A kind of water scale and corrosion inhibitor and preparation method thereof

Abstract

The present invention provides a water-based scale and corrosion inhibitor and its preparation method, belonging to the technical field of scale and corrosion inhibitors. The invention comprises the following components by weight: 10-30% scale inhibitor; 35-40% hydrolyzed polymaleic anhydride; 12-20% acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer; 4-7.5% water-soluble zinc salt; and the balance water. The water-based scale and corrosion inhibitor of the present invention can address scaling and corrosion issues caused by circulating water operating under conditions of high hardness and alkalinity, ensuring safe operation of circulating water systems with minimal wastewater discharge, addressing the issue of phosphorus-free and environmentally friendly operation, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of scale and corrosion inhibitors, and in particular to a scale and corrosion inhibitor for water and a preparation method thereof. Background Art

[0002] The circulating water system's self-draining water is de-hardened and desalted and then reused in the circulating water system. The main components of the common scale and corrosion inhibitors used include scale inhibitors, dispersants, and corrosion inhibitors. This common scale and corrosion inhibitor has a good effect on the scale and corrosion inhibition treatment of circulating water systems in alkaline environments. At present, phosphorus-containing chemicals occupy the main market in the field of industrial circulating water treatment chemicals. After decades of development, phosphorus-containing chemicals have become quite mature, low-cost, and the treatment effect fully meets the standards of relevant industries. However, the discharge of phosphorus-containing circulating water, on the one hand, causes eutrophication of water bodies and damages the water quality ecology, and on the other hand, increases the discharge management and reuse of circulating water. In recent years, with the improvement and strengthening of people's and society's environmental awareness, the use of phosphorus-containing chemicals has been restricted by various manufacturers. The research and development and production of phosphorus-free scale and corrosion inhibitors have broad application value in the water treatment industry.

[0003] The use of oxidized starch in water treatment scale inhibitors has been reported, but this occurs in the form of a homogeneous composition, mixed with other ingredients for water treatment. For example, Chinese invention patent CN102452723B discloses a phosphorus-free composite scale inhibitor composed of 10%-13% polyaspartic acid, 25%-28% sodium lignin sulfate, 10%-13% oxidized starch, and 50%-55% deionized water. Chinese invention patent CN110342654B discloses a novel phosphorus-free corrosion and scale inhibitor, composed of the following raw materials in the following weight percentages: 30-80% modified chitosan quaternary ammonium salt mixture, 10-50% oxidized starch mixture, and 10-25% alkylamine emulsion. Currently, there are no reports demonstrating the scale and corrosion inhibition properties of modified oxidized starch. Summary of the Invention

[0004] The purpose of the present invention is to propose a water-based scale and corrosion inhibitor and a preparation method thereof, which can solve the scaling and corrosion problems caused when circulating water is running under conditions of high hardness and alkalinity, ensure the safe operation of the circulating water system under the condition of small amount of sewage discharge, solve the problem of phosphorus-free and environmental protection, and have broad application prospects.

[0005] The technical solution of the present invention is achieved as follows:

[0006] The present invention provides a water scale and corrosion inhibitor, comprising the following components in percentage by mass:

[0007] 10-30% antiscalant;

[0008] 35-40% hydrolyzed polymaleic anhydride;

[0009] 12-20% acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer;

[0010] 4-7.5% water-soluble zinc salt;

[0011] and the balance of water.

[0012] As a further improvement of the present invention, the scale inhibitor is at least one of polyepoxysuccinic acid, polyaspartic acid, and modified oxidized starch.

[0013] As a further improvement of the present invention, the water-soluble zinc salt is at least one of zinc sulfate, zinc nitrate, zinc chloride, and zinc acetate.

