Alumina, absorbent

Cleaning Up All organic material from this experiment can go in the organic solvents container. The alumina absorbent, if free of organic solvents, can go in the nonhazardous solid waste container. If it is wet with organic solvents, it is a hazardous solid waste. Spread it in the hood to dry. 

Tbe reaction rate improves in the presence of moisture. Alumina absorbs enough moisture during the recovery of tbe product that it can be recycled again by mixing with fresh borohydride and reused for subsequent reductions without any loss in activity. 

The amount of soluble silica available to plants in soil moisture is greatly affected by the chemical composition. Free oxides or iron or alumina absorb and insolubilize the silica. Oats take up silica at a rate that depends directly on the amount of silica in solution in the soil and the total. silica increases with the amount of water transpired. In the oat plant, silica thus plays a passive role from a biochemical standpoint (137). ... 

Constit. of various woods, e.g. Morus alba. First isol. in 1830. Used as fluorescent alumina absorbent for column chromatography. Used as 0.025% soln. in EtOH for photometric detn. of In, rare earth elements, Sc, Th, Sn, W, V, Hf, Zr (2 420 nm, e 51000). Textile dye. Pale-yellow needles + IH2O (AcOH aq.). Sol. EtOH, alkalis si. sol. Et20, H2O. Mp 303-304°. 

This is used extensively for qualitative analysis, for it is a rapid process and requires simple apparatus. The adsorbent is usually a layer, about 0 23 mni. thick, of silica gel or alumina, with an inactive binder, e.g. calcium sulphate, to increase the strength of the layer.. A. i i slurry of the absorbent and methanol is commonly coated on glass plates (5 20 cm. or 20 x 20 cm.), but microscope... 

Aluminium oxide. The commercial material, activated alumina, is made from aluminium hydroxide it will absorb 15-20 per cent, of its weight of water, can be re-activated by heating at 175° for about seven hours, and does not appreciably deteriorate with repeated use. Its main application is as a drying agent for desiccators. 

Transition metals absorbed onto a solid support metal Pd,Pt, Ni, Rh support Carbon, alumina, silica solvent EtOH, EtOAc, Et20, hexanes, etc. 

Health and Safety Factors. Sulfur hexafluoride is a nonflammable, relatively unreactive gas that has been described as physiologically inert (54). The current OSHA standard maximum allowable concentration for human exposure in air is 6000 mg/m (1000 ppm) TWA (55). The Underwriters Laboratories classification is Toxicity Group VI. It should be noted, however, that breakdown products of SF, produced by electrical decomposition of the gas, are toxic. If SF is exposed to electrical arcing, provision should be made to absorb the toxic components by passing the gas over activated alumina, soda-lime, or molecular sieves (qv) (56). 

By-product water formed in the methanation reactions is condensed by either refrigeration or compression and cooling. The remaining product gas, principally methane, is compressed to desired pipeline pressures of 3.4—6.9 MPa (500—1000 psi). Einal traces of water are absorbed on siHca gel or molecular sieves, or removed by a drying agent such as sulfuric acid, H2SO4. Other desiccants maybe used, such as activated alumina, diethylene glycol, or concentrated solutions of calcium chloride (see Desiccants). 

Reduction of the aromatic nuclei contained in catalytic C-9 resins has also been accomplished in the molten state (66). Continuous downward concurrent feeding of molten resin (120°C softening point) and hydrogen to a fixed bed of an alumina supported platinum—mthenium (1.75% Pt—0.25% Ru) catalyst has been shown to reduce approximately 100% of the aromatic nuclei present in the resin. The temperature and pressure required for this process are 295—300°C and 9.8 MPa (lOO kg/cni2), respectively. The extent of hydrogenation was monitored by the percent reduction in the uv absorbance at 274.5 nm. 

Chlorides may be found in natural gas, particularly associated with offshore reservoirs. Modified alumina catalysts have been developed to irreversibly absorb these poisons from the feed gas. 

In a second example, a cell—gelatin mixture is cross-linked with glutaraldehyde (43). When soluble enzyme is used for binding, the enzyme is first released from the cell, then recovered and concentrated. Examples of this type of immobilization include binding enzyme to a DEAE-ceUulose—titanium dioxide—polystyrene carrier (44) or absorbing enzyme onto alumina followed by cross-linking with glutaraldehyde (45,46). 

Ring Liners. Liners are either cellulose, which readily absorbs water, or ceramic, which does not absorb water or investment Uquid (123). Both are available in many si2es. Ceramic liners are made from fibers of alumino-siUcate glass derived from kaolin. The principal components in the glass are alumina, 47—65 wt %, and siUca, 35—50 wt %. Ceramic liners are highly heat resistant to 1300°C. Reports suggest that the fiber from ceramic ring liners may be a possible health risk (124). 

The most common equipment for cleaning recirculated air from particles is fabric filters, mechanical collectors, electrostatic precipitators, and cleaners and wet collectors.For cleaning of recirculated air from gases, absorbers and adsorbers such as activated carbon, sometimes with impregnation for specific gases, and impregnated alumina are most common. The performance of different air cleaning equipment is described in many textbooks and handbooks. 

Certain chemicals (sorbents) have the ability to absorb moisture from a gas they may be either solid or liquid. Performance of a chemical dehumidifi cation device depends on the sorbent used. The sorbent must t>e able to attract and remove the sorbate, such as water, from the gas stream, Stirbems absorb water on the surface of the material by adsorption or by chemically combining with water (absorption). If the unit is regenerative, the process is reversible, allowing water to be removed. This is achieved by a sorbent such as silica gel, alumina gel, activated alumina, lithium chloride salt, lithium chloride solution, glycol solution, or molecular sieves. In the case of nonregenerative equipment, hygroscopic salts such as calcium chloride, urea, or sodium chloride are used. 

Activated alumina Hydrated aluminum oxide, a granular desiccant activated at high temperature that absorbs moisture and gases. 

Although details vary considerably, the Mo is typically incorporated in a generator in the form of MoOa " absorbed on a substrate such as alumina where it decays according to the scheme ... 

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