Liming chemistry

The back end is the conipoiicii 1 oT IlypcrChcm LhaL performs the more Lime-ccm siiming sclen Lific calculation s. This is where molecular mechanical and quail Lit m mechanical calculations are performed. The back end can be thought of as the compii laLion al chemistry component of HyperChem. ... 

Acid—Base Chemistry. Acetic acid dissociates in water, pK = 4.76 at 25°C. It is a mild acid which can be used for analysis of bases too weak to detect in water (26). It readily neutralizes the ordinary hydroxides of the alkaU metals and the alkaline earths to form the corresponding acetates. When the cmde material pyroligneous acid is neutralized with limestone or magnesia the commercial acetate of lime or acetate of magnesia is obtained (7). Acetic acid accepts protons only from the strongest acids such as nitric acid and sulfuric acid. Other acids exhibit very powerful, superacid properties in acetic acid solutions and are thus useful catalysts for esterifications of olefins and alcohols (27). Nitrations conducted in acetic acid solvent are effected because of the formation of the nitronium ion, NO Hexamethylenetetramine [100-97-0] may be nitrated in acetic acid solvent to yield the explosive cycl o trim ethyl en etrin itram in e [121 -82-4] also known as cyclonit or RDX. 

The differences in the amino acid chemistry of the hide coUagen and the hair keratin are the basis of the lime-sulfide unhairing system. Hair contains the amino acid cystine. This sulfur-containing amino acid cross-links the polypeptide chains of mature hair proteins. In modem production of bovine leathers the quantity of sulfide, as Na2S or NaSH, is normally 2—4% based on the weight of the hides. The lime is essentially an unhmited supply of alkah buffered to pH 12—12.5. The sulfide breaks the polypeptide S—S cross-links by reduction. Unhairing without sulfide may take several days or weeks. The keratin can be easily hydrolyzed once there is a breakdown in the hair fiber stmcture and the hair can be removed mechanically. The coUagen hydrolysis is not affected by the presence of the sulfides (1—4,7). 

Emulsifiers are incorporated in oil and synthetic mud formulations to maintain a stable emulsion of the internal brine phase. These materials include calcium and magnesium soaps of fatty acids and polyamines and amides and their mixtures (123,127). The specific chemistry of these additives depends on the nature of the continuous phase of the mud, ie, whether diesel oil, mineral oil, or a synthetic Hquid. Lime is added along with the fatty acid to form the... 

Causticization, the reaction of hydrated lime [1305-62-0], Ca(OH)2, with sodium carbonate to regenerate sodium hydroxide and precipitate calcium carbonate, is an important part of the Bayer process chemistry. 

Unit Operations. The chemistries elaborated by all of these systems are described by seven unit operations (Fig. 5). The first six, the use of lime and carbon dioxide as clarification agents, were laid out during the first half of the twentieth century and only the appHcation technology has changed since, mainly from small batch processes designed to handle 1000 Hters in a few hours to continuous systems capable of processing up to 10,000 L/min. 

Juice Purification Chemistry. Lime in juice purification serves as a source of calcium, a source of alkalinity, and a source of calcium carbonate which serves as the clarification—filtration medium. 

Lime-Sulfuric. Recovery of citric acid by calcium salt precipitation is shown in Figure 3. Although the chemistry is straightforward, the engineering principles, separation techniques, and unit operations employed result in a complex commercial process. The fermentation broth, which has been separated from the insoluble biomass, is treated with a calcium hydroxide (lime) slurry to precipitate calcium citrate. After sufficient reaction time, the calcium citrate slurry is filtered and the filter cake washed free of soluble impurities. The clean calcium citrate cake is reslurried and acidified with sulfuric acid, converting the calcium citrate to soluble citric acid and insoluble calcium sulfate. Both the calcium citrate and calcium sulfate reactions are generally performed in agitated reaction vessels made of 316 stainless steel and filtered on commercially available filtration equipment. 

Tlie importance of bis(cyclopeniadienyl)irou (Fe(jj -C5H3)2( in the developmenl of organo-metallic chemistry has already been alluded to (p. 924). Tile compound, which forms orange crystals, mpl74°, has extraordinary thermal stability (>500°) and a remarkable structure which was unique when first established. It also has an extensive aromatic-lype reaction chernisiry which is reflected in its common name ferrocene The molecular structure of ferrocene in the ciysialline slac features two parallel cyclopentadienyl rings at one lime Ihese... 

Roger Adams (1889-1971) wa s born in Boston, Massachusetts, and received his Ph.D. in 1912 at Harvard. He taught at the University of Illinois from 1916 until his retirement in 1957, during which lime he had an enormous influence on the development of organic chemistry in the United States. Among many other accomplishments, he established the structure of tetrahydrocannabinol, the active ingredient in marijuana. 

Glasson, P. R. (1963). Reactivity of lime and related oxides. VIII. Production of activated lime and magnesia. Journal of Applied Chemistry, 13, 111-19. 

Gel breakers used in nonaqueous systems have a completely different chemistry than those used in aqueous systems. A mixture of hydrated lime and... 

In 1875 Pollacci (7) reported grape leaves treated with sulfur produced hydrogen sulfide gas. Recently it has been reported that hydrogen sulfide gas is produced by sulfur-dusted lemons and oranges (22). This gas which emanates from sulfured plants is also produced by the reactions of ingredients in the widely used lime-sulfur sprays. St. John and Groves (9) have excellently reviewed the chemistry of these mixtures. 

Boynton, R. S. (1980), Chemistry and Technology of Lime and Limestone, Wiley, New York. 

Although arsenic is not an essential plant nutrient, small yield increases have sometimes been observed at low soil arsenic levels, especially for tolerant crops such as potatoes, com, rye, and wheat (Woolson 1975). Arsenic phytotoxicity of soils is reduced with increasing lime, organic matter, iron, zinc, and phosphates (NRCC 1978). In most soil systems, the chemistry of As becomes the chemistry of arsenate the estimated half-time of arsenic in soils is about 6.5 years, although losses of 60% in 3 years and 67% in 7 years have been reported (Woolson 1975). Additional research is warranted on the role of arsenic in crop production, and in nutrition, with special reference to essentiality for aquatic and terrestrial wildlife. 

Burnett, D.G. and Douglas, R.W. (1970). Liquid-liquid phase separation in the soda-lime-silica system. Physics and Chemistry of Glasses 11 125-135. 

Melcher, M. and Schreiner, M. (2004). Statistical evaluation of potash-lime-silica glass weathering. Analytical and Bioanalytical Chemistry 379 628-639. 

Surface Chemistry of Activation of Lime-Depressed Pyrite... 

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