[0014] As a further improvement of the present invention, the preparation method of the modified oxidized starch is as follows:

[0015] S1. Preparation of composite oxidized starch: corn starch, potassium permanganate, and sulfuric acid were added to water, heated and stirred to react, the pH of the solution was adjusted to, hydrogen peroxide was added dropwise, a catalyst was added, microwaved, kept warm and continued to react, the pH of the solution was adjusted to, filtered, washed, and dried to obtain composite oxidized starch;

[0016] S2. Grafting of aspartic acid and lysine: Adding composite oxidized starch to water, adding NHS and EDC, stirring to activate, adding aspartic acid and lysine, stirring to react, dialyzing, and freeze-drying to obtain grafted composite oxidized starch;

[0017] S3 chlorination: The grafted composite oxidized starch was added to the ionic liquid, thionyl chloride was added, the reaction was stirred, ethanol was added for precipitation, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch;

[0018] S4 reaction with cyclodextrin: β-cyclodextrin was dissolved in water, modified grafted composite oxidized starch and triethylamine were added, the reaction was heated with stirring, centrifuged, washed, and dried to obtain cyclodextrin-modified grafted composite oxidized starch;

[0019] S5. Ultrasonic treatment: adding the prepared cyclodextrin-modified grafted composite oxidized starch into water, ultrasonically treating it, and drying it to obtain modified oxidized starch.

[0020] As a further improvement of the present invention, the mass ratio of corn starch, potassium permanganate, sulfuric acid, hydrogen peroxide, and catalyst in step S1 is 20-30:4-7:3-5:10-12:0.5-1, the catalyst is copper chloride or copper sulfate, the temperature of the heating and stirring reaction is 50-60°C, the time is 2-4 hours, and the power of the microwave treatment is 1000-1500W, and the time is 1-3 hours.

[0021] As a further improvement of the present invention, the mass ratio of the composite oxidized starch, NHS, EDC, aspartic acid and lysine in step S2 is 12-15:3-4:3-4:5-7:2-4, the dialysis bag pore size used in the dialysis is 8-12KDa, and the dialysis time is 10-12h.

[0022] As a further improvement of the present invention, the mass ratio of the grafted composite oxidized starch, dithionyl chloride, and ionic liquid in step S3 is 10:3-5:30-40, the stirring reaction time is 2-4 hours, and the ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium dihydrogen phosphate, and 1-butyl-3-methylimidazolium hydrogen sulfate.

[0023] As a further improvement of the present invention, in step S4, the mass ratio of β-cyclodextrin, modified grafted composite oxidized starch and triethylamine is 3-5:12-15:2-4, and the heating and stirring reaction temperature is 50-60° C. and the time is 3-5 hours.

[0024] As a further improvement of the present invention, the power of the ultrasonic treatment in step S5 is 1500-2500 W, and the time is 20-30 min.

[0025] The present invention further provides a method for preparing the above-mentioned water scale and corrosion inhibitor, comprising the following steps:

[0026] (1) adding hydrolyzed polymaleic anhydride into water, then adding a water-soluble zinc salt and stirring, mixing uniformly to obtain a solution;

[0027] (2) At room temperature, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer and scale inhibitor are added to the solution and stirred evenly to prepare a water scale and corrosion inhibitor.

[0028] The present invention has the following beneficial effects:

[0029] Polyaspartic acid is a biomimetic, water-soluble polymer that is phosphorus-free, non-toxic, pollution-free, and completely biodegradable, making it a green chemical. It possesses strong chelating, dispersing, and adsorption properties, and exhibits excellent compatibility.

[0030] Polyepoxysuccinic acid is a phosphorus-free, non-nitrogen, "green," environmentally friendly, multi-component scale and corrosion inhibitor. Polyepoxysuccinic acid has excellent scale inhibition and dispersibility for calcium carbonate, calcium sulfate, barium sulfate, calcium fluoride, and silica scale in water, and its scale inhibition effect is superior to that of commonly used organic phosphine scale inhibitors. Polyepoxysuccinic acid and phosphonates exhibit a synergistic effect. Polyepoxysuccinic acid also exhibits a certain corrosion inhibition effect, making it a multi-component scale inhibitor. Polyepoxysuccinic acid (PESA) is a nitrogen-free, non-phosphorus organic compound that combines the dual effects of scale and corrosion inhibition, has good biodegradability, and is suitable for high-alkaline, high-metal content water systems, making it a green water treatment chemical.

[0031] Starch is a natural high-molecular-weight cyclic polymer with the characteristics of "hydrophilic outer cavity and hydrophobic inner cavity". The large number of hydroxyl groups on its outer side have a chelating effect on high-valent metal ions and have certain corrosion and scale inhibition properties. However, its performance needs to be further improved, and its poor water solubility limits its wide application.

