Aluminium hydroxide

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Aluminum hydroxide
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This article is about Al(OH)3. For AlOH, see aluminium monohydroxide.

Aluminium hydroxide
Unit cell ball and stick model of aluminium hydroxide
Sample of aluminium hydroxide in a vial
Names
Preferred IUPAC name
Aluminium hydroxide
Systematic IUPAC name
Trihydroxidoaluminium
Other names
  • Aluminic acid
  • Aluminic hydroxide
  • Alumanetriol
  • Aluminium(III) hydroxide
  • Aluminium hydroxide
  • Aluminium trihydroxide
  • Hydrated alumina
  • Orthoaluminic acid
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.040.433 Edit this at Wikidata
KEGG
RTECS number
  • BD0940000
UNII
  • InChI=1S/Al.3H2O/h;3*1H2/q+3;;;/p-3 checkY
    Key: WNROFYMDJYEPJX-UHFFFAOYSA-K
    A02AB02 (WHO) (algeldrate) ☒N
  • InChI=1/Al.3H2O/h;3*1H2/q+3;;;/p-3
    Key: WNROFYMDJYEPJX-DFZHHIFOAJ
  • [OH-].[OH-].[OH-].[Al+3]
Properties[1][2]
Al(OH)3
Molar mass 78.003 g·mol−1
Appearance White
amorphous
powder
Density 2.42 g/cm3, solid
Melting point 300 °C (572 °F; 573 K)
0.0001 g/(100 mL)
3×10−34
Solubility soluble in acids and alkalis
Acidity (pKa) >7
Isoelectric point 7.7
Thermochemistry[3]
Std enthalpy of
formation
(ΔfH⦵298)
 −1277 kJ·mol−1
Pharmacology[4]
A02AB01 (WHO)
Hazards
GHS labelling:
no GHS pictograms
no hazard statements
P261, P264, P271, P280, P304+P340, P305+P351+P338, P312, P337+P313
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
>5000 mg/kg (rat, oral)
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
 None
Related compounds
  • Aluminium oxide hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Aluminium hydroxide,

aluminium oxide hydroxide, AlO(OH), and aluminium oxide or alumina (Al2O3), the latter of which is also amphoteric. These compounds together are the major components of the aluminium ore bauxite
. Aluminium hydroxide also forms a gelatinous precipitate in water.

Structure

Al(OH)3 is built up of double layers of hydroxyl groups with aluminium ions occupying two-thirds of the octahedral holes between the two layers.

disputed – discuss
]:

Hydrargillite, once thought to be aluminium hydroxide, is an aluminium phosphate. Nonetheless, both gibbsite and hydrargillite refer to the same polymorphism of aluminium hydroxide, with gibbsite used most commonly in the United States and hydrargillite used more often in Europe. Hydrargillite is named after the Greek words for water (hydra) and clay (argylles).[citation needed]

Properties

Aluminium hydroxide is

Brønsted–Lowry base. It neutralizes the acid, yielding a salt:[9]

3 HCl + Al(OH)3 → AlCl3 + 3 H2O

In bases, it acts as a Lewis acid by binding hydroxide ions:[9]

Al(OH)3 + OH− → [Al(OH)4]−

Production

Red mud reservoirs (this one in Stade, Germany) contain the corrosive residues from the production of aluminium hydroxide.

Virtually all the aluminium hydroxide used commercially is manufactured by the

bauxite tailings, is removed and aluminium hydroxide is precipitated from the remaining solution of sodium aluminate. This aluminium hydroxide can be converted to aluminium oxide or alumina by calcination.[citation needed
]

The residue or

bauxite tailings, which is mostly iron oxide, is highly caustic due to residual sodium hydroxide. It was historically stored in lagoons; this led to the Ajka alumina plant accident in 2010 in Hungary, where a dam bursting led to the drowning of nine people. An additional 122 sought treatment for chemical burns. The mud contaminated 40 square kilometres (15 sq mi) of land and reached the Danube. While the mud was considered non-toxic due to low levels of heavy metals, the associated slurry had a pH of 13.[11]

Uses

Filler and fire retardant

Aluminium hydroxide finds use as a fire retardant filler for polymer applications. It is selected for these applications because it is colorless (like most polymers), inexpensive, and has good fire retardant properties.[12] Magnesium hydroxide and mixtures of huntite and hydromagnesite are used similarly.[13][14][15][16][17] It decomposes at about 180 °C (356 °F), absorbing a considerable amount of heat in the process and giving off water vapour.

