**3.1 Bentonite**

The word "bentonite" is a bit of a misnomer. It is a rock consisting of extremely colloidal and plastic clays, mostly montmorillonite, a clay mineral of the smectite group, and created by in situ devitrification of volcanic ash, according to geologists [24]. Bentonite generated from ash falls is usually found in uniformly thick strata (ranging from a few millimeters to 15 meters) that cover enormous regions [24]. It is found in layers from ash falls and other sources all throughout the planet, although it is most plentiful in Cretaceous and newer rocks.

Bentonite is a rock made up of extremely colloidal and malleable clays, mostly montmorillonite, a smectite group clay mineral, that is created by devitrification of volcanic ash in situ. Bentonite may also contain feldspar, cristobalite, and crystalline

### *Classification of Clay Minerals DOI: http://dx.doi.org/10.5772/intechopen.103841*

quartz in addition to montmorillonite. The ability to produce thixotrophic gels with water, the ability to absorb huge amounts of water, and a high cation exchange capacity are all characteristics of bentonite.

In the foundry business, bentonites are used to bind sands into suitable forms in which metals may be cast. To hold the sand grains together, just 3–5% bentonite is required. Bentonites have a greater green, dry, and hot strength than any other form of clay due to their tiny particle size and the nature of their water adsorption. The taconite industry is quickly increasing the usage of bentonite as a bonding agent [25]. A variety of sodium bentonite's unique features are used in hazardous waste containment. Because of its swelling capacity, bentonite is an efficient soil sealant, since it fills the gaps in the soil by expanding inside the interstices of the soil with which it is combined, forming a very low permeability barrier. The capacity of bentonite to swell is facilitated by the potential of a very tiny average particle size, which allows it to fill even the tiniest of spaces. The strong cation exchange capacity improves waste retention, particularly for heavy metals. A combination of sodium bentonite and dirt also generates a stiff, flexible mastic that is exceptionally resistant and difficult to rupture. The capacity of bentonite to bind cationic metals and some pesticides has been used in experiments to detoxify paraquat poisoning patients and to reduce radiocaesium transfer to milk and other animal-derived foods.

### **3.2 Kaolinite**

The word "kaolin" comes from the Chinese word Kau-Ling, which means "high ridge," and refers to a hill near Jau-chau Fu, where kaolin was first mined [26]. Kaolin, often known as china clay, is a clay that comprises 10–95% kaolinite and is generally composed primarily of kaolinite (85–95%).

Kaolin, sometimes known as china clay, is a mineral combination. Kaolinite is the primary component, however it also contains quartz, mica, feldspar, illite, and montmorillonite. Kaolinite is made up of triclinic crystal sheets with pseudohexagonal shape. Rock weathering is responsible for its formation. It has the ability to exchange cations. There are three methods for kaolinite to form:


The use of kaolin as a paper coating accounted for about half of total domestic consumption and roughly 80% of kaolin exports. Kaolin-coated papers are widely used in the production of cigarettes [24]. Smokers may be exposed to kaolinite particles by inhaling. Kaolin was also used as a filler in the manufacture of paint, paper, and rubber, as a component of fiber glass and mineral wool, as a landfill liner, and as a catalyst in the refinement of oil and gas. Historically, the use of kaolin in the making of porcelain and chinaware amounted for less than 1% of total domestic consumption in the United States. In 2003, ceramics accounted for 80–85% of overall manufacturing in China, with paper accounting for 5%, rubber for 3%, and paint accounting for 2%. Ceramics consumed 290,000 tonnes, paints 84,000 tonnes, paper/paperboard 68,000 tonnes, detergents 29,000 tonnes, and rubber 27,500 tonnes in India. Kaolinite has a variety of

medically useful qualities. It is a good adsorbent that will adsorb not just lipids and proteins but also other substances [24] including viruses and bacteria [27]. It can be used to cause platelet aggregation and to start plasma coagulation by activating factor XII. [28] Also, non-specific haemaglutinin inhibitors should be removed from the serum. Kaolin is utilized as a local and gastrointestinal adsorbent in medicinal treatment (Kaopectate, bolus alba). Kaolin may be found in a variety of cosmetics, including eyeshadows, blushers, face powders, "powders," mascaras, foundations, and makeup bases. Kaolin was found in 509 different cosmetics in the United States in 1998, with concentrations ranging from 5 to 30%, but exceeding 84% in certain paste masks [29]. Medical, pharmaceutical, and cosmetic applications, on the other hand, accounted for around 0.01% of total kaolin usage in the United States.
