MAGNESIUM OXIDE
MAGNESIUM OXIDE
IUPAC Name: oxomagnesium
CAS Number: 1309-48-4
EC Number: 215-171-9
Chemical formula: MgO
Molar mass: 40.304
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide).
Magnesium oxide has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding.
Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to remove moisture.
Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia – other sources give magnesia alba as MgCO3), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese.
Related oxides
While “magnesium oxide” normally refers to MgO, magnesium peroxide MgO2 is also known as a compound.
According to evolutionary crystal structure prediction, MgO2 is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa.
Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals.
Production
Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide.
The latter is obtained by the treatment of magnesium chloride MgCl 2 solutions, typically seawater, with limewater or milk of lime.
Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+
Calcining at different temperatures produces magnesium oxide of different reactivity.
High temperatures 1500 – 2000 °C diminish the available surface area and produces dead-burned (often called dead burnt) magnesia, an unreactive form used as a refractory.
Calcining temperatures 1000 – 1500 °C produce hard-burned magnesia, which has limited reactivity and calcining at lower temperature, (700–1000 °C) produces light-burned magnesia, a reactive form, also known as caustic calcined magnesia.
Although some decomposition of the carbonate to oxide occurs at temperatures below 700 °C, the resulting materials appears to reabsorb carbon dioxide from the air.
Applications
Heating elements
MgO is prized as a refractory material, i.e. a solid that is physically and chemically stable at high temperatures.
Magnesium oxide has two useful attributes: high thermal conductivity and low electrical conductivity. Filling the spiral Calrod range top heating elements on kitchen electric stoves is a major use.
“By far the largest consumer of magnesia worldwide is the refractory industry, which consumed about 56 % of the magnesia in the United States in 2004, the remaining 44 % being used in agricultural, chemical, construction, environmental, and other industrial applications”.
MgO is used as a basic refractory material for crucibles.
Fireproofing
Magnesium oxide is a principal fireproofing ingredient in construction materials.
As a construction material, magnesium oxide wallboards have several attractive characteristics: fire resistance, termite resistance, moisture resistance, mold and mildew resistance, and strength.
Niche uses
Magnesium oxide is one of the components in Portland cement in dry process plants.
Magnesium oxide is used extensively in the soil and groundwater remediation, wastewater treatment, drinking water treatment, air emissions treatment, and waste treatment industries for its acid buffering capacity and related effectiveness in stabilizing dissolved heavy metal species.[according to whom?]
Many heavy metals species, such as lead and cadmium are most soluble in water at acidic pH (below 6) as well as high pH (above 11).
Solubility of metals affects bioavailability of the species and mobility soil and groundwater systems.
Most metal species are toxic to humans at certain concentrations, therefore Magnesium oxide is imperative to minimize metal bioavailability and mobility.
Granular MgO is often blended into metals-contaminated soil or waste material, which is also commonly of a low pH (acidic), in order to drive the pH into the 8–10 range where most metals are at their lowest solubilities (basic).
Metal-hydroxide complexes have a tendency to precipitate out of aqueous solution in the pH range of 8–10. MgO is widely regarded as the most effective metals stabilization compound when compared to Portland cement, lime, kiln dust products, power generation waste products, and various proprietary products due to MgO’s superior buffering capacity, cost effectiveness, and ease/safety of handling.
Most, if not all products that are marketed as metals stabilization technologies create very high pH conditions in aquifers whereas MgO creates an ideal aquifer condition with a pH of 8–10. Additionally, magnesium, an essential element to most biological systems, is provided to soil and groundwater microbial populations during MgO-assisted metals remediation as an added benefit.
Medical
Magnesium oxide is used for relief of heartburn and dyspepsia, as an antacid, magnesium supplement, and as a short-term laxative.
Magnesium oxide is also used to improve symptoms of indigestion. Side effects of magnesium oxide may include nausea and cramping.
In quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction.
Other
As a food additive, it is used as an anticaking agent. It is known to the US Food and Drug Administration for cacao products; canned peas; and frozen dessert.
Magnesium oxide has an E number of E530.
It was historically used as a reference white color in colorimetry, owing to its good diffusing and reflectivity properties.
Magnesium oxide may be smoked onto the surface of an opaque material to form an integrating sphere.
Magnesium oxide is used extensively as an electrical insulator in tubular construction heating elements.
There are several mesh sizes available and most commonly used ones are 40 and 80 mesh per the American Foundry Society.
