Chemical blacking

The process is conducted at the high pH in the presence of sodium sulfide, sodium hydrosulfide, and sodium hydroxide at 150-180°C for about 2 hours (Fig. 33.26). Along with the primary cellulose product, the process generates a solution containing dissolved lignin, most of the wood s hemicellu-loses, and spent pulping chemicals ( black liquor ). This solution is used in the kraft recovery boiler as a source of power for the mill and fuel for chemical recovery operations crucial to economic operation. The chemistry of pulping reactions has been the subject of much study, and summaries are available the literature.425 127... 

Individuals with multiple chemical sensitivities may have undiagnosed psychiatric illnesses or histories of physical and sexual abuse presenting as illness from chemicals (Black 1993 Friedman 1994 Staudenmayer et al. 1992). 

When the structure of picric acid is compared with the structure of TNT, the only difference is the fuel that the nitro functional groups were placed on the number of nitro groups is exactly the same. The explosive power of picric acid is similar to that of TNT. There are other Class 1.1 to 1.3 materials that are nitro compounds and some that are made up of other chemicals. Black powder is a low-order explosive made up of a mixture of potassium or sodium nitrate, charcoal, and sulfur in 75, 15, and 10% proportions, respectively. It has an appearance of a fine powder to dense pellets, which may be black or have a grayish-black color. It is a dangerous fire and explosion risk, is sensitive to heat, and will deflagrate rapidly. 

Fig. 10 Mechanical properties of polymeric hydrogels based on catechol-functiomalized PEG at different pH and comparison of a chemical and a physictil hydrogel, assessed by their elastic (GO and viscous (G O shear moduli, a Frequency-dependent loss (G") and storage (GO moduli of gels at pH 5 (green), pH 8 (blue), and pH 12 (red) (C circles-, G" triangles), b Comparison of physically (red) and chemically (black) crosslinked hydrogels, c Recovery of stiffness and cohesiveness after tearing by shear stress (same color code as in b). Modified from Waite et al. [121]. Copyright 2011 National Academy of Sciences of the United States...

Many solids have foreign atoms or molecular groupings on their surfaces that are so tightly held that they do not really enter into adsorption-desorption equilibrium and so can be regarded as part of the surface structure. The partial surface oxidation of carbon blacks has been mentioned as having an important influence on their adsorptive behavior (Section X-3A) depending on conditions, the oxidized surface may be acidic or basic (see Ref. 61), and the surface pattern of the carbon rings may be affected [62]. As one other example, the chemical nature of the acidic sites of silica-alumina catalysts has been a subject of much discussion. The main question has been whether the sites represented Brpnsted (proton donor) or Lewis (electron-acceptor) acids. Hall... 

Fig. XVII-22. Isosteric heats of adsorption for Kr on graphitized carbon black. Solid line calculated from isotherms at 110.14, 114.14, and 117.14 K dashed line calculated from isotherms at 122.02, 125.05, and 129.00 K. Point A reflects the transition from a fluid to an in-registry solid phase points B and C relate to the transition from the in-registry to and out-of-registry solid phase. The normal monolayer point is about 124 mol/g. [Reprinted with permission from T. P. Vo and T. Fort, Jr., J. Phys. Chem., 91, 6638 (1987) (Ref. 131). Copyright 1987, American Chemical Society.]...

Silver has little tendency to formally lose more than one electron its chemistry is therefore almost entirely restricted to the + 1 oxidation state. Silver itself is resistant to chemical attack, though aqueous cyanide ion slowly attacks it, as does sulphur or a sulphide (to give black Ag S). hence the tarnishing of silver by the atmosphere or other sulphur-containing materials. It dissolves in concentrated nitric acid to give a solution of silver(I) nitrate. AgNOj. 

Fig. 7.12 Experimental and calculated infrared spectra for liquid water. The black dots are the experimental values. The thick curve is the classical profile produced by the molecular dynamics simulation. The thin curve is obtained by applying quantum corrections. (Figure redrawn from Guilbt B 1991. A Molecular Dynamics Study of the Infrared Spectrum of Water. Journal of Chemical Physics 95 1543-1551.)...

