Also known as potash alum, alum NF, and potassium alum, Al2[S04]3.K2S04.24H20 [sometimes written AlK[S04]2·12H20] is white, odorless crystals having an astringent taste, and is soluble in water, insoluble in alcohol, and noncombustible. Solutions in water are acid. Derived from alumite, leucite, or similar minerals, and also by crystallization from a solution made by dissolving aluminum sulfate and potassiwn sulfate and mixing, Used in dyeing [mordant], paper, matches, paints, tanning agents, waterproofing agents, purification of water, aluminum salts, food additive, baking powder, astringent, and as a cement hardener.
Chemical Properties
white powder[s]; absorbs atmospheric moisture [MER06]
Chemical Properties
The PhEur 6.0 describes potassium alum as a granular powder, or colorless, transparent, crystalline masses. The JP XV describes it as colorless or white crystals or powder. Potassium alum is odorless and has a slightly sweet, strongly astringent taste.
Uses
Astringent [topical].
Definition
ChEBI: A metal sulfate composed of potassium, aluminium and sulfate ions in the ration 1:1:2.
Production Methods
Potassium alum is manufactured by treating bauxite with sulfuric acid and then potassium sulfate. Alternatively, aluminum sulfate is reacted with potassium sulfate.
Flammability and Explosibility
Non flammable
Pharmaceutical Applications
Potassium alum precipitates proteins and is a powerful astringent. The ability to precipitate proteins is utilized in the manufacture of vaccines, where purified proteins are coprecipitated with and adsorbed onto potassium alum. Potassium alum is often included in preparations used as mouthwashes or gargles and in dermatological preparations, and it may be used as a topical hemostatic, either as a solid or as a solution. Intravesical instillation of potassium alum, typically as a 1% solution, has been used for hemorrhagic cystitis.
Safety
Potassium alum is often included in preparations used as mouthwashes or gargles and in dermatological preparations. Large doses of potassium alum act as an irritant and may be corrosive; gum necrosis and gastrointestinal hemorrhage have occurred. Acute encephalopathy has been reported following bladder irrigation with alum solutions in the treatment of bladder hemorrhage. Anecdotal evidence suggests that this practice should be avoided for patients with renal insufficiency.
storage
Store in a cool, dry place in tightly closed containers. Stable under normal temperatures and pressures. When kept for a long time at 60–65°C [or over sulfuric acid] potassium alum dodecahydrate loses water, which is reabsorbed on exposure to air. It becomes anhydrous at about 200°C.
Incompatibilities
Potassium alum is incompatible with strong oxidizing agents, aluminum, copper, steel, and zinc. When it is dispensed in powders with phenol, salicylates, or tannic acid, gray or green colors may be developed owing to traces of iron in the alum.
Regulatory Status
GRAS listed. Included in the FDA Inactive Ingredients Database [vaginal; suppository]. Included in medicines licensed in the UK.