Magnesium oxide, 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 Magnesium oxide can be reversed by heating it to remove moisture.

CAS: 1309-48-4
MF: MgO
MW: 40.3
EINECS: 215-171-9

Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese.
While "magnesium oxide" normally refers to MgO, the compound magnesium peroxide MgO2 is also known.
According to evolutionary crystal structure prediction, Magnesium oxide is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa.
Because of its stability, Magnesium oxide is used as a model system for investigating vibrational properties of crystals.

Magnesium is an element your body needs to function normally.
Magnesium oxide may be used for different reasons.
Some people use Magnesium oxide as an antacid to relieve heartburn, sour stomach, or acid indigestion.
Magnesium oxide also may be used as a laxative for short-term, rapid emptying of the bowel (before surgery, for example).
Magnesium oxide should not be used repeatedly.
Magnesium oxide also is used as a dietary supplement when the amount of magnesium in the diet is not enough.
Magnesium oxide is available without a prescription.

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.

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 supplements are taken orally.
Magnesium oxide is available in 140-mg capsules as well as 400- and 425-mg tablets.
Magnesium gluconate (Magonate) is available in 500-mg tablets.

Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral, often found as a powder, which occurs naturally as periclase and is a source of magnesium.
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 oxide is only very slightly soluble in water but in aqueous media combines quickly with water to form magnesium hydroxide.
The majority of magnesium oxide produced today is obtained from the calcination of naturally occurring minerals, magnesite, MgCO3, being the most common.
Other important sources of magnesium oxide are seawater, underground deposits of brine and deep salt beds from which magnesium hydroxide [Mg(OH)2] is processed.
In medicine, magnesium oxide can be used as an antacid to relieve heartburn, sour stomach, or acid indigestion, as a laxative for short-term, rapid emptying of the bowel (before surgery, for example) and as a mineral supplement used to prevent and treat low amounts of magnesium in the blood.
Besides, magnesium oxide also has many nonmedicinal uses.
Caustic calcined magnesia is used in a wide range of industrial applications e.g. plastics, rubber, adhesives and acid neutralization.
Magnesium oxide with lower chemical activity can be used for fertilizers and animal feed.
Dead-burned magnesia and finally fused magnesia can be used for a variety of refractory and electrical applications e.g. furnace lining, crucibles and fireproofing boarding.

Magnesium oxide Chemical Properties
Melting point: 2852 °C (lit.)
Boiling point: 3600 °C
Density: 3.58
Refractive index: 1.736
Fp: 3600°C
Storage temp.: no restrictions.
Solubility: 5 M HCl: 0.1 M at 20 °C, clear, colorless
Form: nanopowder
Color: White
Specific Gravity: 3.58
Odor: wh. powd. or cryst., odorless
PH: 10.3 (H2O, 20℃)(saturated solution)
Water Solubility: 6.2 mg/L (20 ºC), reacts
Sensitive: Air Sensitive
λmax: λ: 260 nm Amax: ≤0.040
λ: 280 nm Amax: ≤0.025
Merck: 14,5677
Exposure limits: ACGIH: TWA 10 mg/m3
OSHA: TWA 15 mg/m3
NIOSH: IDLH 750 mg/m3
Stability: Stable. Incompatible with bromine trifluoride, bromine trichloride, phosphorus pentachloride.
InChIKey: CPLXHLVBOLITMK-UHFFFAOYSA-N
CAS DataBase Reference: 1309-48-4(CAS DataBase Reference)
NIST Chemistry Reference: Magnesium monoxide(1309-48-4)
EPA Substance Registry System: Magnesium oxide (1309-48-4)

Magnesium oxide is a typical alkaline earth metal oxide, chemical formula MgO.
White powder, melting point 2852 ℃, boiling point 3600 ℃, the relative density of 3.58 (25℃).
Magnesium oxide is soluble in acid and ammonium salt solution.
Magnesium oxide's slow action with water can produce magnesium hydroxide.
Magnesium oxide can be dissolved in carbon dioxide aqueous solution to produce magnesium bicarbonate.
In the air, Magnesium oxide can gradually absorb moisture and carbon dioxide.
Heating releases irritating fumes.
Magnesite (MgCO3), dolomite (MgCO3 • CaCO3) and seawater are the main raw materials for the production of magnesium oxide.

Two forms of magnesium oxide exist: a bulky form termed light magnesium oxide and a dense form termed heavy magnesium oxide.
The USP 32 and JP XV define both forms in a single monograph, while the BP 2009 and PhEur 6.4 have separate monographs for each form.
For the heavy variety, 15 g has an apparent volume before settling of not more than 60 mL; for the light variety, 15 g has an apparent volume before settling of not more than 100mL as defined by the BP 2009 and PhEur 6.4.
Both forms of magnesium oxide occur as fine, white, odorless powders.
Magnesium oxide possesses a cubic crystal structure, though the BP 2009 and PhEur 6.4 describe the appearance of light magnesium oxide as an amorphous powder.
A very bulky, white powder known as light magnesium oxide or a relatively dense, white powder known as heavy magnesium oxide.
Five g of light magnesium oxide occupies a volume of approximately 40 to 50 mL, while 5 g of heavy magnesium oxide occupies a volume of approximately 10 to 20 mL.
Magnesium oxide is practically insoluble in water and is insoluble in alcohol.
Magnesium oxide is soluble in dilute acids.

