How to classify water treatment agents
The water treatment agent includes a corrosion inhibitor, a scale inhibitor, a bactericide, a flocculant, a purifying agent, a cleaning agent, a pre-filming agent, and the like. In practical applications, a composite formulation of a water treatment agent or a combination of various water treatment agents is often used. Therefore, it is necessary to pay attention to the antagonistic effects between the components due to improper compounding, so that the effect is reduced or lost, and the synergistic effect (the synergistic effect produced by the coexistence of several agents) is also fully utilized to increase the efficiency. In addition, most water treatment systems are open systems with a certain amount of emissions, taking into account the environmental impact of various water treatment agents.
Corrosion inhibitors : A type of chemical that can prevent or slow the corrosion of water to metal materials or equipment by adding it to water at an appropriate concentration and form. It has good effects, low dosage, and ease of use.
There are many types and varieties of corrosion inhibitors. According to the types of compounds, they can be classified into inorganic corrosion inhibitors and organic corrosion inhibitors. The reaction inhibited by the reaction is an anode reaction, a cathodic reaction or both, and can be classified into an anode type corrosion inhibitor, a cathode type corrosion inhibitor or a mixed type corrosion inhibitor. The corrosion inhibitor can also be classified into a passivation film type, a precipitation film type, an adsorption film type, and the like according to a mechanism of forming a protective film on the metal surface. At present, passivation film type corrosion inhibitors commonly used in water treatment such as chromate, nitrite, molybdate, etc.; commonly used precipitation film type corrosion inhibitors are polymeric phosphates, zinc salts, etc.; commonly used adsorption membranes Type corrosion inhibitors such as organic amines.
Scale inhibitor ：Also known as scale inhibitor, it refers to a class of chemicals that can inhibit the formation of scale by the formation of scale salts such as calcium and magnesium in water. There are natural scale inhibitors such as tannins, lignin derivatives, etc.; inorganic scale inhibitors such as sodium hexametaphosphate, sodium tripolyphosphate, etc.; organic and high molecular scale inhibitors, among which polymer antifouling agents are most effective. Good, has a promising future. There are two types of organic and high-molecular scale inhibitors used in water treatment: 1 organic phosphonic acids such as EDTMP (ethylenediaminetetramethylenephosphonic acid), HEDP (hydroxyethylidene diphosphonic acid), etc. 2 polycarboxylic acid, such as polyacrylate, hydrolyzed polymaleic anhydride, and the like. The scale inhibition of these two types of scale inhibitors is usually achieved by lattice distortion and dispersion-coacervation. It is widely used in oilfield water, boiler water and industrial cooling water.
Fungicides ：Also known as bactericidal algaecides or sludge strippers, anti-sludge agents, etc., refer to a class of chemicals used to inhibit the growth of microorganisms such as algae in water to prevent the formation of microbial slime. It is usually divided into two types: oxidizing fungicides and non-oxidizing fungicides. Oxidizing bactericides, such as commonly used chlorine gas, sodium hypochlorite, bleaching powder, etc.; non-oxidizing bactericides have good effects and are widely used in the cell wall and cytoplasmic chemicals that can destroy bacteria, such as quaternary ammonium salts. Among the quaternary ammonium salts, such as dodecyldimethylbenzylammonium chloride or dodecyldimethylbenzylammonium bromide, etc., often have various effects such as sterilization, peeling, corrosion inhibition, etc., and have a promising future. It has been applied to oilfield water and industrial cooling water.
Flocculant A class of chemicals used to remove or reduce turbidity or suspended solids in water to accelerate the rate of sediment and sludge settling in water. The earliest application of flocculants is inorganic flocculants such as alum and ferric chloride. Organic and high-molecular flocculants are widely used as flocculants in feedwater and wastewater treatment. Can be divided into anionic flocculants, such as carboxymethyl cellulose, sodium polyacrylate, etc.; cationic flocculants, such as polyvinylamine; and non-ionic flocculants, such as polyacrylamide. Their flocculation is mainly achieved by charge neutralization and adsorption bridging.
A special chemical used in water treatment of purifying oil fields to remove mechanical impurities and oil from oily sewage. In addition to the separated suspended solids or mechanical impurities from the flocculant, it also has the purification effect of oil-water separation. . Therefore, such a scavenger often contains some surfactants in addition to general flocculant components such as aluminum salts, polyacrylamides and the like. For the purification effect of the purifying agent, it is generally measured by a membrane filter, and the size of the membrane factor (see filtration) indicates the purification effect.
Cleaning agent A type of chemical that has a cleaning action. In the pretreatment step of water treatment, it is often necessary to use some chemicals to clean deposits on the surface of metal equipment, such as corrosion products and scales, 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.; passivating agents such as sodium benzoate. At present, the sodium sulfonated succinic acid bis(α-ethylhexyl) salt is a surfactant used as a special cleaning agent for cleaning impurities such as oil stains and floating rust on metal surfaces.
Pre-filming agent A type of chemical that can form a protective film on a metal surface in a pretreatment step of water treatment. There are two purposes for pre-filming: one is to increase the concentration of the chemical in the initial stage of corrosion inhibition; the other is to use a special pre-filming agent to add a small amount of corrosion inhibitor in normal operation. Maintain and repair protective film, saving pharmacy and cost. Currently used pre-filming agents are sodium hexametaphosphate plus zinc salt, sodium tripolyphosphate and the like.
