Iron transparent

Transparent iron oxide pigments have exceUent weatherabiHty, Hghtfastness, and chemical resistance, comparable to opaque iron oxides. 

Transparent red iron oxide is composed mainly of hematite, a-Ee202, having primary particles about 10 nm. It is prepared by a precipitation reaction from a dilute solution of an iron salt at a temperature around 30°C, foUowed by a complete oxidation in the presence of some seeding additives,... 

Transparent iron oxides are produced by BASE (Germany), Johnson Matthey (U.K.), and Hilton Davis (U.S.). The mid-1990s aimual production is estimated to be around 2000 metric tons. 

Two blue pigments can be prepared in transparent form cyanide iron blue and cobalt aluminum blue. These pigments are used in achieving a blue shade of the metal effect pigments in metallic paints. Transparent cyanide iron blue is prepared by a precipitation reaction similar to the one used for the preparation of the opaque pigment, but considerably lower concentrations of solutions are used. It is produced by Degussa (Germany), Manox (U.K), and Dainichiseika (Japan). 

Transparent fused silica can be formed at a temperature of 1200°C and a pressure of 13.8 MPa (2000 psi) from silica powder consisting of 15 nm ultimate particles (92) or by electric arc fusion of pure silica sand having low iron and alkali metal contents. The cooled product is ground to the desired particle size. Fused sihca is primarily manufactured by C-E Minerals, Minco, and Precision Electro Minerals in the United States by Chuo Denko, Denki Kagaku Kogyo, NKK, Showa Denko, and Toshiba Ceramics in Japan. Based on 1988 data and projected growth, an estimated 135,000 metric tons of fused siUca were used in 1994 as a sacrificial component or investment casting in the manufacture of metals and as a component in refractory materials (62). 

Special forms of highly transparent iron oxides are made for use in durable metallized polychromatic finishes. These products are more brown than yellow however, when used in metallized finishes, they impart a golden color. This type of iron oxide tends to be more reactive than the opaque yellows. 

Suppose one wishes nevertheless to use x-ray emission spectrography for the determination of iron in these materials. In principle, this can be done if the absorption effect is eliminated or kept constant—-if, for example, the material is placed in dilute solution in a relatively transparent solvent (7.8). 

Laby21 demonstrated in 1930, with a photographic plate as detector, that copper or iron in zinc could be detected in concentrations approaching 1 part per million by weight. To be sure, he used electron excitation so that absorption effects were minimized (7.10). By contrast, attempts made in the authors laboratory to estimate alkaline-earth metals in brines were unsuccessful, primarily because of the high absorption effects that accompanied x-ray excitation. The use of dilution with a relatively transparent solvent can sometimes reduce or eliminate absorption effects (7.8), but this procedure will fail if the element to be determined is present at too low a concentration in the presence of another substance (the salt in brine in the example cited) primarily responsible for the absorption effect. A case in which dilution is helpful in connection with the absorption effect of the. element sought is that of tetraethyllead fluid in gasoline (7.13). 

It is perhaps ironic that, many years after his interest was first aroused, Stacey was to experience a fermentation failure owing to an unwanted dextran. He, and a large group of colleagues (potential co-tasters ), published a report of an attempt to make elderberry wine. A viscous, transparent gum, rather than a delicious drink, was produced. The gum was a typical, but unwelcome, dextran. 

P 12] A falling film micro reactor was applied for generating thin liquid films [6]. A reaction plate with 32 micro channels of channel width, depth and length of 600 pm, 300 pm and 66 mm, respectively, was used. Reaction plates made of pure nickel and iron were employed. The micro device was equipped with a quartz window transparent for the wavelength desired. A 1000 W xenon lamp was located in front of the window. The spectrum provided ranges from 190 to 2500 nm the maximum intensity of the lamp is given at about 800 nm. 

A regenerative photogalvanic cell with oxidative quenching (Fig. 5.58b) is based, for example, on the Fe3+-Ru(bpy)2+ system. In contrast to the iron-thionine cell, the homogeneous photoredox process takes place near the (optically transparent) cathode. The photoexcited Ru(bpy)2+ ion reduces Fe3+ and the formed Ru(bpy)3+ and Fe2+ are converted at the opposite electrodes to the initial state. 

Ferruginous quartz Vitreous Transparent or translucent Red/yellow-brown Inclusions of iron and asbestos... 

The presence of mica in pearlescent pigments only partly accounts for the appearance of the pigment. A very thin layer of the inorganic oxide titanium dioxide (TiC>2) or iron oxide (Fe2C>3) or both is coated on the mica platelets. The various colors and pearlescent effects are created as light is both refracted and reflected from the titanium dioxide layers. The very thin platelets are highly reflective and transparent. With their plate-like shape, the platelets are easily oriented into parallel layers as the paint medium is applied. Some of the incident light is reflected... 

Figure 1 Spectra of iron hexacyanoferrate films on ITO-coated glass at various potentials [(i) +0.50 (PB, blue), (ii) —0.20 (PW, transparent), (iii) +0.80 (PG, green), (iv) +0.85 (PG, green), (v) +0.90 (PG, green), and (vi) +1.20V (PX, yellow) (potentials vs. SCE)] with 0.2 mol dm-3 KC1 + 0.01 mol dm-3 HC1 as supporting electrolyte (reproduced by permission of the Royal Society of Chemistry from J. Chem. Soc., Dalton Trans.

CO and H2 reactions with, 14 511 natural, 19 397-398 pigment used in makeups, 7 836t synthetic, 19 398-402 transparant, adsorption energy to pigments or fillers, 8 683t Iron(II) oxide, 14 541 Iron(III) oxide, 14 541-542 19 398,... 

Iron oxide-coated sand (IOCS), for arsenic removal, 3 279, 284-285 Iron oxide control, in industrial water treatment, 26 133 Iron oxide pastes, 19 402 Iron oxide pigments, 19 397-402 production of, 19 385 transparent, 19 412 economic aspects of, 14 557-559... 

Mercury emissions data will be provided to the authorities with total transparency, including independent third-party auditing, on a plant-by-plant basis. Ironically this goes beyond what some governments have been willing to offer up to now, as there has been considerable reticence in some countries about revealing the performance of individual plants in international discussions. 

P.R.171 is used in plastics and in paints. Its lightfastness in PVC equals step 7 to step 8 on the Blue Scale, depending on the exact composition of the tested system, the pigment concentration, and the Ti02 content. Incorporated in plasticized PVC, P.O.171 is migration resistant and heat stable up to 180°C. It is used in conjunction with organic yellow pigments, frequently also with iron oxides, to produce shades of brown. Shades of bordeaux are accessible in deep transparent colorations. 

Figure 8.3 Illustration of in situ spectroelectrochemistry, showing a set of UV-vis ( electronic ) spectra of solid-state Prussian Blue (iron(ii,iii) hexacyanoferrate(ii)) adhered to an ITO-coated optically transparent electrode. The spectra are shown as a function of applied potential (i) —0.2 (ii) -1-0.5 (iii) -1-0.8 (iv) -1-0.85 (v) -1-0.9 (vi) +1.2 V (all vs. SCE). From Mortimer, R. J. and Rosseinsky, D. R., J. Chem. Soc., Dalton Trans., 2059-2061 (1984). Reproduced by permission of The Royal Society of Chemistry.

The common gray, brown, or black flint result from admixed iron oxides or organic compounds. Pure quartz is usually colorless and transparent. The conchoidal fracture typical of flint was a boon to primitive humans, who desired clean, smooth, sharp edges that were not susceptible to uniform wear. This physical attribute and the densities of flint reflect the patterns of aggregation of its fibrous constituents. 

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