A composite corrosion and scale inhibitor, its preparation method and application

Abstract

This invention belongs to the technical field of corrosion and scale inhibitors, and relates to a composite corrosion and scale inhibitor, its preparation method, and its application. The composite corrosion and scale inhibitor comprises, by weight percentage: 10%-20% phosphorus compound, 25%-40% polycarboxylic acid composition, 2%-5% organic amine compound, 2%-5% amino acid, 5-10% water-soluble inorganic metal salt, and deionized water to make up to 100%. This composite corrosion and scale inhibitor has a relatively low organic phosphorus content and overcomes the shortcomings of traditional single-agent agents, such as significant critical threshold effects and high environmental toxicity, through the synergistic effect of multiple components. Furthermore, it can be directly applied to weakly acidic water bodies with a pH less than 7.

Description

Technical Field

[0001] This invention belongs to the technical field of corrosion and scale inhibitors, and relates to a composite corrosion and scale inhibitor, its preparation method and application, particularly a composite corrosion and scale inhibitor suitable for industrial circulating cooling water systems, its preparation method and application. Background Technology

[0002] Circulating cooling water systems provide cooling or temperature control services to production processes through the evaporation of circulating water, accompanying the entire production process. During use, the circulating cooling water continuously evaporates and concentrates, and the dissolved salts are continuously concentrated, resulting in severe scaling and corrosion of the cooling water pipes. It is also prone to the growth of bacteria and algae, which affects the heat transfer effect of the equipment and shortens its service life. To solve these problems, it is necessary to treat the circulating cooling water.

[0003] Organophosphonic acids are a widely used class of water treatment agents. Developed abroad in the mid-1960s and confirmed in the 1970s, they possess good chemical stability, high-temperature resistance, and the advantages of low dosage, corrosion inhibition, and scale inhibition. Furthermore, organophosphonic acids exhibit excellent chelating ability for many metal ions, solving the problem of calcium carbonate scale formation in systems. The presence of CP bonds contributes to their chemical stability and high-temperature resistance, exhibiting significant "solution limit effect" and "synergistic effect." However, organophosphonic acids cannot effectively inhibit the deposition of calcium phosphate, zinc, and iron oxide scale in phosphorus-based and phosphorus-zinc-based water treatment formulations. The discharge of phosphorus-containing wastewater can also cause eutrophication and red tides. Foreign countries have implemented phosphorus restriction or ban measures, and my country is also strongly advocating the development of low-phosphorus and phosphorus-free products. Copolymer scale inhibitors are a new type of water treatment agent developed in the 1980s. They offer superior performance, good compatibility, and phosphorus-free pollution, with broad development prospects. However, their high price and inability to meet water treatment needs when used alone necessitate the addition of other components for compounding. Meanwhile, when replenishing the circulating water with an alkalinity of less than 30 mg / L (calculated as calcium carbonate), the pH of the naturally running circulating water is generally less than 7.0. Most current water treatment formulas are alkaline. When treating weakly acidic water with a pH less than 7.0, it is generally necessary to add alkaline substances to the circulating water system to adjust the pH of the circulating water to above 7.5, and then use an alkaline water treatment formula for treatment. This method consumes a lot of alkali and is costly. In addition, it is labor-intensive and has limited treatment effect.

[0004] CN101560022B discloses a composite corrosion and scale inhibitor, which is made from organic phosphonic acid, acrylic acid or acrylic acid copolymer, polymaleic acid, azole derivatives, poly-organic amine sulfonates, dimethylformamide or alcohol, and water in a specific mass ratio. This composite corrosion and scale inhibitor is used in systems where greywater is used as circulating cooling water, and can solve the corrosion caused by greywater circulating water to equipment. However, this composite corrosion and scale inhibitor has a high phosphorus content and complex composition, and is only suitable for systems where greywater is used as circulating cooling water, thus limiting its application. CN109110935A discloses a corrosion and scale inhibitor for low hardness and low alkalinity and its preparation method. This formulation is a high-phosphorus formulation. Low-salinity systems generally have a high concentration ratio, resulting in phosphorus enrichment in the system. In addition, a certain amount of calcium ions in the water is required to participate in the film-forming reaction. CN101805067A discloses a phosphorus-free green composite corrosion and scale inhibitor, which contains polyaspartic acid or polyepoxysuccinic acid, maleic acid homopolymer, acrylic copolymer, inorganic zinc salt, ECH corrosion inhibitor synergist and water. The phosphorus-free green composite corrosion and scale inhibitor is only suitable for treating alkaline water and not for treating acidic water.

