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Galvanized wire A stable layer of zinc is coated on the outside of the wire, which is used to protect the wire and make the wire service life longer. When producing galvanized wire, the wire is pickled. Pickling is to use some acid mist or acid to wash off some oxides on the surface of iron, that is, rust, and some other corrosive substances, to achieve the purpose of cleaning iron, so that zinc will fall off when galvanizing.

FDA’s response

As of August 7, the use of titanium dioxide in food is banned in the European Union. Europe is taking a precautionary principle approach based on findings from the European Food Safety Authority (EFSA).

Algaecidal effect of Lithopon: After 5 years of exposure to weathering in Alpen (Lower Rhine)  

CAS: 1345-05-7

Titanium dioxide (TiO₂) is a naturally occurring mineral that is mined from the earth, processed and refined, and added to a variety of foods, as well as other consumer products. White in color, it is used to enhance the color and sheen of certain foods and is also key for food safety applications. In its natural state it exists in different bulk crystalline forms, such as anatase and rutile, but during processing it is ground into a very fine powder.

Breathing problems in offspring

China’s government is working on its plan to eliminate outmoded capacities of TiO2 and strengthen environmental protection measurements. Small and middle-sized enterprises, with a production capacity under 50,000t/a, are the ones to suffer. They mostly get merged or need to withdraw from the market. Without their production capacity of about 500,000 tonnes yearly, the domestic output might shrink about 20%. This will enhance the power of listed companies in China immensely, which is one of the main reasons for the effort to go public.

Further outstanding properties of Lithopone are its high lightness, neutral white colour and its diffuse reflectance in the near UV range.

White powder

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.

States looking to ban titanium dioxide as a food additive