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.
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.[1] One supplier quotes a typical analysis for one of their products as 14SiO2·Al2O3·Na2O·3H2O,(Na2Al2Si14O32·3H2O).[2]
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.[3] Sodium aluminosilicate is used as molecular sieve in medicinal containers to keep contents dry.
Sodium aluminosilicate may also be listed as:
The formation of sodium aluminosilicate makes the Bayer process uneconomical for bauxites high in silica.[citation needed]
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).[citation needed]
Synthetic zeolites have complex structures and examples (with structural formulae) are: