Alum is a mineral composed of hydrated aluminum potassium sulfate, with the chemical formula KAl(SO)12HO. It is a white, crystalline solid that is soluble in water. Alum is used in a variety of applications, including water purification, papermaking, and food preservation.
Alum has been used for centuries as a natural coagulant in water purification. It works by causing suspended particles in the water to clump together, making them easier to remove. Alum is also used in the production of paper. It helps to bind the fibers together, making the paper stronger and more durable. In food preservation, alum is used as a pickling agent. It helps to prevent the growth of bacteria and fungi, extending the shelf life of food.