[0032] The present invention prepares a modified oxidized starch. By overlapping the oxidation of starch with potassium permanganate and hydrogen peroxide, potassium permanganate is used as an oxidant to oxidize the starch, thereby preparing an oxidized starch with a high carboxyl content and a low degree of depolymerization. Hydrogen peroxide easily penetrates deep into starch granules, causing oxidation, breaking the starch molecules at C2 and C3, thereby depolymerizing the starch. Generally, the degree of oxidation is low and the degree of depolymerization is high. Using the two to alternately overlap oxidation can achieve the purpose of increasing the carboxyl content and appropriately reducing the molecular weight of starch, thereby increasing the solubility of the starch and improving the scale and corrosion inhibition properties of the obtained product. Excess hydrogen peroxide eventually decomposes into water, which will not affect the purity of the product or the environment, and is an ideal green process.

[0033] Furthermore, the present invention adopts aspartic acid and lysine grafted composite oxidized starch, which significantly improves the scale and corrosion inhibition effect. The dicarboxyl structure of aspartic acid and the diamino structure of lysine provide abundant chelating sites for complexing metal ions, greatly improving the chelation efficiency of metal ions, and is safer and more environmentally friendly, avoiding eutrophication of water bodies and secondary pollution of emissions. It has a strong chelating ability for metal ions and has the dual effects of corrosion inhibition and scale inhibition. Therefore, it has a good scale inhibition effect on scale-forming salts such as calcium carbonate, calcium sulfate, barium sulfate, and calcium phosphate, and the scale inhibition rate for calcium carbonate can reach 100%.

[0034] The hydroxyl groups on the grafted composite oxidized starch are chlorinated and coupled with β-cyclodextrin. β-cyclodextrin has a hydrophilic exterior and a hydrophobic interior cavity, which can encapsulate scale ions (such as Ca 2+ Mg 2+) or scale precursor molecules are enclosed in its cavity, thereby preventing these ions from combining with anions such as carbonate to form scale. In addition, the functional groups in its polymer structure (such as hydroxyl, carboxyl, etc.) can interact with ions on the surface of scale crystals, interfere with the normal growth of scale crystals, cause lattice distortion, and reduce the adhesion of the scale layer.

[0035] The cyclodextrin-modified grafted composite oxidized starch is subjected to ultrasonic treatment, and the surface of the starch granules is deformed, forming holes and grooves that improve water permeability. The enhanced permeability promotes the expansion and size increase of the starch granules, so that the prepared modified oxidized starch can form a protective film on the metal surface through physical adsorption or chemical adsorption, preventing the corrosive medium from contacting the metal. It has strong steric hindrance, can isolate and resist the attack of corrosive ions, and has good alkali resistance, thereby achieving corrosion inhibition.

[0036] The water scale and corrosion inhibitor of the present invention can solve the scaling and corrosion problems generated when circulating water is running under conditions of high hardness and alkalinity, ensure the safe operation of the circulating water system under the condition of small amount of sewage discharge, solve the problem of phosphorus-free and environmental protection, and has broad application prospects. DETAILED DESCRIPTION

[0037] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. 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.

[0038] NHS, N-hydroxysuccinimide; EDC, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0039] Preparation Example 1 Preparation of modified oxidized starch

[0040] The following steps are involved:

[0041] Preparation of composite oxidized starch: 20 g corn starch, 4 g potassium permanganate, and 3 g sulfuric acid were added to 500 mL of water and heated to 50°C with stirring for 2 h. The pH of the solution was adjusted to 3. 10 g hydrogen peroxide was then added dropwise, and 0.5 g copper chloride was added. The mixture was microwaved at 1000 W for 1 h. The reaction was continued for 2 h, and 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 5.5, filtered, washed, and dried to obtain composite oxidized starch.

[0042] S2. Grafting of aspartic acid and lysine: 12 g of composite oxidized starch was added to 200 mL of water, 3 g of NHS and 3 g of EDC were added, and the mixture was stirred for 30 min. 5 g of aspartic acid and 2 g of lysine were added and the mixture was stirred for 10 h. The mixture was dialyzed using a dialysis bag with a pore size of 8 kDa for 10 h and freeze-dried to obtain a grafted composite oxidized starch.

