Application of 3-aminopropanesulfonic acid modified polyaspartic acid in the preparation of compound scale inhibitor

Abstract

This invention belongs to the field of environmental water treatment, specifically disclosing the application of 3-aminopropanesulfonic acid modified polyaspartic acid in the preparation of compound scale inhibitors, and further providing a method for preparing the 3-aminopropanesulfonic acid modified polyaspartic acid, and applying it in the preparation of compound scale inhibitors, thereby providing a composite scale inhibitor. This scale inhibitor also contains a terpolymer acrylic acid copolymer, which, when used in combination with the above-mentioned 3-aminopropanesulfonic acid modified polyaspartic acid, can fully exert the synergistic effect of the two scale inhibitors, giving the scale inhibitor excellent water solubility, high scale inhibition efficiency, and a wide range of applications.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection water treatment, and specifically discloses the application of 3-aminopropane sulfonic acid modified polyaspartic acid in the preparation of a compound scale inhibitor and a preparation method of the corresponding compound scale inhibitor. Background Art

[0002] In recent years, my country's industrial development level has increased rapidly. A large amount of circulating water is needed in industrial production for cooling equipment in industrial production, electricity, coal mining and other processes, resulting in an increase in the amount of industrial circulating water in my country year by year. However, the current efficiency of industrial circulating water is very low, resulting in a large amount of industrial circulating water waste every year, which cannot meet the needs of the rapid improvement of industrial development level. Therefore, improving the efficiency of industrial circulating water is of great significance to meet the needs of industrial development, alleviate water shortage and save energy and reduce emissions.

[0003] At present, the utilization efficiency of circulating water in industrial cooling water circulation system is very low. The main reason for this phenomenon is that various metal ions and organic matter are deposited on the inner wall of the instrument during the water circulation process, forming scale, which may even cause blockage in severe cases. A large amount of scale deposition leads to low heat exchange efficiency between circulating water and equipment, so more circulating water is needed to cool the equipment. Therefore, developing efficient circulating water scale inhibitors to solve the problem of scale deposition in industrial cooling water circulation system is one of the main problems faced in current industrial production.

[0004] The existing descaling agents are mainly phosphorus-containing scale inhibitors, acrylic polymers, and sulfonic acid polymers. Phosphorus-containing scale inhibitors will discharge a large amount of phosphorus-containing substances into the nature, causing eutrophication of water bodies and destroying the ecological balance. The scale inhibition effect of acrylic acid scale inhibitors is average, and they need to be used in combination with other scale inhibitors. Sulfonic acid scale inhibitors have excellent water solubility, but the strong acidity of the sulfonic acid group will reduce the hydrogen bonding effect, resulting in low scale inhibition efficiency, and they must be mixed with other scale inhibitors. Therefore, the development of a new type of composite scale inhibitor with excellent water solubility and high scale inhibition efficiency is of great significance for energy conservation and emission reduction. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the inventors firstly provide an application of 3-aminopropane sulfonic acid modified polyaspartic acid in the preparation of a compound scale inhibitor, and further provide a preparation method of the 3-aminopropane sulfonic acid modified polyaspartic acid, and apply it in the preparation of a compound scale inhibitor, and then provide a composite scale inhibitor, which also contains a ternary acrylic acid copolymer. After compounding with the above-mentioned 3-aminopropane sulfonic acid modified polyaspartic acid, the synergistic effect of the two scale inhibitors can be fully exerted, so that the scale inhibitor has excellent water solubility, high scale inhibition efficiency and a wide range of applications.

