An environmentally friendly all-round corrosion inhibitor for closed circulating water system and preparation method thereof

Abstract

The present invention discloses an environmentally friendly, all-purpose corrosion inhibitor for closed-circulating water systems and its preparation method. The environmentally friendly, all-purpose corrosion inhibitor for closed-circulating water systems comprises the following components, by weight: 10%-20% organic polycarboxylic acid, 15%-30% alkylolamine, 0.5%-3% copper protective agent, 1%-5% molybdate, 1%-5% tungstate, and the balance pure water. The corrosion inhibitor provided by the present invention contains no phosphorus, silicon, zinc, or other toxic or hazardous heavy metals. It exhibits strong high-temperature resistance, maintaining the shine of carbon steel, brass, and space aluminum test pieces for 72 hours at 65±1°C. It is compatible with a variety of water qualities, including tap water, deionized softened water, and pure water. Its corrosion rates for carbon steel, copper alloys, and aluminum alloys in various water qualities are below the standards specified in GB50050-2017.

Description

Technical Field

[0001] The present invention relates to the field of corrosion inhibitors, and in particular to an environmentally friendly all-purpose corrosion inhibitor for a closed circulating water system and a preparation method thereof. Background Art

[0002] A closed-loop water system is a type of circulating cooling water system. Its characteristics include: no evaporation-induced concentration, minimal make-up water requirements, and the use of demineralized, softened, or purified water. Operating conditions are stringent, including operating temperatures as high as 170°C. The entire system is composed of complex materials, including cast iron, carbon steel, copper alloy, and aluminum alloy, and most are connected. Closed-loop water systems primarily cause oxygen corrosion, caused by the depolarization of dissolved oxygen at the cathode. This corrosion is particularly severe for cast iron, carbon steel, and particularly copper and aluminum.

[0003] Given the current corrosion situation in closed-circulating water systems, the most direct anti-corrosion measure is to add corrosion inhibitors to the circulating water that can significantly inhibit the corrosion of multiple metals. Circulating water system corrosion inhibitors have evolved from initial chromates and polyphosphates to organic phosphonates, and from high-phosphorus, metal-containing formulations to low-phosphorus, all-organic formulations. This demonstrates that water treatment corrosion inhibitors are developing in a diverse, high-efficiency, low-toxic, and environmentally friendly direction. In recent years, with increasing global environmental awareness, new requirements have been placed on the toxic effects and effectiveness of corrosion inhibitors, as well as on the eutrophication caused by harmful elements such as phosphorus and their incompatibility with oxidizing biocides. In line with the sustainable development strategy, promoting green chemistry and researching and developing high-performance, inexpensive, non-toxic, harmless, and pollution-free, environmentally friendly, all-round corrosion inhibitors are the future direction of water treatment corrosion inhibitors.

[0004] At present, in the application of environmentally friendly all-round formulas in China, either the comprehensive corrosion inhibition effect is poor, or the high-temperature corrosion resistance is poor, or the formula ingredients are not environmentally friendly, so there are almost no successful application examples.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The present invention provides an environmentally friendly all-round corrosion inhibitor for a closed circulating water system and a preparation method thereof, which can significantly enhance the comprehensive corrosion inhibition ability of the corrosion inhibitor.

[0007] The present invention adopts the following technical solutions:

[0008] The invention provides an environmentally friendly all-purpose corrosion inhibitor for a closed circulating water system. The corrosion inhibitor comprises the following components by weight: 10% to 20% of an organic polycarboxylic acid, 15% to 30% of an alkyl alcohol amine, 0.5% to 3% of a copper protective agent, 1% to 5% of a molybdate, 1% to 5% of a tungstate, and the balance being pure water.

[0009] Furthermore, the organic polycarboxylic acid includes at least one of a dicarboxylic acid, a tricarboxylic acid, a tetracarboxylic acid, and a pentacarboxylic acid.

[0010] Furthermore, the alkylolamine includes at least one of monoethanolamine, diethanolamine, triethanolamine, and isopropanolamine.

[0011] Furthermore, the copper protective agent includes benzotriazole and / or mercaptobenzothiazole.

[0012] Furthermore, the molybdate includes at least one of sodium molybdate, ammonium molybdate and potassium molybdate.

[0013] Furthermore, the tungstate includes at least one of sodium tungstate, ammonium tungstate, and potassium tungstate.

[0014] The present invention also provides a method for preparing the above-mentioned environmentally friendly all-purpose corrosion inhibitor for closed circulating water systems, comprising the following steps: dissolving organic polycarboxylic acid, alkylolamine, copper protective agent, molybdate, and tungstate in pure water to obtain the environmentally friendly all-purpose corrosion inhibitor for closed circulating water systems.

[0015] Furthermore, the organic polycarboxylic acid, alkylolamine, copper protective agent, molybdate, and tungstate are dissolved in pure water, comprising: adding the alkylolamine to pure water and stirring until completely dissolved; adding the copper protective agent to the resulting solution and stirring and dissolving until the solution is homogeneous and transparent; adding the organic polycarboxylic acid to the resulting solution and stirring and dissolving until the solution is homogeneous and transparent; adding the molybdate to the resulting solution and stirring and dissolving until the solution is homogeneous and transparent; and adding the tungstate to the resulting solution and stirring and dissolving until the solution is homogeneous and transparent.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Contains no phosphorus, silicon, zinc or other toxic or harmful heavy metals.

[0018] 2. Strong high temperature resistance. At a temperature of 65±1℃, carbon steel, brass and space aluminum test pieces will remain as bright as new within 72 hours.

[0019] 3. Applicable to a variety of water qualities, it can be used in tap water, deionized softened water, and pure water. The corrosion rate of carbon steel, copper alloy, and aluminum alloy in various water qualities is lower than the standards specified in GB50050-2017. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 These are the performance test results of the products prepared in Examples 1-3 and the commercially available product TW-1802;

[0022] Figure 2 These are the performance test results of the products made from Example 1 and Comparative Examples 1-5. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical methods in the embodiments of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] An embodiment of the present invention provides an environmentally friendly, all-purpose corrosion inhibitor for closed-circulating water systems. The inhibitor comprises the following components, by weight: 10% to 20% organic polycarboxylic acid, 15% to 30% alkanolamine, 0.5% to 3% copper protectant, 1% to 5% molybdate, 1% to 5% tungstate, and the balance pure water. The sum of the weight percentages of each component is 100%. For example, the environmentally friendly, all-purpose corrosion inhibitor for closed-circulating water systems comprises the following components, by weight: 18% organic polycarboxylic acid, 18% alkanolamine, 2% copper protectant, 2% molybdate, 1% tungstate, and 59% pure water.

[0025] The weight percentage of the organic polycarboxylic acid in the corrosion inhibitor can be 10%, 15%, 20%, etc. The organic polycarboxylic acid can include at least one of a dicarboxylic acid, a tricarboxylic acid, a tetracarboxylic acid, or a pentacarboxylic acid. In other words, the organic polycarboxylic acid can be any one of a dicarboxylic acid, a tricarboxylic acid, a tetracarboxylic acid, or a pentacarboxylic acid, or a combination of two or more. For example, the organic polycarboxylic acid can be a dicarboxylic acid, or a mixture of a tricarboxylic acid and a tetracarboxylic acid. Of course, other combinations are also possible and will not be elaborated here.

[0026] The active ingredients of the above-mentioned organic polycarboxylic acids can react with the oxides on the metal surface to form a uniform and dense complex. These complexes form a stable protective film with good adhesion and isolation properties. This protective film can isolate the metal from the external environment, inhibit the electrochemical reaction, and prevent oxygen and water from further reacting with the metal, thereby slowing down the corrosion rate of the metal.

[0027] The weight percentage of the alkanolamine in the corrosion inhibitor can be 15%, 20%, 25%, 30%, etc. The alkanolamine can include at least one of monoethanolamine, diethanolamine, triethanolamine, and isopropanolamine. In other words, the alkanolamine can be any one of monoethanolamine, diethanolamine, triethanolamine, and isopropanolamine, or a combination of two or more. For example, the alkanolamine can be monoethanolamine, or a mixture of diethanolamine and triethanolamine. Of course, other combinations are also possible and will not be discussed here.