[0043] S3 chlorination: 10g of grafted composite oxidized starch was added to 30g of 1-butyl-3-methylimidazole dihydrogen phosphate ionic liquid, 3g of thionyl chloride was added, the reaction was stirred for 2h, ethanol was added to the ethanol content of the system was 80wt%, precipitated for 1h, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch;

[0044] S4. Reaction with cyclodextrin: 3 g of β-cyclodextrin was dissolved in 150 mL of water, 12 g of modified grafted composite oxidized starch and 2 g of triethylamine were added, heated to 50 ° C, stirred for 3 h, centrifuged, washed, and dried to obtain cyclodextrin-modified grafted composite oxidized starch;

[0045] S5. Ultrasonic treatment: 1 g of cyclodextrin-modified grafted composite oxidized starch was added to 50 mL of water, ultrasonically treated at 1500 W for 20 min, and dried to obtain modified oxidized starch.

[0046] Preparation Example 2 Preparation of modified oxidized starch

[0047] The following steps are involved:

[0048] Preparation of composite oxidized starch: 30 g corn starch, 7 g potassium permanganate, and 5 g sulfuric acid were added to 500 mL of water and heated to 60°C with stirring for 4 h. The pH of the solution was adjusted to 4. 12 g hydrogen peroxide was then added dropwise. 1 g copper sulfate was added and microwaved at 1500 W for 3 h. The reaction was continued for 4 h. 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 6. The mixture was filtered, washed, and dried to obtain composite oxidized starch.

[0049] S2. Grafting of aspartic acid and lysine: 15 g of composite oxidized starch was added to 200 mL of water, 4 g of NHS and 4 g of EDC were added, and the mixture was stirred for 30 min. 7 g of aspartic acid and 4 g of lysine were added and the mixture was stirred for 12 h. The mixture was dialyzed using a 12 kDa dialysis bag for 12 h and freeze-dried to obtain a grafted composite oxidized starch.

[0050] S3 chlorination: 10g of grafted composite oxidized starch was added to 40g of 1-butyl-3-methylimidazolium bromide ionic liquid, 5g of thionyl chloride was added, the reaction was stirred for 4h, ethanol was added to the ethanol content of the system was 80wt%, precipitated for 1h, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch;

[0051] S4. Reaction with cyclodextrin: 5 g of β-cyclodextrin was dissolved in 150 mL of water, 15 g of modified grafted composite oxidized starch and 4 g of triethylamine were added, heated to 60 ° C, stirred for 5 h, centrifuged, washed, and dried to obtain cyclodextrin-modified grafted composite oxidized starch;

[0052] S5. Ultrasonic treatment: 1 g of cyclodextrin-modified grafted composite oxidized starch was added to 50 mL of water, ultrasonically treated at 2500 W for 30 min, and dried to obtain modified oxidized starch.

[0053] Preparation Example 3 Preparation of modified oxidized starch

[0054] The following steps are involved:

[0055] Preparation of composite oxidized starch: 25 g corn starch, 5.5 g potassium permanganate, and 4 g sulfuric acid were added to 500 mL of water and heated to 55°C with stirring for 3 h. The pH of the solution was adjusted to 3.5. 11 g hydrogen peroxide was then added dropwise, and 0.7 g copper sulfate was added. The mixture was microwaved at 1200 W for 2 h. The reaction was continued for 3 h, and 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 5.7, filtered, washed, and dried to obtain composite oxidized starch.

[0056] S2. Grafting of aspartic acid and lysine: 13 g of composite oxidized starch was added to 200 mL of water, 3.5 g of NHS and 3.5 g of EDC were added, and the mixture was stirred for 30 min. 6 g of aspartic acid and 3 g of lysine were added, and the mixture was stirred for 11 h. The mixture was dialyzed using a 10 kDa dialysis bag for 11 h and freeze-dried to obtain a grafted composite oxidized starch.

[0057] S3 chlorination: 10g of grafted composite oxidized starch was added to 35g of 1-butyl-3-methylimidazolium chloride ionic liquid, 4g of thionyl chloride was added, the reaction was stirred for 3h, ethanol was added to the ethanol content of the system was 80wt%, precipitated for 1h, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch;

[0058] S4. Reaction with cyclodextrin: 4 g of β-cyclodextrin was dissolved in 150 mL of water, 13 g of modified grafted composite oxidized starch and 3 g of triethylamine were added, heated to 55 ° C, stirred for 4 h, centrifuged, washed, and dried to obtain cyclodextrin-modified grafted composite oxidized starch;

[0059] S5. Ultrasonic treatment: 1 g of cyclodextrin-modified grafted composite oxidized starch was added to 50 mL of water, ultrasonically treated at 2000 W for 25 min, and dried to obtain modified oxidized starch.