Electric properties
Pure Magnesium oxide is not conductive and has a high resistance to electric current at room temperature.
The pure powder of Magnesium oxide has a relative permittivity inbetween 3.2 to 9.9k with an approximate dielectric loss of tan(δ) > 2.16x103 at 1kHz.

Uses
Light magnesium oxide is used in ceramics, enamel, refractory crucible, refractory bricks, etc., also used as polishing agent, binder, paint and paper filler, neoprene accelerator, activator.
In medicine, Magnesium oxide can be used as antacids, laxatives, for the treatment of hyperacidity and duodenal ulcer disease, but also for glass, phenolic, plastics and other industries.
Dead-roasted magnesium oxide, namely magnesite, has granular type and brick type, being widely used as the refractory materials of steel furnace, cement kiln and glass furnace.
Alkaline granular refractory, mainly used for metal refining industry, with massive refractory for the furnace, or granular material for maintenance; Use spray, coating method to have it attached to the furnace wall in order to enhance the furnace fire resistance.
Magnesium oxide produce a positive charge inside the water with most of the suspended material being negatively charged, acting absorption role, can improve the filtration effect.
Magnesium oxide is an efficient moisture absorbent used by many libraries for preserving books.
Magnesium oxide is also one of the raw materials for making cement in dry process plants; specifically, Portland cement.

If too much of Magnesium oxide is added, the cement may become expansive.
In medicine, magnesium oxide is used for relief of heartburn and sore stomach, 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.
Magnesium Oxide is a source of magnesium which functions as a nutrient and dietary supplement.

Magnesium oxide exists as a bulky white powder termed light magnesium oxide or as a dense white powder known as heavy magnesium oxide.
Magnesium oxide is practically insoluble in water and is insoluble in alcohol.
manufacture of refractory crucibles, fire bricks, magnesia cements and boiler scale compounds, "powdered" oils, casein glue.
Reflector in optical instruments; white color standard.
Insulator at low temp.

Industrial uses
Magnesium oxide is a synthetic mineralproduced in electric arc furnaces or by sinteringof amorphous powder (periclase).
Refractoryapplications consume a large quantity of Magnesium oxide.
Both brick and shapes are fabricated at leastpartially of sintered grain for use primarily inthe metal-processing industries.
Heating unitinsulation is another major application for periclase.
Principal advantages of periclase are Magnesium oxide's thermal conductivity and electrical resistivity atelevated temperatures.
Specialty crucibles and shapes also are fabricatedfrom MgO.

These are used in pyrometallurgicaland other purifying processes for specialtymetals.
Both slip-casting and pressingtechniques are employed to manufactureshapes.
Thermocouple insulation comprises stillanother outlet for periclase. Since most of thesego into nuclear applications, a high-purity productis required.
Magnesium oxide is also an important glazeconstituent.
Single crystals of MgO have received attentionbecause of their use in ductile ceramic studies.
Extreme purity is required in this area.
Periclase windows are also of potential interest ininfrared applications because of their transmissioncharacteristics.

Heating elements
Magnesium oxide 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."
Magnesium oxide 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.

Gas mantles
Most gas mantles utilize magnesium oxide.
Early iterations such as the Clamond basket used only this.
Later versions use ~60% magnesium oxide, with other components such as lanthanum oxide or yttrium oxide making up the rest.
Another exception would be thoriated gas mantles.

Niche uses
MgO 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.

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 Magnesium oxide 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 Magnesium oxide 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 indigestion, 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 may rarely cause enteroliths to form, resulting in bowel obstruction.

Other
As a food additive, Magnesium oxide is used as an anticaking agent.
Magnesium oxide 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.
Magnesium oxide 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.
Magnesium oxide 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.
Magnesium oxide 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.

Pressed Magnesium oxide 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 Magnesium oxide 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 Magnesium oxide 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.
Magnesium oxide has an important place as a commercial plant fertilizer and as animal feed.
An aerosolized solution of Magnesium oxide is used in library science and collections management for the deacidification of at-risk paper items.

In this process, the alkalinity of Magnesium oxide (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration.
Magnesium oxide 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, Magnesium oxide shows characteristics superior to those of the commonly used amorphous Al2O3.
In particular, spin polarization of about 85% has been achieved with Magnesium oxide 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).

Production
Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide.
The latter is obtained by the treatment of magnesium chloride MgCl2 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 appear to reabsorb carbon dioxide from the air.

