Sodium aluminosilicate

Sodium aluminosilicate refers to compounds which contain sodium, aluminium, silicon and oxygen, and which may also contain water. These include synthetic amorphous sodium aluminosilicate, a few naturally occurring minerals and synthetic zeolites. Synthetic amorphous sodium aluminosilicate is widely used as a food additive, E 554.

Amorphous sodium aluminosilicate
This substance is produced with a wide range of compositions and has many different applications. It is encountered as an additive E 554 in food where it acts as an anticaking (free flow) agent. As it is manufactured with a range of compositions it is not strictly a chemical compound with a fixed stoichiometry. One supplier quotes a typical analysis for one of their products as 14SiO2·Al2O3·Na2O·3H2O,(Na2Al2Si14O32·3H2O).

The US FDA has as of April 1, 2012 approved sodium aluminosilicate (sodium silicoaluminate) for direct contact with consumable items under 21 CFR 182.2727. Sodium aluminosilicate is used as molecular sieve in medicinal containers to keep contents dry.

Sodium aluminosilicate may also be listed as:
 * aluminium sodium salt
 * sodium silicoaluminate
 * aluminosilicic acid, sodium salt
 * sodium aluminium silicate
 * aluminum sodium silicate
 * sodium silico aluminate
 * sasil

As a problem in industrial processes
The formation of sodium aluminosilicate makes the Bayer process uneconomical for bauxites high in silica.

Minerals sometimes called sodium aluminosilicate
Naturally occurring minerals that are sometimes given the chemical name, sodium aluminosilicate include albite (NaAlSi3O8, an end-member of the plagioclase series) and jadeite (NaAlSi2O6).

Synthetic zeolites sometimes called sodium aluminosilicate
Synthetic zeolites have complex structures and examples (with structural formulae) are:
 * Na12Al12Si12O48·27H2O, zeolite A (Linde type A sodium form, NaA), used in laundry detergents
 * Na16Al16Si32O96·16H2O, Analcime, IUPAC code ANA
 * Na12Al12Si12O48·q H2O, Losod
 * Na384Al384Si384O1536·518H2O, Linde type N