Chemistry:Magnesium oxide

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Short description: Chemical compound naturally occurring as periclase


Magnesium oxide
Magnesium oxide.jpg
Magnesium-oxide-3D-vdW.png
Names
IUPAC name
Magnesium oxide
Other names
Magnesia
Periclase
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
EC Number
  • 215-171-9
KEGG
RTECS number
  • OM3850000
UNII
Properties
MgO
Molar mass 40.304 g/mol[1]
Appearance White powder
Odor Odorless
Density 3.6 g/cm3[1]
Melting point 2,852 °C (5,166 °F; 3,125 K)[1]
Boiling point 3,600 °C (6,510 °F; 3,870 K)[1]
Solubility Soluble in acid, ammonia
insoluble in alcohol
Band gap 7.8 eV[2]
−10.2·10−6 cm3/mol[3]
Thermal conductivity 45–60 W·m−1·K−1[4]
1.7355
6.2 ± 0.6 D
Structure
Halite (cubic), cF8
Fm3m, No. 225
a = 4.212Å
Octahedral (Mg2+); octahedral (O2−)
Thermochemistry
37.2 J/mol K[8]
26.95 ± 0.15 J·mol−1·K−1[9]
−601.6 ± 0.3 kJ·mol−1[9]
-569.3 kJ/mol[8]
Pharmacology
1=ATC code }} A02AA02 (WHO) A06AD02 (WHO), A12CC10 (WHO)
Hazards
Main hazards Metal fume fever, Irritant
Safety data sheet ICSC 0504
GHS pictograms GHS07: Harmful
GHS Signal word Warning
H315, H319, H335
P261, P264, P271, P273, P280, P302+352, P304+340, P305+351+338, P312, P333+313, P337+313, P362, P363, P391, P403+233, P405
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 15 mg/m3 (fume)[10]
REL (Recommended)
 None designated[10]
IDLH (Immediate danger)
 750 mg/m3 (fume)[10]
Related compounds
Other anions
 Magnesium sulfide
Other cations
 Beryllium oxide
Calcium oxide
Strontium oxide
Barium oxide
Related compounds
 Magnesium hydroxide
Magnesium nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is ☑Y☒N ?)
Infobox references

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). It 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), to differentiate it from magnesia nigra, a black mineral containing what is now known as manganese.

Related oxides

While "magnesium oxide" normally refers to MgO, the compound magnesium peroxide MgO2 is also known. According to evolutionary crystal structure prediction,[11] 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.[12]

Electric properties

Pure MgO is not conductive and has a high resistance to electric current at room temperature. The pure powder of MgO has a relative permittivity inbetween 3.2 to 9.9 [math]\displaystyle{ k }[/math] with an approximate dielectric loss of tan(δ) > 2.16x103 at 1kHz.[5][6][7]

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.[13]

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.[citation needed]

Applications

Refractory insulator

MgO is prized as a refractory material, i.e. a solid that is physically and chemically stable at high temperatures. It has the useful attributes of high thermal conductivity and low electrical conductivity. According to a 2006 reference book:[14]

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 refractory material for crucibles. It is also used as an insulator in heat-resistant electrical cable.

Heating elements

It is used extensively as an electrical insulator in tubular construction heating elements as in electric stove and cooktop 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.

Cement

MgO is one of the components in Portland cement in dry process plants.

Sorel cement uses MgO as the main component in combination with MgCl2 and water.

Fertilizer

MgO has an important place as a commercial plant fertilizer[15] and as animal feed.[16]

Fireproofing

It 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, but also a severe downside as it attract moist and can cause moisture damage to surrounding materials [17][14][1]


Medical

Magnesium oxide is used for relief of heartburn and indigestion, as an antacid, magnesium supplement, and as a short-term laxative. It is also used to improve symptoms of indigestion. Side effects of magnesium oxide may include nausea and cramping.[18] In quantities sufficient to obtain a laxative effect, side effects of long-term use may rarely cause enteroliths to form, resulting in bowel obstruction.[19]

Waste treatment

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 least soluble in water at mildly basic conditions (pH in the range 8–11). Solubility of metals increases their undesired bioavailability and mobility in soil and groundwater. Granular MgO is often blended into metals-contaminating soil or waste material, which is also commonly of a low pH (acidic), in order to drive the pH into the 8–10 range. Metal-hydroxide complexes tend to precipitate out of aqueous solution in the pH range of 8–10.

