High hardness high alkalinity circulating cooling water corrosion and scale inhibitor and preparation method thereof

Abstract

The application relates to the technical field of circulating cooling water agents, and particularly discloses a high-hardness and high-alkalinity circulating cooling water corrosion and scale inhibitor and a preparation method thereof. The high-hardness and high-alkalinity circulating cooling water corrosion and scale inhibitor is made of the following raw materials in percentage by weight: polyepoxysuccinic acid 15-25%, dendritic pyridine inner salt ligand 5-15%, benzene propyl triazole 5-10%, 2-thiouracil 3-8%, molybdenum salt 3-8%, polyhydric alcohol 5-10%, polyoxyethylene ether 2-4%, bacteriostatic agent 0.5-1.5%, and water. The corrosion and scale inhibitor is applied to high-hardness and high-alkalinity circulating cooling water through mutual cooperation between the raw materials, effectively reduces the corrosion rate of carbon steel, brass and stainless steel, prolongs the service life of the metal base material, makes the corrosion and scale inhibitor exhibit higher corrosion inhibition effect, and meets the market demand.

Description

Technical Field

[0001] This application relates to the field of circulating cooling water agents, and more specifically, it relates to a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water and its preparation method. Background Technology

[0002] In industrial production, circulating cooling water systems are a crucial component for maintaining normal equipment operation. They are primarily used to cool products and equipment, thereby ensuring industrial production efficiency. During long-term use, the concentration of solutes in the circulating cooling water increases with water evaporation, thus increasing the hardness and alkalinity of the water. Direct use of high-hardness, high-alkalinity circulating cooling water can easily lead to corrosion and scaling of equipment and pipelines, posing a safety hazard to the operational stability of these systems. In existing technologies, some researchers use corrosion and scale inhibitors in circulating cooling water. These inhibitors are generally composed of organophosphorus compounds, copolymers, and zinc salts. While they can provide some corrosion inhibition, the effect is insufficient and needs further improvement. Summary of the Invention

[0003] To improve the corrosion inhibition effect of corrosion and scale inhibitors, this application provides a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water and its preparation method.

[0004] In a first aspect, this application provides a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water, employing the following technical solution:

[0005] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water is made from the following raw materials in weight percentages: 15-25% polyepoxysuccinic acid, 5-15% dendritic pyridine inner salt ligand, 5-10% benzotriazole, 3-8% 2-thiouracil, 3-8% molybdenum salt, 5-10% polyol, 2-4% polyoxyethylene ether, 0.5-1.5% antibacterial agent, and the balance being water.

[0006] The corrosion and scale inhibitor of this application, through the synergistic effect of the raw materials, is applied to high-hardness, high-alkalinity circulating cooling water. The circulating cooling water has a calcium hardness of 240 ppm and an alkalinity of 195 ppm, both of which are calculated as calcium carbonate. Under these conditions, the corrosion rate of carbon steel is <0.005 mm / a, the corrosion rate of brass is <0.002 mm / a, and the corrosion rate of stainless steel is <0.002 mm / a. This allows the corrosion and scale inhibitor to exhibit the advantage of high corrosion inhibition, meeting market demand.

[0007] Adding polyols and polyoxyethylene ethers to the raw materials effectively increases their compatibility and improves the stability of the corrosion and scale inhibitor during storage and use. Adding polyepoxysuccinic acid and dendritic pyridine internal salt ligands to the raw materials effectively chelates metal ions to form stable chelates. In particular, the dendritic pyridine internal salt ligands, containing a large number of pyridine and carboxyl groups, not only have a chelating effect, disrupting scale formation, but also hindering contact and aggregation between chelates. Simultaneously, they can form a protective film on the metal substrate surface, isolating the metal substrate from corrosive substances, reducing the corrosion rate of the metal substrate, extending its service life, and enabling the corrosion and scale inhibitor to exhibit superior corrosion inhibition performance.

[0008] Optionally, the molybdenum salt is one or more of sodium molybdate, potassium molybdate, and ammonium molybdate.

[0009] By adopting the above technical solutions, the molybdenum salt is optimized, making the selection of molybdenum salt easier. Moreover, the raw materials for sodium molybdate, potassium molybdate, and ammonium molybdate are abundant and inexpensive.

[0010] Optionally, the polyol is one or more of ethylene glycol, glycerol, pentaerythritol, xylitol, and sorbitol.

[0011] By adopting the above technical solutions, the polyols are optimized, making the selection of polyols easier. Moreover, the raw materials for ethylene glycol, glycerol, pentaerythritol, xylitol, and sorbitol are abundant and inexpensive.

[0012] Optionally, the antibacterial agent is one or more of sodium dichloroisocyanurate, bromochlorohydantoin, and methylchloroisothiazolinone.

[0013] By adopting the above technical solutions, the antibacterial agents are optimized, making it easier to select them. Moreover, sodium dichloroisocyanurate, bromochlorohydantoin, and methylchloroisothiazolinone all have good bactericidal and bacteriostatic effects, as well as excellent stability, long-lasting effect, and safety, making them suitable for circulating cooling water.

[0014] Optionally, the dendritic pyridine inner salt ligand is prepared using the following method:

[0015] T1. The organic solvent, butanediamine, and ethyl acrylate were added and reacted. The mixture was then added again and reacted. The mixture was then added again and reacted. Finally, ethyl isonicotinic acid was added and reacted. The mixture was concentrated under reduced pressure and dried to obtain a dendritic intermediate.

[0016] T2. Mix the organic solvent, the dendritic intermediate, and methyl 4-(bromomethyl)benzoate, heat to react, cool, filter, wash, and dry to obtain a semi-finished product.

[0017] T3. Mix the sodium hydroxide aqueous solution and the semi-finished product, heat the mixture to react, cool it down, filter, wash, and dry it to obtain the dendritic pyridine inner salt ligand.

[0018] The weight ratio of the first addition of butanediamine, the first addition of ethyl acrylate, the second addition of butanediamine, the second addition of ethyl acrylate, the third addition of butanediamine, ethyl isonicotinate, and methyl 4-(bromomethyl)benzoate is (0.5-1.5):(4-5):(3-5):(8-10):(7-9):(25-30):(35-45).

[0019] By employing the above technical solution, firstly, the amino groups in the first addition of butanediamine react with the carbon-carbon double bonds in the first addition of ethyl acrylate, introducing ester groups and increasing the number of branches. The introduced ester groups react with the amino groups in the second addition of butanediamine, introducing amide and amino groups. The introduced amino groups react with the carbon-carbon double bonds in the second addition of ethyl acrylate, introducing ester groups again and increasing the number of branches. The introduced ester groups react with the amino groups in the third addition of butanediamine, introducing amide and amino groups. The introduced amino groups react with the ester groups in ethyl isonicotinic acid, achieving grafting and introducing pyridine groups, obtaining a dendritic intermediate containing a large number of amide and pyridine groups. Then, methyl 4-(bromomethyl)benzoate is added, causing the bromine groups therein to react with the pyridine groups in the dendritic intermediate, achieving grafting and introducing ester groups. Further, under the action of sodium hydroxide aqueous solution, the ester groups undergo hydrolysis to form salts, obtaining dendritic pyridine inner salt ligands.

[0020] The method for preparing dendritic pyridine internal salt ligands in this application involves reacting the raw materials in stages, which facilitates reaction control, increases the stability of the preparation, and ensures the quality of the dendritic pyridine internal salt ligands. Furthermore, the dendritic pyridine internal salt ligands contain a large number of branches, as well as numerous amide, pyridine, and carboxyl groups. Utilizing the synergistic effects between these groups, corrosion and scale inhibitors can be applied to circulating cooling water to reduce the corrosion rate of metal substrates, resulting in superior performance.

[0021] Optionally, the weight ratio of methyl 4-(bromomethyl)benzoate to sodium hydroxide aqueous solution is (35-45):(700-1300), and the mass concentration of sodium hydroxide aqueous solution is 5-15%. Preferably, the weight ratio of methyl 4-(bromomethyl)benzoate to sodium hydroxide aqueous solution is (35-45):(900-1100), and the mass concentration of sodium hydroxide aqueous solution is 7-13%. More preferably, the weight ratio of methyl 4-(bromomethyl)benzoate to sodium hydroxide aqueous solution is (35-45):1000, and the mass concentration of sodium hydroxide aqueous solution is 9-11%.

[0022] By adopting the above technical solution, the weight ratio of methyl 4-(bromomethyl)benzoate and sodium hydroxide aqueous solution is optimized, and the mass concentration of sodium hydroxide aqueous solution is also optimized, thereby achieving the optimization of the weight ratio of methyl 4-(bromomethyl)benzoate and sodium hydroxide, which facilitates the complete hydrolysis of ester groups in the semi-finished product and the formation of salt.

[0023] Optionally, in step S1, the reaction time for the first addition of butanediamine and the first addition of ethyl acrylate is 18-22h, the reaction time for the second addition of butanediamine is 13-17h, the reaction time for the second addition of ethyl acrylate is 18-22h, the reaction time for the third addition of butanediamine is 13-17h, and the reaction time for the addition of ethyl isonicotinic acid is 13-17h.

[0024] In step S2, the reaction temperature of the dendritic intermediate and methyl 4-(bromomethyl)benzoate is 70-80℃ and the reaction time is 7-9h.

[0025] In step S3, the reaction temperature of the sodium hydroxide aqueous solution and the semi-finished product is 80-90℃ and the reaction time is 3-5h.

[0026] By adopting the above technical solution, the reaction time in step S1 is limited, as are the reaction temperature and reaction time in step S2 and step S3, ensuring the stability of the reaction and facilitating the preparation of dendritic pyridine internal salt ligands.

[0027] In step S1, in several embodiments, the reaction time for the first addition of butanediamine and the first addition of ethyl acrylate is 20 hours. However, the reaction time can also be set to 18 hours, 19 hours, 21 hours, or 22 hours as needed, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. In several embodiments, the reaction time for the second addition of butanediamine is 15 hours. However, the reaction time can also be set to 13 hours, 14 hours, 16 hours, or 17 hours as needed, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. In several embodiments, the reaction time for the third addition of butanediamine is 15 hours. However, the reaction time can also be set to 13 hours, 14 hours, 16 hours, or 17 hours as needed, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. In several implementations, the reaction time for adding ethyl isonicotinic acid is 15 hours. The reaction time can also be set to 13 hours, 14 hours, 16 hours, or 17 hours as needed, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] In step S2, in several embodiments, the reaction temperature of the dendritic intermediate and methyl 4-(bromomethyl)benzoate is 78°C and the time is 8h. The temperature can also be set to 70°C, 72°C, 75°C, or 80°C as needed, and the time can also be set to 7h, 7.5h, 8.5h, or 9h as needed, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] In step S3, the reaction temperature of the sodium hydroxide aqueous solution and the semi-finished product is 90℃ and the time is 4h. The temperature can also be set to 80℃, 82℃, 85℃, or 88℃ as needed, and the time can be set to 3h, 3.5h, 4.5h, or 5h as needed. However, it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Optionally, in step S1, the organic solvent is ethanol, and in step S2, the organic solvent is acetonitrile.

[0031] By employing the above technical solution, the organic solvent in step S1 is limited, which facilitates the selection of the organic solvent and the reaction of butanediamine, ethyl acrylate, and ethyl isonicotinate. Furthermore, ethanol, which is the same as the organic solvent, is generated during the amidation reaction, facilitating subsequent vacuum concentration and drying. The organic solvent in step S2 is also limited, ensuring thorough mixing of the dendritic intermediate and methyl 4-(bromomethyl)benzoate, guaranteeing reaction stability, and facilitating the subsequent precipitation of the semi-finished product.

[0032] Optionally, in step S1, the weight ratio of butanediamine to organic solvent added for the first time is (0.5-1.5):(700-1300). Preferably, the weight ratio of butanediamine to organic solvent added for the first time is (0.5-1.5):(900-1100). More preferably, the weight ratio of butanediamine to organic solvent added for the first time is (0.5-1.5):1000.

[0033] Optionally, in step S2, the weight ratio of methyl 4-(bromomethyl)benzoate to the organic solvent is (35-45):(700-1300). Preferably, the weight ratio of methyl 4-(bromomethyl)benzoate to the organic solvent is (0.5-1.5):(900-1100). More preferably, the weight ratio of methyl 4-(bromomethyl)benzoate to the organic solvent is (0.5-1.5):1000.

[0034] By adopting the above technical solution, the amount of organic solvent added in step S1 is limited, and the amount of organic solvent added in step S2 is also limited, so that the raw materials are fully mixed.

