2: Clarification mechanism of coagulant

Chemical coagulation is a process in which chemical agents (coagulants) are added to water treatment to make colloidal dispersion system destabilize and agglomerate. In the coagulation process, small suspended particles and colloidal impurities are aggregated into larger solid particles to separate particulate impurities from water, which is called coagulation clarification.

After adding coagulant into water, colloidal particles and other small particles can be polymerized into larger flocs through the comprehensive action of mixing, coagulation and flocculation. The whole process of coagulation and flocculation is called coagulation.

(1) Destabilization and condensation of colloids

Adding electrolyte to water can compress the electric double layer and destabilize the colloid. The main mechanism is that the electric double layer of colloidal particles in water is compressed or neutralized by adding aluminum salt or iron salt coagulant. The coagulant and raw water are mixed rapidly and evenly, and a series of chemical reactions are produced to destabilize. This process takes a short time, generally about 1 min. Some cationic polymers can also play a role in the destabilization and condensation of colloids in water. These polymers have a long chain structure and positive charge in water. Their destabilization and condensation of colloids in water is due to the interaction of van der Waals force adsorption and electrostatic attraction.

(2) Flocculation and formation of floc (alum)

The particle size of the initial flocculate formed by colloid destabilization and coagulation in water is generally more than 1 m. at this time, Brownian motion can no longer push them to collide and form larger particles. In order to make the initial flocs collide with each other to form large flocs, it is necessary to input additional energy into the water to produce a velocity gradient. Sometimes it is necessary to add organic polymer flocculant into water, and the adsorption bridging effect of long chain molecules of flocculant is used to improve the probability of collision and adhesion. Flocculation efficiency usually increases with the increase of flocculate concentration and flocculation time.

Compared with polyaluminum chloride, polyaluminum chloride has the advantages of high density, fast settling speed and wide pH adaptability; the coagulation effect is less affected by temperature than that of polyaluminum sulfate; however, when adding ferric salt, it should be noted that when the equipment is not in normal operation, the iron ions will make the effluent color, and may pollute the subsequent desalination equipment.

At present, the equipment and manufacturing process of domestic manufacturers of polyvinyl butyral are constantly getting closer to those abroad. For example, the wonderful use of polyvinyl butyral (PVB) has occurred in the printing industry and ceramic industry. Therefore, the domestic application of polyvinyl butyral (PVB) has an obvious upward trend in recent years.

For example, in the glass industry, it is because polyvinyl butyral (PVB) has good low-temperature impact strength, windability, light transmittance, light resistance, weather resistance, sound insulation, UV insulation and other properties, so that once the laminated glass is sealed together, the glass sandwich (i.e. laminated material) will appear as a whole and look like ordinary glass. For example, in the porcelain industry, polyvinyl butyral is made into a film and used for printing paper film of ceramic (or enamel) products. First, it reduces the original glue small paper Decal process, reduces the production cycle and production cost, and second, it makes its ceramic (or enamel) patterns bright in color and smooth in texture.

With the rapid development of science and technology in recent years, more and more industries have found the characteristics of polyvinyl butyral (PVB): high strength, high toughness, fatigue resistance, corrosion resistance and so on. Compared with traditional materials, polyvinyl butyral (PVB) is more and more widely used because of its larger development space and wider application fields!

Application field of polyvinyl butyral -- safety glass

The membrane made of polyvinyl butyral (PVB) is a special product used to manufacture safety glass and bulletproof glass. Safety glass is a special glass made of a layer of PVB diaphragm sandwiched between two layers of ordinary glass. It has good low-temperature impact strength, windability, light transmittance, light resistance, weather resistance, sound insulation, ultraviolet insulation and other properties. When subjected to strong external impact, PVB diaphragm can absorb impact energy, so that the glass will not break or prevent debris from hurting people. Moreover, the safety glass added with PVB diaphragm has the characteristics of high transparency, water resistance and aging resistance, and can be used in the environment of - 60 ℃. In addition, it can also be used as transparent material to replace plexiglass.

Application field of polyvinyl butyral -- ceramic film flower paper