In addition to behaving as a fire retardant, it is very effective as a smoke suppressant in a wide range of polymers, most especially in polyesters, acrylics, ethylene vinyl acetate, epoxies, polyvinyl chloride (PVC) and rubber.[18]

Aluminium hydroxide is used as filler in some artificial stone compound material, often in acrylic resin.[citation needed]

Precursor to Al compounds

Aluminium hydroxide is a

calcined aluminas, aluminium sulfate, polyaluminium chloride, aluminium chloride, zeolites, sodium aluminate, activated alumina, and aluminium nitrate.[6]

Freshly precipitated aluminium hydroxide forms

adsorbent in gas purification, and catalyst supports.[12]

Pharmaceutical

Under the generic name "algeldrate", aluminium hydroxide is used as an

dyspepsia. Such products can cause constipation, because the aluminium ions inhibit the contractions of smooth muscle cells in the gastrointestinal tract, slowing peristalsis and lengthening the time needed for stool to pass through the colon.[21] Some such products are formulated to minimize such effects through the inclusion of equal concentrations of magnesium hydroxide or magnesium carbonate, which have counterbalancing laxative effects.[22]

This compound is also used to control

intestines and reduce the amount of phosphorus that can be absorbed.[23][24]

Precipitated aluminium hydroxide is included as an adjuvant in some vaccines (e.g. anthrax vaccine). One of the well-known brands of aluminium hydroxide adjuvant is Alhydrogel, made by Brenntag Biosector.[25][full citation needed][dead link] Since it absorbs protein well, it also functions to stabilize vaccines by preventing the proteins in the vaccine from precipitating or sticking to the walls of the container during storage. Aluminium hydroxide is sometimes called "alum", a term generally reserved for one of several sulfates.[citation needed]

Vaccine formulations containing aluminium hydroxide stimulate the

B cells.[26] It appears to contribute to induction of a good Th2 response, so is useful for immunizing against pathogens that are blocked by antibodies. However, it has little capacity to stimulate cellular (Th1) immune responses, important for protection against many pathogens,[27] nor is it useful when the antigen is peptide-based.[28]

Safety

In the 1960s and 1970s it was speculated that aluminium was related to various neurological disorders, including Alzheimer's disease.[29][30] Since then, multiple epidemiological studies have found no connection between exposure to environmental or swallowed aluminium and neurological disorders, though injected aluminium was not looked at in these studies.[31][32][33]

Neural disorders were found in experiments on mice motivated by

Gulf War illness (GWI). Aluminium hydroxide injected in doses equivalent to those administered to the United States military, showed increased reactive astrocytes, increased apoptosis of motor neurons and microglial proliferation within the spinal cord and cortex.[34]

References

  1. ^ For solubility product: "Solubility product constants". Archived from the original on 15 June 2012. Retrieved 17 May 2012.
  2. ISSN 0008-4042
    .
  3. ISBN 978-0-618-94690-7
    .
  4. PMID 12825840
    . Retrieved 1 July 2017.
  5. ^ Wells, A. F. (1975), Structural Inorganic Chemistry (4th ed.), Oxford: Clarendon Press
  6. ^
    ISBN 9780751401035
    .
  7. ISBN 978-0-470-58768-3
    .
  8. ^
    OCLC 894928306
    .
  9. ^ a b Boundless (26 July 2016). "Basic and Amphoteric Hydroxides". Boundless Chemistry. Archived from the original on 22 August 2017. Retrieved 2 July 2017.
  10. doi:10.1016/S0927-7757(98)00798-5
    .
  11. ^ "Hungary Battles to Stem Torrent of Toxic Sludge". BBC News Website. 5 October 2010.
  12. ^
    ISBN 978-3527306732
    .
  13. doi:10.1016/j.polymdegradstab.2010.08.019
    .
  14. doi:10.1016/j.tca.2010.06.012
    .
  15. doi:10.1016/j.polymdegradstab.2012.01.024
    .
  16. doi:10.1016/j.tca.2011.11.002
    .
  17. S2CID 96208830
    .
  18. ^ Huber Engineered Materials. "Huber Non-Halogen Fire Retardant Additives" (PDF). Retrieved 3 July 2017.
  19. ^ Galbraith, A; Bullock, S; Manias, E; Hunt, B; Richards, A (1999). Fundamentals of pharmacology: a text for nurses and health professionals. Harlow: Pearson. p. 482.
  20. ISBN 9781416028888
    .
  21. ISBN 978-0-8493-5444-1
    .
  22. ISBN 9780323444026
    .
  23. ISBN 9780470959640
    .
  24. ^ Lifelearn Inc. (1 November 2010). "Aluminum Hydroxide". Know Your Pet. Retrieved 30 June 2017.
  25. ^ "About Brenntag Biosector - Brenntag". brenntag.com. Retrieved 19 April 2018.
  26. PMID 18362170
    .
  27. S2CID 154670
    .
  28. ISBN 978-1-59259-399-6
    .
  29. ^ "Alzheimer's Myth's". Alzheimer's Association. Retrieved 29 July 2012.
  30. ^ Khan, A (1 September 2008). "Aluminium and Alzheimer's disease". Alzheimer's Society. Archived from the original on 11 March 2012. Retrieved 8 March 2012.
  31. PMID 12222737
    .
  32. S2CID 32190038
    .
  33. PMID 9861186
    .
  34. PMID 19740540
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Aluminium_hydroxide&oldid=1212150006"