Definition and classification of water treatment agents

Water treatment chemicals refer to the chemical agents used in water treatment. Chemicals commonly used for sewage treatment. Widely used in chemical, petroleum, light industry, daily chemical, textile, printing and dyeing, construction, metallurgy, machinery, medicine, health, transportation, urban and rural environmental protection and other industries, in order to achieve the purpose of saving water and prevent water pollution. Such as cooling water and boiler water treatment, sea water desalination, membrane separation, biological treatment, flocculation and ion exchange, etc.. Such as corrosion inhibitor, scale inhibitor, sterilization, algae removal agent, flocculant, ion exchange resin, cleaning agent, cleaning agent, pre membrane agent, etc..
Therefore, it is necessary to note each group between due to inappropriate compound and antagonism, the effect of lowering or loss, should fully utilize synergistic effect (the coexistence of several insecticides synergism) and efficiency. In addition, most of the water treatment system is open system, there will be a certain amount of emissions, use to take into account the impact of various types of water treatment agent on the environment. A class of corrosion inhibitor with appropriate concentration and form in the water, can prevent or slow down the corrosion of water on metal materials or equipment chemicals, with good effect, less dosage, easy to use and so on.
There are many types and varieties of corrosion inhibitors, according to the types of compounds, can be divided into inorganic and organic corrosion inhibitor. The inhibition of the reaction is anodic reaction, cathode reaction or both, can be divided into anodic type corrosion inhibitor, cathodic type inhibitor or mixed type corrosion inhibitor. The corrosion inhibitor can also be divided into the passive film type, the precipitation film type and the adsorption film type by the mechanism of forming a protective film on the metal surface. At present, in the water treatment widely used passivation membrane type corrosion agents such as chromate, nitrite, molybdate and; common precipitation membrane type corrosion inhibitor polymeric phosphate, zinc salt; commonly used adsorption membrane type corrosion agent such as organic amine.
Inhibitor also called scale inhibitor, which can inhibit the calcium and magnesium salts and other chemicals to form scale scaling. Natural inhibitors such as tannin, lignin derivatives; inorganic inhibitor such as six partial sodium phosphate, sodium tripolyphosphate, etc.; organic polymer, scale inhibitor, which polymer scale inhibitor effect best, with future development. Widely used in water treatment in organic and polymer scale inhibitors are of two kinds: organic phosphonic acids such as EDTMP (ethylene diamine tetra (methylene phosphonic acid), HEDP (hydroxy ethylene diphosphonic acid), poly carboxylic acid, such as polyacrylic acid salt, hydrolysis of poly maleic anhydride and so on. The scale inhibition effect of these two kinds of scale inhibitors is usually achieved through the crystal lattice distortion, and the dispersion and aggregation function, and the system is widely used in oilfield water, boiler water and industrial cooling water.
Bactericidal agent, also known as bactericidal algae or sludge stripping agent, anti sludge agent, etc., refers to a class of microorganisms used to inhibit the growth of algae and other microorganisms in the water to prevent the formation of microbial slime chemicals. Usually divided into oxidizing and non oxidizing fungicides two types of fungicides. Oxidative bactericidal agent, such as commonly used chlorine, sodium hypochlorite, bleaching powder, etc.; non oxidizing bactericide has good effect, widely used is destroying the bacterial cell wall and cytoplasm of chemicals, such as quaternary ammonium salt. Quaternary ammonium salt such as chlorinated dodecyl dimethyl benzyl ammonium bromide or dodecyl dimethyl benzyl ammonium, often both sterilization, peeling, corrosion inhibition, future development. It has been used in oil field water, industrial cooling water.
A class of chemicals that are used to remove or reduce turbidity or suspended solids in water, to speed up the removal of impurities and sludge in water. The earliest application of the flocculant is inorganic flocculants, such as alum, ferric chloride. Organic and polymeric flocculant are widely used in water supply and wastewater treatment in the future. Can be divided into anionic flocculant, such as carboxymethyl cellulose, sodium polyacrylate, cationic flocculant, such as polyethylene amine, etc., as well as non ionic flocculant, such as polyacrylamide and so on. The flocculation effect is realized mainly by charge neutralization and adsorption bridging.
Cleaning agents for oilfield water treatment in the application of a kind of special chemicals to remove oily wastewater in mechanical impurities and oil, its role besides the flocculants the separation of suspended solids or mechanical impurities, also has separation of oil and water purification. Therefore, in addition to the purification agent containing a general flocculant components such as aluminum salts, polyacrylamide, etc., often contain a number of surface active agent. For the purification effect of purifying agent, the general use of membrane filter to be measured, with the filter factor (see filter) the size of the purification effect of good or bad.
Cleaning agent a class of chemicals with cleaning action. In the preprocessing step of water treatment, it is often necessary to use some chemical cleaning equipment metal surface sediments, such as corrosion and scale and microbial slime. According to the different requirements of cleaning, the cleaning agent can be divided into pickling agents such as hydrochloric acid, sulfuric acid, hydrofluoric acid, citric acid, etc.; a passivating agent such as sodium benzoate. At present, the use of the sulfonated succinate two (alpha ethyl ester) sodium salt, is a surfactant, as a special cleaning agent for cleaning the metal surface of the oil and rust and other impurities.
A class of chemicals that can form a protective film on the metal surface prior to the pretreatment of the film in water treatment. Pre film has two purposes: one is in the use of chemicals inhibiting corrosion increased at the beginning of dosing concentration; the second is the use of a special pre filming agent, to in the normal operation of the investment plus a small amount of corrosion inhibitor, can maintain and repair protective film, saving reagent and fees

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