Hydroxyethylidene diphosphonic acid (HEDP), chemical product, an organic phosphoric acid scale inhibitor, can form stable complexes with various metal ions such as iron, copper, zinc, etc., and can dissolve oxides on metal surfaces.
Product FeaturesHEDP is an organic phosphate scale inhibitor that forms stable complexes with various metal ions such as iron, copper and zinc, and dissolves oxides on metal surfaces. HEDP can still play a good role in corrosion inhibition and scale inhibition at 250 ° C. It is stable at high pH and is not easy to be hydrolyzed. It is not easy to decompose under light and heat conditions. Acid and alkali resistance and chlorine oxidation resistance are better than other organic phosphoric acid (salt). HEDP can form a six-ring chelate with metal ions in water, especially calcium ions. Therefore, HEDP has good scale inhibition effect and obvious solubility limiting effect. It is ideal when used in combination with other water treatment agents. Synergistic effect.
HEDP solids are high-purity products suitable for use in cold winters; they are especially suitable for cleaning agents and household chemicals in the electronics industry.
Product Usage
[Use 1] is a scale inhibitor and corrosion inhibitor for boilers and heat exchangers, a complexing agent for cyanide-free plating, a chelating agent for soaps, a cleaning agent for metals and non-metals.
[Use 2] It is often used as a scale and corrosion inhibitor in boiler water, circulating water, and oilfield water injection treatment. Often formulated with polyhydroxy acid scale inhibitors and dispersants. It can also be used as a cyanide-free plating complexing agent, a fixing agent for bleaching and dyeing industry, and a hydrogen peroxide stabilizer.
[Use 3] This product is the main material for cyanide-free plating. It is formulated into a cyanide-free copper plating solution, and the copper plating layer directly on the steel has good bonding strength. The coating is smooth and the color is good. The general dosage is 60% and the content is 100-120 ml/L. The amount of copper sulfate is 15-20 g/L. In addition, before plating, the plated parts are immersed in the 1% to 2% solution of the product to turn the plated parts into an activated state, and then electroplating can further improve the effect.
[Use 4] This product is a new type of chlorine-free electroplating complexing agent, which is used as a main agent for water quality stabilization in the circulating cooling water system to prevent corrosion and scale inhibition. This product is one of the organic polyphosphonate-free water tablets. There are also some varieties of such products in China, such as aminotrimethylenephosphonic acid (ATMP): [CH2PO(OH)2]3N and B. Diamine tetramethylene phosphate (EDTMP) and the like. Organic polyphosphonic acid is a type of water treatment agent developed in the late 1960s and confirmed around the 1970s. The emergence of such treatments has made water slab technology a big step forward. Compared with organic polyphosphates, organic polyphosphonic acids have good chemical stability, are not easy to hydrolyze, can withstand higher temperatures and small amounts of chemicals, and have the characteristics of botheviating erosion performance. It is a kind of cathode type corrosion inhibitor and a kind of non-chemical equivalent scale inhibitor. When used in combination with other water treatment agents, it exhibits an ideal synergistic effect. It has excellent chelating energy for many metal ions such as calcium, magnesium, copper, zinc, etc., and even has good deactivation of inorganic salts such as CaSO4, CaCO3, MgSiO3, etc., so it is widely used in water treatment. technology. The product is low in toxicity, and the subcutaneous injection LD50 of the mice is 486.4 mg/kg.
[Usage 5] As a scale inhibitor, the concentration is generally 1~10mg/L, and the concentration is generally 10~50mg/L. The cleaning agent is generally used at a concentration of 1000~2000mg/L; usually with polycarboxylate type scale inhibition The dispersant is used in combination.
