Calcium principal characteristics

Neutralization. The choice of a reagent for pH adjustment depends on cost ease and safety of storage and handling effectiveness, eg, for removing heavy metals, buffet characteristics of the pH titration curve as they affect pH control and avadabihty. The three principal reagents for neutralization of acid wastes are sodium hydroxide, sodium carbonate, and hydrated calcium hydroxide. 

Filter aids should have low bulk density to minimize settling and aid good distribution on a filter-medium surface that may not be horizontal. They should also be porous and capable of forming a porous cake to minimize flow resistance, and they must be chemically inert to the filtrate. These characteristics are all found in the two most popular commercial filter aids diatomaceous silica (also called diatomite, or diatomaceous earth), which is an almost pure silica prepared from deposits of diatom skeletons and expanded perhte, particles of puffed lava that are principally aluminum alkali siheate. Cellulosic fibers (ground wood pulp) are sometimes used when siliceous materials cannot be used but are much more compressible. The use of other less effective aids (e.g., carbon and gypsum) may be justified in special cases. Sometimes a combination or carbon and diatomaceous silica permits adsorption in addition to filter-aid performance. Various other materials, such as salt, fine sand, starch, and precipitated calcium carbonate, are employed in specific industries where they represent either waste material or inexpensive alternatives to conventional filter aids. 

CALCIUM CARBONATE. [CAS I3I7-65-3I- Calcium carbonate, [CAS. 471-34-11- CaCOi, mol wi 100.09. occurs naturally as the principal constituent of limestone, marble, and chalk. Powdered calcium carbonate is produced by two methods on the industrial scale. It is quarried and ground from naturally occurring deposits and in some cases beneftciated. It is also made by precipitation from dissolved calcium hydroxide and carbon dioxide. The natural ground calcium carbonate and the precipitated material compete industrially based primarily on particle size and the characteristics imparted to a product. 

In order to determine the chemical characteristics of Japanese rain, the major chemical components were determined at eleven stations throughout Japan for two years. The principal component analysis showed that nitrate and calcium can be used to characterize the local factors. The deposition of sulfate is discussed in relation to its origin. Some typical differences were observed between the stations on the Pacific side and the Japan Sea side of Honshu Is. 

The principal components of ash are calcium carbonate— in the form of precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC)—that typically constitutes 20% and up to 75% of dry sludge content, and clay. These two minerals are typically loaded into paper as a coating and filler to improve the mechanical characteristics as well as the appearance of paper. The resulting papermaking sludge, particularly mixed office paper sludge, consists primarily of two major components, that is, fiber and minerals finely mixed with each other. 

Edwards et al. (1958) have used infrared spectroscopy in the qualitative analysis of 30 specimens of human biliary calculi. The spectra of cholesterol, calcium bilirubinate, and calcium carbonate display prominent and characteristic bands that do not overlap in certain areas of the spectrum. Bands at 3380, 2910, and 1055cm" indicate the presence of cholesterol, a doublet at 1670 and 1630 cm" is characteristic of calcium bilirubinate, and a sharp band at 875 cm is produced by calcium carbonate. It is thus possible to verify the principal constituents of biliary calculi—whether they are (1) pure gallstones that are composed of either cholesterol, calcium bilirubinate, or calcium carbonate, or are (2) mixed gallstones that are composed chiefly of two or three of these components, or are (3) combined llstones with a nucleus of one kind and a shell of another substance. 

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