[0005] Therefore, there is a need for a composite corrosion and scale inhibitor with low phosphorus content that can be directly applied to weakly acidic water bodies with a pH less than 7. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention aims to provide a composite corrosion and scale inhibitor, its synthesis method, and its application. This composite corrosion and scale inhibitor has a relatively low organic phosphorus content and overcomes the shortcomings of traditional single agents, such as significant critical threshold effects and high environmental toxicity, through the synergistic effect of multiple components. Furthermore, it can be directly applied to weakly acidic water bodies with a pH less than 7.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution.

[0008] A composite corrosion and scale inhibitor comprises, by weight percentage: 10%-20% phosphorus compound, 25%-40% polycarboxylic acid composition, 2%-5% organic amine compound, 2%-5% amino acid, 5-10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0009] Furthermore, the phosphine compounds are inorganic phosphorus compounds and organic phosphorus compounds.

[0010] Furthermore, the weight ratio of inorganic phosphorus compounds to organic phosphorus compounds is 0.1-0.4:1.

[0011] Furthermore, the inorganic phosphorus compound is one or more combinations of phosphoric acid and its potassium, sodium, ammonium and aluminum salts.

[0012] Furthermore, the organophosphorus compound contains at least one functional group selected from amino, hydroxyl, carboxyl, or ester groups.

[0013] Furthermore, the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers.

[0014] Furthermore, the weight ratio of polyepoxysuccinic acid and sulfonate copolymer is 0.75-2:1.

[0015] Furthermore, the sulfonate copolymer is one or more combinations of acrylic acid / propyl sulfonic acid copolymer, acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid copolymer, acrylic acid / methyl ethyl acrylate sulfonic acid copolymer, acrylic acid / propoxy polyethoxy sulfonate copolymer, maleic anhydride / propoxy polyethoxy sulfonate copolymer, or acrylic acid / isoprene sulfonate / hydroxypropyl acrylate copolymer.

[0016] Furthermore, the organic amine compound is one or more combinations of ethanolamine, diethanolamine, triethanolamine, hexadecylamine, octadecylamine, dihexylamine, cyclohexylamine, aliphatic polyamine, aromatic polyamine, or ammonium dodecyl sulfate.

[0017] Furthermore, the amino acid is one or more combinations of glycine, tryptophan, alanine, or arginine.

[0018] Furthermore, the water-soluble inorganic metal salts are zinc salts, sodium salts, potassium salts, or calcium salts.

[0019] A method for preparing a composite corrosion and scale inhibitor includes the following steps:

[0020] Step 1: Dissolve the phosphorus compound in deionized water at 40-50℃ to obtain mixed solution 1;

[0021] Step 2: Add the polycarboxylic acid composition to mixed solution 1 and stir for 30-60 minutes to obtain mixed solution 2;

[0022] Step 3: Add organic amine compound, amino acid and water-soluble inorganic metal salt to mixed solution 2 in sequence, adjust the pH of the solution to 8-10, and obtain mixed solution 3;

[0023] Step 4: Filter the mixed solution 3 to obtain a light yellow transparent liquid, which is the composite corrosion and scale inhibitor.

[0024] This composite corrosion and scale inhibitor is suitable for industrial circulating cooling water systems.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0026] 1. The composite corrosion and scale inhibitor prepared by the present invention using phosphorus compounds, polycarboxylic acid compositions, organic amine compounds, amino acids, water-soluble inorganic metal salts and deionized water can be effectively applied to various industrial circulating cooling water systems, effectively inhibiting scale formation, and has outstanding anti-corrosion performance. It can effectively improve the heat transfer efficiency of equipment, reduce energy consumption, and reduce equipment failures and maintenance frequency caused by scaling.

[0027] 2. Based on the system of this invention, the combined use of inorganic phosphorus compounds and organic phosphorus compounds, when organic phosphorus-containing corrosion and scale inhibitors are used in combination with low relative molecular mass polyelectrolytes, produces a synergistic effect, thereby improving the corrosion and scale inhibition effect of the agents. The addition of inorganic phosphorus compounds effectively improves the chelation and dispersion of organic phosphorus compounds, more efficiently forming stable soluble chelates with scale-forming ions such as calcium and magnesium in water, increasing the solubility of calcium and magnesium salts, inhibiting scale formation, and interfering with the crystallization process of inorganic salts, leading to lattice distortion, preventing crystal nuclei or crystal particles from growing according to the normal lattice arrangement, thus dispersing them in water and slowing down the scaling rate. At the same time, the organic phosphorus content is much lower than that of commercially available conventional corrosion and scale inhibitors, which helps to reduce environmental pollution and lower production costs.