[0028] The aforementioned alkanolamine corrosion inhibitor is an adsorbent organic corrosion inhibitor that absorbs into the gaps of the passivation film, making the film dense and complete, thereby improving the corrosion inhibition rate. In this corrosion inhibitor formulation, it also reacts with the organic heterocyclic polycarboxylic acid to form a polyacid ammonium salt, accelerating the dissolution of the copper protective agent during production.

[0029] The weight percentage of the copper protective agent in the corrosion inhibitor can be 0.5%, 1%, 2%, 3%, etc. The copper protective agent can include benzotriazole and / or mercaptobenzothiazole. In other words, the copper protective agent can be benzotriazole, mercaptobenzothiazole, or a mixture of benzotriazole and mercaptobenzothiazole.

[0030] The copper protective agent in the above corrosion inhibitor formula mainly relies on a chemical adsorption effect with the active copper atoms or copper ions on the surface of the metal copper, or a chelation effect to form a dense and firm protective film, so that the copper equipment is well protected.

[0031] The weight percentage of molybdate in the corrosion inhibitor can be 1%, 2%, 3%, 4%, 5%, etc. The molybdate can include at least one of sodium molybdate, ammonium molybdate, and potassium molybdate. In other words, the molybdate can be any one of sodium molybdate, ammonium molybdate, and potassium molybdate, or a combination of two or more. For example, the molybdate can be sodium molybdate, or a mixture of ammonium molybdate and potassium molybdate. Of course, other combinations are also possible, which will not be elaborated here.

[0032] The weight percentage of tungstate in the corrosion inhibitor can be 1%, 2%, 3%, 4%, 5%, etc. The tungstate can include at least one of sodium tungstate, ammonium tungstate, and potassium tungstate. In other words, the tungstate can be any one of sodium tungstate, ammonium tungstate, and potassium tungstate, or a combination of two or more. For example, the tungstate can be sodium tungstate, or a mixture of ammonium tungstate and potassium tungstate. Of course, other combinations are also possible, which will not be detailed here.

[0033] The molybdate and tungstate in the above-mentioned corrosion inhibitor formula have excellent anodic corrosion inhibition effects. When used in combination with other agents, they can inhibit pitting corrosion, have high thermal stability, and do not form calcium precipitates with calcium ions.

[0034] The corrosion inhibitor of the present invention makes the corrosion inhibition process include the reaction with ferrous ions Fe 2+ First, a non-protective complex is formed, and then the ferrous ion Fe 2+ Then it is oxidized to Fe by dissolved oxygen in water 3+ , at this time Fe 2+ The complex is converted into high iron complex and covers the metal surface to form a protective film.

[0035] The various ingredients in the corrosion inhibitor formula of the present invention exhibit excellent synergistic effects, significantly enhancing the comprehensive corrosion inhibition capability of the corrosion inhibitor. At high temperatures, the inner surfaces of cast iron, carbon steel, brass, and space aluminum test pieces remained bright for 72 hours.

[0036] Compared with existing products, the corrosion inhibitor provided by the present invention has the following advantages:

[0037] 1. Contains no phosphorus, silicon, zinc or other toxic or harmful heavy metals.

[0038] 2. Strong high temperature resistance. At a temperature of 65±1℃, carbon steel, brass and space aluminum test pieces will remain as bright as new within 72 hours.

[0039] 3. Applicable to a variety of water qualities, it can be used in tap water, deionized softened water, and pure water. The corrosion rate of carbon steel, copper alloy, and aluminum alloy in various water qualities is lower than the standards specified in GB50050-2017.

[0040] The present invention also provides a method for preparing the above-mentioned environmentally friendly all-purpose corrosion inhibitor for closed circulating water systems, comprising the following steps: dissolving organic polycarboxylic acid, alkylolamine, copper protective agent, molybdate, and tungstate in pure water to obtain the environmentally friendly all-purpose corrosion inhibitor for closed circulating water systems.