[0006] The inventors firstly provide a method for preparing 3-aminopropane sulfonic acid modified polyaspartic acid, the specific steps of which are as follows:

[0007] By weight, 40-50 parts of polysuccinimide are dispersed in 600-1000 parts of water under stirring conditions, heated to 40°C-50°C, stirred for 5-15 minutes, 160-200 parts of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid are added dropwise to the mixed solution, and the dropping time is controlled to be 0.5-1 hour. After the dropwise addition is completed, the mixed solution continues to be stirred and reacted at 40°C-50°C for 1-1.5 hours, cooled to 15°C-25°C, and the pH value of the reaction solution is adjusted to 7.0 with hydrochloric acid, and then the reaction solution is poured into 6000-10000 parts of solvent A, stirred for 1-2 hours, filtered, and the solid is washed with 600-1000 parts of solvent A and dried to obtain 3-aminopropane sulfonic acid modified polyaspartic acid.

[0008] The preparation method of aminosulfonic acid and L-serine modified polyaspartic acid scale inhibitor has been reported in the existing literature. In the scale inhibitor, the amino group is directly connected to the sulfonic acid group, which easily leads to the close position of the sulfonic acid group and the imino group to form an intramolecular hydrogen bond, increase the molecular rigidity, reduce the water solubility of the product and the chelation effect of the sulfonic acid group on metal ions. The amino group and the carboxyl group in L-serine are also close to each other and are easily combined through hydrogen bonding, resulting in the general solubility of most amino acids in water. After being grafted to polyaspartic acid, the solubility of the product will also be reduced. The present invention reacts 3-aminopropane sulfonic acid with polysuccinimide to prepare modified polyaspartic acid. Since there are three methylene groups between the amino group and the sulfonic acid group in the structure of 3-aminopropane sulfonic acid, the electron-withdrawing effect of the sulfonic acid group on the amino group is reduced, so the reactivity of the electron-rich amino group is also high. At the same time, the structure of 3-aminopropane sulfonic acid contains a flexible carbon chain composed of three methylene groups, which has high molecular flexibility and the distance between the sulfonic acid group and the imino group is relatively far, which can effectively reduce the rigidity of the polyaspartic acid molecule and improve its water solubility. The structure of 6-aminocaproic acid also contains a long flexible carbon chain, which avoids intramolecular hydrogen bonds, further improves the flexibility and stability of the molecule, and makes the modified polyaspartic acid molecule more stable and water-soluble.

[0009] Therefore, the inventors selected 3-aminopropane sulfonic acid and 6-aminocaproic acid as modifiers, and a mixed solution of the two was prepared according to the following method: 20 parts by weight of 3-aminopropane sulfonic acid and 16 parts of 6-aminocaproic acid were added to 180 parts of a 10%-15% sodium hydroxide aqueous solution, and stirred for 10 minutes to obtain a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid.

[0010] The molecular weight of the polysuccinimide used in the preparation process is 7000-8000; the concentration of hydrochloric acid is 0.5-0.8 mol / L; and the solvent A is methanol or ethanol.

[0011] After obtaining the above 3-aminopropane sulfonic acid modified polyaspartic acid, the inventors further disclosed its application in the preparation of a compound scale inhibitor, and the specific steps are as follows:

[0012] (1) The preparation of 3-aminopropane sulfonic acid modified polyaspartic acid is completed according to the above method and composition.

[0013] (2) Preparation of ternary acrylic acid copolymer:

[0014] 25-30 parts of maleic anhydride, 34-38 parts of sodium allyl sulfonate and 0.4-0.8 parts of sodium bisulfite are added to 500-800 parts of deionized water by weight, stirring is started, air in the reaction kettle is replaced with nitrogen, and then the reaction kettle is heated to 80-90° C., and 18-29 parts of acrylic acid and 13-16 parts of ammonium persulfate aqueous solution are added dropwise to the reaction solution at a time of 20-40 minutes. After the addition is completed, stirring is continued for 4 hours, the temperature is lowered to 15-25° C., the pH value is adjusted to 7.0 with sodium hydroxide, the reaction solution is poured into 5000-8000 parts of solvent B, stirred for 1-2 hours, filtered, the solid is washed with 400-600 parts of solvent B, and dried to obtain a ternary acrylic acid copolymer;

[0015] In the above steps, the mass fraction of the ammonium persulfate aqueous solution is 30%-40%; the mass fraction of the sodium hydroxide is 5%-10%; and the solvent B is methanol.

