Potash alum

Potash Alum

Potash alum, also known as Potassium alum or Potassium aluminium sulfate, is a chemical compound commonly used in water purification, leather tanning, and dyeing. It is a double salt, usually the double sulfate of potassium and aluminium. Its chemical formula is KAl(SO4)2.

History

Potash alum was known to the ancients and mentioned in Pliny's Natural History. It was used in various applications, including as a mordant in dyeing and in medicine. Its name comes from the mineral alunite which was a source of it.

Production

Potash alum is produced industrially by using aluminium hydroxide, sulfuric acid and potassium sulfate as raw materials. The aluminium hydroxide is reacted with sulfuric acid to produce aluminium sulfate, which is then reacted with potassium sulfate to produce potash alum.

Uses

Potash alum has a wide range of uses. It is used in water purification to cause impurities to coagulate and be removed. In leather tanning, it helps to stabilize the proteins in the hides, preventing them from rotting. In dyeing, it is used as a mordant, helping the dye to bind to the fabric. It is also used in baking powder and as a fire retardant.

Health and Safety

Potash alum is generally safe to handle, but ingestion or inhalation of large amounts can be harmful. It can cause irritation to the eyes, skin, and respiratory tract. It is not considered to be a carcinogen.

See Also

• Alum
• Potassium sulfate
• Aluminium sulfate