[0035] Secondly, this application provides a method for preparing the aforementioned corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water, employing the following technical solution:

[0036] A method for preparing a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water includes the following steps:

[0037] A corrosion and scale inhibitor is obtained by mixing water, polyepoxysuccinic acid, dendritic pyridine internal salt ligand, benzotriazole, 2-thiouracil, molybdenum salt, polyol, polyoxyethylene ether, and antibacterial agent.

[0038] By adopting the above technical solution, it is convenient to prepare corrosion and scale inhibitors.

[0039] Optionally, the corrosion and scale inhibitor can be prepared by adding polyol and polyoxyethylene ether to water, then adding polyepoxysuccinic acid, dendritic pyridine inner salt ligand, benzotriazole, and 2-thiouracil, followed by adding molybdenum salt and antibacterial agent to obtain the corrosion and scale inhibitor.

[0040] In summary, this application has at least the following beneficial effects:

[0041] 1. This application relates to a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water. Through the synergistic effect of the raw materials, it is applied to high-hardness, high-alkalinity circulating cooling water. The metal substrate exhibits a low corrosion rate: carbon steel corrosion rate <0.005mm / a, brass corrosion rate <0.002mm / a, and stainless steel corrosion rate <0.002mm / a. This gives the corrosion and scale inhibitor the advantage of high corrosion inhibition, meeting market demand.

[0042] 2. In the preparation method of the dendritic pyridine internal salt ligand of this application, butanediamine and ethyl acrylate are reacted stepwise, followed by grafting of ethyl isonicotinate, then grafting of methyl 4-(bromomethyl)benzoate, and finally hydrolyzing the ester groups to obtain the dendritic pyridine internal salt ligand. Using the above method, the raw materials react in steps, which facilitates reaction control, increases the stability of the preparation, ensures the quality of the dendritic pyridine internal salt ligand, and improves the corrosion inhibition effect of the corrosion and scale inhibitor. Detailed Implementation

[0043] To make this application easier to understand, the following detailed description will be provided with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of this application. Unless otherwise specified, the raw materials or components used in this application can be obtained commercially or by conventional methods.

[0044] Preparation Example

[0045] Preparation Example 1

[0046] A dendritic pyridine inner salt ligand is prepared by the following method:

[0047] T1. At a speed of 500 r / min, 1 g of butanediamine and 4.5 g of ethyl acrylate were added to 1000 g of organic solvent for the first time, and the mixture was stirred for 20 h.

[0048] Add 4g of butanediamine for the second time and stir the reaction for 15 hours.

[0049] Add 9.1g of ethyl acrylate for the second time and stir to react for 20h.

[0050] Add 8g of butanediamine for the third time and stir the reaction for 15 hours.

[0051] Add 27.5g of ethyl isonicotinic acid and stir for 15 hours.

[0052] Then, the mixture is concentrated under reduced pressure to remove most of the ethanol. After drying, the remaining ethanol is removed to obtain the dendritic intermediate.

[0053] The organic solvent is ethanol.

[0054] T2. At a rotation speed of 500 r / min, add the dendritic intermediate obtained in step T1 and 41.6 g of methyl 4-(bromomethyl)benzoate to 1000 g of organic solvent. Heat to 78 °C, maintain the temperature and stir for 8 h, then cool to 23 °C. Filter and wash three times with acetonitrile, using 50 g of acetonitrile each time. Then dry to obtain the semi-finished product.

[0055] The organic solvent is acetonitrile.

[0056] T3. At a rotation speed of 500 r / min, the semi-finished product obtained in step T2 was added to 1000 g of sodium hydroxide aqueous solution. The temperature was raised to 90℃, and the reaction was maintained at this temperature with stirring for 4 h. The temperature was then lowered to 23℃. The mixture was then filtered and washed three times with 50 g of ethanol each time. After drying, the dendritic pyridine inner salt ligand was obtained.

[0057] The sodium hydroxide aqueous solution has a mass concentration of 10%.

