Understand Bentonite in One Go! 8 Key Concepts You Need to Know
1.Bentonite
Bentonite, also known as "bentonite rock" or "bentonitic clay," is a non-metallic mineral with montmorillonite as its core mineral component. It is often accompanied by small amounts of illite, kaolinite, zeolite, feldspar, calcite, and others. The content of montmorillonite directly determines the practical value of bentonite.
2.Montmorillonite
Montmorillonite is a large group of minerals with complex chemical compositions. The International Clay Association classifies them as the Montmorillonite Group or Smectite Group. This group is further divided into dioctahedral and trioctahedral subgroups, comprising over ten mineral species. The bentonite used industrially typically contains minerals from the dioctahedral subgroup, such as montmorillonite, beidellite, and nontronite.
3.Calcium-Based and Sodium-Based Bentonite
Bentonite is categorized based on the type, content, and crystal chemical properties of its exchangeable cations into calcium-based bentonite, sodium-based bentonite, magnesium-based bentonite, and calcium-sodium-based bentonite. Among them, calcium-based and sodium-based bentonite are the most common. Sodium-based bentonite surpasses calcium-based bentonite in swelling capacity, cation exchange capacity, dispersibility, viscosity, lubricity, and thermal stability. However, in China, sodium-based bentonite reserves are scarce, with calcium-based bentonite being the predominant type.
4.Organoclay (Organic Bentonite)
Organoclay is produced by replacing the exchangeable cations in montmorillonite with organic ammonium cations, giving it hydrophobic and lipophilic properties. Based on function and composition, organoclay can be categorized into high-viscosity, easily dispersible, self-activating, and high-purity types. These types are further classified into low-polarity, medium-polarity, and high-polarity models according to the hydrophilic-lipophilic balance (HLB) of the intercalated surfactants.
5.Lithium-Based Bentonite
Lithium-based bentonite is a scarce resource and is mainly produced via artificial lithification. It can gel in organic solvents and exhibits excellent swelling, thickening, and suspension properties, making it widely used in architectural coatings, latex paints, casting coatings, and other products.
6.Activated Clay
Activated clay is a porous, white to grayish powder obtained by treating clay (primarily bentonite) with inorganic acid or salts. It features a microporous structure and strong adsorption capacity and is mainly used for decolorizing and refining petroleum products and industrial animal/vegetable oils. It is also used as an adsorbent and catalyst carrier in the chemical industry.
7.Pillared Montmorillonite
Pillared montmorillonite is a mineral material with two-dimensional pores formed by inserting polymeric inorganic cations or organic ions (molecules) between montmorillonite layers. It has a large specific surface area, excellent thermal stability, strong surface acidity, and adjustable pore size. It is widely used in petrochemicals, wastewater treatment, antimicrobial materials, and other fields. Pillared montmorillonite can be classified into various types based on the intercalating agents used.
8.Inorganic Bentonite Gel
Inorganic bentonite gel is a high-value colloidal product made mainly from bentonite through processes such as purification, sodium modification, phosphate modification, and gelation. It is widely used in various industries as a thixotropic agent, thickener, dispersant, suspending agent, and stabilizer.
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