[Use 6] In the case of simulating the quality of industrial boilers, the method for determining HEDP in furnace water was optimized, the high temperature dissociation characteristics of HEDP, and the scale inhibition performance and corrosion inhibition performance of HEDP were studied. Some of the following conclusions. HEDP is used as a scale and corrosion inhibitor in boiler water. The first problem to be solved is the determination of HEDP. However, the HG/T3537-1999 standard method is cumbersome for the analysis and detection of HEDP (the measurement time generally takes 2-3 hours), and the method of detecting HEDP using cerium nitrate complex titration, although the measurement procedure is simple, lanthanum nitrate is one kind of Radioactive substances not only impose a great burden on the environment, but are also harmful to the human body. The determination of HEDP was studied by an improved spectrophotometry, and the measurement time was greatly reduced (the measurement can be completed within 20-30 minutes). In addition, the effects of various ions that may exist in the industrial boiler water were investigated, and the measurement conditions (wavelength 470 nm, pH less than 2, reaction time 5 minutes, color development time 15 minutes) were determined. When the content of NaCl in the furnace water is lower than 500mg/L; the concentration of Ca2+ is less than 300mg/L; the content of phosphate is less than 20mg/L; and the content of SO42- is less than 50mg/L, it will not interfere with the detection of HEDP. Through the precision test of the HEDP in the simulated furnace water, the relative standard deviation is less than 1%, and the method has the advantages of simple, rapid, sensitive and anti-interference. The stability of HEDP in furnace water directly affects the performance of scale inhibition and corrosion inhibition. Therefore, the thermal decomposition characteristics of HEDP in simulated industrial boiler water under aerobic and anaerobic conditions and different pH conditions are studied. Under aerobic conditions With the increase of temperature, the decomposition rate of HEDP also increases, and the decomposition of CHEDP at 140 °C is intensified. When the temperature reaches 160 °C, HEDP is almost completely decomposed, and the decomposition products are mainly phosphate compounds. Under anaerobic conditions, HEDP also decomposes with increasing temperature. HEDP will decompose to a large extent above 200 °C, but it can withstand higher temperatures than HEDP decomposition under aerobic conditions. This shows that to make HEDP work well, it is very important to control the oxygen content in the furnace water. The effect of pH value change on the thermal decomposition characteristics of HEDP was studied at 150 °C. Experiments show that the change of pH has little effect on the thermal decomposition of HEDP, and HEDP can exist stably under high alkaline conditions. The scale inhibition performance of HEDP was tested by conductance method and static scale inhibition experiment. The results show that the conductivity method and static scale inhibition method have consistent evaluation of the scale inhibition performance of HEDP. With the increase of HEDP concentration, the scale inhibition rate gradually increases. Increase, but the scale inhibition efficiency of HEDP has a certain critical value. After increasing to a certain extent, the scale inhibition rate will not change much. Adding 5-7mg/L HEDP to the solution can achieve higher scale inhibition rate; in addition, its scale inhibition performance is also related to the concentration ratio and pH value of the solution; the effect of temperature on the scale inhibition performance of HEDP Large, as the temperature increases, the scale inhibition performance of HEDP also decreases. Under the conditions of low calcium ion concentration and HCO3-concentration, HEDP has a good inhibitory effect on calcium carbonate scale. High calcium ion concentration and HCO3-concentration can inhibit the scale inhibition performance of HEDP. The corrosion inhibition performance of HEDP on carbon steel No. 20 under normal temperature conditions was studied by electrochemical impedance spectroscopy, Tafel polarization curve method and autoclave coupon experiment. Experiments show that a certain concentration of HEDP (25mg / L) can effectively inhibit the corrosion of carbon steel, electrochemical experiments and high temperature coupon experiments have consistent results; HEDP autoclave coupon test shows that within the operating temperature range of industrial boilers, The oxidation rate of No. 20 carbon steel in the simulated furnace water is smaller than the dissolution rate, and the test piece shows weight loss. Although the addition of HEDP can not reduce the Cl- concentration in the furnace water, the addition of HEDP can effectively inhibit the corrosion of chloride ions directly on the metal. Thereby the presence of a relatively high concentration of chloride ions in the boiler water can be tolerated. Through the test and analysis of HEDP concentration in the simulated furnace water to affect the HEDP scale inhibition and corrosion inhibition performance, the aggressive anion in the furnace water, temperature and other factors, the scale inhibition performance of HEDP and the corrosion inhibition of No. 20 carbon steel were comprehensively evaluated. Performance, get the appropriate condition parameters, can provide reference for actual production.