[0058] Preparation Example 2

[0059] A dendritic pyridine inner salt ligand differs from that in Preparation Example 1 in that, in step T1, the amounts of butanediamine, ethyl acrylate, butanediamine, ethyl acrylate, and isonicotinic acid ethyl ester added are different: the first addition of butanediamine is 0.5 g, the first addition of ethyl acrylate is 4 g, the second addition of butanediamine is 5 g, the second addition of ethyl acrylate is 10 g, the third addition of butanediamine is 7 g, and the third addition of isonicotinic acid ethyl ester is 25 g. Simultaneously, in step T2, the amount of methyl 4-(bromomethyl)benzoate added is different, and the amount of methyl 4-(bromomethyl)benzoate added is 45 g.

[0060] Preparation Example 3

[0061] A dendritic pyridine inner salt ligand differs from that in Preparation Example 1 in that, in step T1, the amounts of butanediamine, ethyl acrylate, butanediamine, ethyl acrylate, and isonicotinic acid ethyl ester added are different: the first addition of butanediamine is 1.5 g, the first addition of ethyl acrylate is 5 g, the second addition of butanediamine is 3 g, the second addition of ethyl acrylate is 8 g, the third addition of butanediamine is 9 g, and the third addition of isonicotinic acid ethyl ester is 30 g. Similarly, in step T2, the amount of methyl 4-(bromomethyl)benzoate added is different, and the amount of methyl 4-(bromomethyl)benzoate added is 35 g.

[0062] Example

[0063] Table 1. Dosage of raw materials for corrosion and scale inhibitors (unit: g)

[0064]

[0065]

[0066] Example 1

[0067] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water, the raw materials and their proportions are shown in Table 1.

[0068] The polyepoxysuccinic acid content was 99%, and it was selected from Hubei Huada Fine Chemical Co., Ltd.; the molybdenum salt was sodium molybdate; the polyol was glycerol; the polyoxyethylene ether was polyoxyethylene ether OE-35; the antibacterial agent was sodium dichloroisocyanurate; and the dendritic pyridine inner salt ligand was prepared by the method of Preparation Example 1.

[0069] A method for preparing a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water includes the following steps:

[0070] At a rotation speed of 500 r / min, polyol and polyoxyethylene ether were added to water and stirred for 3 min. Then, polyepoxysuccinic acid, dendritic pyridine internal salt ligand, benzotriazole, and 2-thiouracil were added and stirred for 5 min. After that, molybdenum salt and antibacterial agent were added and stirred for 5 min to obtain corrosion and scale inhibitor.

[0071] Example 2

[0072] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that the raw material ratio of the corrosion and scale inhibitor is different, and the raw material ratio of the corrosion and scale inhibitor is shown in Table 1.

[0073] Example 3

[0074] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that the raw material ratio of the corrosion and scale inhibitor is different, and the raw material ratio of the corrosion and scale inhibitor is shown in Table 1.

[0075] Example 4

[0076] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that the source of the dendritic pyridine internal salt ligand in the raw materials of the corrosion and scale inhibitor is different, and the dendritic pyridine internal salt ligand is prepared by the method of Preparation Example 2.

[0077] Example 5

[0078] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that the source of the dendritic pyridine internal salt ligand in the raw materials of the corrosion and scale inhibitor is different, and the dendritic pyridine internal salt ligand is prepared by the method of Preparation Example 3.

[0079] Comparative Example

[0080] Comparative Example 1

[0081] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that an equal amount of diethylenetriaminepentimethylenephosphonic acid replaces the dendritic pyridine inner salt ligand in the raw materials of the corrosion and scale inhibitor.

[0082] Comparative Example 2

[0083] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that an equal amount of hydroxypropanesulfonic acid pyridine salt replaces the dendritic pyridine internal salt ligand in the raw materials of the corrosion and scale inhibitor.

[0084] Comparative Example 3

[0085] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that an equal amount of dendritic intermediates replace the dendritic pyridine internal salt ligands in the raw materials of the corrosion and scale inhibitor. The dendritic intermediates are prepared using the method in step T1 of Example 1.

[0086] Comparative Example 4

[0087] A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Example 1 in that an equal amount of pyridine inner salt ligand is used to replace the dendritic pyridine inner salt ligand in the raw materials of the corrosion and scale inhibitor.

[0088] Pyridine inner salt ligands were prepared using the following method:

[0089] T1. At a rotation speed of 500 r / min, add 27.5 g of ethyl isonicotinate and 41.6 g of methyl 4-(bromomethyl)benzoate to 1000 g of organic solvent. Heat to 78 °C and stir for 8 h. Then cool to 23 °C. Filter and wash three times with acetonitrile, using 50 g of acetonitrile each time. Dry to obtain a semi-finished product.

