Sodium aluminium silicate is a chemical compound consisting of a series of amorphous hydrated sodium aluminium silicates with generally varying proportions of 66-88% for SiO₂ and 5-15% for Al₂O₃ . It is obtained by the reaction of aluminium sulphate with sodium silicate followed by precipitation. It is also known as 'synthetic zeolite' .

The name describes the structure of the molecule

• Sodium - Indicates the presence of sodium ions.
• Aluminium - Indicates the presence of aluminium ions.
• Silicate - Refers to an anion based on silicon and oxygen.

Description of raw materials used in production

• Sand - A primary source of silicon.
• Caustic soda (sodium hydroxide) - Provides sodium ions.
• Bauxite or clay - A source of aluminum.

Synthesis process

• Extraction - Silicon is extracted from sand and aluminum from bauxite or clay.
• Reaction - Silicon and aluminum react with sodium hydroxide under appropriate conditions to form Sodium Aluminium Silicate.

It appears in the form of a white powder.

What it is used for and where

Food

Ingredient included in the list of European food additives as E554 with an anti-caking function. Icing sugar, non-dairy creams and other dry powdered products may contain this ingredient.

Cosmetics

Abrasive agent. It contains abrasive particles to remove stains or biofilm that accumulate on the stratum corneum or teeth. Baking soda, kieselguhr, silica and many others have abrasive properties. Peeling or exfoliating products used in dermatology or cosmetic applications contain abrasive agents in the form of synthetic microspheres, however these microspheres or abrasive particles are not biodegradable and create pollution in aquatic ecosystems.

Bulking agent. It regulates the water content, dilutes other solids, can increase the volume of a product for better flow, acts as a buffer against organic acids, helps to keep the pH of the mixture within a certain level.

Viscosity control agent. It controls and adapts, Increasing or decreasing, viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

Other uses

• Anti-Caking Agent - Used in table salt and other food products to prevent caking.
• Ceramic Industry - Used as a raw material in the production of ceramics.
• Filling Agent - Often used in paints, plastics, and rubber as a filler to enhance consistency and mechanical properties.
• Abrasive - Can be used in toothpaste as a mild abrasive agent.
• Pharmaceutical Industry - May be used as a flow agent or as an excipient in some drug preparations.

Safety

The Panel on Food Additives and Flavourings (FAF) provided a scientific opinion reviewing the safety of sodium aluminium silicate (E554) and potassium aluminium silicate (E555) as food additives. Exposure to aluminium from this single use at the maximum permitted level could theoretically far exceed the tolerable weekly intake. Considering the availability of very limited toxicological data and insufficient information on the physicochemical characterisation of both food additives, the Panel concluded that it was not possible to assess the safety of sodium aluminium silicate (E554) and potassium aluminium silicate (E555). (1)

It should be considered that the risk of cumulative intake of aluminium, which can pose a danger to human health, cannot be excluded as this ingredient can be found in widely consumed food products (2).

Other uses

• pesticide
• phosphate substitute in detergents
• animal feed

• Molecular Formula   AlNaO₆Si₂
• Molecular Weight    202.14 
• CAS  1344-00-9
• UNII  058TS43PSM
• EC Number   215-684-8    

References_____________________________________________________________________

(1) EFSA Panel on Food Additives and Flavourings (FAF), Younes, M., Aquilina, G., Castle, L., Engel, K.H., Fowler, P., Frutos Fernandez, M.J., Fürst, P., Gürtler, R., Gundert‐Remy, U. and Husøy, T., 2020. Re‐evaluation of sodium aluminium silicate (E 554) and potassium aluminium silicate (E 555) as food additives. EFSA Journal, 18(6), p.e06152.

(2) Wong, W.W., Chung, S.W., Kwong, K.P., Yin Ho, Y. and Xiao, Y., 2010. Dietary exposure to aluminium of the Hong Kong population. Food Additives and Contaminants, 27(4), pp.457-463.

Bratakos, S.M., Lazou, A.E., Bratakos, M.S. and Lazos, E.S., 2012. Aluminium in food and daily dietary intake estimate in Greece. Food Additives and Contaminants: Part B, 5(1), pp.33-44.