Aluminum sulfate
Synonyms: alluminiumsulphate;alum(non-specificname);aluminiumsulfate(non-specificname);aluminumalum;aluminumsulfate(2:3);aluminumsulfate(al2(so4)3);aluminumsulfate,anhydrous;aluminumsulfate,solid
CAS: 10043-01-3
MF: Al2O12S3
MW: 342.15
EINECS: 233-135-0
Melting point 770 °C (dec.)(lit.)
density 2.71 g/mL at 25 °C(lit.)
Water Solubility soluble
Merck 14,366
Physical and Chemical Properties Colorless or white crystals. Odorless, slightly sweet taste. Because of containing iron etc, industrial product looks like a yellowish-green, tastes sour. It was Stable in the air, heated to 250 ℃ to lose crystal water, when heated above 700 ℃, begin decompose into aluminum oxide, sulfur trioxide and water vapor, etc. Soluble in water, aqueous solution is acidic. Al2 (SO4) 3 + 2H2O → Al2 (SO4) 2 (OH) 2 + H2SO4, when hydrate were heated, violently swell and become spongy, when heated to a red heat, it decomposes into sulfur trioxide and alumina. Flocculent or sponge-like Al (OH) 3 has a strong adsorption capacity, good absorption of pigments and fibers, and thus used as a mordant in dyeing industry, also used to purify drinking water. In addition, in the paper industry, it can added to the pulp with rosin simultaneously for fiber bonding.
Aluminum sulfate has Anhydride and a variety of patterns of hydrate existing (16,18,27, etc). Among aluminum sulfate, the more stable is anhydrous aluminum sulfate [1] and 18 hydrated aluminum sulfate [2]. [1] is a colorless orthorhombic crystals, shiny, or white crystalline powder. Relative molecular mass is 342.15. The relative density is 2.71. Gradually heating to melt, it begins to lose crystal water at 250 ℃, decompose at 770 ℃. The refractive index is 1.47. Dissolved in water, slightly soluble in ethanol, aqueous solution is acidic. Solubility in water: 37.9 at 0 ℃, 38.1 at 10 ℃, 38.5 at 25 ℃, 38.9 at 30 ℃, 40.4 at 40 ℃,44.9 at 60 ℃, 48.8 at 70 ℃, 89 at 100 ℃. [2] is a colorless monoclinic needles. Relative molecular mass is 666.43. The relative density is 1.69 (17/4 ℃). decompose at 86.5 ℃. Dissolved in water, not soluble in ethanol. The solubility in water is 86.9 at 0 ℃, 1104 at 100 ℃. Aqueous solution is acidic due to hydrolysis.
Aluminum sulfate easily absorb water to agglomerate, use plastic bags lined with plastic bags of glass for packaging. Storage and transportation should prevent rain and damp.
Purpose and effect of aluminum sulfate Aluminum sulfate is mainly used for turbidity water purification, also used as a precipitating agent, fixing agent, fillers, etc. It is used as antiperspirant cosmetic ingredients (astringent) in cosmetics. In addition, aluminum sulfate can also be used as paper industry sizing agent (rosin sizing, so that the color will be attached to the paper), leather tanning agents, mordant, purifying agent (flocculant, the resulting aluminum hydroxide floc may be coated with microparticles suspended in the water to promote rapid sedimentation separation), foam fire extinguisher inside agent (outside agent is sodium bicarbonate, carbon dioxide is generated after the reaction), raw materials for manufacturing alum, and white aluminum, oil bleaching, deodorization agent; pharmaceutical raw materials, as food curing agent (excipient); for impurities removal of oil, water, etc, pasteurized albumin stabilizer, lake raw materials, waste water treatment agent, waterproof concrete materials, fireproof raw materials.