MgO is packed in bags around transuranic waste in the disposal cells (panels) at the Waste Isolation Pilot Plant, as a CO
2 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 over CaO since the resulting hydration product (Mg(OH)2) is less soluble and releases less hydration heat. Another advantage is to impose a lower pH value (about 10.5) in case of accidental water ingress into the dry salt layers, in contast to the more soluble Ca(OH)2 which 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 disruption.[20]

Niche uses

Unpolished MgO crystal
  • 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.[21] It has an E number of E530.
  • As a reagent in the installation of the carboxybenzyl (Cbz) group using benzyl chloroformate in EtOAc for the N-protection of amines and amides.[22]
  • Doping MgO (about 1–5% by weight) into hydroxyapatite, a bioceramic mineral, increases the fracture toughness by migrating to grain boundaries, where it reduces grain size and changes the fracture mode from intergranular to transgranular.[23][24]
  • Pressed MgO is used as an optical material. It is transparent from 0.3 to 7 μm. The refractive index is 1.72 at 1 μm and the Abbe number is 53.58. It 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.[25]
  • 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.[26]
  • 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[27] versus 40–60 % with aluminium oxide.[28] The value of tunnel magnetoresistance is also significantly higher for MgO (600% at room temperature and 1,100 % at 4.2 K[29]) than Al2O3 (ca. 70% at room temperature[30]).

Historical uses

Precautions

Inhalation of magnesium oxide fumes can cause metal fume fever.[32]

See also

Notes

  1. ↑ At room temperature.[5][6][7]