[0028] 3. Based on the system of this invention, the combined use of phosphorus compounds and polycarboxylic acid compositions effectively improves scale inhibition efficiency and enhances corrosion inhibition effect. Phosphorus compounds can form stable soluble chelates with scale-forming ions such as calcium and magnesium in water, increasing the solubility of these metal ions. Polycarboxylic acid scale inhibitors, through the negatively charged molecular chains generated by ionization, form water-soluble complexes or chelates with calcium ions, further improving the solubility of scale-forming compounds. At the same time, both phosphorus compounds and polycarboxylic acid compositions can adsorb around crystal nuclei or crystal particles at the initial stage of scale salt formation, preventing them from growing according to the normal crystal lattice arrangement, thus dispersing them in the water. This lattice distortion effect effectively prevents scale formation. The combination of the two has a synergistic effect, significantly enhancing this chelation and lattice distortion effect, and has a wider range of action.

[0029] 4. Based on the system of this invention, organic amine compounds and amino acids are used in combination. Both organic amine compounds and amino acid molecules contain polar groups, which can be firmly attached to the metal surface through electrostatic adsorption or van der Waals forces to form a protective film that isolates the metal from the corrosive medium, thereby inhibiting the corrosion reaction. The synergistic effect of the combination of the two significantly enhances the corrosion inhibition effect. At the same time, the addition of strong alkaline organic amine compounds enables this composite corrosion and scale inhibitor to maintain excellent performance in a weakly acidic environment and can be directly applied to weakly acidic water bodies with a pH of less than 7.

[0030] 5. Based on the system of this invention, by adding water-soluble inorganic metal salts, a protective film can be formed on the metal surface, isolating the metal from contact with corrosive media (such as oxygen, acid and alkali ions), thereby significantly slowing down the corrosion rate. At the same time, the addition of water-soluble inorganic metal salts and the polycarboxylic acid composition produce a synergistic effect of chelation, solubilization and solubility enhancement, lattice distortion and scale structure optimization, and corrosion inhibition, which complement each other. After the inorganic metal salts and polycarboxylic acid substances are combined, they can form more stable complexes. These complexes can more effectively bind metal ions, preventing them from reacting with anions to form scale, thereby significantly improving the scale inhibition effect and the corrosion inhibition performance of the system. The polycarboxylic acid composition generates negatively charged molecular chains through ionization, increasing the solubility of scale-forming compounds. This solubilization effect is synergistic with the complexation effect of inorganic metal salts, further reducing the tendency of scale precipitation. After the inorganic metal salts and polycarboxylic acid compositions are combined, the polymer chains can be more uniformly adsorbed on the scale surface, interfering with the normal growth of grains and making them smooth and soft. This lattice distortion significantly improves the fluidity of the scale layer, making it easier for water to wash away, thereby enhancing the scale inhibition performance. Both water-soluble inorganic metal salts and polycarboxylic acid compositions reduce the activity of metal ions through complexation reactions, reducing the risk of corrosion. The synergistic effect of the two can more comprehensively protect metal equipment and extend its service life.

[0031] 6. Based on the system of this invention, the combination of inorganic phosphorus compounds and inorganic metal salts results in a synergistic effect whereby they work together to act on scale-forming ions in water. By forming stable complexes and precipitates, they reduce scale formation and prevent corrosion of metal surfaces. This synergistic effect not only improves the scale inhibition efficiency of the corrosion and scale inhibitor but also enhances its corrosion inhibition performance, thereby effectively protecting metal equipment from corrosion. At the same time, the specific combination of inorganic phosphorus compounds and inorganic metal salts effectively improves the stability of the system, ensuring that the composite corrosion and scale inhibitor does not or rarely exhibits precipitation or stratification during long-term storage.

[0032] In summary, this composite corrosion and scale inhibitor maintains excellent performance even in a weakly acidic environment and can be directly applied to weakly acidic water bodies with a pH less than 7. Detailed Implementation

[0033] To facilitate understanding of the present invention, the technical solution of the present invention will be fully described below in conjunction with specific embodiments. However, the embodiments described below are only some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] A composite corrosion and scale inhibitor comprises, by weight percentage: 10%-20% phosphorus compound, 25%-40% polycarboxylic acid composition, 2%-5% organic amine compound, 2%-5% amino acid, 5-10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0035] In this embodiment, the phosphine compound is an inorganic phosphorus compound or an organic phosphorus compound.

