Bentonite
Description:
- Fine, soft powder with a white, gray, or yellowish color.
- Odorless.
- Feels smooth and slightly greasy to the touch.
Uses:
Bentonite’s absorbent and swelling properties make it valuable in various industries:
- Foundry Industry: Bentonite is a major binder in foundry sand molds used for metal casting. It helps the sand retain its shape and withstand high temperatures.
- Drilling Industry: Bentonite forms a drilling mud used in well drilling to lubricate the drill bit, cool the borehole, and prevent collapse of the well walls.
- Clarification and Filtration: Bentonite can be used in clarifying liquids like wine, juice, and oils by adsorbing suspended particles and impurities.
- Cosmetics and Skincare: Bentonite clay is a popular ingredient in facial masks and beauty products due to its ability to absorb oil and impurities from the skin.
- Environmental Applications: Bentonite can be used to absorb spills of oil, grease, and other contaminants due to its high absorbency.
- Pet Litter: Some clumping cat litter formulations utilize bentonite to absorb moisture and form clumps for easier disposal.
- Pharmaceuticals and Food Additives: Bentonite has limited uses in some pharmaceutical and food additive applications as a binding, thickening, or anticaking agent. Strict regulations and processing are required to ensure safety.
Chemical Composition:
- Primarily montmorillonite (a smectite clay) with a layered structure.
- Montmorillonite is composed of aluminum silicate sheets with various cations (positively charged ions) like sodium (Na+), calcium (Ca2+), or magnesium (Mg2+) between the layers.
- The specific type of cation present influences the properties of the bentonite (e.g., sodium bentonite swells more than calcium bentonite).
- May also contain small amounts of other minerals depending on the source rock.
Physical Properties:
- Density: Around 2500-2900 kg/m3 (depending on particle size and packing)
- Solubility in Water: Low solubility in pure water. However, swells significantly when it comes into contact with water, forming a gel-like paste.
- Melting Point: Decomposes before melting.
- Cation Exchange Capacity (CEC): High CEC due to its layered structure. Bentonite can exchange the cations between its layers, which contributes to its adsorption properties.
Safety Information:
- Generally considered safe for external use in cosmetics and industrial applications.
- Inhaling bentonite dust can irritate the respiratory system. Wear a dust mask when handling dry bentonite powder.
- Bentonite can bind to certain nutrients and medications if ingested in large quantities. Consult with a healthcare professional before using bentonite internally for medicinal purposes.
- Keep out of reach of children and pets.