[0016] (3) Preparation of compound antiscalant:

[0017] The 3-aminopropane sulfonic acid modified polyaspartic acid prepared in step (1) and the ternary acrylic acid copolymer prepared in step (2) are blended to obtain a composite scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid.

[0018] In the above preparation method, maleic anhydride, sodium allyl sulfonate and acrylic acid are used as raw materials to prepare the ternary acrylic acid copolymer. The reaction process is simple and effectively avoids the shortcomings of single acrylic acid and sulfonic acid scale inhibitors. After the ternary acrylic acid copolymer is mixed with 3-aminopropane sulfonic acid modified polyaspartic acid, the synergistic effect of the two scale inhibitors can be fully exerted, so that the scale inhibitor has excellent water solubility, high scale inhibition efficiency and a wide range of application occasions.

[0019] Compared with the prior art, the above technical solution of the present invention has the following beneficial effects:

[0020] 3-aminopropane sulfonic acid is reacted with polysuccinimide to prepare modified polyaspartic acid. Since 3-aminopropane sulfonic acid contains 3 methylene groups between the amino group and the sulfonic acid group in the structure, the electron-withdrawing effect of the sulfonic acid group on the amino group can be effectively reduced, so the reactivity of the electron-rich amino group is also high. In the aminosulfonic acid and L-serine modified polyaspartic acid reported in the existing literature, the amino group is directly connected to the sulfonic acid group, resulting in the sulfonic acid group and the imino group being closer, and it is easy to form intramolecular hydrogen bonds, increase molecular rigidity, reduce the water solubility of the product and the chelation of the sulfonic acid group to metal ions. In L-serine, the amino group and the carboxyl group are also closer, and it is easy to combine through hydrogen bonding, resulting in the general solubility of most amino acids in water, and the solubility of the product will also be reduced after being grafted to polyaspartic acid. The 3-aminopropane sulfonic acid structure of the present invention contains a flexible carbon chain composed of 3 methylene groups, and the molecular flexibility is high, and the sulfonic acid group and the imino group are farther apart, which can effectively reduce the rigidity of the polyaspartic acid molecule and improve water solubility. The structure of 6-aminocaproic acid also contains a long flexible carbon chain, which avoids intramolecular hydrogen bonds, further improves the flexibility and stability of the molecule, and makes the modified polyaspartic acid molecule more stable and water-soluble.

[0021] The present invention uses maleic anhydride, sodium allyl sulfonate and acrylic acid as raw materials to prepare a ternary acrylic acid copolymer. The reaction process is simple, and the shortcomings of single acrylic acid and sulfonic acid scale inhibitors are effectively avoided. After the ternary acrylic acid copolymer is mixed with 3-aminopropane sulfonic acid modified polyaspartic acid, the synergistic effect of the two scale inhibitors can be fully exerted, so that the scale inhibitor has excellent water solubility, high scale inhibition efficiency and a wide range of applications. According to tests, when the scale inhibitor concentration is 5 mg / L, the scale inhibition rate of calcium carbonate in the present invention reaches more than 85%, and the scale inhibition rate of calcium sulfate is more than 95%. In the prior art, the scale inhibition rate of calcium carbonate of aminosulfonic acid and L-serine modified polyaspartic acid scale inhibitor is about 80%, and the scale inhibition rate of calcium sulfate is about 93%. Compared with these, the present application has a very significant improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the test result of the scale inhibition rate of calcium carbonate in Experimental Example 1;

[0023] Figure 2 This is the test result of the calcium sulfate scale inhibition rate in Experimental Example 2;

[0024] Figure 3 This is a result diagram of the effect of temperature on the scale inhibition rate of the composite scale inhibitor of the present application in Experimental Example 3;

