Aluminum sulfate

Aluminium sulfate or Aluminium Sulphate, written as Al2(SO4)3 or Al2O12S3Aluminium sulfateis an industrial chemical used as a flocculating agent in the purification of drinking water and wastewater treatment plants, and also in paper manufacturing.

Aluminium sulfate is sometimes incorrectly referred to as alum but alums are closely relatedcompounds typified by KAl(SO4)2.12H2O. The anhydrous form occurs naturally as a rare mineralmillosevichite, found e.g. in volcanic environments and on burning coal-mining waste dumps.

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. The heptadecahydrate, whose formula can be written as [Al(H2O)6]2(SO4)3•5H2O, occurs naturally as the mineral alunogen.