The chemical name of alum is Potassium Aluminum Sulfate Dodecahydrate. Its corresponding chemical formula is KAl(SO4)2-12H2O, and it is a complex salt of potassium sulfate and aluminum sulfate containing water of crystallization.

The chemical is soluble in water and insoluble in ethanol. It can be used to prepare aluminum salt, baking powder, paint, tanning material, clarifying agent, mordant, papermaking, waterproofing agent, etc. It is often used for water purification in life.

Aluminum potassium sulfate dodecahydrate (alum) national restrictions:

1, due to the doughnuts, steamed bread, noodles, puffed food and other food in the processing may be used in the process of aluminum-containing food additives, long-term consumption of the human body is very harmful, especially to the children's growth and development and intelligence will be affected.

2, the National Health and Planning Commission and other five departments, from July 1, 2014 onwards, steamed bread, cakes and other noodle products (in addition to deep-fried noodle products, hanging batter, wrapping powder, frying powder) can not be added to the aluminum-containing bulking agent aluminum potassium sulfate and aluminum ammonium sulfate, which is commonly known as "alum", and the compound type of bulking agent (i.e., baking powder), the main aluminum-containing food additives. Baking powder) is the main ingredient of the above two substances.

3, puffed food, no longer allowed to use any aluminum-containing food additives.

Reference to the above? Baidu Encyclopedia-Aluminum potassium sulfate dodecahydrate