References

  1. ↑ 1.0 1.1 1.2 1.3 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.74. ISBN 1439855110. 
  2. ↑ Taurian, O.E.; Springborg, M.; Christensen, N.E. (1985). "Self-consistent electronic structures of MgO and SrO". Solid State Communications 55 (4): 351–5. doi:10.1016/0038-1098(85)90622-2. Bibcode: 1985SSCom..55..351T. http://users-phys.au.dk/nec/Papers/necSSC/SSC55351.pdf. Retrieved 2012-03-27. 
  3. ↑ Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.133. ISBN 1439855110. 
  4. ↑ Application of magnesium compounds to insulating heat-conductive fillers . konoshima.co.jp
  5. ↑ 5.0 5.1 A P, Johnson (November 1986). Structural and electrical properties of magnesium oxide powders (Masters). Durham University.
  6. ↑ 6.0 6.1 Subramanian, M. A.; Shannon, R. D.; Chai, B. H. T.; Abraham, M. M.; Wintersgill, M. C. (November 1989). "Dielectric constants of BeO, MgO, and CaO using the two-terminal method" (in en). Physics and Chemistry of Minerals 16 (8): 741–746. doi:10.1007/BF00209695. ISSN 0342-1791. Bibcode: 1989PCM....16..741S. http://link.springer.com/10.1007/BF00209695. 
  7. ↑ 7.0 7.1 Hornak, Jaroslav; Trnka, Pavel; Kadlec, Petr; Michal, Ondřej; Mentlík, Václav; Šutta, Pavol; Csányi, Gergely; Tamus, Zoltán (2018-05-30). "Magnesium Oxide Nanoparticles: Dielectric Properties, Surface Functionalization and Improvement of Epoxy-Based Composites Insulating Properties" (in en). Nanomaterials 8 (6): 381. doi:10.3390/nano8060381. ISSN 2079-4991. PMID 29848967. 
  8. ↑ 8.0 8.1 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 5.15. ISBN 1439855110. 
  9. ↑ 9.0 9.1 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 5.2. ISBN 1439855110. 
  10. ↑ 10.0 10.1 10.2 NIOSH Pocket Guide to Chemical Hazards. "#0374". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0374.html. 
  11. ↑ Zhu, Qiang; Oganov A.R.; Lyakhov A.O. (2013). "Novel stable compounds in the Mg-O system under high pressure". Phys. Chem. Chem. Phys. 15 (20): 7696–7700. doi:10.1039/c3cp50678a. PMID 23595296. Bibcode: 2013PCCP...15.7696Z. http://uspex.stonybrook.edu/pdfs/Mg-O-paper-2013.pdf. Retrieved 2013-11-06. 
  12. ↑ Mei, AB; O. Hellman; C. M. Schlepütz; A. Rockett; T.-C. Chiang; L. Hultman; I. Petrov; J. E. Greene (2015). "Reflection Thermal Diffuse X-Ray Scattering for Quantitative Determination of Phonon Dispersion Relations.". Physical Review B 92 (17): 174301. doi:10.1103/physrevb.92.174301. Bibcode: 2015PhRvB..92q4301M. 
  13. ↑ Margarete Seeger; Walter Otto; Wilhelm Flick; Friedrich Bickelhaupt; Otto S. Akkerman. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_595.pub2. 
  14. ↑ 14.0 14.1 Mark A. Shand (2006). The chemistry and technology of magnesia. John Wiley and Sons. ISBN 978-0-471-65603-6. https://books.google.com/books?id=0ShuV4W0V2gC. Retrieved 10 September 2011. 
  15. ↑ Nutrient Science. fertilizer101.org. Retrieved on 2017-04-26.
  16. ↑ Magnesium oxide for the Animal Feed Industry. lehvoss.de
  17. ↑ Mármol, Gonzalo; Savastano, Holmer (July 2017). "Study of the degradation of non-conventional MgO-SiO 2 cement reinforced with lignocellulosic fibers". Cement and Concrete Composites 80: 258–267. doi:10.1016/j.cemconcomp.2017.03.015. 
  18. ↑ Magnesium Oxide. MedlinePlus. Last reviewed 02/01/2009
  19. ↑ Tatekawa Y; Nakatani K; Ishii H et al. (1996). "Small bowel obstruction caused by a medication bezoar: report of a case". Surgery Today 26 (1): 68–70. doi:10.1007/BF00311997. PMID 8680127. 
  20. ↑ wipp.energy.gov Step-By-Step Guide for Waste Handling at WIPP. Waste Isolation Pilot Plant. wipp.energy.gov
  21. ↑ "Compound Summary for CID 14792 – Magnesium Oxide". PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_oxide. 
  22. ↑ Dymicky, M. (1989-02-01). "Preparation of Carbobenzoxy-L-Tyrosine Methyl and Ethyl Esters and of the Corresponding Carbobenzoxy Hydrazides". Organic Preparations and Procedures International 21 (1): 83–90. doi:10.1080/00304948909356350. ISSN 0030-4948. 
  23. ↑ Tan, C.Y.; Yaghoubi, A.; Ramesh, S.; Adzila, S.; Purbolaksono, J.; Hassan, M.A.; Kutty, M.G. (December 2013). "Sintering and mechanical properties of MgO-doped nanocrystalline hydroxyapatite". Ceramics International 39 (8): 8979–8983. doi:10.1016/j.ceramint.2013.04.098. http://www.aun.edu.eg/reserches_files/13211.pdf. Retrieved 2015-08-08. 
  24. ↑ Tan, Chou Yong; Singh, Ramesh; Tolouei, R.; Sopyan, Iis; Teng, Wan Dung (2011). "Synthesis of High Fracture Toughness of Hydroxyapatite Bioceramics". Advanced Materials Research 264-265: 1849–1855. doi:10.4028/www.scientific.net/amr.264-265.1849. ISSN 1662-8985. 
  25. ↑ Stephens, Robert E.; Malitson, Irving H. (1952). "Index of Refraction of Magnesium Oxide". Journal of Research of the National Bureau of Standards 49 (4): 249–252. doi:10.6028/jres.049.025. 
  26. ↑ "Mass Deacidification: Saving the Written Word". Library of Congress. https://www.loc.gov/preservation/scientists/projects/mass_deacid.html. 
  27. ↑ Parkin, S. S. P.; Kaiser, C.; Panchula, A.; Rice, P. M.; Hughes, B.; Samant, M.; Yang, S. H. (2004). "Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers". Nature Materials 3 (12): 862–867. doi:10.1038/nmat1256. PMID 15516928. Bibcode: 2004NatMa...3..862P. 
  28. ↑ Monsma, D. J.; Parkin, S. S. P. (2000). "Spin polarization of tunneling current from ferromagnet/Al2O3 interfaces using copper-doped aluminum superconducting films". Applied Physics Letters 77 (5): 720. doi:10.1063/1.127097. Bibcode: 2000ApPhL..77..720M. 
  29. ↑ Ikeda, S.; Hayakawa, J.; Ashizawa, Y.; Lee, Y. M.; Miura, K.; Hasegawa, H.; Tsunoda, M.; Matsukura, F. et al. (2008). "Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB/MgO/CoFeB pseudo-spin-valves annealed at high temperature". Applied Physics Letters 93 (8): 082508. doi:10.1063/1.2976435. Bibcode: 2008ApPhL..93h2508I. 
  30. ↑ Wang, D.; Nordman, C.; Daughton, J. M.; Qian, Z.; Fink, J.; Wang, D.; Nordman, C.; Daughton, J. M. et al. (2004). "70% TMR at Room Temperature for SDT Sandwich Junctions with CoFeB as Free and Reference Layers". IEEE Transactions on Magnetics 40 (4): 2269. doi:10.1109/TMAG.2004.830219. Bibcode: 2004ITM....40.2269W. 
  31. ↑ Tellex, Peter A.; Waldron, Jack R. (1955). "Reflectance of Magnesium Oxide". JOSA 45 (1): 19. doi:10.1364/JOSA.45.000019. 
  32. ↑ Magnesium Oxide. National Pollutant Inventory, Government of Australia.

External links



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