[0036] In this embodiment, the weight ratio of inorganic phosphorus compound to organic phosphorus compound is 0.1-0.4:1; preferably, the weight ratio of inorganic phosphorus compound to organic phosphorus compound is 0.2-0.25:1.

[0037] In this embodiment, the inorganic phosphorus compound is one or more combinations of phosphoric acid and its potassium, sodium, ammonium and aluminum salts; preferably, the inorganic phosphorus compound is one or more combinations of potassium dihydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate.

[0038] In this embodiment, the organophosphorus compound contains at least one functional group selected from amino, hydroxyl, carboxyl, or ester groups; preferably, the organophosphorus compound is hydroxyethylidene diphosphonic acid, 2-hydroxyphosphonoacetic acid, aminotrimethylphosphonic acid, ethylenediaminetetramethylidene phosphonic acid, hexamethylenediaminetetramethylidene phosphonic acid, diethylenetriaminepentamethylenephosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, polyaminopolyether methylphosphonic acid, bis(1,6-hexyltriaminepentamethylenephosphonic acid) and their potassium, sodium, ammonium, and aluminum salts, as well as one or more combinations of polyol phosphates and polyether alcohol phosphates.

[0039] In this embodiment, the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers.

[0040] In this embodiment, the weight ratio of polyepoxysuccinic acid to sulfonate copolymer is 0.75-2:1; preferably, the weight ratio of polyepoxysuccinic acid to sulfonate copolymer is 1-1.5:1.

[0041] In this embodiment, the sulfonate copolymer is one or more combinations of acrylic acid / propyl sulfonic acid copolymer, acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid copolymer, acrylic acid / methyl ethyl acrylate sulfonic acid copolymer, acrylic acid / propoxy polyethoxysulfonate copolymer, maleic anhydride / propoxy polyethoxysulfonate copolymer, or acrylic acid / isoprene sulfonate / hydroxypropyl acrylate copolymer; preferably, the sulfonate copolymer is acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, and the molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid is 2.5-3.5:1.

[0042] In this embodiment, the organic amine compound is one or more combinations of ethanolamine, diethanolamine, triethanolamine, hexadecylamine, octadecylamine, dihexylamine, cyclohexylamine, aliphatic polyamine, aromatic polyamine, or ammonium dodecyl sulfate; preferably, the organic amine compound is ethanolamine.

[0043] In this embodiment, the amino acid is one or more combinations of glycine, tryptophan, alanine, or arginine; preferably, the amino acid is glycine.

[0044] In this embodiment, the water-soluble inorganic metal salt is a zinc salt, sodium salt, potassium salt, or calcium salt; preferably, the water-soluble inorganic metal salt is one or more combinations of zinc nitrate, zinc sulfate, zinc chloride, sodium chloride, sodium sulfate, sodium nitrate, sodium dihydrogen phosphate, or disodium hydrogen phosphate; more preferably, the water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, wherein the mass ratio of zinc sulfate to sodium chloride is 4~6:1.

[0045] A method for preparing a composite corrosion and scale inhibitor includes the following steps:

[0046] Step 1: Dissolve the phosphorus compound in deionized water at 40-50℃ to obtain mixed solution 1;

[0047] Step 2: Add the polycarboxylic acid composition to mixed solution 1 and stir for 30-60 minutes to obtain mixed solution 2;

[0048] Step 3: Add organic amine compound, amino acid and water-soluble inorganic metal salt to mixed solution 2 in sequence, adjust the pH of the solution to 8-10, and obtain mixed solution 3;

[0049] Step 4: Filter the mixed solution 3 to obtain a light yellow transparent liquid, which is the composite corrosion and scale inhibitor.

[0050] Example 1.

[0051] A composite corrosion and scale inhibitor comprises, by weight percentage: 18% phosphorus compound, 35% polycarboxylic acid composition, 5% organic amine compound, 3% amino acid, 10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0052] The phosphorus compound is a combination of sodium dihydrogen phosphate and hydroxyethylidene diphosphonic acid, with a mass ratio of 0.25:1; the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers, with a mass ratio of 1.5:1, and the sulfonate copolymer is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, with a molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid of 3:1; the organic amine compound is ethanolamine; the amino acid is glycine; and the water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, with a mass ratio of 4:1.

