Magnesium hydroxide, use

Deacidifying Agents. Magnesium bicarbonate solution (pH 6.4) was made from laboratory grade magnesium hydroxide using dry ice as the source of carbon dioxide (10). 

Definition Complexation prod, of stearic acid with aluminum/magnesium hydroxide Uses Emulsion stabilizer in cosmetics... 

The main sectors for magnesium hydroxide use are in elastomers and thermoplastics, since they cause excessive thickening in the main thermoset application of unsaturated polyester systems. It is also much more expensive than ATH with which it shares comparable properties and flame retardancy, and so ATH will be preferred by processors wherever possible. As a result the principle opportunities are in applications where the extra thermal stability is essential, mainly in PP and polyamides. 

Magnesium glycerophosphate n. MgP04 C3Hs(OH)2. a colorless powder, derived by the action of glycerophosphoric acid on magnesium hydroxide, used as a stabilizer for plastics. 

Liauw and co-workers have studied the adsorption of stearic acid onto magnesium hydroxide, using a variety of techniques, including DRIFTS and flow micro-calorimetry [8, 21]. The mono-layer level was again found to correspond well with a close packed vertical mono-layer. Evidence for order in the adsorbed layer was obtained by a number of techniques, including X-ray and differential scanning calorimetry. 

Ashton and co-workers have studied MPBD adsorption onto magnesium hydroxide using Fourier Transform Infrared (FTIR) spectroscopy, flow microcalorimetry and classical adsorption techniques [43]. They confirmed the formation of a carboxylate salt at the filler surface and found the chemisorbed layer to be only about 15 A thick. This implies loopy adsorption and multiple point attachment. 

The increase of unmodified (MDH3) and surface modified by aminosilane (MDH2) magnesium hydroxide used in high-density polyethylene increases the strength and modulus and decreases the elongation as compared to PE-HD. Surface modification of... 

C12H9N3O4. A brownish-red powder, soluble in sodium hydroxide. Used for the detection and estimation of magnesium, with which it forms a blue lake in alkaline solutions. 

Magnesium Hydroxide. Magnesium hydroxide [1309-42-8] is another metal hydrate that decomposes endothermically, accompanied by the formation of water. It decomposes at 330°C, which is 100°C higher than alumina trihydtate, and can therefore be used in polymers that ate processed at higher temperatures. 

F. Molesky in Recent Advances in Flame Retardamy of Polymeric Materials, Stamford, Coim., 1990 F. Molesky, "The Use of Magnesium Hydroxide for Flame Retarded Low Smoke Polypropylene," Polyolefins IHInternational Conference, Feb. 24,1991, Houston, Tex. 

Magnesium sulfate heptahydrate may be prepared by neutralization of sulfuric acid with magnesium carbonate or oxide, or it can be obtained directly from natural sources. It occurs abundantly as a double salt and can also be obtained from the magnesium salts that occur in brines used for the extraction of bromine (qv). The brine is treated with calcium hydroxide to precipitate magnesium hydroxide. Sulfur dioxide and air are passed through the suspension to yield magnesium sulfate (see Chemicals frombrine). Magnesium sulfate is a saline cathartic. 

Manufacture and Processing. Most commercial-grade magnesium hydroxide is obtained from seawater or brine using lime or dolomitic... 

Slurry Viscosity. Viscosities of magnesium hydroxide slurries are determined by the Brookfield Viscometer in which viscosity is measured using various combinations of spindles and spindle speeds, or other common methods of viscometry. Viscosity decreases with increasing rate of shear. Fluids, such as magnesium hydroxide slurry, that exhibit this type of rheological behavior are termed pseudoplastic. The viscosities obtained can be correlated with product or process parameters. Details of viscosity deterrnination for slurries are well covered in the Hterature (85,86). 

Uses. The principal use of magnesium hydroxide is in the pulp (qv) and paper (qv) industries (52). The main captive use is in the production of magnesium oxide, chloride, and sulfate. Other uses include ceramics, chemicals, pharmaceuticals, plastics, flame retardants/smoke suppressants, and the expanding environmental markets for wastewater treatment and SO removal from waste gases (87). 

Economic Aspects. The quantity of magnesium hydroxide shipped and used in the United States decreased by 17% from 1990 to 1991, then decreased further from 1991 to 1993. These shipments, excluding material produced as an intermediate step in the manufacture of other magnesium compounds, are given in Table 14 (52,103). 

Dead Seas Periclase Ltd., on the Dead Sea in Israel, uses yet another process to produce magnesium oxide. A concentrated magnesium chloride brine processed from the Dead Sea is sprayed into a reactor at about 1700°C (127,128). The brine is thermally decomposed into magnesium oxide and hydrochloric acid. To further process the magnesia, the product is slaked to form magnesium hydroxide which is then washed, filtered, and calcined under controlled conditions to produce a variety of MgO reactivity grades. A summary of MgO purities, for the various processes is given in Table 20. 

Typical values for mf n are 0.5 to 2.5. Gommercially used bases include sodium hydroxide, potassium hydroxide, calcium hydroxide (lime), magnesium hydroxide, sodium carbonate, sodium alurninate, calcium carbonate, or various mixtures. For certain appHcations, PAG can be made from waste grades of aluminum chloride [7446-70-0] such as spent catalyst solutions from Friedel-Grafts synthesis (see Friedel-Grafts reaction). 

---