Магний углекислый химические свойства, назначение, производство
Описание
Magnesium carbonate is obtained mainly by mining
the natural mineral magnesite. The trihydrate salt,
MgCO3·3H2O, is prepared by mixing solutions of magnesium
and carbonate ions in the presence of carbon
dioxide.
Химические свойства
Magnesium carbonate occurs as light, white-colored friable masses
or as a bulky, white-colored powder. It has a slightly earthy taste
and is odorless but, since it has a high absorptive ability, magnesium
carbonate can absorb odors.
The USP 32 describes magnesium carbonate as either a basic
hydrated magnesium carbonate or a normal hydrated magnesium
carbonate. However, the PhEur describes magnesium carbonate as
being a hydrated basic magnesium carbonate in two separate
monographs: heavy magnesium carbonate and light
magnesium carbonate. The molecular formulas for
heavy magnesium carbonate and light magnesium carbonate vary,
but heavy magnesium carbonate may generally be regarded as the
tetrahydrate [(MgCO3)3·Mg(OH)2·4H2O], while light magnesium
carbonate may be regarded as the trihydrate [(MgCO3)3·
Mg(OH)2·3H2O].
The molecular weights of the heavy and light forms of
magnesium carbonate are 383.32 and 365.30, respectively.
Физические свойства
This material is available in a very light, fluffy grade which absorbs well. The before-mentioned qualities are why magnesium carbonate is often used to absorb perfume before incorporation into face powders.
Использование
Some applications of magnesiumcarbonate are uses in
flooring, fireproofing and fire-extinguishing compositions;
as a filler material and smoke suppressant in plastics;
as a reinforcing agent in neoprene rubber; as a drying
agent and for color retention in foods; in cosmetics.
Magnesium carbonate is used as an antacid in medicine
and as an additive to table salt. Another important application
of magnesium carbonate is as a starting material in
producing a number of magnesium compounds.
Because of its water-insoluble, hygroscopic properties,
MgCO3 was first added to salt in 1911 to make the
salt flow more freely. Magnesium carbonate, most often
referred to as “chalk”, is used as a drying agent for hands
in gymnastics, weight lifting and rock climbing. Magnesium
carbonate is also used in taxidermy for whitening
skulls. It can be mixed with hydrogen peroxide to create
a paste, which is then spread on the skull to give it awhite
finish. Basic magnesium carbonate is used as a clay in
face masks and it has mild astringent properties and
helps to smooth and soften skin. It is recommended for
use on normal to dry skins.
Определение
A whitecompound, MgCO3, existing in anhydrousand hydrated forms. The anhydrousmaterial (trigonal; r.d.2.96) is found in the mineral magnesite.There is also a trihydrate,MgCO3.3H2O (rhombic; r.d. 1.85),which occurs naturally as nesquehonite,and a pentahydrate, MgCO3.5H2O (monoclinic; r.d. 1.73),which occurs as lansfordite. Magnesiumcarbonate also occurs in themixed salt dolomite (CaCO3.MgCO3)and as basic magnesium carbonatein the two minerals artinite(MgCO3.Mg(OH)2.3H2O) and hydromagnesite(3MgCO3.Mg(OH)2.3H2O).The anhydrous salt can be formed byheating magnesium oxide in astream of carbon dioxide:
MgO(s) + CO2(g) → MgCO3(s)
Above 350°C, the reverse reactionpredominates and the carbonate decomposes.Magnesium carbonate isused in making magnesium oxideand is a drying agent (e.g. in tablesalt). It is also used as a medicalantacid and laxative (the basic carbonateis used) and is a componentof certain inks and glasses.
Методы производства
Depending upon the manufacturing process used, the composition
of the magnesium carbonate obtained may vary from normal
hydrated magnesium carbonate to basic hydrated magnesium
carbonate.
Light magnesium carbonate may be manufactured by saturating
an aqueous suspension of dolomite, CaMg(CO3)2, with carbon
dioxide under pressure. On increase of the temperature, calcium
carbonate precipitates almost entirely. The filtered solution is then
heated to boiling; the magnesium bicarbonate in the solution loses precipitates.