[0025] A is the effect of temperature on the scale inhibition efficiency of calcium carbonate, where the scale inhibitor concentration is 6 mg / L, and B is the effect of temperature on the scale inhibition efficiency of calcium sulfate, where the scale inhibitor concentration is 5 mg / L;

[0026] Figure 4This is a result diagram of the effect of pH on the scale inhibition rate of the composite scale inhibitor of the present application in Experimental Example 4;

[0027] A is the effect of pH on the scale inhibition efficiency of calcium carbonate, where the scale inhibitor concentration is 6 mg / L, and B is the effect of pH on the scale inhibition efficiency of calcium sulfate, where the scale inhibitor concentration is 5 mg / L. DETAILED DESCRIPTION

[0028] The above contents of the present invention are further described in detail below by specific implementation methods in the form of examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. Unless otherwise specified, the raw materials used in the following examples are all commercially available products, and the parts are all weight parts.

[0029] Example 1 Application of 3-aminopropane sulfonic acid modified polyaspartic acid in the preparation of a compound scale inhibitor, the specific steps are as follows:

[0030] Preparation of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid: Add 20 parts of 3-aminopropane sulfonic acid and 16 parts of 6-aminocaproic acid into 180 parts of a 10% sodium hydroxide aqueous solution and stir for 10 minutes to obtain a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid.

[0031] (1) Preparation of 3-aminopropane sulfonic acid modified polyaspartic acid:

[0032] 40 parts of polysuccinimide are dispersed in 600 parts of water under stirring, heated to 40°C, stirred for 5 minutes, 160 parts of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid are added dropwise to the mixture, and the dropping time is controlled to be 0.5 hour. After the dropping is completed, the mixture is continued to be stirred and reacted at 40°C for 1 hour, cooled to 15°C, and the pH value of the reaction solution is adjusted to 7.0 with a 0.5 mol / L hydrochloric acid aqueous solution, and then the reaction solution is poured into 6000 parts of ethanol, stirred for 1 hour, filtered, and the solid is washed with 600 parts of ethanol and dried to obtain 3-aminopropane sulfonic acid modified polyaspartic acid.

[0033] (2) Preparation of ternary acrylic acid copolymer:

[0034] 25 parts of maleic anhydride, 34 parts of sodium allyl sulfonate and 0.4 parts of sodium bisulfite are added to 500 parts of deionized water, stirring is started, the air in the reactor is replaced with nitrogen, and then heated to 80°C, 18 parts of acrylic acid and 13 parts of 30% ammonium persulfate aqueous solution are added dropwise to the reaction solution at the same time, and the dropping time is controlled within 20 minutes. After the dropping is completed, stirring is continued for 4 hours, the temperature is lowered to 15°C, the pH value is adjusted to 7.0 with a 5% sodium hydroxide aqueous solution, the reaction solution is poured into 5000 parts of methanol, stirred for 1 hour, filtered, the solid is washed with 400 parts of methanol, and dried to obtain a ternary acrylic acid copolymer.

[0035] (3) Preparation of compound scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid:

[0036] The 3-aminopropane sulfonic acid modified polyaspartic acid prepared in step (1) and the ternary acrylic acid copolymer prepared in step (2) are blended to obtain a composite scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid.

[0037] Example 2 Application of 3-aminopropane sulfonic acid modified polyaspartic acid in the preparation of a compound scale inhibitor, the specific steps are as follows:

[0038] Preparation of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid: Add 20 parts of 3-aminopropane sulfonic acid and 16 parts of 6-aminocaproic acid into 180 parts of a 15% sodium hydroxide aqueous solution and stir for 10 minutes to obtain a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid.

