxidation by air or by a bath of chloride of lime serves to convert this into peroxide, a bottom of the so-called manganese-bronze being obtained. On passing into an acid solution of aniline, aniline black is precipitated on the fibre in a firmly adherent condition. 

However, chromic acid is the oxidant generally employed. An aniline solution containing free sulphuric acid is mixed with a soluble bichromate, and the goods entered. On heating, the black is precipitated on the fibre. In all cases the aniline-black salt formed is converted into the free base by a weak alkaline bath (soda, soap, or chalk). 

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