Heavy magnesium carbonate may be manufactured by mixing a
hot concentrated solution of magnesium chloride or magnesium
sulfate with a solution of sodium carbonate. The heavy magnesium
carbonate may be either precipitated to produce a granular material
or spray-dried. Varying the temperature of the reaction solutions
produces heavy magnesium carbonate with differing physical
properties: e.g. material with a higher specific surface area is
produced at a lower reaction temperature. Low processing
temperature provided the largest surface area, which produced
optimum granules or spray-dried powder.If dilute magnesium
chloride or magnesium sulfate solutions are used for the reaction, a
less dense material is produced.
Magnesium carbonates in varying states of hydration are also
found as minerals in nature.
Общее описание
White, yellowish, grayish-white or brown crystalline solid or crystalline powder. Density: 3-3.1 g cm-3. An important ore for magnesium. Used in the manufacture of materials capable of withstanding very high temperatures. Sometimes used to produce carbon dioxide.
Профиль реактивности
Magnesium carbonate has generally low chemical reactivity. Non-flammable and non-combustible. Reacts with acids and acidic salts to generate gaseous carbon dioxide with effervescence (bubbling). The reaction may be rapid and exothermic with concentrated solutions of acids. The efferversence can create foaming. Incompatible with formaldehyde.
Опасность
A nuisance particulate.
Угроза здоровью
Magnesite is considered to be a
nuisance dust.
Сельскохозяйственное использование
Hydromagnesite is a magnesium ore which occurs as a carbonate. Magnesium carbonate occurs in a mixed salt dolomite (CaCO3.MgCO3) and as basic magnesium carbonate in two minerals, namely, artinite (MgCO3.Mg(OH)2.3H2O) and hydromagnesite (3MgCO3.Mg(OH)2.3H2O).
Фармацевтические приложения
As an excipient, magnesium carbonate is mainly used as a directly
compressible tablet diluent in concentrations up to 45% w/w.
Heavy magnesium carbonate produces tablets with high crushing
strength, low friability, and good disintegration properties.
However, magnesium carbonate can have varying effects on
dissolution and stability.Magnesium
carbonate has been incorporated in microsphere formulations for
the purpose of stabilizing encapsulated proteins. It has also been
coencapsulated in poly(lactide-co-glycolide) microsphere formulations
to neutralize acidity and enhance the immunogenicity of a
contraceptive peptide vaccine. Magnesium carbonate is also used
to absorb liquids, such as flavors, in tableting processes.
Magnesium carbonate is additionally used as a food additive and
therapeutically as an antacid.
Безопасность
Magnesium carbonate is used as an excipient in oral solid-dosage
pharmaceutical formulations and is generally regarded as an
essentially nontoxic and nonirritant material. However, the use of
magnesium salts, such as magnesium carbonate, is contraindicated
in patients with renal impairment. In certain studies, magnesium
carbonate has been shown to be an effective phosphate binder in
short-term use for patients with chronic kidney disease, but the
effects of long-term use require further study.The probable oral
lethal dose in humans has been estimated at 0.5–5.0g/kg bodyweight.
On contact with gastric acid, magnesium carbonate reacts in the
stomach to form soluble magnesium chloride and carbon dioxide.
Magnesium carbonate should therefore not be used as an antacid by
those individuals whose stomachs cannot tolerate the evolution of
carbon dioxide. Some magnesium is absorbed but is usually
excreted in the urine. As with other magnesium salts, magnesium
carbonate has a laxative effect and may cause diarrhea.
Therapeutically, the usual dose of magnesium carbonate as an
antacid is 250–500mg, and 2.0–5.0g as a laxative.
хранилище
Magnesium carbonate is stable in dry air and on exposure to light.
The bulk material should be stored in a well-closed container in a
cool, dry place.
Несовместимости
Incompatible with phenobarbital sodium,diazepam solution at
a pH≥5, some binary powder mixtures, lansoprazole,
and formaldehyde. Acids will dissolve magnesium carbonate,
with the liberation of carbon dioxide. Slight alkalinity is imparted to
water. Magnesium carbonate was also found to increase the
dissolution of acetazolamide formulations at a pH of 1.12; however,
dissolution was retarded at a pH of 7.4.
Регуляторный статус
GRAS listed. Accepted as a food additive in Europe. Included in the
FDA Inactive Ingredients Database (oral capsules and tablets).
Included in nonparenteral medicines licensed in the UK.
Магний углекислый препаратная продукция и сырье
сырьё
препарат