Aluminium sulfate



Aluminium sulfate
IUPAC name Aluminium sulfate
hexadecahydrate
Other names Cake alum
Filter alum
Papermaker's alum
alumogenite
Aluminum sulfate
Aluminium sulphate
Identifiers
CAS number 10043-01-3
EINECS number 233-135-0
RTECS number BD1700000
Properties
Molecular formula Al2(SO4)3·16H2O
Molar mass 342.15 g/mol as anhydrous salt
Appearance white crystalline solid
Density 2.672 g/cm³, solid
Melting point

770 °C decomp.

Solubility in water 870 g/L
Structure
Crystal structure monoclinic (hydrate)
Related Compounds
Other cations Gallium sulfate
Magnesium sulfate
Related compounds See Alum
Supplementary data page
Structure and
properties 		εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data MS
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Aluminium sulfate, written as Al2(flocculating agent in the purification of drinking water[1][2] and waste water treatment plants, and also in paper manufacturing.

Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al2(SO4)3•16H2O and octadecahydrate Al2(SO4)3•18H2O are the most common.

It can also be very effective as a molluscicide, killing spanish slugs. [1]

Recent research suggests aluminum sulfate may contribute to dementia and Alzheimer's disease.

Preparation

Aluminium sulfate may be made by dissolving sulfuric acid, H2SO4:

2Al(OH)3 + 3H2SO4 + 3H2O → Al2(SO4)3·6H2O

Uses

Aluminium Sulfate is used in flocculation.

When dissolved in a large amount of neutral or slightly-alkaline water, aluminium sulfate produces a gelatinous precipitate of aluminium hydroxide, Al(OH)3. In dyeing and printing cloth, the gelatinous precipitate helps the dye adhere to the clothing fibers by rendering the pigment insoluble.

Aluminium sulfate is sometimes used to reduce the sulfuric acid solution.

Aluminium sulfate is the active ingredient of some antiperspirants; however, beginning in 2005 the US Food and Drug Administration no longer recognized it as a wetness reducer.

Aluminum Sulfate is usually found in baking powder.

In construction industry it is used as waterproofing agent and accelerator in fire fighting foam.

It is also used in styptic pencils, and pain relief from stings and bites; it is the active ingredient in popular pain relief products such as Stingose.

See also

  • Camelford, a town in Cornwall (UK) where the local water supplies were accidentally contaminated with aluminium sulfate.

References

  1. ^ Global Health and Education Foundation (2007). Conventional Coagulation-Flocculation-Sedimentation. Safe Drinking Water is Essential. National Academy of Sciences. Retrieved on 2007-12-01.
  2. ^ Kvech S, Edwards M (2002). "Solubility controls on aluminum in drinking water at relatively low and high pH". WATER RESEARCH 36 (17): 4356-4368. PMID 12420940.
  • Pauling, Linus (1970). General Chemistry. W.H. Freeman: San Francisco. ISBN 0-486-65622-5. 
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Aluminium_sulfate". A list of authors is available in Wikipedia.