💊 Chemical information

Bentoniitti; Bentonit; Bentonita; Bentonitas; Bentonitum; E558; Mineral Soap; Soap Clay; Wilkinite.
CAS — 1302-78-9.


In Eur., Int., and Jpn. Also in USNF, which also includes a purified form.

Ph. Eur. 6.2

(Bentonite). A natural clay containing a high proportion of montmorillonite, a native hydrated aluminium silicate in which some aluminium and silicon atoms may be replaced by other atoms such as magnesium and iron. A very fine, homogeneous, greyish-white powder with a more or less yellowish or pinkish tint. Practically insoluble in water and in aqueous solutions, but swells with a little water forming a malleable mass.

USNF 26 (Bentonite). A native, colloidal, hydrated aluminium silicate. A very fine, odourless, hygroscopic, pale buff or creamcoloured to greyish powder, free from grit. Insoluble in water, but swells to about 12 times its volume when added to water; insoluble in, and does not swell in, organic solvents. pH of a 2% suspension in water, mixed vigorously to facilitate wetting, is between 9.5 and 10.5. Store in airtight containers.

USNF 26 (Purified Bentonite). A colloidal montmorillonite that has been processed to remove grit and nonswellable ore components. An odourless, fine, micronised powder, or small flakes that are creamy when viewed on their flat surfaces and tan to brown when viewed on their edges. Insoluble in water and in alcohol. Swells when added to water or glycerol. pH of a 5% suspension in water is between 9.0 and 10.0. Store in airtight containers.

💊 Uses

Bentonite absorbs water readily to form sols or gels, depending on its concentration. It is used in pharmaceutical manufacturing as a suspending and stabilising agent and as an adsorbent or clarifying agent. It is also used as an anticaking agent in the food industry. Bentonite may be used as an oral adsorbent in paraquat poisoning.

💊 Preparations

USNF 26: Bentonite Magma.

Proprietary Preparations

Gr.: Bentonine†. Multi-ingredient: Indon.: Stomagel; Malaysia: Clearasil Pimple Treatment; S.Afr.: Clearasil T; Singapore: Clearasil Pimple Treatment.
Published October 20, 2018.