Magnesium aluminum silicate hydrated

Kaolin is a naturally occurring hydrated magnesium aluminum silicate (attapulgite), and pectin is an indigestible carbohydrate derived from apples. Both appear to act as absorbents of bacterial toxins and fluid, thereby decreasing stool liquidity and number. They may be useful in acute diarrhea but are seldom used on a chronic basis. A common nonprescription preparation is Kaopectate. The usual dosage is 1.2-1.5 g after each loose bowel movement (maximum 9 g/d). Kaolin-pectin formulations are not absorbed and have no significant adverse effects except constipation. They should not be taken within 2 hours of other medications (which they may bind). 

Clays Magnesium aluminum silicate (V eegum) Anionic 0.5-2.5 Disperses and hydrates readily. Hot water increases rate of hydration 3-11 Plastic/ thixotropy Partially flocculated by electrolytes and incompatible with acidic solution [Pg.168]

Thixotropy can be obtained at fairly low loading concentrations with colloidal silica, bentonite, metallic leafing powders, and hydrated magnesium aluminum silicates. If required, thixotropic adhesive pastes may be formulated which will not flow during cure even at elevated temperatures and which are useful for bonding loose-fitting joints. 

Other mineral additives have been used for many years as functional extenders and fillers in adhesives and sealants. These include kaolin (hydrated aluminum silicate), bentonite (hectorite clay), talc (magnesium silicate), and attapulgite (hydrated magnesium aluminum silicate) additives.1213 Kaolin and talc are considered to be viscosity thickeners whereas attapulgite is more of a conventional thixotrope. They are considered to be very cost-effective rheological additives. 

Tliese clays are hydrated magnesium aluminum silicates containing some iron and calcium. 

Suspending agent systems such as a pseudoplastic (sodium carboxymethylcellulose) in combination with a clay (hydrated colloidal magnesium aluminum silicate) or blends and coprecipitates of sodium carboxymethylcellulose and microcrystalline cellulose exhibit some thixotropic flow characteristics. Other pseudoplastics such as hydroxyethylcellulose or hydroxy-propyl methyl cellulose may be required to overcome possible in compatibilities with sodium carboxymethylcellulose. 

Attapulgite is a purified native hydrated magnesium aluminum silicate consisting of the clay mineral palygorskite, with the empirical formula Mg(Alo.5-iFeo-o.5)Si40io(OH)-4H20. 

Bentonite is a native colloidal hydrated aluminum silicate consisting mainly of montmorillonite, Al203-4Si02-H20 it may also contain calcium, magnesium, and iron. The average chemical analysis is expressed as oxides, see Table I, in comparison with magnesium aluminum silicate. 

Saponite is a naturally occurring phyllosilicate clay of the smectite (montmorillonite) group. It is a magnesium-rich hydrated aluminum silicate and is present as a component of some commercial magnesium aluminum silicate clays. Saponite is a mineral with an approximate empirical formula owing to the variability in cation substitution see Table I. 

Absorbents, such as kaolin (a hydrated aluminum silicate clay mineral), pectin (a complex carbohydrate often extracted from fruits), and atta-pulgite (a hydrated magnesium aluminum silicate clay mineral), form a thickening powder that absorbs excess fluid and any bacterial toxins present (action of kaolin and attapulgite) and increases the consistency of the stool by forming a viscous colloidal solution (action of pectin). However, these agents may also absorb essential body enzymes and nutrients. 

Silicic acid. See Silica, hydrated Silicic acid, aluminum calcium sodium salt. See Aluminum calcium sodium silicate Silicic acid, aluminum magnesium salt. See Magnesium aluminum silicate Silicic acid aluminum salt. See Aluminum (III) silicate (2 1)... 

Lithium hydroxide absorbent, carbon monoxide Copper chloride (ous) absorbent, chemical processes Iron (III) oxide hydrated absorbent, chemical specialties Magnesium aluminum silicate absorbent, CO2... 

Hydrated lime See calcium hydroxide. Hydrated magnesium aluminum silicate n. 

In the field of mineralogy, the first ab initio calculations based on density functional theory were performed on cordierite (magnesium aluminum silicate Mg2Al4Si50ig) by Winkler et al. (71). The DFT methods based on local density approximation (LDA) have been performed for hydrated Mg end-member cordierite to elucidate the location, orientation, and total energy of hydration in the ground state. The calculations shoed that the energetically most stable orientation... 

Hydrated Magnesium Aluminum Silicate n 3Mg0-1.5Al203-8Si02-9H20. Natural adsorptive clay with a primary constituent of attapulgite clay which has rodlike particle shape. Density, 2.36 g/cm (19.7 Ib/gal) O.A., 80-190, particle size, 0.13 pm. Syn ... 

The medium particle non-black silicates, such as Zeolex 23, a synthetic sodium aluminum silicate, Hydrex N sodium magnesium aluminum silicate, and Pyrax hydrated aluminum silicate, are widely used in NBR compounds as they process well, are lower cost, and can be colored. The chemical and water resistance of these materials is poorer and needs to be a consideration in designing a formulation. These fillers impart hardness like N762 carbon black, about 3.5 phr for every Shore A point increase. The inclusion of silane, tri-ethanolamine, or polyethylene glycol is advisable with these fillers as well. If low water swell or chemical resistance is a factor a silane needs to be added or a pretreated version used. 

Vermiculite Concentrate (also raw or unexfoliated vermiculite)—The mineralogical name given to hydrated laminar magnesium-aluminum-iron silicate (Mg,Ca,K,Fe(II)3(Si,Al,Fe(III)40io(OH)204H20) minerals, which resemble mica in appearance. This mineral has the unusual property of exfoliating or expanding to a low density, bulky material when heated (see Vermiculite). 

Hydrated magnesium silicate (Talc, 3Mg0 4Si02 H20, CAS No. 14807-96-6) is a magnesium silicate commonly referred to as "soapstone". It is obtained from natural sources and may contain a small amount of aluminum silicate. It is composed of MgO (31.7%), Si02 (63.5%), and H2O (4.8%). It is a crystalline nonhygroscopic, odorless, tasteless powder which is practically insoluble in water, dilute mineral acids, dilute solutions of alkali halides, and alkaline hydroxides but is soluble in hot concentrated sulfuric acid. 

The PhEur 2005 describes bentonite as a natural clay containing a high proportion of montmorillonite, a native hydrated aluminum silicate in which some aluminum and silicon atoms may be replaced by other atoms such as magnesium and iron. 

Talc is a purified, hydrated, magnesium silicate, approximating to the formula Mgg(Si205)4(0H)4. It may contain small, variable amounts of aluminum silicate and iron. 

Bentonite, Wilkinite. A colloidal native hydrated aluminum silicate (clay) found in the midwest of the U.S A. and in Canada. Consists principally of montmori]Ionite. Alj034Si0,.Ha0. Usually contains some magnesium, iron, and calcium carbonate. Review J. Alexander Ind. Eng. Chem. 16, 1140 (1924). 

---