Aluminum hydroxide uses

Aluminum hydroxide is a common compound of aluminum, hydrogen, and oxygen that can be considered either a base, with the formula Al(OH)3, or an acid, with the formula H3 AlO3. The compound is frequently treated as a hydrate—a water-bonded compound—of aluminum oxide and designated variously as hydrated alumina, or aluminum hydrate or trihydrate, hydrated aluminum, or hydrated aluminum oxide, with the formula Al2 O3 (H2 0)x.

UsesAluminum hydroxide and its closely related compounds have a number of practical uses. In one process of water purification, for example, aluminum sulfate, Al2 (SO4)3, or alum (usually potassium aluminum sulfate, KAl(SO4)2), is mixed with lime (calcium hydroxide, Ca(OH)2) in a container of water to be purified. The reaction between these compounds forms the gelatinous precipitate aluminum hydroxide. As the precipitate settles out of solution, it adsorbs on its surface particles of dirt and bacteria that were suspended in the impure water, which can then be removed by filtering off the aluminum hydroxide precipitate. 

The ability of aluminum hydroxide to adsorb substances on its surface explains a number of its other applications. It is used in a number of chemical operations, for example, as a filtering medium and in ion-exchange and chromatography devices. Aluminum hydroxide is popular as an antacid. It behaves as a base, reacting with and neutralizing excess stomach acid (hydrochloric acid) to bring relief from heartburn. It is also used as a mordant (fixative) in dyeing. In most cases, the compound is precipitated out of a water solution onto the fibers to be dyed.