A preparation method of high-hardness and high-sulfate water quality scale inhibitor

Abstract

The present invention relates to a preparation method of a high-hardness and high-sulfate water quality scale inhibitor, belonging to the technical field of water treatment, the present invention uses carboxymethyl cellulose as a stabilizer, prepares sodium carboxymethyl cellulose sulfur quantum dots, and then copolymerizes with 2-acrylamide-2-methylpropane sulfonic acid and itaconic acid to obtain modified sodium carboxymethyl cellulose sulfur quantum dots, polysuccinimide and 4-aminophthalic acid and 2-aminoethanesulfonic acid react to obtain polyaspartic acid derivatives; the modified sodium carboxymethyl cellulose sulfur quantum dots and the polyaspartic acid derivatives are mixed as scale inhibitors, and the two act synergistically, significantly improving the scale inhibition rate of the scale inhibitor, and at the same time, due to the generation of a large number of new hydrogen bonds between the modified sodium carboxymethyl cellulose sulfur quantum dots and the polyaspartic acid derivatives, it is beneficial to improve the stability of the polymer structure, thereby improving the temperature resistance of the scale inhibitor. The scale inhibitor is green and environmentally friendly, and has excellent scale inhibition efficiency for high-hardness and high-sulfate water quality.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular, relates to a method for preparing a high-hardness and high-sulfate water quality scale inhibitor. Background Art

[0002] As a resource, water is becoming increasingly scarce in most parts of the world. Water is the basis of our industry, agriculture and life. However, with the continuous advancement of industrialization, the contradiction between the rapid development of industry and the relative shortage of water resources has become increasingly prominent. In order to save water, all walks of life have adopted circulating water systems, and the generation of scale is a serious problem in water recycling. At present, the main scales in industrial water are calcium carbonate and calcium sulfate. Calcium carbonate can be easily eliminated by acid treatment, while calcium sulfate scale is a yellow-white hard and dense solid. Once it is formed, it is difficult to remove, which seriously affects industrial production. In order to avoid scaling, the generally effective method is to add scale inhibitors.

[0003] Scale inhibitors can generally be divided into inorganic phosphate scale inhibitors, organic phosphonate scale inhibitors, polymer scale inhibitors, synthetic green scale inhibitors and natural organic scale inhibitors. Inorganic phosphate scale inhibitors and organic phosphonate scale inhibitors have been widely used in various industries, but their excessive use can easily cause environmental pollution. Synthetic green scale inhibitors such as polyaspartic acid are non-toxic and biodegradable, and are a kind of green and environmentally friendly scale inhibitor, but they are not ideal for preventing calcium sulfate, the scale inhibition effect is general, and the temperature resistance is poor. Natural organic scale inhibitors mainly include tannins, lignin, chitosan and cellulose, etc., which are used in large quantities in actual applications and their use effects are easily affected by the external environment. Therefore, it is necessary to provide an environmentally friendly scale inhibitor with good temperature resistance and good scale inhibition performance for high hardness and high sulfate water. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a high-hardness and high-sulfate water quality scale inhibitor, wherein modified sodium carboxymethyl cellulose-sulfur quantum dots containing a large number of carboxylic acid, amide and sulfonic acid groups and polyaspartic acid derivatives containing a large number of carboxyl groups, benzene rings and sulfonic acid groups are mixed as scale inhibitors, and the two act synergistically to significantly improve the scale inhibition rate of the scale inhibitor. At the same time, since a large number of new hydrogen bonds are generated between the modified sodium carboxymethyl cellulose-sulfur quantum dots and the polyaspartic acid derivatives, it is beneficial to improve the stability of the polymer structure, thereby improving the temperature resistance of the scale inhibitor. The prepared scale inhibitor is biodegradable, is a green and environmentally friendly scale inhibitor, and has excellent scale inhibition efficiency for high-hardness and high-sulfate water quality.

[0005] The technical problem to be solved by the present invention is that inorganic phosphate scale inhibitors and organic phosphonate scale inhibitors have been widely used in various industries, but their excessive use can easily cause environmental pollution. Natural polymer scale inhibitors such as polyaspartic acid are non-toxic and biodegradable, and are green and environmentally friendly scale inhibitors, but they are not ideal for preventing calcium sulfate, have a general scale inhibition effect, and have poor temperature resistance.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0008] A1. Carboxymethyl cellulose and sublimated sulfur powder are placed in a sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen is introduced and the system temperature is raised to 90-130° C. for heating reaction. After the reaction is completed, filtration, dialysis, and freeze-drying are performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0009] Furthermore, in step A1, the heating reaction time is 30-42 hours.