The extensive use is due to its high dielectric strength and average thermal conductivity. MgO is usually crushed and compacted with minimal airgaps or voids.
The electrical heating industry also experimented with aluminium oxide, but it is not used anymore.
As a reagent in the installation of the carboxybenzyl (Cbz) group using benzyl chloroformate in EtOAc for the N-protection of amines and amides.
Magnesium oxide is also used as an insulator in heat-resistant electrical cable.
MgO doping has been shown to effectively inhibit grain growth in ceramics and improve their fracture toughness by transforming the mechanism of crack growth at nanoscale.
Unpolished MgO crystal
Pressed MgO is used as an optical material.
Magnesium oxide is transparent from 0.3 to 7 µm.
The refractive index is 1.72 at 1 µm and the Abbe number is 53.58.
Magnesium oxide is sometimes known by the Eastman Kodak trademarked name Irtran-5, although this designation is obsolete.
Crystalline pure MgO is available commercially and has a small use in infrared optics.
MgO is packed in bags around transuranic waste in the disposal cells (panels) at the Waste Isolation Pilot Plant, as a CO2 getter to minimize the complexation of uranium and other actinides by carbonate ions and so to limit the solubility of radionuclides.
The use of MgO is preferred to this of CaO as the resulting hydration product (Mg(OH)2) is less soluble and releases less hydration heat.
Another advantage is to impose a lower pH value of ~ 10.5 in case of accidental water ingress in the dry salt layers while the more soluble Ca(OH)2 would create a higher pH of 12.5 (strongly alkaline conditions).
The Mg2+ cation being the second most abundant cation in seawater and in rocksalt, the potential release of magnesium ions dissolving in brines intruding the deep geological repository is also expected to minimize the geochemical perturbations.
MgO has an important place as a commercial plant fertilizer and as animal feed.
An aerosolized solution of MgO is used in library science and collections management for the deacidification of at-risk paper items. In this process, the alkalinity of MgO (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration.
MgO is also used as a protective coating in plasma displays.
Magnesium oxide is used as an oxide barrier in spin-tunneling devices.
Owing to the crystalline structure of its thin films, which can be deposited by magnetron sputtering, for example, it shows characteristics superior to those of the commonly used amorphous Al2O3.
In particular, spin polarization of about 85% has been achieved with MgO versus 40–60 % with aluminium oxide.
The value of tunnel magnetoresistance is also significantly higher for MgO (600% at room temperature and 1,100 % at 4.2 K) than Al2O3 (ca. 70% at room temperature)
Appearance: White powder
Odor: Odorless
Density: 3.6 g/cm3[1]
Melting point: 2,852 °C (5,166 °F; 3,125 K)
Boiling point: 3,600 °C (6,510 °F; 3,870 K)
Solubility: Soluble in acid, ammonia but insoluble in alcohol
Band gap: 7.8 eV
Magnetic susceptibility(χ): −10.2·10−6 cm3/mol
Thermal conductivity: 45–60 W·m−1·K−1[4]
Refractive index(nD): 1.7355
Dipole moment: 6.2 ± 0.6 D
Crystal structure: Halite (cubic), cF8
Space group: Fm3m, No. 225
Lattice constant: a = 4.212Å
Coordination geometry: Octahedral (Mg2+); octahedral (O2−)
Thermochemistry
Heat capacity(C): 37.2 J/mol K
Std molar entropy(So298): 26.95 ± 0.15 J·mol−1·K−1
Std enthalpy of formation(ΔfH⦵298): −601.6 ± 0.3 kJ·mol−1
Gibbs free energy(ΔfG˚): -569.3 kJ/mol
Magnesium oxide is an inorganic salt of magnesium formed with ions of magnesium and oxygen.
Magnesium oxide is one of many forms of magnesium available for purchase in supplement form.
Magnesium oxide is added to dietary supplements as well as over-the-counter medications used to treat constipation, indigestion, and headaches.
Compared with other forms of magnesium, it may be less effective at raising blood magnesium levels.
How does it compare with other forms of magnesium?
Magnesium oxide and other inorganic salts of magnesium like magnesium carbonate are high in elemental magnesium, which is the total amount of magnesium in a supplement.
However, they have a low solubility rate, making them less bioavailable than other forms of the mineral. So, even though magnesium oxide supplements provide a good amount of magnesium, it’s not the most available form for your body to utilize.