[0060] Comparative Preparation Example 1

[0061] Compared with Preparation Example 3, the difference is that hydrogen peroxide oxidation is not performed in step S1.

[0062] The details are as follows:

[0063] S1. Preparation of oxidized starch: Add 25 g corn starch, 5.5 g potassium permanganate, and 4 g sulfuric acid to 500 mL of water, heat to 55°C, and stir to react for 3 h. Adjust the pH value of the solution to 5.7, filter, wash, and dry to obtain oxidized starch.

[0064] Comparative Preparation Example 2

[0065] Compared with Preparation Example 3, the difference is that potassium permanganate oxidation is not performed in step S1.

[0066] The details are as follows:

[0067] S1. Preparation of oxidized starch: Add 25 g corn starch to 500 mL water, adjust the solution pH to 3.5, continue to dropwise add 11 g hydrogen peroxide, add 0.7 g copper sulfate, microwave at 1200 W power for 2 h, keep warm and continue the reaction for 3 h, add 1 g sodium bisulfite to terminate the reaction, adjust the solution pH to 5.7, filter, wash, and dry to obtain oxidized starch.

[0068] Comparative Preparation Example 3

[0069] Compared with Preparation Example 3, the difference is that aspartic acid is not added in step S2.

[0070] The details are as follows:

[0071] S2. Grafting lysine: 13 g of composite oxidized starch was added to 200 mL of water, along with 3.5 g of NHS and 3.5 g of EDC. The mixture was stirred and activated for 30 min. 9 g of lysine was added and the mixture was stirred for 11 h. The mixture was dialyzed using a 10 kDa dialysis bag for 11 h and freeze-dried to obtain the grafted composite oxidized starch.

[0072] Comparative Preparation Example 4

[0073] Compared with Preparation Example 3, the difference is that lysine is not added in step S2.

[0074] The details are as follows:

[0075] S2. Grafting of aspartic acid: 13 g of composite oxidized starch was added to 200 mL of water, along with 3.5 g of NHS and 3.5 g of EDC. The mixture was stirred and activated for 30 min. 9 g of aspartic acid was added and the mixture was stirred for 11 h. The mixture was dialyzed using a 10 kDa dialysis bag for 11 h and freeze-dried to obtain the grafted composite oxidized starch.

[0076] Comparative Preparation Example 5

[0077] Compared with Preparation Example 3, the difference is that step S2 is not performed.

[0078] The details are as follows:

[0079] Preparation of composite oxidized starch: 25 g corn starch, 5.5 g potassium permanganate, and 4 g sulfuric acid were added to 500 mL of water and heated to 55°C with stirring for 3 h. The pH of the solution was adjusted to 3.5. 11 g hydrogen peroxide was then added dropwise, and 0.7 g copper sulfate was added. The mixture was microwaved at 1200 W for 2 h. The reaction was continued for 3 h, and 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 5.7, filtered, washed, and dried to obtain composite oxidized starch.

[0080] S2 chlorination: 10g of composite oxidized starch was added to 35g of 1-butyl-3-methylimidazolium chloride ionic liquid, 4g of thionyl chloride was added, the reaction was stirred for 3h, ethanol was added to the ethanol content of the system was 80wt%, precipitated for 1h, filtered, the solid was washed, and dried to obtain a modified composite oxidized starch;

[0081] S3. Reaction with cyclodextrin: 4 g of β-cyclodextrin was dissolved in 150 mL of water, 13 g of modified grafted composite oxidized starch and 3 g of triethylamine were added, heated to 55 ° C, stirred for 4 h, centrifuged, washed, and dried to obtain cyclodextrin-modified composite oxidized starch;

[0082] S4. Ultrasonic treatment: 1 g of cyclodextrin-modified composite oxidized starch was added to 50 mL of water, ultrasonically treated at 2000 W for 25 min, and dried to obtain modified oxidized starch.

[0083] Comparative Preparation Example 6

[0084] Compared with Preparation Example 3, the difference is that steps S3 and S4 are not performed.

