What is bentonite?

Bentonite is an absorbent swelling clay that is mostly composed of montmorillonite. This material is usually formed from the weathering of volcanic ash in sea water. This causes the volcanic glass present in the ash to be converted into clay minerals and is formed in the form of sandwich layers among other types of rocks. Bentonite beds are white, green, or pale blue when exposed to air, and they turn cream and then yellow, red, or brown in contact with air.

Since bentonite is known as a swelling clay, it has the ability to absorb water to a high extent and can absorb eight times its volume of water. This makes the use of this material inappropriate in construction and road construction. However, due to its swelling properties, it is used in mud excavations for underground dams.

The combination of montmorillonite with bentonite is an aluminum phyllosilicate mineral that forms microscopic sheet grains. This shape gives clays a high total surface area and makes bentonite a valuable absorbent material. These sheets stick to each other when there is moisture, and this leads to the creation of cohesive properties in the clay and makes the use of this material useful as an adhesive. Also, by adding it to kaolinite clay for use in pottery, the plasticity of improves it.

Types of bentonite

In geology, the term bentonite is a type of clay that mainly consists of montmorillonite. Bentonite has different types, the two main categories of which are used in industrial purposes are sodium bentonite and calcium bentonite.

Sodium bentonite is very valuable while calcium bentonite is very common and has no special value.

There is another type of bentonite called potash bentonite or K-bentonite, which is actually potassium bentonite.

Applications of bentonite

Considering that there are many uses of bentonite, but a few of them are considered among the main uses of bentonite.

Application of bentonite as drilling mud

• It is used as a drilling fluid (Drilling mud) to lubricate and cool the tools used for drilling (such as drills).

The use of bentonite as a binder

• Bentonite is widely used as a binding sand in steel and iron foundries. Normally, sodium bentonite is used in large castings where dry molds are used. While calcium bentonite is used for smaller castings where wet or green molds are used.
• Bentonite is used in smaller percentages as an ingredient in commercial and domestic clay bodies as well as ceramic glazes. This material significantly increases the plasticity of clay bodies and reduces the speed of deposition in glazes, and finally makes it easy to use these materials for various applications.
• The existence of an ionic surface in bentonite and having useful properties creates a sticky coating on sand grains. Therefore, adding a small amount of bentonite to wet hard sand will cause the clay to stick to the sand particles and create a moldable mass known as green sand for sand casting.

Application of bentonite for purification

• Bentonites are used to decolorize various mineral, vegetable and animal oils. They are also used to clarify wine, spirits, sweet wine, beer and vinegar.
• Bentonite has the property of absorbing relatively large amounts of protein molecules from aqueous solutions. As a result, bentonite is uniquely useful in the winemaking process, where the removal of large amounts of protein is required. The reason for removing these proteins is that they show harmful and adverse effects when exposed to hot air.
• Bentonite is also considered an effective low-cost adsorbent for the removal of chromium (VI) ions from aqueous solutions (contaminated wastewater).

Application of bentonite as absorbent

• Bentonite is used in soils used for pets such as cats to absorb animal feces. On the other hand, it is also used as an absorbent of oil and grease.

The use of bentonite as a carrier

• Bentonite is used as an ineffective carrier of pesticides, fertilizers and fire retardants. It assures you that the active agent is evenly dispersed and that pesticides and fertilizers are retained on the plants.

Application of bentonite as a filler

• Bentonite is used as a filler in a wide range of products such as adhesives, cosmetics, paint, rubber and soaps. Bentonite acts as a stabilizer and expander in these products.

Application of bentonite as a sealant

• Sodium bentonite has high absorption properties due to contact with water, and for this purpose it is used as an absorbent. This material is used as a sealant for sealing disposal systems under the surface of the earth and also for impermeability in places with nuclear fuel consumption. He mentioned this substance in the industry and required fields as chemical absorbents and sealants for containers.

Application of bentonite as a catalyst

• High purity calcium bentonite is used as a catalyst in breaking oil chains into smaller hydrocarbon chains in heavy oil fractions.

Application of bentonite in medicine

• Bentonite is also used as a laxative, and because it has the approval of the US Food and Drug Administration, it has a higher absorption capacity than other drying materials such as silica gel.

Application of bentonite in pottery

• The use of bentonite in ceramic glazes is to slow down or prevent the sedimentation of the glaze.