A 2019 study confirmed this by testing 15 magnesium supplements and finding that a supplement containing only magnesium oxide had the lowest bioavailability.
Meanwhile, a supplement with both inorganic and organic magnesium salts — magnesium oxide and magnesium glycerophosphate, respectively — had the highest bioavailability.
Because of its low absorption rate in your intestines, magnesium oxide may lead to digestive effects like diarrhea. In fact, its strong laxative effects are why it’s commonly used to treat constipation.
In contrast, magnesium citrate, magnesium acetyl taurate, magnesium malate, and magnesium glycinate all have high absorption rates and are more effective at increasing magnesium levels in the body.
Still, magnesium oxide has been shown to offer several benefits and is commonly used to treat medical conditions like chronic constipation.
Magnesium oxide is an inorganic salt of magnesium. Even though it contains high amounts of magnesium, it has low absorbability in the body.
Still, it has been shown to offer health benefits like constipation relief.
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 1
Rotatable Bond Count: 0
Exact Mass: 39.9799563
Monoisotopic Mass: 39.9799563
Topological Polar Surface Area: 17.1 Ų
Heavy Atom Count: 2
Formal Charge: 0
Complexity: 2
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
Magnesium oxide is a type of magnesium mineral supplement that is mostly made of magnesium.
Magnesium oxide actually contains more magnesium than other magnesium supplements.
Magnesium oxide is acquired by burning magnesium with pure oxygen, but this method is quite costly.
The cheaper method is to expose oxygen to magnesium salts using underground deposits, seawater, or salt beds.
With this method, the source of the magnesium salt determines the quality of the magnesium oxide that is produced.
Magnesium oxide (MgO)-NPs were also reported to exhibit antimicrobial activity against certain vegetative bacteria and bacteria spores.
Moreover, the inactivation of viruses and aflatoxins has been observed when using nanoscale MgO powder possessing active forms of halogens.
To the authors’ knowledge, food packaging applications using MgO-NPs have not been reported in the scientific literature yet.
However, few in vitro studies against foodborne pathogens have been performed using MgO-NPs alone or in combination with other antimicrobials.
Thereby, it was found that MgO-NPs distort and damage the bacterial cell membrane so that intracellular contents are leaking which in turn leads to cell death.
Jin and He demonstrated that MgO-NPs are highly effective against pathogens, achieving more than 7 log reductions in bacterial counts of E. coli O157:H7 and Salmonella Stanley.
In addition, they investigated the antibacterial effect of the MgO-NPs in combination with other antimicrobials such as nisin and ZnO-NPs.
Whereas by the addition of nisin a synergistic effect was observed, the combination of MgO and ZnO-NPs did not enhance the antibacterial activity against both pathogens.
Other authors investigated the antimicrobial activity of nano-assembled metallic oxides (MgO, CaO, and ZnO) against a wide range of spoilage microorganisms of fruit juices.
They found that all the microorganisms tested were susceptible to at least one of the nano metal oxides clearly indicating a selective toxicity of the applied NPs.
In combination, however, the authors suggested the nano metal oxides to be a promising alternative to the use of synthetic preservatives for pathogen control in fruit juices.
Magnesium oxide supplements’ main uses include treating low magnesium levels in the body.
The body needs magnesium for normal functioning of nerves, muscles, and cells.
Lack of magnesium after a liver transplant can lead to irritability, muscle weakness, irregular heartbeat, or seizures.
Magnesium-providing medications also can be used to treat heartburn, acid indigestion, or sour stomach.
Note: The best dietary sources of magnesium include green leafy vegetables, avocados, bananas, nuts, peas, beans, wheat germ, and grains.
A high-fat diet causes the body to absorb smaller amounts of magnesium than normal to be absorbed. Cooking decreases the magnesium content of foods.
Magnesium oxide is an over-the-counter mineral effective as treatment for constipation, indigestion, magnesium deficiency, high blood pressure during pregnancy (pre-eclampsia and eclampsia), irregular heartbeat, asthma, pain caused by nerve damage associated with cancer, cerebral palsy, chronic fatigue syndrome, chronic obstructive pulmonary disease (COPD), cluster headache, colon and rectal cancer, chest pain (angina) due to clogged arteries, cystic fibrosis, diabetes, fibromyalgia, hearing loss, high cholesterol, metabolic syndrome, diseases of heart valves (mitral valve prolapse), weak bones (osteoporosis), pain after hysterectomy, pain after surgery, premenstrual syndrome (PMS), and chest pain due to blood vessel spasms (vasopastic angina).