[0085] The details are as follows;

[0086] Preparation of composite oxidized starch: 25 g corn starch, 5.5 g potassium permanganate, and 4 g sulfuric acid were added to 500 mL of water and heated to 55°C with stirring for 3 h. The pH of the solution was adjusted to 3.5. 11 g hydrogen peroxide was then added dropwise, and 0.7 g copper sulfate was added. The mixture was microwaved at 1200 W for 2 h. The reaction was continued for 3 h, and 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 5.7, filtered, washed, and dried to obtain composite oxidized starch.

[0087] S2. Grafting of aspartic acid and lysine: 13 g of composite oxidized starch was added to 200 mL of water, 3.5 g of NHS and 3.5 g of EDC were added, and the mixture was stirred for 30 min. 6 g of aspartic acid and 3 g of lysine were added, and the mixture was stirred for 11 h. The mixture was dialyzed using a 10 kDa dialysis bag for 11 h and freeze-dried to obtain a grafted composite oxidized starch.

[0088] S3. Ultrasonic treatment: 1 g of grafted composite oxidized starch was added to 50 mL of water, ultrasonically treated at 2000 W for 25 min, and dried to obtain modified oxidized starch.

[0089] Comparative Preparation Example 7

[0090] Compared with Preparation Example 3, the difference is that step S5 is not performed.

[0091] The details are as follows:

[0092] Preparation of composite oxidized starch: 25 g corn starch, 5.5 g potassium permanganate, and 4 g sulfuric acid were added to 500 mL of water and heated to 55°C with stirring for 3 h. The pH of the solution was adjusted to 3.5. 11 g hydrogen peroxide was then added dropwise, and 0.7 g copper sulfate was added. The mixture was microwaved at 1200 W for 2 h. The reaction was continued for 3 h, and 1 g sodium bisulfite was added to terminate the reaction. The pH of the solution was adjusted to 5.7, filtered, washed, and dried to obtain composite oxidized starch.

[0093] S2. Grafting of aspartic acid and lysine: 13 g of composite oxidized starch was added to 200 mL of water, 3.5 g of NHS and 3.5 g of EDC were added, and the mixture was stirred for 30 min. 6 g of aspartic acid and 3 g of lysine were added, and the mixture was stirred for 11 h. The mixture was dialyzed using a 10 kDa dialysis bag for 11 h and freeze-dried to obtain a grafted composite oxidized starch.

[0094] S3 chlorination: 10g of grafted composite oxidized starch was added to 35g of 1-butyl-3-methylimidazolium chloride ionic liquid, 4g of thionyl chloride was added, the reaction was stirred for 3h, ethanol was added to the ethanol content of the system was 80wt%, precipitated for 1h, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch;

[0095] S4. Reaction with cyclodextrin: Dissolve 4 g of β-cyclodextrin in 150 mL of water, add 13 g of modified grafted composite oxidized starch and 3 g of triethylamine, heat to 55°C, stir and react for 4 hours, centrifuge, wash, and dry to obtain cyclodextrin-modified grafted composite oxidized starch, i.e., modified oxidized starch.

[0096] Example 1

[0097] This embodiment provides a water-based scale and corrosion inhibitor, comprising the following components in percentage by weight:

[0098] 15% polyepoxysuccinic acid;

[0099] 35% hydrolyzed polymaleic anhydride;

[0100] 15% acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer;

[0101] 5% zinc nitrate;

[0102] 30% water.

[0103] The preparation method comprises the following steps:

[0104] (1) Add hydrolyzed polymaleic anhydride to water, then add zinc nitrate and stir for 10 minutes to obtain a solution;

[0105] (2) At room temperature, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer and polyepoxysuccinic acid were added to the solution and stirred for 30 minutes to prepare a water scale and corrosion inhibitor.

[0106] Example 2

[0107] Compared with Example 1, the difference is that the scale inhibitor is the modified oxidized starch prepared in Preparation Example 1.

[0108] Example 3

[0109] Compared with Example 1, the difference is that the scale inhibitor is the modified oxidized starch prepared in Preparation Example 2.

[0110] Example 4

[0111] Compared with Example 1, the difference is that the scale inhibitor is the modified oxidized starch prepared in Preparation Example 3.