[0041] Specifically, (1) add a formulated amount of alkyl alcohol amine to a formulated amount of pure water at room temperature and stir until completely dissolved. (2) add a formulated amount of copper protective agent to the solution obtained in the above step (1), stir and dissolve until the solution is uniform and transparent. (3) add a formulated amount of organic polycarboxylic acid to the solution obtained in the above step (2), stir and dissolve until the solution is uniform and transparent. (4) add a formulated amount of molybdate to the solution obtained in the above step (3), stir and dissolve until the solution is uniform and transparent. (5) add a formulated amount of tungstate to the solution obtained in the above step (4), stir and dissolve until the solution is uniform and transparent, and obtain an environmentally friendly all-purpose corrosion inhibitor for a closed circulating water system.

[0042] The following is a detailed description with reference to specific embodiments:

[0043] Example 1

[0044] Ingredients:

[0045] 18 parts by weight of tricarboxylic acid-TAT [2,4,6, tris (aminocaproic acid) -1,3,5, -triazine]

[0046] 18 parts by weight of triethanolamine

[0047] 2 parts by weight of benzotriazole

[0048] 2 parts by weight of ammonium molybdate

[0049] 1 part by weight of sodium tungstate

[0050] 59 parts by weight of water

[0051] Preparation method:

[0052] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0053] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0054] (3) Add the formulated amount of TAT to the solution obtained in step (2) above and stir until the solution becomes homogeneous and transparent.

[0055] (4) Add the formulated amount of ammonium molybdate to the solution obtained in step (3) above, and stir until the solution becomes homogeneous and transparent.

[0056] (5) Add the formulated amount of sodium tungstate to the solution obtained in the above step (4), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0057] Example 2

[0058] Ingredients:

[0059] 18 parts by weight of tetracarboxylic acid-NEUF 985 (product of Nuotai Company)

[0060] 18 parts by weight of triethanolamine

[0061] 2 parts by weight of benzotriazole

[0062] 2 parts by weight of ammonium molybdate

[0063] 1 part by weight of sodium tungstate

[0064] 59 parts by weight of water

[0065] Preparation method:

[0066] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0067] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0068] (3) Add the formulated amount of NEUF985 to the solution obtained in step (2) above and stir until the solution becomes homogeneous and transparent.

[0069] (4) Add the formulated amount of ammonium molybdate to the solution obtained in step (3) above, and stir until the solution becomes homogeneous and transparent.

[0070] (5) Add the formulated amount of sodium tungstate to the solution obtained in the above step (4), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0071] Example 3

[0072] Ingredients:

[0073] 8 parts by weight of dicarboxylic acid-aspartic acid

[0074] Tricarboxylic acid-TAT 10 parts by weight

[0075] 18 parts by weight of triethanolamine

[0076] 2 parts by weight of benzotriazole

[0077] 2 parts by weight of ammonium molybdate

[0078] 1 part by weight of sodium tungstate

[0079] 59 parts by weight of water

[0080] Preparation method:

[0081] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0082] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0083] (3) Add the formulated amount of aspartic acid and TAT to the solution obtained in step (2) above, and stir until the solution is homogeneous and transparent.

[0084] (4) Add the formulated amount of ammonium molybdate to the solution obtained in step (3) above, and stir until the solution becomes homogeneous and transparent.

[0085] (5) Add the formulated amount of sodium tungstate to the solution obtained in the above step (4), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0086] Comparative Example 1

[0087] The only difference from Example 1 is that no organic polycarboxylic acid is added to the corrosion inhibitor, specifically as follows:

[0088] Ingredients:

[0089] 18 parts by weight of triethanolamine

[0090] 2 parts by weight of benzotriazole

[0091] 2 parts by weight of ammonium molybdate

[0092] 1 part by weight of sodium tungstate

[0093] 59 parts by weight of water

[0094] Preparation method:

[0095] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0096] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0097] (3) Add the formulated amount of ammonium molybdate to the solution obtained in step (2) above, and stir until the solution becomes homogeneous and transparent.