[0010] Furthermore, in step A1, the mass concentration of the sodium hydroxide solution is 4-7%.

[0011] Furthermore, in step A1, the usage ratio of carboxymethyl cellulose, sublimated sulfur powder and sodium hydroxide solution is (5-5.3) g: (7.9-8.6) g: (330-380) mL.

[0012] A2, sodium carboxymethyl cellulose-sulfur quantum dots are dispersed in deionized water, nitrogen is introduced and the temperature is raised to 70-80°C, stirred for 0.5-1h, and then isopropanol and ammonium persulfate are added in sequence, stirred for 15-30min, and itaconic acid is added dropwise, and the reaction is carried out for 0.5-1h; after the reaction is completed, 2-acrylamido-2-methylpropanesulfonic acid and the remaining itaconic acid are added dropwise in sequence, nitrogen is introduced, and the remaining isopropanol and the remaining ammonium persulfate are added, and the reaction is stirred for 2-6h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0013] Furthermore, in step A2, the mass ratio of sodium carboxymethyl cellulose-sulfur quantum dots, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, isopropanol and ammonium persulfate is (2.2-2.5):(1.8-2.3):(1-1.2):(0.42-0.78):(0.48-0.86).

[0014] Furthermore, in step A2, the mass ratio of itaconic acid added twice is (1-1.5):(1-1.5).

[0015] Furthermore, in step A2, the mass ratio of the isopropanol added twice is (0.9-1.2):(0.8-1).

[0016] Furthermore, in step A2, the mass ratio of the ammonium persulfate added twice is (1-1.2):(0.7-0.9).

[0017] A3, adding polysuccinimide to deionized water to form solution A, dissolving 4-aminophthalic acid in sodium hydroxide solution a to form solution B, dissolving 2-aminoethanesulfonic acid in sodium hydroxide solution b to form solution C, adding solution B and solution C dropwise to solution A, reacting at 40-60° C. for 12-18 hours, adjusting to neutrality after the reaction, then precipitating with anhydrous ethanol, and then solid-liquid separation and drying to obtain a polyaspartic acid derivative;

[0018] Furthermore, in step A3, the mass concentration of sodium hydroxide solution a and sodium hydroxide solution b is 10-15%.

[0019] Furthermore, in step A3, the molar ratio of polysuccinimide, 4-aminophthalic acid and 2-aminoethanesulfonic acid is 1:(0.7-1.1):(0.9-1.3).

[0020] Furthermore, in step A3, the usage ratio of polysuccinimide and deionized water is (1-1.2) g: (100-150) mL.

[0021] Furthermore, in step A3, the usage ratio of 4-aminophthalic acid and sodium hydroxide solution a is (1-1.2) g: (12-15) mL.

[0022] Furthermore, in step A3, the usage ratio of 2-aminoethanesulfonic acid and sodium hydroxide solution b is (1-1.2) g: (10-13) mL.

[0023] A4. Add modified sodium carboxymethyl cellulose-sulfur quantum dots and polyaspartic acid derivatives into deionized water and stir for 1-3 hours to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0024] Furthermore, in step A4, the mass ratio of modified sodium carboxymethyl cellulose-sulfur quantum dots to polyaspartic acid derivative is (65-75): (25-35).

[0025] In the above technical scheme, carboxymethyl cellulose is first used as a stabilizer to prepare sodium carboxymethyl cellulose-sulfur quantum dots. When carboxymethyl cellulose exists alone, the molecular chains are easily cross-linked and entangled. After the present invention combines carboxymethyl cellulose and sulfur quantum dots, the electronegativity increases, and the repulsion between the carboxymethyl cellulose molecular chains increases, making it difficult for the molecular chains to entangle, exposing more active sites, thereby improving the scale inhibition rate. In order to further improve the scale inhibition rate, the present invention copolymerizes sodium carboxymethyl cellulose-sulfur quantum dots with 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid, greatly increasing the content of carboxylic acid, amide and sulfonic acid groups. At the same time, since sodium carboxymethyl cellulose is combined with sulfur quantum dots to expose more active sites, the content of carboxylic acid, amide and sulfonic acid groups is further increased, thereby significantly improving the scale inhibition rate and water solubility.