Magnesium oxide is a compound commonly used as a laxative for the symptomatic relief of acid indigestion and upset stomach, and in health supplements for cardiovascular and neuromuscular health.
Synonyms
oxomagnesium
Magnesia
Periclase
Magnesium oxide (MgO)
Seawater magnesia
Magnesium oxide fume
Uro-Mag
MFCD00011109
1317-74-4
Magnesium oxide, -325 mesh
Magnesia grooves
Causmag
Granmag
Maglite
Seasorb
Animag
Magcal
Marmag
Oxymag
Heavy magnesia
Light magnesia
BayMag
Maglite de
Calcined brucite
Magnesa preprata
Akro-mag
Liquimag A
Liquimag B
Calcined magnesia
Caustic magnesite
Maglite D
Maglite K
Maglite S
Maglite Y
Magnesia monoxide
Anscor P
Hamag LP
Magox OP
FloMag HP
Fert-O-Mag
Kyowamag 20
Kyowamag 30
Kyowamag 40
Kyowamag 60
Elastomag 100
Elastomag 170
FloMag HP-ER
Kyowamag 100
Kyowamag 150
Kyowamag 150B
Kyowaway 150
Heavy magnesium oxide
Kyowaad 100
Luvatol MK 35
Magchem 100
Magox 85
Magox 90
Magox 95
Magox 98
Mag Chem 10
Mag Chem 35
Heavy calcined magnesia
Mag Chem 200AD
KM 3 (oxide)
KMACH-F
Mag Chem 200D
FMR-PC
Magnesium oxide, p.a., 95.0%
HP 10 (oxide)
Magmilax bolus
Magnezu tlenek
100A (oxide)
Magnezu tlenek [Polish]
Mag Chem 10-40
AM 2 (cement additive)
Mag Chem 10-200
Mag Chem 10-325
Magnesium oxide substrate, 10x10x0.5mm, polished one side, 100 orientation
Magnesium oxide substrate, 10x10x0.5mm, polished one side, 110 orientation
Periclase (MgO)
CCRIS 3659
Magnesium oxide, fume
HSDB 1652
SLO 369
SLO 469
KM 40
EINECS 215-171-9
KMB 100-200
Magnesium oxide [USP:JAN]
Maox
Calcined magnesite
MgO Nanoparticles
Mag-Ox
Magnesium oxide (fume), Inhalable
Magmitt (TN)
Magnesium oxide heavy
Magnesium oxide, CP
Magnesium oxide, heavy
Magnesium oxide (fume)
Magnesium oxide, 97%
Magnesium Oxide nanowire
Magnesium Oxide DC USP
Magnesium Oxide Dispersion
Magnesium Oxide Nanopowder
Magnesium oxide ACS Reagent
Magnesium Oxide DC Granular
Nano Magnesium Oxide Powder
Magnesium Oxide Light, USP
Magnesium oxide, Respirable dust and fume, as Mg
Magnesium oxide (JP17/USP)
Magnesium oxide, light, 95%
Active Magnesium Oxide RA 40
INS NO.530
CHEMBL1200572
DTXSID9049665
Active Magnesium Oxide RA 110
Active Magnesium Oxide RA 150
INS-530
Magnesium Oxide-Technical Grade KP
Light Active Magnesium Oxide RA 70
Magnesium Oxide Powder, 99% Nano
Magnesium oxide, ACS reagent, 97%
NSC761263
Magnesium Oxide Powder,>= 99% Nano
NSC-761263
Pharmaceutical Grade Magnesium Oxide HA4
E530
Magnesium Oxide (MgO) Sputtering Targets
Magnesium Oxide Single Crystal Substrates
Magnesium oxide, -10-+50 mesh, 98%
Magnesium oxide, Vetec(TM) reagent grade
Magnesium Oxide Nanoparticles / Nanopowder
Magnesium oxide, 99.995% (metals basis)
E-530
FT-0628095
Magnesium Oxide Special Industrial Grade SIG
Magnesium oxide, 99.99% trace metals basis
Active Pharmaceutical Magnesium Oxide PHRA50
Magnesium Oxide Reactive Technical Grade KPLL
Magnesium oxide, SAJ first grade, >=96.0%
Magnesium oxide, SAJ first grade, >=98.0%
D01167
Magnesium oxide, >=99.99% trace metals basis
Magnesium oxide, 2 part ceramic adhesive paste
Magnesium oxide, SAJ special grade, >=99.0%
Pharmaceutical Magnesium Oxide Grade HA and HA5