[0053] The preparation of the composite corrosion and scale inhibitor includes the following steps:

[0054] (1) Dissolve sodium dihydrogen phosphate and hydroxyethylidene diphosphonic acid in deionized water at 40-50℃;

[0055] (2) Add polyepoxysuccinic acid and sulfonate copolymer in sequence, and stir for about 30 minutes;

[0056] (3) Add ethanolamine, glycine, zinc sulfate, and sodium chloride to adjust the pH to 8.5-9.5;

[0057] (4) Filter to obtain a light yellow transparent liquid, which is a composite corrosion and scale inhibitor.

[0058] Example 2.

[0059] A composite corrosion and scale inhibitor comprises, by weight percentage: 15% phosphorus compound, 35% polycarboxylic acid composition, 5% organic amine compound, 3% amino acid, 10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0060] The phosphorus compound is a combination of sodium dihydrogen phosphate and aminotrimethylphosphonic acid, with a mass ratio of sodium dihydrogen phosphate to aminotrimethylphosphonic acid of 0.25:1; the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers, with a mass ratio of polyepoxysuccinic acid to sulfonate copolymers of 1.5:1, and the sulfonate copolymer is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, with a molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid of 3:1; the organic amine compound is ethanolamine; and the water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, with a mass ratio of zinc sulfate to sodium chloride of 4:1.

[0061] A composite corrosion and scale inhibitor was prepared according to the preparation method in Example 1.

[0062] Example 3.

[0063] A composite corrosion and scale inhibitor comprises, by weight percentage: 18% phosphorus compound, 30% polycarboxylic acid composition, 5% organic amine compound, 3% amino acid, 10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0064] The phosphorus compound is a combination of sodium dihydrogen phosphate and hydroxyethylidene diphosphonic acid, with a mass ratio of 0.25:1. The polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers, with a mass ratio of 1.5:1. The sulfonate copolymer is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, with a molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid of 3:1. The amino acid is glycine. The water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, with a mass ratio of 4:1.

[0065] A composite corrosion and scale inhibitor was prepared according to the preparation method in Example 1.

[0066] Example 4.

[0067] A composite corrosion and scale inhibitor comprises, by weight percentage: 18% phosphorus compound, 35% polycarboxylic acid composition, 2% organic amine compound, 3% amino acid, 10% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0068] The phosphorus compound is a combination of sodium dihydrogen phosphate and hydroxyethylidene diphosphonic acid, with a mass ratio of sodium dihydrogen phosphate to hydroxyethylidene diphosphonic acid of 0.25:1; the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers, with a mass ratio of polyepoxysuccinic acid to sulfonate copolymers of 1.5:1; the sulfonate copolymer is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, with a molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid of 3:1; the organic amine compound is ethanolamine; the amino acid is glycine; and the water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, with a mass ratio of zinc sulfate to sodium chloride of 4:1.

[0069] A composite corrosion and scale inhibitor was prepared according to the preparation method in Example 1.

[0070] Example 5.

[0071] A composite corrosion and scale inhibitor comprises, by weight percentage: 18% phosphorus compound, 35% polycarboxylic acid composition, 5% organic amine compound, 3% amino acid, 6% water-soluble inorganic metal salt, and deionized water to make up to 100%.

[0072] The phosphorus compound is a combination of sodium dihydrogen phosphate and hydroxyethylidene diphosphonic acid, with a mass ratio of 0.25:1; the polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers, with a mass ratio of 1.5:1, and the sulfonate copolymer is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, with a molar ratio of acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid of 3:1; the organic amine compound is ethanolamine; the amino acid is glycine; and the water-soluble inorganic metal salt is a mixture of zinc sulfate and sodium chloride, with a mass ratio of 4:1.

[0073] A composite corrosion and scale inhibitor was prepared according to the preparation method in Example 1.

[0074] Comparative Example 1

[0075] The method is the same as in Example 1, except that hydroxyethylidene diphosphonic acid is not added.

[0076] Comparative Example 2

[0077] The method is the same as in Example 1, except that sodium dihydrogen phosphate is not added.

[0078] Comparative Example 3

[0079] The method is the same as in Example 1, except that polyepoxysuccinic acid is not added.

[0080] Comparative Example 4

[0081] The method is the same as in Example 1, except that no sulfonate copolymers are added.

[0082] Comparative Example 5

[0083] The method is the same as in Example 1, except that no organic amine compound is added.

[0084] Comparative Example 6

[0085] The method is the same as in Example 1, except that zinc sulfate is not added.

[0086] Performance testing:

[0087] The results of observing the apparent phenomena of the composite corrosion and scale inhibitors prepared in Examples 1-5 and Comparative Examples 1-6 are shown in Table 1.

