Colloidal black

In ethanol nickel(II) acetate treated with NaBFLt produces a nearly colloidal black suspension63. Variation of the solvent in the preparation of the nickel catalyst results in an amorphous nickel boride catalyst67,68. This P-2 nickel catalyst is much more sensitive to the double-bond structure69,70. In the hydrogenation of the strained double bonds of nor-bomadienes, P-2 nickel shows high selectivity (95%) and low isomerization characteristics (equations 20 and 21). 

This includes furnace black, colloidal black, thermal black, channel black, and acetylene black. 

The term carbon black includes furnace black, colloidal black, thermal black, channel black, and acetylene black. Carbon black is mostly derived from petroleum and involves partial combustion or a combination of combustion and thermal cracking of hydrocarbons, and to a lesser extent natural gas, at 1200 tol400°C. 

Figure 7. TEM pictures, the scale bars are 20 mn a) a micelle of 52Tri07H, b) gold colloid (black particles) covered wiA 52Tri07H.

J. L. Moilliet, B. Collie, and W. Black, Surface Activity, E. F. N. Spon, London, 1961. D. H. Napper, Polymeric Stabilization of Colloidal Dispersions, Academic, New York,... 

In contrast to the reaction with lithium amide, the sodium amide suspension immediately settles out after stopping the stirring and the supernatant ammonia has a grey or black colour, due to colloidal iron. In some cases it took a long time before all of the sodium had been converted (note 4). A further 0.1 g of iron(III) nitrate was then added to accelerate the reaction and some liquid ammonia was introduced to compensate for the losses due to evaporation. 

Palladium catalysts have been prepared by fusion of palladium chloride in sodium nitrate to give palladium oxide by reduction of palladium salts by alkaline formaldehyde or sodium formate, by hydrazine and by the reduction of palladium salts with hydrogen.The metal has been prepared in the form of palladium black, and in colloidal form in water containing a protective material, as well as upon supports. The supports commonly used are asbestos, barium carbonate, ... 

A substitute may be prepared thus 0 05 gram palladous chloride is placed in a special shaking flask with 50 c.c, of 50 per cent, alcohol and 1 or 2 c c. of 1 per cent, aqueous solution of gum-arabic, the weight of gum being about one-fourth the weight of the palladous chloride. On shaking this mixture in an atmosphere of hydrogen the chloride is reduced with formation of a black solution of colloidal platinum, which is rendered stable by the small quantity of gum present. 

Two methods are commonly used for the determination of magnesium. Titan yellow may be used to obtain a coloured colloidal suspension, or solochrome black to give a red soluble complex. In most cases the second of these is to be preferred. 

Both silver (m.p. 962°C, b.p. 2212°C) and gold (m.p. 1065°C, b.p. 2807°C) have characteristic brilliant white and yellow colours in bulk but when finely divided are black or, in the case of gold, can be purple, ruby red or blue. Thus reduction of gold compounds by SnCl2 gives the colloid known as Purple of Cassius , which is used as a ceramic colorant. 

This treatment converts the selenium from the red, colloidal form into the more easily filterable black modification. 

Rh colloids were isolated during the hydrosilylation of trimethy(vinyl)silane with triethoxysilane using RhCl3 in EtOH as pre-catalyst. The colour changes observed during the catalytic reaction (from yellow, to red and black) are due to the formation of colloids as demonstrated by TEM this fact was in agreement with the catalytic activity behaviour observed [14]. 

Instead of postulating Zn," as intermediate, as it has a highly negative potential and is possibly unstable in ZnO, one may write the above mechanism with Zn e pairs. The blue-shift in the absorption upon illumination was explained by the decrease in particle size. The Hauffe mechanism was abandoned after it was recognized that an excess electron on a colloidal particle causes a blue-shift of the absorption threshold (see Fig. 19). In fact, in a more recent study it was shown that the blue-shift is also produced in the electron transfer from CH2OH radicals to colloidal ZnO particles When deaerated propanol-2 solutions of colloidal ZnO were irradiated for longer times, a black precipitate of Zn metal was formed. In the presence of 10 M methyl viologen in the alcohol solution, MV was produced with a quantum yield of 80 %... 

CdjPj and CdjAs are low band gap semiconductors (0.5 and 0.1 eV, respectively). The bulk materials are black and start to absorb in the infrared. These materials have been prepared as colloids in alkaline solution by precipitation of Cd with phosphine and arsine Depending on the conditions of preparation, particles of different sizes (between about 2 and 10 nm) were obtained, which could also be recovered in the solid state after evaporation of the solvent. The color of these materials ranged from black to colorless with decreasing particle size, with all kinds of intermediate colors in the visible. 

G. Calloni, N. Moroni, and F. Miano. Carbon black A low cost colloidal additive for controlling gas migration in cement slurries. In Proceedings Volume, pages 563-574. Offshore Mediter Conf (Ravenna, Italy, 3/15-3/17), 1995. 

Figure 3. Distribution coefficient (Ka) versus particle concentration for Th. Note that, for typical open-ocean particle concentrations, Th is about lO times more likely to adhere to a mass of particles than to remain in the same mass of water. This tendency to be found in the particulate phase decreases with particle concentration, probably due to the presence of a larger number of colloids which, because they pass through filters, appear to be in the dissolved phase (Honeyman et al. 1988). Grey squares are " Th data from Honeyman et al. (1988) gray triangles are " Th data from the continental shelf from McKee et al. (1986) and black circles are a compilation of open ocean °Th data from Henderson et al. (1999a).

Colloidal metals, metallic sponges or blacks, skeletal metals, metal powders, evaporated metal films, electrodeposited films, wires, foils, gauzes... 

Colloidal metals are usually prepared by reduction of a salt with a reducing agent, such as phosphorus, acetone, tannin, or carbon monoxide. Platinum metals can also be prepared as finely divided very active blacks by reducing the metal salt in an aqueous solution of sodium or potassium borohydride. 

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