[0112] Comparative Example 1

[0113] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 1.

[0114] Comparative Example 2

[0115] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 2.

[0116] Comparative Example 3

[0117] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 3.

[0118] Comparative Example 4

[0119] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 4.

[0120] Comparative Example 5

[0121] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 5.

[0122] Comparative Example 6

[0123] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 6.

[0124] Comparative Example 7

[0125] Compared with Example 4, the difference is that the scale inhibitor is the modified oxidized starch prepared in Comparative Preparation Example 7.

[0126] Test Example 1 Rotating Coupon Corrosion Test

[0127] 1. Test Principle

[0128] The rotating coupon corrosion test is a test method that uses rotating coupons to assess the degree of water corrosion under given laboratory conditions. By strictly controlling the specified test conditions, including simulated water quality, test materials, test temperature, and rotation speed, the test is conducted for a specified time to select corrosion inhibitors and evaluate the corrosion inhibition effect of the formulation.

[0129] 2. Test conditions

[0130] Agent: water scale and corrosion inhibitor prepared in Examples 1-4 and Comparative Examples 1-7;

[0131] Dosage concentration: water scale and corrosion inhibitor 25-35 mg / L;

[0132] Temperature: around 25°C;

[0133] Time: 72 hours;

[0134] Operating conditions

[0135] Coupon and material: Standard test coupon (surface area: 28cm 2 Carbon steel coupon (density: 7.85g / cm 3 ), stainless steel hanging sheet (density: 7.93g / cm 3 )wait;

[0136] Test water quality: Make up water with K=7.5 concentrated water;

[0137] Test water temperature: 45℃±1℃;

[0138] Rotation speed: 75 rpm;

[0139] Linear speed: 0.35 m / s;

[0140] Operating time: 96 hours.

[0141] 3. Test methods

[0142] According to the test conditions, the test piece was fixed on a rotating rack and rotated in a test solution containing different concentrations of water-based scale and corrosion inhibitor. During the test, the water quality was carefully maintained. After 72 hours of operation, the test piece was removed, cleaned of surface dirt, dried, weighed, and the corrosion rate was calculated to determine the optimal agent and dosage.

[0143] 4. Calculation formula:

[0144] Corrosion rate F = C × ΔW / A × t × p

[0145] Where: F——corrosion rate (mm / y); △W——test piece corrosion weight loss (g); C——calculation constant 8.76×10 4 ; t——corrosion test time (h); A——surface area of ​​test piece (cm 2 ); p——test piece material density (g / cm 3 ).

[0146] The results are shown in Table 1.

[0147] Table 1

[0148]

[0149] As can be seen from the above table, the water scale and corrosion inhibitors prepared in Examples 1-4 of the present invention have good corrosion inhibition effects.

[0150] Take 10 mg of the water scale and corrosion inhibitor prepared in Examples 1-4 and Comparative Examples 1-7 and add them to a 1000 mL volumetric flask, dilute to the mark with tap water (CaCO3 hardness of about 200 mg / L), and shake well to obtain a 1 mg / mL stock solution. Take a certain amount of the stock solution and 12.5 mL of 0.1 mol / L NaHCO3 solution in a 250 mL volumetric flask, dilute with 200 ml of tap water, then add 12.5 mL of 0.05 mol / L CaCl2 solution, dilute to the mark with tap water, shake well, and the CaCO3 hardness of the solution is about 450 mg / L. Pour it into a beaker, cover the beaker with a plastic bag, and place it in a water bath at 60±1°C for 24 hours. After cooling, pipette 50 mL of the supernatant and add 5 mL of NH₄OH-NH₄Cl buffer and 2-3 drops of KB indicator to a conical flask. Titrate with 0.02 mol / L EDTA until the color changes from purple-red to blue-green and does not fade within 30 seconds. This is the endpoint. Record the EDTA consumption.

[0151] Scale inhibition rate (%) = (V a -V o ) / (V b -V o )×100%

[0152] Where: V o V is the volume of EDTA consumed without adding scale inhibitor (mL); a V is the volume of EDTA consumed after adding the scale inhibitor (mL); b is the volume of EDTA (mL) consumed by the total calcium.

[0153] The results are shown in Table 2.