[0088] Table 1. Apparent phenomena of composite corrosion and scale inhibitors.

[0089]

[0090] As can be seen from the results in Table 1, the method of the present invention can be used to prepare a clear and transparent composite corrosion and scale inhibitor, which is stable in state.

[0091] The corrosion inhibition and scale inhibition performance of the composite corrosion and scale inhibitors in Examples 1-5 and Comparative Examples 1-6 were evaluated using laboratory tap water as the test water. The laboratory tap water was adjusted to weak acidity with HCl. The specific water quality data are shown in Table 2. The evaluation test methods refer to GB / T 18175-2014 (corrosion inhibition performance) and GB / T 16632-2019 (scale inhibition performance).

[0092] Table 2. Laboratory tap water data.

[0093]

[0094] The evaluation results of the composite corrosion and scale inhibitors prepared in Examples 1-5 and Comparative Examples 1-6 are shown in Table 3.

[0095] Table 3 Evaluation test results of composite corrosion and scale inhibitors.

[0096]

[0097] As shown in Table 3, the composite corrosion and scale inhibitors prepared in Examples 1-5 all exhibited low corrosion rates and high scale inhibition rates. The corrosion rates were all below 0.030 mm / a, and the scale inhibition rates were all above 99%. Example 1 showed better performance than the other examples, with the lowest corrosion rate (0.012 mm / a) and the highest scale inhibition rate (99.6%). Examples 2 and 3 showed relatively high corrosion rates, exceeding 0.020 mm / a, while Examples 2 and 5 showed relatively low scale inhibition rates (99.2%). The composite corrosion and scale inhibitors prepared in Comparative Examples 1-6 showed significantly higher corrosion rates and significantly lower scale inhibition rates than the examples.

[0098] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, various different embodiments of the present invention can be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A composite corrosion and scale inhibitor, characterized in that, By weight percentage: 10%-20% phosphorus compounds, 25%-40% polycarboxylic acid composition, 2%-5% organic amine compounds, 2%-5% amino acids, 5-10% water-soluble inorganic metal salts, and deionized water to bring the total to 100%. The phosphorus compound is an inorganic phosphorus compound and an organophosphorus compound; the weight ratio of the inorganic phosphorus compound to the organophosphorus compound is 0.1-0.4:1; The polycarboxylic acid composition is a mixture of polyepoxysuccinic acid and sulfonate copolymers; the weight ratio of the polyepoxysuccinic acid and the sulfonate copolymers is 0.75-2:

1.

2. The composite corrosion and scale inhibitor according to claim 1, characterized in that, The inorganic phosphorus compound is one or more combinations of phosphoric acid and its potassium, sodium, ammonium and aluminum salts.

3. The composite corrosion and scale inhibitor according to claim 1, characterized in that, The organophosphorus compound contains at least one functional group selected from amino, hydroxyl, carboxyl, or ester groups.

4. The composite corrosion and scale inhibitor according to claim 1, wherein, The sulfonate copolymer is one or more combinations of acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer, acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid copolymer, or acrylic acid / isoprene sulfonate / hydroxypropyl acrylate copolymer.

5. The composite corrosion and scale inhibitor according to claim 1, wherein, The organic amine compound is one or more combinations of ethanolamine, diethanolamine, triethanolamine, hexadecylamine, octadecylamine, dihexylamine, cyclohexylamine, aliphatic polyamine, aromatic polyamine, or ammonium dodecyl sulfate.

6. The composite corrosion and scale inhibitor according to claim 1, wherein, The amino acid is one or more combinations of glycine, tryptophan, alanine, or arginine; the water-soluble inorganic metal salt is a zinc salt, sodium salt, potassium salt, or calcium salt.

7. A method for preparing the composite corrosion and scale inhibitor according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Dissolve the phosphorus compound in deionized water at 40-50℃ to obtain mixed solution 1; Step 2: Add the polycarboxylic acid composition to mixed solution 1 and stir for 30-60 minutes to obtain mixed solution 2; Step 3: Add organic amine compound, amino acid and water-soluble inorganic metal salt to mixed solution 2 in sequence, adjust the pH of the solution to 8-10, and obtain mixed solution 3; Step 4: Filter the mixed solution 3 to obtain a light yellow transparent liquid, which is the composite corrosion and scale inhibitor.

8. Use of a complex corrosion and scale inhibitor according to any one of claims 1 to 6, characterized in that, This composite corrosion and scale inhibitor is suitable for industrial circulating cooling water systems.

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