[0039] (1) Preparation of 3-aminopropane sulfonic acid modified polyaspartic acid:

[0040] Disperse 50 parts of polysuccinimide in 1000 parts of water under stirring, heat to 50°C, stir for 15 minutes, add 200 parts of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid dropwise to the mixture, and control the dropping time to 1 hour. After the dropping is completed, the mixture continues to stir and react at 50°C for 1.5 hours, cools to 25°C, adjusts the pH value of the reaction solution to 7.0 with 0.8 mol / L hydrochloric acid aqueous solution, and then pours the reaction solution into 10,000 parts of ethanol, stirs for 2 hours, filters, washes the solid with 1000 parts of ethanol, and dries to obtain 3-aminopropane sulfonic acid modified polyaspartic acid.

[0041] (2) Preparation of ternary acrylic acid copolymer:

[0042] 30 parts of maleic anhydride, 38 parts of sodium allyl sulfonate and 0.8 parts of sodium bisulfite are added to 800 parts of deionized water, stirring is started, the air in the reactor is replaced with nitrogen, and then heated to 90°C, 29 parts of acrylic acid and 16 parts of 40% ammonium persulfate aqueous solution are added dropwise to the reaction solution at the same time, and the dropping time is controlled within 40 minutes. After the dropping is completed, stirring is continued for 4 hours, the temperature is lowered to 25°C, the pH value is adjusted to 7.0 with a 10% sodium hydroxide aqueous solution, the reaction solution is poured into 8000 parts of methanol, stirred for 2 hours, filtered, the solid is washed with 600 parts of methanol, and dried to obtain a ternary acrylic acid copolymer.

[0043] (3) Preparation of compound scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid:

[0044] The 3-aminopropane sulfonic acid modified polyaspartic acid prepared in step (1) and the ternary acrylic acid copolymer prepared in step (2) are blended to obtain a composite scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid.

[0045] Example 3 Application of 3-aminopropane sulfonic acid modified polyaspartic acid in the preparation of a compound scale inhibitor, the specific steps are as follows:

[0046] Preparation of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid: Add 20 parts of 3-aminopropane sulfonic acid and 16 parts of 6-aminocaproic acid into 180 parts of a 10% sodium hydroxide aqueous solution and stir for 10 minutes to obtain a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid.

[0047] (1) Preparation of 3-aminopropane sulfonic acid modified polyaspartic acid:

[0048] 44 parts of polysuccinimide were dispersed in 800 parts of water under stirring conditions, heated to 45°C, stirred for 10 minutes, and 180 parts of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid were added dropwise to the mixture. The dropping time was controlled to be 0.8 hours. After the dropping was completed, the mixture was continued to react at 45°C with stirring for 1.2 hours, cooled to 20°C, and the pH value of the reaction solution was adjusted to 7.0 with a 0.5 mol / L aqueous hydrochloric acid solution. The reaction solution was then poured into 8000 parts of methanol, stirred for 1.5 hours, filtered, and the solid was washed with 800 parts of methanol and dried to obtain 3-aminopropane sulfonic acid modified polyaspartic acid.

[0049] (2) Preparation of ternary acrylic acid copolymer:

[0050] 28 parts of maleic anhydride, 36 parts of sodium allyl sulfonate and 0.6 parts of sodium bisulfite are added to 600 parts of deionized water, stirring is started, the air in the reactor is replaced with nitrogen, and then heated to 85°C, 25 parts of acrylic acid and 14 parts of 35% ammonium persulfate aqueous solution are added dropwise to the reaction solution at the same time, and the dropping time is controlled within 30 minutes. After the dropping is completed, stirring is continued for 4 hours, the temperature is lowered to 20°C, the pH value is adjusted to 7.0 with a 5% sodium hydroxide aqueous solution, the reaction solution is poured into 6000 parts of methanol, stirred for 1.5 hours, filtered, the solid is washed with 500 parts of methanol, and dried to obtain a ternary acrylic acid copolymer.

[0051] (3) Preparation of compound scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid:

[0052] The 3-aminopropane sulfonic acid modified polyaspartic acid prepared in step (1) and the ternary acrylic acid copolymer prepared in step (2) are blended to obtain a composite scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid.

