Water treatment agent<br>Water treatment agent refers to the chemicals added in the water treatment process in order to remove most harmful substances (such as corrosives, metal ions, dirt, microorganisms, etc.) in the water and get the civil or industrial water meeting the requirements. Water treatment agent is an important category of fine chemical products, which has a strong specificity. Different water treatment agents are required for different purposes and treatment objects.<br>brief introduction<br>Water treatment agent is a kind of chemical agent for water treatment, which is widely used in petroleum, chemical industry, metallurgy, transportation, light industry, textile and other industrial sectors. Water treatment agents include corrosion inhibitor, scale inhibitor, bactericide, flocculant, purifying agent, cleaning agent, pre membrane agent, etc. In practical application, water treatment agents with compound formula are often used, or all kinds of water treatment agents are used comprehensively. Therefore, we should not only pay attention to the antagonism between the components due to improper combination, so as to reduce or lose the effect, but also make full use of the synergistic effect (the synergistic effect produced by the coexistence of several chemicals) to increase the efficiency. In addition, most of the water treatment systems are open systems, which will have a certain amount of emissions. The impact of various water treatment agents on the environment should be considered when using.<br>Common water treatment agents include: flocculant, ferrous sulfate heptahydrate, polymerized iron salt, calcium hydroxide, ferric chloride hexahydrate, bactericide and algaecide, chlorine dioxide, scale and corrosion inhibitor, polyacrylamide (cation, anion, non-ion), polyaluminium chloride, polyaluminium chloride iron, ferrous sulfate, etc.<br>classification<br>Water treatment agent corrosion inhibitor<br>A kind of chemicals, which can prevent or slow down the corrosion of metal materials or equipment by water after being added into water with proper concentration and form, has the characteristics of good effect, small amount and convenient use. There are many types and varieties of corrosion inhibitors. According to the types of compounds, they can be divided into inorganic and organic corrosion inhibitors. According to its inhibition reaction is anode reaction, cathode reaction or both, it can be divided into anode type inhibitor, cathode type inhibitor or mixed type inhibitor. The inhibitor can also be divided into passivation film, precipitation film and adsorption film according to the mechanism of forming protective film on the metal surface. In water treatment, passivation film inhibitors are commonly used, such as chromate, nitrite, molybdate, etc.; precipitation film inhibitors are commonly used, such as polyphosphate, zinc salt, etc.; adsorption film inhibitors are commonly used, such as organic amine, etc.<br>Water treatment agent dispersant<br>The earliest scale inhibitor and dispersant is polyacrylic acid (sodium), which has good scale inhibition performance on calcium carbonate scale, but has very low inhibition on calcium phosphate deposition. This kind of polycarboxylic acid scale inhibitor not only has the function of agglomeration and dispersion, but also causes crystal lattice distortion in the growth process, thus hindering the solid deposition of scale layer on the metal heat transfer surface. Later, it was found that acrylic acid copolymers had excellent inhibition ability to both, so they gradually replaced polyacrylic acid (sodium). Organic polyphosphonate is not only an anionic corrosion inhibitor, but also a non chemical equivalent chelating scale inhibitor. It not only has a significant low limit effect on calcium, magnesium, zinc and iron plasma, but also has a synergistic effect on other agents, which is widely used in cooling water treatment. Organic phosphonate is a kind of cationic corrosion inhibitor, and the main mechanism of scale inhibition is lattice distortion. It is a kind of corrosion inhibitor for metal iron, but also has the function of controlling calcium scale; the dosage is smaller than phosphonate and can be hydrolyzed, so there is no problem of accumulation of dosage and pollution discharge, and the hydrolysate can be biodegraded.<br>Water treatment agent scale inhibitor<br>Also known as scale inhibitor, it refers to a kind of chemicals that can inhibit the formation of scale salts such as calcium and magnesium in water. There are natural scale inhibitors such as tannin and lignin derivatives, inorganic scale inhibitors such as sodium hexametaphosphate and sodium tripolyphosphate, organic and polymer scale inhibitors, among which polymer scale inhibitors have the best effect and have a bright future. There are two kinds of organic and polymer scale inhibitors widely used in water treatment: ① organic phosphonic acids such as edtmps (ethylenediamine tetramethylene phosphonic acid), HEDP (hydroxyethylenediphosphonic acid), etc.; ② polycarboxylic acids such as polyacrylic acid, hydrolyzed polymaleic anhydride, etc. The scale inhibition of these two kinds of scale inhibitors is usually realized by lattice distortion and dispersion agglomeration. They are widely used in oilfield water, boiler water and industrial cooling water systems.<br>Water treatment agent bactericide<br>It is also called bactericide and algaecide, sludge stripper, anti sludge agent, etc. It refers to a kind of chemicals used to inhibit the growth of microorganisms such as bacteria and algae in water, so as to prevent the formation of microbial slime. Generally, it can be divided into two categories: oxidizing bactericide and non oxidizing bactericide. Oxidizing fungicides, such as chlorine, sodium hypochlorite, bleaching powder (main component calcium hypochlorite), chlorine dioxide, etc.; non oxidizing fungicides, which have good effect and are widely used, are chemicals that can damage the cell wall and cytoplasm of bacteria, such as quaternary ammonium salt, etc. Quaternary ammonium salts, such as dodecyl dimethylbenzyl ammonium chloride or dodecyl dimethylbenzyl ammonium bromide, often have multiple functions such as sterilization, stripping, corrosion inhibition and so on. They have a bright future and have been used in oilfield water, industrial cooling water and so on.<br>Water treatment agent flocculant<br>A class of chemicals used to remove or reduce turbidity or suspended matter in water and accelerate the settling speed of impurities and sludge in water. Inorganic flocculants, such as alum and ferric chloride, were the first used in scientific and innovative flocculants. Organic and polymer flocculants are widely used in water supply and wastewater treatment in the future. It can be divided into anionic flocculants, such as carboxymethylcellulose, sodium polyacrylate, etc.; cationic flocculants, such as polyvinylamine, etc.; and non-ionic flocculants<br>
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