[0098] (4) Add the formulated amount of sodium tungstate to the solution obtained in the above step (3), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0099] Comparative Example 2

[0100] The only difference from Example 1 is that no alkyl alcohol amine is added to the corrosion inhibitor, specifically as follows:

[0101] Ingredients:

[0102] 18 parts by weight of tricarboxylic acid-TAT [2,4,6, tris (aminocaproic acid) -1,3,5, -triazine]

[0103] 2 parts by weight of benzotriazole

[0104] 2 parts by weight of ammonium molybdate

[0105] 1 part by weight of sodium tungstate

[0106] 59 parts by weight of water

[0107] Preparation method:

[0108] (1) Add the formulated amount of benzotriazole to the formulated amount of water and stir until the solution is homogeneous and transparent.

[0109] (2) Add the formulated amount of TAT to the solution obtained in step (1) above and stir until the solution becomes homogeneous and transparent.

[0110] (3) Add the formulated amount of ammonium molybdate to the solution obtained in step (2) above, and stir until the solution becomes homogeneous and transparent.

[0111] (4) Add the formulated amount of sodium tungstate to the solution obtained in the above step (3), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0112] Comparative Example 3

[0113] The only difference from Example 1 is that no copper protective agent is added to the corrosion inhibitor, specifically as follows:

[0114] Ingredients:

[0115] 18 parts by weight of tricarboxylic acid-TAT [2,4,6, tris (aminocaproic acid) -1,3,5, -triazine]

[0116] 18 parts by weight of triethanolamine

[0117] 2 parts by weight of ammonium molybdate

[0118] 1 part by weight of sodium tungstate

[0119] 59 parts by weight of water

[0120] Preparation method:

[0121] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0122] (2) Add the formulated amount of TAT to the solution obtained in step (1) above and stir until the solution becomes homogeneous and transparent.

[0123] (3) Add the formulated amount of ammonium molybdate to the solution obtained in step (2) above, and stir until the solution becomes homogeneous and transparent.

[0124] (4) Add the formulated amount of sodium tungstate to the solution obtained in the above step (3), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0125] Comparative Example 4

[0126] The only difference from Example 1 is that no molybdate is added to the corrosion inhibitor, specifically as follows:

[0127] Ingredients:

[0128] 18 parts by weight of tricarboxylic acid-TAT [2,4,6, tris (aminocaproic acid) -1,3,5, -triazine]

[0129] 18 parts by weight of triethanolamine

[0130] 2 parts by weight of benzotriazole

[0131] 1 part by weight of sodium tungstate

[0132] 59 parts by weight of water

[0133] Preparation method:

[0134] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0135] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0136] (3) Add the formulated amount of TAT to the solution obtained in step (2) above and stir until the solution becomes homogeneous and transparent.

[0137] (4) Add the formulated amount of sodium tungstate to the solution obtained in the above step (3), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0138] Comparative Example 5

[0139] The only difference from Example 1 is that no tungstate is added to the corrosion inhibitor.

[0140] Ingredients:

[0141] 18 parts by weight of tricarboxylic acid-TAT [2,4,6, tris (aminocaproic acid) -1,3,5, -triazine]

[0142] 18 parts by weight of triethanolamine

[0143] 2 parts by weight of benzotriazole

[0144] 2 parts by weight of ammonium molybdate

[0145] 59 parts by weight of water

[0146] Preparation method:

[0147] (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until completely dissolved.

[0148] (2) Add the formulated amount of benzotriazole to the solution obtained in step (1) above, and stir until the solution becomes homogeneous and transparent.

[0149] (3) Add the formulated amount of TAT to the solution obtained in step (2) above and stir until the solution becomes homogeneous and transparent.

[0150] (4) Add the formulated amount of ammonium molybdate to the solution obtained in the above step (3), and stir until the solution is homogeneous and transparent to obtain a corrosion inhibitor.

[0151] Test Example 1

[0152] The performance of the products prepared according to Examples 1-3 and a commercially available product (TW-1802 frozen water corrosion inhibitor, manufactured by General Bedi Company) was tested as follows.

