Clay particles have natural nano properties, but there is a strong van der Waals effect between ordinary clay layers, so under normal circumstances, the crystal layers are condensed into one body and cannot reflect nano properties. The key to nanoclays is to open the distance between the crystal layers of clay mineral and make it exist stably. Nanoclays is a silicate mineral with a water-bearing layered structure with a particle diameter of less than 100nm. The preparation of nanoclays has the characteristics of abundant raw materials, simple process and low cost. Therefore, the research of nanoclay has become a hot spot in materials science research.
- Sewage treatment: The surface of nanoclays particles has permanent electronegativity due to the isomorphism replacement between layers, and the broken bond on the end surface will also make the clay particles have variable electrical properties. The stability of nanoclays particles in water systems mainly depends on the characteristics of the electric double layer structure caused by these electrical properties, and the electric double layer structure will change due to electrolyte or pH. Therefore, the dispersion and flocculation of nanoclays particles in the water system can be controlled by adding electrolytes or adjusting the pH value. Utilizing these properties of nanoclays, the pollutants in sewage can be adsorbed, coagulated, and precipitated on the surface to achieve the purpose of pollution control.
- Catalyst: Nanoclays exhibit good catalytic properties due to its large surface area, suitable pore size and surface acidity. After being acidified, nanoclays can greatly improve its catalytic activity, which can not only cause changes in the composition and structure of clay minerals, but also increase its specific surface area, improve its pore size distribution, and enhance its surface adsorption.
- Polymer/nanoclays composite material: Nanoclays has the special properties of compounding with organic matter, and its composite adsorption force comes from ion exchange, van der Waals force, hydrogen bond and ion dipole force. Nanoclays composite organics can be roughly divided into three types: neutral molecular organics, high molecular polymers, and organic cations. In addition to the direct compounding of organic matter, nanoclays can also be used to prepare organic clays with better adsorption and exchange properties through artificial organic compounding, such as organic bentonite.
Figure 1. Nanoclays composite material.
- Antibacterial materials: Organic-inorganic composite antibacterial agents have both the high efficiency and sustainability of organic antibacterial agents and the safety and heat resistance of inorganic antibacterial agents. The interlayer insertion technology is used to introduce the organic antibacterial agent into the interlayer gaps of the silver ion-exchanged layered clay, and the silver ions and the organic antibacterial agent can be slowly released together, thereby obtaining antibacterial and anti-mildew effects.
- Energy storage materials: Some nanoclays have structural nanopores, such as sepiolite and palygorskite, and their nanopores can be in a one-dimensional or multi-dimensional scale. According to the research of scientists, sepiolite-palygorskite has good hydrogen storage capacity for hydrogen.
- Intercalation: This method takes advantage of the ion exchange characteristics of clay minerals and the scalability of the interlayer distance, and replaces the original ions between the clay layers with organic groups much larger than metal cations. It peeled off completely, forming thin slices of clay.
- Ultrasonic dispersion: This method uses mechanical stirring and ultrasonic dispersion techniques to purify clay, improve its purity and improve dispersion.
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