[0053] Comparative Example

[0054] L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitor was prepared according to the method of the literature (Yu Fanxuan. Preparation and performance study of modified polyaspartic acid corrosion inhibitor [D]. Hefei University of Technology, 2022. DOI: 10.27101 / d.cnki.ghfgu.2022.001069), the preparation method is as follows:

[0055] 27 parts of L-serine and 25 parts of aminosulfonic acid were added to 200 parts of 10% sodium hydroxide aqueous solution, stirred for 10 minutes, and a mixed solution of serine and aminosulfonic acid was obtained. 50 parts of polysuccinimide were added to 1000 parts of water, heated to 40°C, stirred for 10 minutes, and the mixed solution of serine and aminosulfonic acid was added dropwise. The addition time was controlled within 1 hour. After the addition was completed, the mixed solution was stirred and reacted at 40°C for 2 hours. The pH value of the reaction solution was adjusted to 7.0 with a 1 mol / L hydrochloric acid aqueous solution. 10,000 parts of ethanol were added to the reaction solution, stirred, filtered, and the solid was dried to obtain L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitor.

[0056] Experimental Example 1 Calcium carbonate scale inhibition performance test:

[0057] According to the method used in the national standard (GB / T 16632-2019), the concentration of calcium ions in each test solution was obtained by EDTA titration, and then the scale inhibition performance of the scale inhibitor on calcium carbonate was calculated, and the scale inhibition rate of calcium carbonate ( A 1 ) is calculated according to the following formula:

[0058]

[0059] in, v 0 Represents the volume of EDTA consumed by the blank group without antiscalant, in mL; v 1 Represents the volume of EDTA consumed by the scale inhibitor test group, in mL; V 2 Represents the volume of EDTA consumed in actual working water or prepared water, in mL.

[0060] Calcium carbonate scale inhibition performance test results are as follows Figure 1 As shown, it can be seen that the scale inhibitors prepared in Examples 1-3 of the present invention have excellent scale inhibition effects, especially the scale inhibitor prepared in Example 3. When the scale inhibitor concentration is 6 mg / L, the scale inhibition efficiency of calcium carbonate reaches 94.44%, and when the concentration is 8 mg / L, the scale inhibition efficiency reaches 98.68%, which is significantly better than the L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitors prepared in the comparative example.

[0061] Experimental Example 2 Calcium sulfate scale inhibition performance test:

[0062] Use sodium sulfate and calcium chloride to prepare a standard solution with a calcium ion mass concentration of 7100 mg / L and a sulfate ion mass concentration of 6800 mg / L.

[0063] Take a certain amount of standard solution, add scale inhibitors with mass concentrations of 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, and 8 mg / L, adjust the pH value to 7.0, place it in a water bath at 80°C for 10 hours, cool it, filter it, take 5 mL of the filtrate, add 5 mL of potassium hydroxide solution with a mass concentration of 200 mg / mL, then add 50 mL of distilled water, shake it well, add calcium carboxylate indicator, and titrate it with 0.01 mol / L EDTA standard solution until the solution changes from purple-red to bright blue, record the volume of EDTA standard solution consumed, and calculate the scale inhibition rate of calcium sulfate according to the following formula ( A 2 ):

[0064]

[0065] in, v 0 Represents the volume of EDTA consumed by the blank group after heating for 10 h; v 1 Represents the volume of EDTA consumed by the solution to which the antiscalant was added after heating for 10 hours; v 2 Represents the volume of EDTA consumed by the blank group without heating.

[0066] The test results of calcium sulfate scale inhibition performance are as follows: Figure 2 As shown, it can be seen that the scale inhibitors prepared in Examples 1-3 of the present invention exhibited a high calcium sulfate scale inhibition efficiency, which was significantly better than the L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitors prepared in the comparative example. In particular, the scale inhibitor prepared in Example 3 had a calcium sulfate scale inhibition efficiency of 96.53% when the scale inhibitor concentration was 5 mg / L. As the concentration of the scale inhibitor continued to increase, the calcium sulfate scale inhibition efficiency increased slightly but not significantly.