[0090] The organic solvent is acetonitrile.

[0091] T2. At a rotation speed of 500 r / min, the semi-finished product obtained in step T1 was added to 1000 g of sodium hydroxide aqueous solution. The temperature was raised to 90℃, and the reaction was maintained at this temperature with stirring for 4 h. The temperature was then lowered to 23℃. The mixture was then filtered, washed three times with 50 g of ethanol each time, and dried to obtain the pyridine inner salt ligand.

[0092] The sodium hydroxide aqueous solution has a mass concentration of 10%.

[0093] Application examples

[0094] Application Example 1

[0095] Application of a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water. The corrosion and scale inhibitor is used in the circulating cooling water with a calcium hardness of 240 ppm and an alkalinity of 195 ppm, both calculated as calcium carbonate. The dosage of the corrosion and scale inhibitor is 30 mg / L based on the circulating cooling water. The corrosion and scale inhibitor is prepared using the method described in Example 1.

[0096] Application Example 2-5

[0097] The application of a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water differs from Application Example 1 in that the source of the corrosion and scale inhibitor is different, and the corrosion and scale inhibitors used in Application Examples 2-5 are prepared sequentially using the methods of Examples 2-5.

[0098] The performance testing was conducted according to GB / T18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotary Coating Method". The corrosion rate of the corrosion-inhibiting and scale-inhibiting agents obtained in Examples 1-5 and Comparative Examples 1-4 was tested, and the test results are shown in Table 2.

[0099] The corrosion-resistant pads were made of Q235 carbon steel, H62 brass, and 304 stainless steel, respectively. The rotation speed of the corrosion-resistant pads was 100 r / min, and the time was 168 h. The calcium hardness of the test water was 240 ppm, the alkalinity was 195 ppm, and the temperature was 70 ℃. Both calcium hardness and alkalinity were expressed as calcium carbonate and based on the test water. The dosage of the corrosion and scale inhibitor was 30 mg / L.

[0100] Table 2 Detection Results

[0101] Testing items Corrosion rate of carbon steel (mm / a) Brass corrosion rate (mm / a) Stainless steel corrosion rate (mm / a) Example 1 0.0028 0.0011 0.0008 Example 2 0.0031 0.0013 0.0009 Example 3 0.0041 0.0019 0.0016 Example 4 0.0037 0.0016 0.0013 Example 5 0.0039 0.0017 0.0015 Comparative Example 1 0.0072 0.0051 0.0046 Comparative Example 2 0.0063 0.0042 0.0035 Comparative Example 3 0.0077 0.0055 0.0051 Comparative Example 4 0.0056 0.0031 0.0029

[0102] As can be seen from Table 2, the corrosion-resistant pads have a low corrosion rate, with carbon steel corrosion rate of 0.0028-0.0041 mm / a, brass corrosion rate of 0.0011-0.0019 mm / a, and stainless steel corrosion rate of 0.0008-0.0016 mm / a. This demonstrates the high corrosion inhibition properties of the corrosion and scale inhibitor, meeting market demands.

[0103] Comparing Example 1 and Comparative Examples 1-2, the raw material of the corrosion and scale inhibitor in Comparative Example 1 contained diethylenetriaminepentamethylenephosphonic acid; the raw material of the corrosion and scale inhibitor in Comparative Example 2 contained pyridine hydroxypropanesulfonic acid; and the raw material of the corrosion and scale inhibitor in Example 1 contained dendritic pyridine inner salt ligands. It can be seen that, compared to diethylenetriaminepentamethylenephosphonic acid and pyridine hydroxypropanesulfonic acid, the addition of dendritic pyridine inner salt ligands to the raw material can significantly reduce the corrosion rates of carbon steel, brass, and stainless steel.

[0104] Comparing Example 1 and Comparative Examples 3-4, the raw material of the corrosion and scale inhibitor in Comparative Example 3 contained a dendritic intermediate; the raw material of the corrosion and scale inhibitor in Comparative Example 4 contained a pyridine inner salt ligand; and the raw material of the corrosion and scale inhibitor in Example 1 contained a dendritic pyridine inner salt ligand. It can be seen that adding a dendritic pyridine inner salt ligand to the raw material has a better corrosion inhibition effect than adding either the dendritic intermediate or the dendritic pyridine inner salt ligand alone, and results in a superior performance of the corrosion and scale inhibitor.

