Adsorbents magnesium carbonate

Green coloration, present in many vegetable oils, poses a particular problem in oil extracted from immature or damaged soybeans. Chlorophyll is the compound responsible for this defect. StmcturaHy, chlorophyll is composed of a porphyrin ring system, in which magnesium is the central metal atom, and a phytol side chain which imparts a hydrophobic character to the stmcture. Conventional bleaching clays are not as effective for removal of chlorophylls as for red pigments, and specialized acid-activated adsorbents or carbon are required. 

For free-flow agents, water-insoluble, finely divided adsorbents such as sodium siUcoalurninate, tricalcium phosphate, calcium siUcate, magnesium carbonate, and siUcon dioxide are used. Concentrations between 0.5 and 2% are typically added to table salt and some industrial grades of salt for use in apphcations where caking may occur. 

Direct experimental determinations of these quantities do not exist. The nearest approach seems to be in some observations made by Nicolson (26) in his work on surface tension. He found that when he made magnesium oxide particles by burning magnesium in air, their lattice constants were the same as those of the bulk material. When the crystals were made by the decomposition of magnesium carbonate in vacuo, the expected change in lattice parameter took place due to the surface tension. These negative results obtained in the first method of preparation were attributed to the presence of gases adsorbed from the air. 

Magnesium carbonate is most water soluble and reacts with hydrochloric acid at a slow rate. Magnesium hydroxide has low water solubility. It reacts with hydrochloric acid promptly. Magnesium trisilicate has low solubility and has the power to adsorb and inactivate pepsin and to protect the ulcer base. 

The manufacture of nitroglycerine was also started in Russia by Pietruszewski, a co-worker of Zinin [2]. Intending to decrease the sensitiveness of nitroglycerine to shock, Pietruszewski mixed the explosive substance with a solid adsorbent, in this case magnesium carbonate. Since about 1867 nitroglycerine has been used in the Upper-Uspienskii district s gold mines in the Trans-Baykal of Siberia [6]. 

A1203 activated by heating to about 200 C in a current of air or carbon dioxide, is the most, widely used absorbent. Other adsorbents used are silica gel (activated in the same manner as alumina), magnesium oxide, magnesium carbonate, calcium carbonate, calcium sulphate, barium carbonate, charocal, sucrose, talc, starch, cellulose and Fuller s earth. The inorganic adsorbents are usually heated to 200-220 C before use. 

Antacids are gastric-acid neutralizing or adsorbing medications, usually containing aluminium and/or magnesium salts (e.g. aluminium hydroxide, magnesium carbonate, hydroxide or trisilicate), which have the ability to decrease the absorption of several medications that are co-administered (often due to the formation of chelates/insoluble unabsorbable complexes). 

Special considerations presence of zinc, copper, iron and nickel compounds accelerated dehydrochlorination combination of basic magnesium carbonate and aluminum hydroxide is used as flame retardant and smoke supressant chlorinated polyethylene adsorbs on the surface of titanium dioxide forming a layer 1-20 nm thick depending on the aciii/base interaction parameter of titanium dioxide ... 

In vitro tests showed that magnesium trisilicate adsorbed proguanil. Two other antacids, aluminium hydroxide and light magnesium carbonate,... 

Russian engineers [47] mixed Nitroglycerin and magnesium carbonate, a type of solid adsorbent, such formulation has been used for gold mining in Trans-Baykal of Siberia, Upper-Uspleaskii [48]. 

Fig. 13. MgO from A.R. basic magnesium carbonate (900°C calcine) showing unidentified adsorbed species bn centrally located crystallites.

Mayorga, S.G., S.J. Weigel, T.R. Gaffney, and J.R. Brzozowski, Carbon Dioxide Adsorbents Containing Magnesium Oxide Suitable for Use at High Temperature, U.S. Patent No. 6,280,503 Bl, August 2001. 

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