[0067] Experimental Example 3 Effect of temperature on scale inhibition rate:

[0068] The above experimental example shows that the scale inhibitor prepared in Example 3 of the present invention has the best scale inhibition efficiency, so this sample is selected for the temperature effect experiment. The test temperatures are selected as 70°C, 75°C, 80°C, 85°C, and 90°C to study the effect of temperature on the scale inhibition efficiency of calcium carbonate and calcium sulfate. The results are as follows: Figure 3 shown.

[0069] When the concentration of the scale inhibitor is 6 mg / L, at 70°C, the scale inhibition efficiency of the scale inhibitor prepared in Example 3 on calcium carbonate is 96.22%, and when the temperature rises to 90°C, the scale inhibition efficiency of calcium carbonate decreases to 90.07%. At 70°C, the scale inhibition efficiency of the L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitors in the comparative example on calcium carbonate is 91.14%, and when the temperature rises to 90°C, the scale inhibition efficiency of calcium carbonate decreases to 84.17%.

[0070] When the concentration of the scale inhibitor is 5 mg / L, when the temperature rises from 70°C to 90°C, the scale inhibition efficiency of the scale inhibitor prepared in Example 3 for calcium sulfate decreases from 97.54% to 91.68%. The scale inhibition efficiency of the L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitors for calcium sulfate in the comparative example decreases from 95.07% to 86.34%. This shows that the scale inhibitor prepared in Example 3 of the present invention has good temperature stability and still has a good scale inhibition effect at 90°C.

[0071] Experimental Example 4 Effect of pH on scale inhibition rate:

[0072] The effect of pH on the scale inhibition efficiency of calcium carbonate and calcium sulfate was studied. The results are as follows Figure 4 The scale inhibitor prepared in Example 3 has a relatively stable calcium carbonate scale inhibition efficiency in the pH range of 5-8, and the scale inhibition rates are 91.75%, 93.37%, 94.44% and 91.55%, respectively, while the L-serine and aminosulfonic acid modified polyaspartic acid in the comparative example have a relatively stable calcium carbonate scale inhibition efficiency in the pH range of 6-8, and the scale inhibition rates are 88.21%, 89.48% and 85.22%, respectively.

[0073] In the pH range of 5-8, the scale inhibition efficiency of the scale inhibitor prepared in Example 3 for calcium sulfate is 91.25%, 94.85%, 96.53% and 92.33%, respectively, while the scale inhibition efficiency of L-serine and aminosulfonic acid modified polyaspartic acid in the comparative example for calcium sulfate in the pH range of 6-8 is 90.46%, 92.14% and 88.15%, respectively.

[0074] The above results show that the scale inhibitor prepared in Example 3 of the present invention has good tolerance to pH and has a relatively stable scale inhibition efficiency in the pH range of 5-8, which is better than the L-serine and aminosulfonic acid modified polyaspartic acid scale inhibitors prepared in the comparative example.

[0075] It can be seen that the scale inhibitor provided by the present invention is a mixture of ternary acrylic acid copolymer and 3-aminopropane sulfonic acid modified polyaspartic acid, which can give full play to the synergistic effect of the two scale inhibitors, so that the scale inhibitor has excellent water solubility, high scale inhibition efficiency and a wide range of application occasions.

[0076] Application Experiment Example

[0077] The scale inhibition effect of the scale inhibitor of Example 3 of the present invention was tested by using the wastewater of a coal chemical industry group as circulating water replenishment:

[0078] The wastewater hardness is 3.63 mmol / L, the alkalinity is 4.21 mmol / L, the calcium ion content is 95.47 mg / L, the sulfate ion content is 41.64 mg / L, the chloride ion content is 185.38 mg / L, and the COD value is 242 mg / L.

