Application knowledge of silica gel

Features

Silica gel is a highly active adsorption material, which belongs to an amorphous substance. Its chemical formula is mSiO2 & nH2O. It is insoluble in water and any solvent, non-toxic and tasteless, with stable chemical properties, and does not react with any substance except strong base and hydrofluoric acid. Various types of silica gel form different microporous structures due to their different manufacturing methods. The chemical composition and physical structure of silica gel determine that it has many characteristics that are difficult to replace by other similar materials: high adsorption performance, good thermal stability, stable chemical properties, high mechanical strength, etc.  

Silica gel can be divided into macroporous silica gel, macroporous silica gel, B-type silica gel and microporous silica gel according to the size of its pore diameter. Because of their different pore structures, their adsorption properties have their own characteristics. Coarse porous silica gel has a higher adsorption capacity in the case of high relative humidity, while fine porous silica gel has a higher adsorption capacity in the case of low relative humidity, while B-type silica gel has a pore structure between coarse and fine porous silica gel, and its adsorption capacity is also between coarse and fine pores. Macroporous silica gel is generally used as catalyst carrier, matting agent, toothpaste abrasive, etc. Therefore, different varieties should be selected according to different uses.  

After absorbing water, silica gel can be regenerated by means of exposure, baking, air drying, etc.  

Safety performance

The main component of silica gel is silica, which is chemically stable and non-toxic.  

Silica gel has a strong adsorption capacity and can dry human skin. If the silica gel gets into your eyes, wash it with plenty of water and seek medical treatment as soon as possible.  

Blue silica gel is toxic because it contains a small amount of cobalt chloride. It should be avoided from contact with food and inhalation. In case of poisoning, a doctor should be consulted immediately.  

Main purpose

Silica gel has the characteristics of strong adsorption, rapid and effective absorption of moisture in sealed packages, stable chemical properties, non-toxic and harmless; In addition to continuous innovation and development in recent years, various silica gels have been widely used in drug purification, DNA separation, food drying, high-precision electronics, advanced cosmetics, sewage purification, beer purification, advanced coatings, resin production or preservation, etc. In our daily life and production and operation activities, silica gel is often used in the following aspects:

Dry and mildew proof packaging for precision optical instruments and electronic appliances;  

In terms of leather drying, for example, it can be placed in leather clothes, leather bags and leather shoes for drying and quality assurance;  

In terms of food drying, it is often found in biscuits and fried food to ensure that the food is crisp;   

In terms of drug drying, it should be put in the drug bottle to ensure that the storage period of drugs is extended;  

Container drying: The transported container will form "internal rain" in the container at different latitudes. If you use silica gel desiccant, it can absorb water equivalent to its own weight. During the ocean transportation for up to 50 days, it can effectively reduce the dew point and control the condensation of the container.  

Hotel articles, such as those placed in the wardrobe, shoes and under the bed, absorb various odors, and keep the air dry and fresh.  

Beer silica gel

Character:

Beer silica gel is a kind of amorphous solid powder with microporous structure. The pore diameter is 8-16nm, and the chemical formula is mSiO2&# 8226; NH2O, insoluble in water and any solvent, does not react with any acid, alkali or salt except caustic soda and hydrofluoric acid, is non-toxic, tasteless, non flammable and non explosive, has strong thermal and cold stability, and is harmless to human body. It is mainly used in beer industry.  

Function:

1. Beer silica gel has a large specific surface area and numerous suitable microporous structures. It may adsorb the protein that causes beer turbidity within a few minutes, and filter it to remove it. The beer storage period can be extended by 180-240 days to prevent beer from cold turbidity.  

2. It does not affect the foam and taste of beer. The physical and chemical properties of beer silica gel determine that it has no effect on beer foam and taste. Practice has also proved that beer silica gel is the safest beer stabilizer recognized by the world beer industry.  

3. Improve the filtering effect. Beer silica gel has stable chemical properties and contains no beer soluble substances. Its surface area and microporous structure are much better than diatomite, and it is a good filter aid. Assisting diatomite filtration can make beer brighter and clearer.  

Blue silica gel

Character:

Blue silica gel is divided into blue gel indicator, color changing silica gel and blue gel. The appearance is blue or light blue glassy particles. According to the shape of the particles, it can be divided into spherical and blocky. It has the function of silica gel to absorb moisture. With the increase of moisture absorption, its color changes from blue to purple, and finally to light red, indicating the humidity of the environment and visually showing whether there is still moisture resistance.  

Purpose:

1. It is mainly used for moisture absorption and rust prevention of instruments, meters and equipment under closed conditions.  

2. It is used together with ordinary silica gel desiccant to indicate the moisture absorption degree of the desiccant and judge the relative humidity of the environment. As a silica gel desiccant for packaging, it is widely used in precision instruments, leather, clothing, food, medicine and household appliances.  

Silica sol

Character: Silica sol is a colloidal solution, odorless and non-toxic. Its molecular formula can be expressed as mSiO2nH2O

1. Because the colloidal particles are fine (10 - 20nm) and have a considerable specific surface area, the particles themselves are colorless and transparent, which will not affect the natural color of the covered objects.  

2. The viscosity is low, and water can penetrate wherever it can, so the dispersivity and permeability are very good when mixed with other substances.  

3. When the water in the silica sol evaporates, the colloidal particles firmly adhere to the surface of the object, forming a silicon oxygen bond between the particles, which is a good adhesive.  

Purpose:

1. It is used as a binder for various refractory materials, with strong adhesion and high temperature resistance (1500-1600 ℃).  

2. It is used in the coating industry, which can make the coating firm, and can also resist pollution, dust, aging, fire and other functions.  

3. It is used for thin shell precision casting, which can make the shell mold strong and the casting finish high. Its molding quality is better than that of sodium silicate, which can reduce the cost and improve the operating conditions.  

4. Silica sol has a high specific surface area and can be used for catalyst manufacturing and catalyst support.  

5. It is used in the paper industry as an anti stick agent for cellophane, a pretreatment agent for photographic paper, and an anti slip agent for cement bags.  

6. It is used as sizing agent for textile industry. It is used together with oil agent to treat the spinnability of wool and rabbit hair, reduce breakage, prevent flying, improve the yield and increase economic benefits.  

7. Used as silicon steel sheet treatment agent, picture tube dispersant, floor wax anti slip, etc.