Production of Magnesium Oxide
Thermal decomposition of magnesite or dolomite generates magnesium oxide.
Magnesium hydroxide precipitate is obtained first by treating seawater with hydrated lime; magnesium oxide is obtained by burning magnesium hydroxide.
Magnesium oxide accounts for the largest amount of magnesium compounds, accounting for about 3/4 of the total magnesium industry.
Magnesia made at temperatures below 900 ° C is light magnesia with low density, having large specific surface area and strong absorbability.

Can be used as a catalyst, rubber filler and improve the performance of rubber accelerator.
Mixing with magnesium chloride solution can make magnesia cement.
Magnesium oxide can also be used as flame retardant for building materials.
Magnesium oxide can be medically used as antacids and laxatives for the treatment of hyperacidity and stomach and duodenal ulcer disease, often combined with calcium carbonate easy to cause constipation.
For animal feed additives and plant fertilizers.
The light magnesium oxide obtained at 950 ~ 1050 ℃ has high density with particle distribution having a certain range and being easier to hydrate.

Use Magnesium oxide to react with the silica on the silicon steel surface at high temperature to produce magnesium silicate film-like product; Magnesium oxide can be used as a silicon steel separator to prevent the sintering of silicon steel upon high-temperature sintering.
The heavy magnesium oxide prepared at high temperature of 1500-1800 ℃ has high density, small specific surface area, be difficult to be decomposed by heat, has low chemical activity, not easily to react with acid and low hydration rate.
Magnesium oxide can be used as high temperature refractory materials and the binder during manufacturing refractory crucible and the furnace lining.

Industrial production of light magnesium oxide
In the salinization industry of sea salt, it is mainly used of bitter brine, heavy brine and high temperature salt as raw materials to produce light magnesium carbonate or light magnesium oxide.
Industrialized production methods include soda ash method, lime and carbon ammonia.

(1) Soda ash process include: 1. Ingredients 2. Reaction 3. Washing 4. Pyrolysis 5. Filter 6.Roasting 7. Crushed packaging.
Soda ash production of light magnesium carbonate or light magnesium oxide has mature technology, higher product quality.
However, consumption of soda ash, fresh water consumption is also large.

(2) Lime method uses lime milk instead of soda ash.
Its reaction with magnesium chloride in brine to generate magnesium hydroxide, followed by carbonation using carbon dioxide gas, generating magnesium bicarbonate.
When using the lime method, the sulfate in the brine should be minimized, otherwise large deposits of calcium sulphate are formed and mixed in the product.
The advantage of this method is the use of lime instead of soda ash, reducing costs.
The disadvantage is that the process and equipment is more complicated than soda ash method, and by-produces large number of CaCl2 solution to be managed.

(3) Raw materials of carbon ammonia method are the high concentrations of bitter brine, brine or salt immersion thick solution.
Carbon ammonia used is ammonia bicarbonate, carbonized ammonia or sending ammonia and carbon dioxide gas directly into the brine, with carbon ammonia instead of soda ash being reacted with the magnesium chloride or magnesium sulfate in the brine to generate the corresponding magnesium carbonate.

The reaction is as follows:
1. Brine containing MgCl2 and MgSO4 reacts with NH4HCO3 solution: MgCl2 + 2NH4HCO3 = Mg (HCO3) 2 + 2NH4Cl MgSO4 + 2NH4HCO3 = Mg (HCO3) 2+ (NH4) 2SO4
2. Directly send ammonia and carbon dioxide to the brine.
3. The generated MgCO3 • 3H2O and Mg (HCO3) 2 are subject to pyrolysis to generate alkaline magnesium carbonate: Mg (HCO3) 2 + 2H2O = MgCO3 • 3H2O + CO2 ↑ 5 {MgCO3.3H2O} = 4MgCO3.Mg H2O + CO2 ↑ + 10H2O
4. Alkaline magnesium carbonate is roasted to generate light magnesium oxide: 4MgCO3.Mg (OH) 2.4H2O = 5MgO + 4CO2 ↑ + 5H2O
Control of carbon ammonia process: 1. Raw material concentration and reaction temperature 2. Pyrolysis temperature; 3. Dehydration, washing and drying; 4. Roasting; 5. Mother liquor treatment.
Compared with the soda ash method, the production of light magnesium carbonate and light magnesium oxide by the carbon ammonia process is simple, the product has a high specific volume, and the supply channel of the ammonium bicarbonate is more and the cost is lower.
However, the mother liquor evaporation and concentration process is of high energy consumption.

Toxicity
Magnesium oxide is mildly irritating to the conjunctiva and nasal mucosa.
Vapors can cause ulcer disease.
Dust can cause breathing problems, chest pain, coughing, diffusive interstitial fibrosis and emphysema.
The maximum allowable concentration in the United States is 10 mg / m3.

Synonyms
seawatermagnesia
Sermag
slo369
slo469
Tanbase
MAGNESIUM OXIDE, NANOPOWDER
MAGNESIUM OXIDE, 98%, A.C.S. REAGENT
MAGNESIUM OXIDE, -325 MESH, 99+%