Calcium caibonate

The physician is concerned with at least three factors when prescribing antacids (1) Acid rebound (associated with calcium carbonate) (2) milk-alkali syndrome (caused by ingestion of large quantities of alkali) and (3) phosphorus depletion (by aluminum salts). The mechanism of add rebound, especially in the long-term use of caldum carbonate, is poorly understood. It has been established that there is an excessive re-addification of the antrum (pylonc gland area) a number of hours after ingestion of calcium caibonate. 

Figure 15.7 Results demonstrating that much more polymeric material can be extract by suitable organic solvents bom vulcanizates derived from polystyrene-polybutadie blends than from vulcanizates from styrene-butadiene copolymers (Shundo et al. [19 ( ) peroxide-vulcanized copolymers (O) sulfur-vulcanized copolymers (O) radi don-vulcanized copolymers (A) peroxide-vulcanized latex blends (A) sulfiir-vulcaniz< latex blends (A) radiation-vulcanized latex blends ( ) peroxide-vulcanized roll blenr ( ) sulfur-vulcanized roll blends (Qf) radiation-vulcanized roll blends. The compoun for peroxide vulcanizates and sulfur vulcanizates were as given in the cation Figure 15.6. The compound for radiation vulcanization was (parts by mass) polymer 10 calcium caibonate ICIO. Roll blending was done at 110°C. Peroxide and sulfur vulca-izatkxis were carried out at 150°C. Radiation vulcanization was achieved using 10 n from a cobaIt-60 source in air at normal ambient temperature...

Types aluminum fiber, aluminum hydroxide, antimony trioxide, calcium caibonate, carbon black, carbon fiber, hollow glass beads, kaolin, magnesinm hydroxide, mica, sand, silica, silica carbide, talc, waste leather particles, wollastonite, wood fiber, wood flour, zeolite... 

Potential adverse effeets calcium carbonate interferes with radiation curing, calcium caibonate may react with pollutant (SO2) to form sulfate, fillers eontaining cadmium, cobalt, copper, iron, lead, or nickel reduce thermal stabihty, low concentration of carbon black and titanium dioxide reduces UV stability, zinc oxide decreases thermal stability, zinc oxide in combination with carbon black reduces UV stability... 

If the chalk is made of calcium carbonate, CaCO, it is made of the same active ingredient found in many antacids. The- calcium oir-bonaie is a base dial icacts to neutralize any excess acids. Be careful, though, never Co take too much calcium caibonate because the stomach is designed ro always he somewhat acidic. 

Enzyme based micron sized sensing system with optical readout was fabricated by co-encapsulation of urease and dextran couple with pH sensitive dye SNARE-1 into polyelectrolyte multilayer capsules. The co-precipitation of calcium caibonate, urease, and dextran followed up by multilayer film coating and Ca- extracting by EDTA resulted in formation of 3.5-4 micron capsules, what enable the calibrated fluorescence response to urea in concentration range from 10 to 10 M. Sensitivity to urea in concentration range of 10 to 10 M was monitored on capsule assemblies (suspension) and on single capsule measurements. Urea presence can be monitored on single capsule level as illustrated by confocal fluorescent microscopy. 

Note that the very important assumption is made that each time the kettle is filled, the calcium caibonate is allowed to reach equilibrium before the kettle is emptied. 

This reaction gives rise to both gas (Hj) and high values of pH. The gas can blanket the electrode and increase the resistance of the stack. High values of pH can cause precipitation of any pH-sensidve materials (e.g., calcium caibonate) in the electrode-rinse stream, which can raise resistance and even make the stack inoperative. 

Table 7.1 summarizes the typical composition and properties of a representative series of mineral additions used in blended cements. Binders based on granulated blast furnace slag and related materials are discussed in mote detail in Chapter 8, and those based on natural and artificial pozzolanas in Chapter 9. Cements containing calcium caibonate ate discussed in section 2.2.14. 

The addition of finely ground calcium caibonate (calcite) to calcium aluminate cement results in the formation of calcium aluminocarbonate hydrate (C ACh j) as the product of hydration, instead of CAHg and CjAHg. At sufficiently high additions of the carbonate conversion of the cement may be avoided, and hence the strength loss associated with it may be prevented (Trivino, 1986). The long-term effectiveness of this measure is questionable, however. 

Crops and stock also remove some calcium caibonate, for example a 7t/ha cereal crop can remove 50 kg and a 500 kg animal sold off the farm removes about 16kg of calcium caibonate in its bones. 

Ground limestone or chalk (also called caibonate of lime or calcium caibonate CaCOj) is the commonest liming material used at present. These are obtained by quanying the limestone or chalk rock and grinding it to a fine powder. The finer the particle size the quicker the reduction of acidity. 

Leong, Y.W., Abu Bakar, M.B., Mohd Ishak, Z.A., et al. Characterization of talc/calcium caibonate filled polypropylene hybrid composites weathered in a natural environment Polym. Degrad. Stab. 83, 411-122 (2004)... 

Calcium hydroxide [Ca(OH)2] is commonly known as slaked lime or hydrated lime. Lime (CaO), which is also referred to as quicklime, is one of the oldest materials known to humankind. Quicklime is produced by the thermal decomposition of calcium caibonate ... 

Hardness is generally reported in terms of calcium caibonate equivalent and is calculated by the general formula ... 

There are numerous reactions such as the decomposition of calcium caibonate into carbon dioxide and lime or dehydration of a hydrated salt into a less hydrated form and water vapor or dissociation of an oxide into metal and oxygem In all these cases, we can see that n -r = 2 and therefore v = 1. According to the law of mass action, gas pressure will be, at equilibrium, a function of temperamre only. 

Bouineau [BOU 98] encountered the case with the step of creation of the defect as the rate-determining step in the deconposition of calcium caibonate. 

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