Magnesium peroxide (MgO₂) is an odorless fine powder

peroxide In chemistry, peroxides are a group of Chemical compound, compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical) and O's are single oxygen atoms. Oxygen atoms are joined ...

with a white to off-white color. It is similar to calcium peroxide because

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

peroxide also releases

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

by breaking down at a controlled rate with water. Commercially, magnesium peroxide often exists as a compound of magnesium peroxide and

magnesium hydroxide Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk o ...

Structure

O₂, similarly to N₂, has the ability to bind either side-on or end-on. The structure of MgO₂ has been calculated as a triangular shape with the O₂ molecule binding side-on to the magnesium. This arrangement is a result of the Mg⁺ donating charge to the oxygen and creating a Mg²⁺O₂²⁻. The bond between to O₂ and the magnesium atom has an approximate dissociation energy of 90 kJ mol⁻¹. In the solid state, MgO₂ has a cubic pyrite-type crystal structure with 6-coordinate Mg²⁺ ions and O₂²⁻ peroxide-groups, according to experimental data and evolutionary crystal structure prediction, the latter predicting a phase transition at the pressure of 53 GPa to a tetragonal structure with 8-coordinate Mg²⁺ ions. While at normal conditions MgO₂ is a metastable compound (less stable than ), at pressures above 116 GPa it is predicted to become thermodynamically stable in the tetragonal phase. This theoretical prediction has been experimentally confirmed via synthesis in a laser-heated diamond anvil cell.

Synthesis

MgO₂ can be produced by mixing MgO with

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

to create magnesium peroxide and water. This being an

exothermic reaction In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change Δ''H''⚬ is negative." Exothermic reactions usually release heat. The term is often confused with exergonic reaction, which IUPAC define ...

should be cooled and kept around 30–40 degrees Celsius. It is also important to remove as much iron from the reaction environment as possible due to iron's ability to catalyze the degradation of the peroxide. The addition of oxygen stabilizers such as

sodium silicate Sodium silicate is a generic name for chemical compounds with the formula or ·, such as sodium metasilicate (), sodium orthosilicate (), and sodium pyrosilicate (). The anions are often polymeric. These compounds are generally colorless tra ...

can also be used to help prevent the premature degradation of the peroxide. Regardless, a good yield from this reaction is only about 35%. : High yields are further complicated by the fact that MgO₂ reacts with water to degrade the peroxide into

, also known as milk of magnesia.

Applications

Magnesium peroxide is a stable

releasing compound, which is used in

agricultural Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...

and environmental industries. It is used to reduce contaminant levels in

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

. Magnesium peroxide is used in the

bioremediation Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in mycoremediation, and plants in phytoremediation), living or dead, is employed for removing environmental pollutants from air, wate ...

of contaminated

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

and can improve the soil quality for

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

growth and

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

. It is also used in the

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

industry for bioremediation. For sanitation purposes magnesium peroxide is often used as a source of oxygen for aerobic organisms in the treatment and disposal of biological waste. Since the breakdown of

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may b ...

in soil is usually quicker in aerobic conditions, MgO₂ can also be added to

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...

piles or in soil to speed up the microbe activities and to reduce the odors produced in the process. In certain circumstances MgO₂ has also been shown to inhibit growth of bacteria. In particular, the growth of

sulfate-reducing bacteria Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate () as termina ...

can be inhibited in an environment containing magnesium peroxide. While the oxygen slowly dissociates, it is theorized that it may then act to displace the sulfate that normally acts as the terminal electron acceptor in their electron transport chain.

Toxicity

Magnesium peroxide is an irritant that can cause redness, itching, swelling, and may burn the skin and eyes on contact. Inhalation can also cause irritation to the lungs, nose, and throat, as well as causing coughing. Long term exposure may lead to lung damage, shortness of breath, and tightening of the chest. Ingestion of MgO₂ can cause numerous adverse effects including: bloating, belching, abdominal pain, irritation of the mouth and throat, nausea, vomiting, and diarrhea. Environmentally, magnesium peroxide is not a naturally occurring compound and is not known to persist in the environment for prolonged times, in its complete state, or to bio-accumulate. The natural degradation of MgO₂ leads to magnesium hydroxide, O₂, and H₂O. If spilled, MgO₂ should be contained and isolated from any waterways, sewer drains, and it should be isolated from combustible materials or chemicals including paper, cloth, and wood.

Common Environmental Reactions

Magnesium exists in the upper atmosphere in a variety of different molecular forms. Due to its ability to react with common oxygen and simple carbon-oxygen compounds the magnesium may exist in oxidized compounds including MgO₂, OMgO₂, MgO, and O₂MgO₂. : MgCO₃ + O → MgO₂ + CO₂ : : OMgO₂ + O → MgO₂ + O₂ : : MgO + O₃ → MgO₂ + O₂ : : MgO₂ + O₂ → O₂MgO₂ : : MgO₂ + O → MgO + O₂ In contact with water it decomposes by the reactions: : MgO₂ + 2 H₂O → Mg(OH)₂ + H₂O₂ : 2 H₂O₂ → 2 H₂O + O₂

References

{{oxygen compounds Peroxides Magnesium compounds Antacids