[0079] The blank group did not use scale inhibitors. The wastewater directly entered the circulation pipeline. After one month, the pipeline was opened for inspection and a large amount of dirt was found on the inner wall of the pipeline. After half a year, the pipeline was opened for inspection and obvious pipeline corrosion was observed after removing the dirt deposits.

[0080] The experimental group used the scale inhibitor prepared in Example 3 of the present invention (dosage was 5 mg / L). After one month, the pipeline was opened for inspection and no obvious scale deposition was found; after half a year, no obvious pipeline deposition was still found.

[0081] The control group added the scale inhibitor prepared in the comparative example (dosage was 5 mg / L). After one month, the pipeline was opened for inspection and no obvious dirt deposition was found. However, after half a year of use, obvious dirt deposition was seen on the inner wall of the pipeline and needed to be cleaned with water.

[0082] It can be seen that the scale inhibitor provided in this application also has a significant effect in practical applications.

[0083] The above embodiments enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 3-aminopropane sulfonic acid modified polyaspartic acid to prepare a composite scale inhibitor, characterized in that: The specific steps are as follows: (1) Preparation of 3-aminopropanesulfonic acid modified polyaspartic acid: By weight, 40-50 parts of polysuccinimide are dispersed in 600-1000 parts of water under stirring conditions, heated to 40°C-50°C, stirred for 5-15 minutes, 160-200 parts of a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid are added dropwise to the mixed solution, and the dropping time is controlled to be 0.5-1 hour. After the dropping is completed, the mixed solution continues to be stirred and reacted at 40°C-50°C for 1-1.5 hours, cooled to 15°C-25°C, and the pH value of the reaction solution is adjusted to 7.0 with a hydrochloric acid aqueous solution, and then the reaction solution is poured into 6000-10000 parts of solvent A, stirred for 1-2 hours, filtered, and the solid is washed with 600-1000 parts of solvent A, and dried to obtain 3-aminopropane sulfonic acid modified polyaspartic acid; (2) Preparation of ternary acrylic acid copolymer: 25-30 parts of maleic anhydride, 34-38 parts of sodium allyl sulfonate and 0.4-0.8 parts of sodium bisulfite are added to 500-800 parts of deionized water by weight, stirring is started, air in the reaction kettle is replaced with nitrogen, and then the reaction kettle is heated to 80-90° C., and 18-29 parts of acrylic acid and 13-16 parts of ammonium persulfate aqueous solution are added dropwise to the reaction solution at a time of 20-40 minutes. After the addition is completed, stirring is continued for 4 hours, the temperature is lowered to 15-25° C., the pH value is adjusted to 7.0 with sodium hydroxide, the reaction solution is poured into 5000-8000 parts of solvent B, stirred for 1-2 hours, filtered, the solid is washed with 400-600 parts of solvent B, and dried to obtain a ternary acrylic acid copolymer; (3) Preparation of compound antiscalant: The 3-aminopropane sulfonic acid modified polyaspartic acid prepared in step (1) and the ternary acrylic acid copolymer prepared in step (2) are blended to obtain a composite scale inhibitor containing 3-aminopropane sulfonic acid modified polyaspartic acid.

2. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (1), a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid is prepared according to the following method: 20 parts by weight of 3-aminopropane sulfonic acid and 16 parts of 6-aminocaproic acid are added to 180 parts of a 10%-15% sodium hydroxide aqueous solution, and stirred for 10 minutes to obtain a mixed solution of 3-aminopropane sulfonic acid and 6-aminocaproic acid.

3. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (1), the molecular weight of polysuccinimide is 7000-8000.

4. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (1), the concentration of hydrochloric acid used is 0.5-0.8 mol / L; and solvent A is methanol or ethanol.

5. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (2), the mass fraction of the ammonium persulfate aqueous solution is 30%-40%.

6. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (2), the mass fraction of sodium hydroxide is 5%-10%.

7. The method for preparing a composite scale inhibitor according to claim 1, characterized in that: In the step (2), solvent B is methanol.

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