[0105] It should be noted that the embodiments described above are only for explaining this application and do not constitute any limitation on this application. This application has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to this application within the scope of the claims, and revisions can be made to the invention without departing from the scope and spirit of this application. Although the application described herein relates to specific methods, materials, and embodiments, it does not mean that this application is limited to the specific examples disclosed herein; on the contrary, this application can be extended to all other methods and applications with the same function.

Claims

1. A corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water, characterized in that: The corrosion and scale inhibitor is made from the following raw materials in weight percentages: 15-25% polyepoxysuccinic acid, 5-15% dendritic pyridine inner salt ligand, 5-10% benzotriazole, 3-8% 2-thiouracil, 3-8% molybdenum salt, 5-10% polyol, 2-4% polyoxyethylene ether, 0.5-1.5% antibacterial agent, and the balance being water; The antibacterial agent is one or more of sodium dichloroisocyanurate, bromochlorohydantoin, and methylchloroisothiazolinone. The dendritic pyridine inner salt ligand was prepared by the following method: T1. The organic solvent, butanediamine, and ethyl acrylate were added and reacted. The mixture was then added again and reacted. The mixture was then added again and reacted. Finally, ethyl isonicotinic acid was added and reacted. The mixture was concentrated under reduced pressure and dried to obtain a dendritic intermediate. T2. Mix the organic solvent, the dendritic intermediate, and methyl 4-(bromomethyl)benzoate, heat to react, cool, filter, wash, and dry to obtain a semi-finished product. T3. Mix the sodium hydroxide aqueous solution and the semi-finished product, heat the mixture to react, cool it down, filter, wash, and dry it to obtain the dendritic pyridine inner salt ligand. The weight ratio of the first addition of butanediamine, the first addition of ethyl acrylate, the second addition of butanediamine, the second addition of ethyl acrylate, the third addition of butanediamine, ethyl isonicotinate, and methyl 4-(bromomethyl)benzoate is (0.5-1.5):(4-5):(3-5):(8-10):(7-9):(25-30):(35-45).

2. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: The molybdenum salt is one or more of sodium molybdate, potassium molybdate, and ammonium molybdate.

3. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: The polyol is one or more of ethylene glycol, glycerol, pentaerythritol, xylitol, and sorbitol.

4. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: The weight ratio of methyl 4-(bromomethyl)benzoate to sodium hydroxide aqueous solution is (35-45):(700-1300), and the mass concentration of sodium hydroxide aqueous solution is 5-15%.

5. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: In step S1, the reaction time for the first addition of butanediamine and the first addition of ethyl acrylate is 18-22h, the reaction time for the second addition of butanediamine is 13-17h, the reaction time for the second addition of ethyl acrylate is 18-22h, the reaction time for the third addition of butanediamine is 13-17h, and the reaction time for the addition of ethyl isonicotinic acid is 13-17h. In step S2, the reaction temperature of the dendritic intermediate and methyl 4-(bromomethyl)benzoate is 70-80℃ and the reaction time is 7-9h. In step S3, the reaction temperature of the sodium hydroxide aqueous solution and the semi-finished product is 80-90℃ and the reaction time is 3-5h.

6. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: In step S1, the organic solvent is ethanol, and in step S2, the organic solvent is acetonitrile.

7. The corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water according to claim 1, characterized in that: In step S1, the weight ratio of butanediamine and organic solvent added for the first time is (0.5-1.5):(700-1300); In step S2, the weight ratio of methyl 4-(bromomethyl)benzoate to organic solvent is (35-45):(700-1300).

8. A method for preparing a corrosion and scale inhibitor for high-hardness, high-alkalinity circulating cooling water as described in any one of claims 1-7, characterized in that: Includes the following steps: A corrosion and scale inhibitor is obtained by mixing water, polyepoxysuccinic acid, dendritic pyridine internal salt ligand, benzotriazole, 2-thiouracil, molybdenum salt, polyol, polyoxyethylene ether, and antibacterial agent.

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