[0154] Table 2

[0155] Group Scale inhibition rate (%) Example 1 86.1 Example 2 88.4 Example 3 87.9 Example 4 89.7 Comparative Example 1 80.1 Comparative Example 2 78.0 Comparative Example 3 75.9 Comparative Example 4 76.2 Comparative Example 5 72.5 Comparative Example 6 68.7 Comparative Example 7 77.9

[0156] It can be seen from the above table that the water scale and corrosion inhibitors prepared in Examples 1-4 of the present invention have good scale inhibition effect.

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water scale and corrosion inhibitor, characterized in that: Includes the following components in percentage by mass: 10-30% scale inhibitor; 35-40% hydrolyzed polymaleic anhydride; 12-20% acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer; 4-7.5% water-soluble zinc salt; and the balance of water; The scale inhibitor is modified oxidized starch, and the preparation method is as follows: S1. Preparation of composite oxidized starch: corn starch, potassium permanganate, and sulfuric acid were added to water, heated and stirred to react, the pH of the solution was adjusted to 3-4, hydrogen peroxide was added dropwise, a catalyst was added, microwaved, and the reaction was continued at room temperature. The pH of the solution was adjusted to 5.5-6, filtered, washed, and dried to obtain composite oxidized starch; S2. Grafting of aspartic acid and lysine: The composite oxidized starch was added to water, NHS and EDC were added, stirred for activation, aspartic acid and lysine were added, stirred for reaction, dialyzed, and freeze-dried to obtain the grafted composite oxidized starch; S3 chlorination: The grafted composite oxidized starch was added to the ionic liquid, thionyl chloride was added, the reaction was stirred, ethanol was added to precipitate, filtered, the solid was washed, and dried to obtain a modified grafted composite oxidized starch; S4. Reaction with cyclodextrin: β-cyclodextrin was dissolved in water, modified grafted composite oxidized starch and triethylamine were added, the reaction was heated with stirring, centrifuged, washed, and dried to obtain cyclodextrin-modified grafted composite oxidized starch; S5. Ultrasonic treatment: adding the prepared cyclodextrin-modified grafted composite oxidized starch to water, ultrasonically treating the starch, and drying the resulting mixture to obtain modified oxidized starch.

2. The water scale and corrosion inhibitor according to claim 1, characterized in that: The water-soluble zinc salt is at least one of zinc sulfate, zinc nitrate, zinc chloride and zinc acetate.

3. The water scale and corrosion inhibitor according to claim 1, characterized in that: In step S1, the mass ratio of corn starch, potassium permanganate, sulfuric acid, hydrogen peroxide, and catalyst is 20-30:4-7:3-5:10-12:0.5-1, the catalyst is copper chloride or copper sulfate, the temperature of the heating and stirring reaction is 50-60° C., the time is 2-4 hours, and the power of the microwave treatment is 1000-1500 W, and the time is 1-3 hours.

4. The water scale and corrosion inhibitor according to claim 1, characterized in that: In step S2, the mass ratio of the composite oxidized starch, NHS, EDC, aspartic acid and lysine is 12-15:3-4:3-4:5-7:2-4, the dialysis bag used in the dialysis has a pore size of 8-12 KDa, and the dialysis time is 10-12 h.

5. The water scale and corrosion inhibitor according to claim 1, characterized in that: In step S3, the mass ratio of the grafted composite oxidized starch, thionyl chloride, and ionic liquid is 10:3-5:30-40, the stirring reaction time is 2-4 hours, and the ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium dihydrogen phosphate, and 1-butyl-3-methylimidazolium hydrogen sulfate.

6. The water scale and corrosion inhibitor according to claim 1, characterized in that: In step S4, the mass ratio of β-cyclodextrin, modified grafted composite oxidized starch and triethylamine is 3-5:12-15:2-4, and the temperature of the heating and stirring reaction is 50-60° C. and the time is 3-5 hours.

7. The water scale and corrosion inhibitor according to claim 1, characterized in that: The ultrasonic treatment in step S5 is performed at a power of 1500-2500 W and for a time of 20-30 min.

8. A method for preparing a water scale and corrosion inhibitor according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Add hydrolyzed polymaleic anhydride to water, then add water-soluble zinc salt and stir until uniformly mixed to obtain a solution; (2) At room temperature, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer and scale inhibitor are added to the solution and stirred evenly to prepare a water scale and corrosion inhibitor.

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