Dissolve 0-5 g. of the substance in 10 ml. of 50 per cent, alcohol, add 0-5 g. of solid ammonium chloride and about 0 -5 g. of zinc powder. Heat the mixture to boiling, and allow the ensuing chemical reaction to proceed for 5 minutes. Filter from the excess of zinc powder, and teat the filtrate with Tollen s reagent Section 111,70, (i). An immediate black or grey precipitate or a silver mirror indicates the presence of a hydroxyl-amine formed by reduction of the nitro compound. Alternatively, the filtrate may be warmed with Fehling s solution, when cuprous oxide will be precipitated if a hydroxylamine is present. Make certain that the original compound does not aflfect the reagent used. 

Sulfur is a component of black gunpowder, and is used in the vulcanization of natural rubber and a fungicide. It is also used extensively in making phosphatic fertilizers. A tremendous tonnage is used to produce sulfuric acid, the most important manufactured chemical. 

Phenol—formaldehyde (PF) was the first of the synthetic adhesives developed. By combining phenol with formaldehyde, which has exceptional cross-linking abiHties with many chemicals and materials, and a small amount of sodium hydroxide, a resin was obtained. The first resins soHdified as they cooled, and it was discovered that if it was ground to a powder with a small amount of additional formaldehyde and the appHcation of more heat, the mixture would Hquify and then convert to a permanently hard material. Upon combination of the powdered resin mixture with a filler material such as wood flour, the result then being placed in a mold and pressed under heat and pressure, a hard, durable, black plastic material was found to result. For many years these resulting products were called BakeHte, the trade name of the inventor. BakeHte products are still produced today, but this use accounts for only a small portion of the PF resins used. 

J. Isaksson and L. Rittfeldt, "Chaiacteiization of Black Powdeis," Proceedings of 3rd Symposium on Chemical Problems Connected with the Stability of Explosives,]oDkofmg, Sweden, 1952, p. 242. 

Approximately 50—55% of the product from a coal-tar refinery is pitch and another 30% is creosote. The remaining 15—20% is the chemical oil, about half of which is naphthalene. Creosote is used as a feedstock for production of carbon black and as a wood preservative. Because of modifications to modem coking processes, tar acids such as phenol and cresyUc acids are contained in coal tar in lower quantity than in the past. To achieve economies of scale, these tar acids are removed from cmde coal tar with a caustic wash and sent to a central processing plant where materials from a number of refiners are combined for recovery. 

Synthetics. The lack of spice products to satisfy demand and the wide variation in price and availabihty have caused the manufacture of selected synthetics, chemically identical to the component in the natural spice, to replace the vital components of some spices. However, synthetic organic chemistry is not yet able to manufacture economically the many homologous piperine [94-62-2] components in black pepper or those capsaicin [404-86-4] amides in... 

TuU Chemical Co. (Oxford, Alabama) is the only producer of sodium fluoroacetate. It is sometimes colored with the black dye nigrosine. It is usually packed in 8 oz (227 g) or 5 kg cans and is almost exclusively exported. There is very limited use in the United States. 

The burning of the ligneous portion of the black Hquor produces sufficient heat in the furnace to sustain flash drying of residual moisture, salt-cake reduction, and chemical smelting. The heat in the gas passing through the furnace, boiler, and economi2er produces steam for power and process. 

The U.S. Department of Commerce estimates total production of about 163,000 t in 1990. Other estimates based on demand data indicate that it was as high as 175,000 t. With demand and supply in balance, it is estimated that in 1997 the demand will be 185,000 t. The distribution in product demand is projected to be the following 1,4-butanediol and other acetylenic chemicals (45%), vinyl chloride monomer (45%), acetylene black (5%), and industrial use (5%). 

Japan and China. During the 1980s, acetylene demand in Japan suffered a significant decline. Chemical use declined from over 100,000 to 42,000 t, acetylene black production declined from 20,000 to less than 10,000 t, and industrial use went from 42,000 to 30,000 t. Thus, based on 1990 estimates, Japan has an excess capacity for acetylene production with capabiUties for 247, 000 t/yr and a demand of only 82,000 t. 

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