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alum

alum

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

alum , any one of a series of isomorphous double salts that are hydrated sulfates of a univalent cation (e.g., potassium, sodium, ammonium, cesium, or thallium) and a trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or titanium). The name alum commonly refers to potassium aluminum sulfate dodecahydrate, or potash alum, KAl(SO 4 ) 2 ·12H 2 O, a colorless-to-white, crystalline compound. It is used in water purification, leather tanning, mordant dyeing, as an astringent, and in baking powder; it occurs in nature as the mineral kalunite. Sodium aluminum sulfate, or soda alum, NaAl(SO 4 ) 2 ·12H 2 O, is also used in baking powder. Ammonium aluminum sulfate, or ammonia alum, NH 4 Al(SO 4 ) 2 ·12H 2 O, is used in tanning, in dyeing and fireproofing textiles, in vegetable glues and porcelain cements, and in water purification. Chromium potassium sulfate, or chrome alum, KCr(SO 4 ) 2 ·12H 2 O, is used as a mordant in dyeing, in tanning, and in photographic fixing baths to harden gelatin films and plates. Aluminum sulfate, Al 2 (SO 4 ) 3 ·18H 2 O, is also called alum. A pseudoalum is a double sulfate salt of a divalent cation (e.g., magnesium or calcium) and a trivalent cation (e.g., aluminum).

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alum

The Oxford Pocket Dictionary of Current English | 2009 | Copyright

a·lum / ˈaləm/ • n. Chem. a colorless astringent compound, AlK(SO4)2.12H2O, a hydrated double sulfate of aluminum and potassium, used in solution medicinally and in dyeing and tanning. ∎  any of a number of analogous crystalline double sulfates of a monovalent metal (or group) and a trivalent metal.

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alum

The Concise Oxford Dictionary of English Etymology | 1996 | | Copyright

alum XIV. — OF. alum (mod. alun) :- L. alūmen.
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T. F. HOAD. "alum." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>.

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alum

Oxford Dictionary of Rhymes | 2007 | Copyright

alum •amalgam • Targum • begum •Brigham • lingam • ogham • sorghum •Nahum • Belgium • dodgem •Brummagem • stratagem • Rackham •Malcolm • Ascham • Beckham •welcome • vade mecum • stickum •dinkum • modicum • hypericum •capsicum • viaticum • practicum •Occam •hokum, locum, oakum •bunkum •alum, Calum, mallam, vallum •Pablum •Haarlem, Harlem, Malayalam, slalom •antebellum, cerebellum, elm, helm, overwhelm, pelham, realm, underwhelm, vellum •emblem • bedlam • peplum •exemplum • wychelm • Kenelm •Salem • velum •aspergillum, chillum, film, vexillum •Whitlam • clingfilm • telefilm •microfilm •asylum, hilum, phylum, whilom •column, olm, solemn •problem • golem • hoodlum • Ulm •incunabulum, pabulum •coagulum • pendulum • speculum •curriculum • cimbalom • paspalum •Absalom • Jerusalem • tantalum

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Free newspaper and magazine articles

Alum curbs phosphorus runoff and more.
Magazine article from: Agricultural Research; 11/1/2006
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Magazine article from: Canadian Journal of Civil Engineering; 1/1/2009
Phosphorus adsorption and oven dried alum residual solids in fixed bed column...
Magazine article from: Journal of Environmental Engineering and Science; 11/1/2007

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Alum. (Image by AudioPervert, GFDL)

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