Magnesium oxide, >26% in a non hazardous diluent
Magnesium oxide, fused, 150-325 mesh, >=95%
Q214769
Magnesium oxide, tested according to Ph.Eur., heavy
Magnesium oxide, >=99% trace metals basis, -325 mesh
Magnesium oxide, nanopowder, <50 nm particle size (BET)
Magnesium oxide, BioUltra, >=97.0% (calcined substance, KT)
Magnesia sticks, for pearl-tests, package of 100 magnesia sticks
Magnesia sticks, for pearl-tests, package of 25 magnesia sticks
Magnesium oxide, fused, chips, -4 mesh, 99.9% trace metals basis
Magnesium oxide substrate, 10x10x0.5mm, polished one side, 111 orientation
Magnesium oxide substrate, 10x10x1mm, polished one side, 100 orientation
Magnesium oxide substrate, 10x10x1mm, polished one side, 110 orientation
Magnesium oxide substrate, 10x10x1mm, polished two sides, 100 orientation
Magnesium oxide, puriss. p.a., >=98.0% (based on calcined substance, KT)
Magnesium oxide, purum, >=97.0% (based on calcined substance, KT), light
Magnesia Rectangular Plate,Length (mm), 105,Width (mm), 50,Thickness (mm), 10
Magnesia Rectangular Plate,Length (mm), 145,Width (mm), 70,Thickness (mm), 15
Magnesium oxide Crucible, Cylindrical, Flat Base, HtxOD (mm), 37×20, Vol (ml), 5
Magnesium oxide Crucible, Cylindrical, Flat Base, HtxOD (mm), 43×24, Vol (ml), 10
Magnesium oxide Crucible, Cylindrical, Flat Base, HtxOD (mm), 90×45, Vol (ml), 100
Magnesium Oxide Crucible, Cylindrical, Flat Base,OD (mm), 25,Height (mm), 25
Magnesium Oxide Crucible, Cylindrical, Flat Base,OD (mm), 32,Height (mm), 32
Magnesium Oxide Crucible, Cylindrical, Flat Base,OD (mm), 44,Height (mm), 44
Magnesium Oxide Crucible, Cylindrical, Flat Base,OD (mm), 76,Height (mm), 76
Magnesium Oxide Rectangular Tray,Length (mm), 100,Width (mm), 100,Height (mm), 25.4
Magnesium Oxide Rectangular Tray,Length (mm), 100,Width (mm), 25,Height (mm), 12.7
Magnesium Oxide Rectangular Tray,Length (mm), 100,Width (mm), 50,Height (mm), 12.7
Magnesium Oxide Rectangular Tray,Length (mm), 150,Width (mm), 100,Height (mm), 25.4
Magnesium Oxide Rectangular Tray,Length (mm), 150,Width (mm), 75,Height (mm), 25.4
Magnesium Oxide Rectangular Tray,Length (mm), 50,Width (mm), 50,Height (mm), 12.7
Magnesium Oxide Rectangular Tray,Length (mm), 75,Width (mm), 75,Height (mm), 25.4
Magnesium oxide sputtering target, 50.8mm (2.0in) dia x 3.18mm (0.125in) thick
Magnesium oxide sputtering target, 50.8mm (2.0in) dia x 6.35mm (0.250in) thick
Magnesium oxide sputtering target, 76.2mm (3.0in) dia x 3.18mm (0.125in) thick
Magnesium oxide sputtering target, 76.2mm (3.0in) dia x 6.35mm (0.250in) thick
Magnesium oxide substrate, 10x10x0.5mm, polished two sides, 100 orientation
Magnesium oxide, puriss. p.a., ACS reagent, >=97% (calcined substance, KT)
Magnesium oxide, (single crystal substrate), <111>, >=99.9% trace metals basis, L x W x thickness 10 mm x 10 mm x 0.5 mm
Magnesium oxide, (single crystal substrate), >=99.9% trace metals basis, <100>, L x W x thickness 10 mm x 10 mm x 0.5 mm
Magnesium oxide, puriss., meets analytical specification of Ph. Eur., BP, USP, FCC, E 530, light, 98.0-100.5% (calc. for dried substance)