[0153] 1. Test conditions:

[0154] Instruments and equipment: RCC-II rotary corrosion tester, analytical balance (0.1 mg)

[0155] Test temperature: 65±1℃

[0156] Test time: from the time the sample is placed in the test solution at a temperature of 65±1℃, to the end of 72 hours of immersion.

[0157] Test water: deionized softened water, pure water, tap water

[0158] 2. Use test piece:

[0159] Standard test pieces: ① cast iron, ② 20# carbon steel, ③ brass, ④ space aluminum

[0160] Wipe the test piece clean of anti-rust grease with filter paper, then wash it with absorbent cotton in acetone and anhydrous ethanol respectively, place it on clean filter paper, dry it with filter paper, place it in a desiccator for more than 4 hours, weigh it (accurate to 0.1 mg), and put it in a desiccator for later use.

[0161] Post-treatment: After 72 hours, take out the test piece, wipe off the corrosion products with a soft cloth, then soak it in anhydrous alcohol, dry it with a hair dryer, and weigh it in an anti-corrosion dryer after 24 hours (accurate to 0.1 mg) to calculate the corrosion rate.

[0162] Total concentration of the drug: 1500mg / L 3000mg / L 5000mg / L

[0163] The test results are as follows Figure 1 As shown in the table.

[0164] It can be seen from the data in the table that the corrosion rate of the corrosion inhibitor of the present invention on carbon steel and space aluminum is much lower than 0.075mm / a specified in the requirements of GB50050-2017 Industrial Circulating Cooling Water Treatment Design Specifications, and the corrosion rate on copper alloy is much lower than 0.005mm / a specified in the requirements of GB50050-2017 Industrial Circulating Cooling Water Treatment Design Specifications, and the effect is more obvious compared with commercially available corrosion inhibitors.

[0165] Test Example 2

[0166] The test results are as follows Figure 2 As shown in the table.

[0167] With reference to Test Example 1, the performance of the products made in Example 1 and Comparative Examples 1-5 was tested, and the results were as follows: As can be seen from the data in the table, compared with Comparative Example 1, Example 1 has better corrosion inhibition performance of the product by adding an organic polycarboxylic acid. Compared with Comparative Example 2, Example 1 has better corrosion inhibition performance of the product by adding an alkyl alcohol amine. Compared with Comparative Example 3, Example 1 has better corrosion inhibition performance of the product by adding a copper protective agent. Compared with Comparative Example 4, Example 1 has better corrosion inhibition performance of the product by adding molybdate. Compared with Comparative Example 5, Example 1 has better corrosion inhibition performance of the product by adding tungstate. It can be seen that in the corrosion inhibitor of the present invention, the organic polycarboxylic acid, alkyl alcohol amine, copper protective agent, molybdate, and tungstate act synergistically to significantly enhance the comprehensive corrosion inhibition ability of the corrosion inhibitor.

[0168] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims, the description and their equivalents.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an environmentally friendly all-purpose corrosion inhibitor for a closed circulating water system, characterized in that: The environmentally friendly all-round corrosion inhibitor for the closed circulating water system includes the following components: 18 parts by weight of tetracarboxylic acid, 18 parts by weight of triethanolamine, 2 parts by weight of benzotriazole, 2 parts by weight of ammonium molybdate, 1 part by weight of sodium tungstate, and 59 parts by weight of water; The preparation method comprises the following steps: (1) Add the formulated amount of triethanolamine to the formulated amount of water at room temperature and stir until it is completely dissolved; (2) Add the formulated amount of benzotriazole to the solution obtained in the above step (1) and stir until the solution is uniform and transparent; (3) Add the formulated amount of tetracarboxylic acid to the solution obtained in the above step (2) and stir until the solution is uniform and transparent; (4) Add the formulated amount of ammonium molybdate to the solution obtained in the above step (3) and stir until the solution is uniform and transparent; (5) Add the formulated amount of sodium tungstate to the solution obtained in the above step (4) and stir until the solution is uniform and transparent, thereby obtaining an environmentally friendly all-purpose corrosion inhibitor for a closed circulating water system.

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