[0026] The polysuccinimide of the present invention is reacted with 4-aminophthalic acid and 2-aminoethanesulfonic acid to prepare a polyaspartic acid derivative. On the one hand, due to the grafting of 4-aminophthalic acid, the carboxylic acid groups on the polyaspartic acid derivative are increased, thereby improving the scale inhibition efficiency. At the same time, the presence of the rigid benzene ring improves the temperature resistance of the polyaspartic acid derivative. On the other hand, due to the grafting of 2-aminoethanesulfonic acid, the content of the sulfonic acid group is increased, thereby improving the water solubility and temperature resistance of the polyaspartic acid derivative.

[0027] The present invention mixes modified sodium carboxymethyl cellulose-sulfur quantum dots containing a large number of carboxylic acid, amide and sulfonic acid groups and polyaspartic acid derivatives containing a large number of carboxyl groups, benzene rings and sulfonic acid groups as scale inhibitors. The two act synergistically to significantly improve the scale inhibition rate of the scale inhibitor; at the same time, since a large number of new hydrogen bonds are generated between the modified sodium carboxymethyl cellulose-sulfur quantum dots and the polyaspartic acid derivatives, it is beneficial to improve the stability of the structure of the polyaspartic acid derivatives, thereby improving the temperature resistance of the polyaspartic acid derivatives.

[0028] Beneficial effects of the present invention:

[0029] (1) In the technical scheme of the present invention, modified sodium carboxymethyl cellulose-sulfur quantum dots containing a large number of carboxylic acid, amide and sulfonic acid groups and polyaspartic acid derivatives containing a large number of carboxyl groups, benzene rings and sulfonic acid groups are mixed as scale inhibitors. The synergistic effect of the two significantly improves the scale inhibition rate of the scale inhibitor, and has excellent scale inhibition efficiency for high hardness and high sulfate water. At the same time, due to the generation of a large number of new hydrogen bonds between the modified sodium carboxymethyl cellulose-sulfur quantum dots and the polyaspartic acid derivatives, it is beneficial to improve the stability of the polymer structure, thereby improving the temperature resistance of the scale inhibitor.

[0030] (2) In the technical solution of the present invention, after carboxymethyl cellulose and sulfur quantum dots are combined, the electronegativity increases, and the repulsion between the carboxymethyl cellulose molecular chains increases, making it difficult for the molecular chains to entangle, exposing more active sites, thereby improving the scale inhibition rate. In order to further improve the scale inhibition rate, the present invention copolymerizes sodium carboxymethyl cellulose-sulfur quantum dots with 2-acrylamide-2-methylpropane sulfonic acid and residual itaconic acid, greatly increasing the content of carboxylic acid, amide and sulfonic acid groups. At the same time, since more active sites are exposed after sodium carboxymethyl cellulose is combined with sulfur quantum dots, the content of carboxylic acid, amide and sulfonic acid groups is further increased, thereby significantly improving the scale inhibition rate.

[0031] (3) In the technical scheme of the present invention, polysuccinimide reacts with 4-aminophthalic acid and 2-aminoethanesulfonic acid to obtain polyaspartic acid derivatives. On the one hand, due to the grafting of 4-aminophthalic acid, the number of carboxylic acid groups on the polyaspartic acid derivatives increases, thereby improving the scale inhibition efficiency. At the same time, the presence of the rigid benzene ring improves the temperature resistance of the polyaspartic acid derivatives. On the other hand, due to the grafting of 2-aminoethanesulfonic acid, the content of sulfonic acid groups is increased, thereby improving the water solubility and temperature resistance of the polyaspartic acid derivatives. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0035] A1. 5 g of carboxymethyl cellulose and 7.9 g of sublimed sulfur powder were placed in 330 mL of a 4% sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen was introduced and the system temperature was raised to 90° C. for heating reaction for 30 h. After the reaction was completed, filtration, dialysis, and freeze-drying were performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0036] A2, 8.8g sodium carboxymethyl cellulose-sulfur quantum dots were dispersed in 100mL deionized water, nitrogen was introduced and the temperature was raised to 70°C, stirred for 0.5h, and then 0.89g isopropanol and 1.13g ammonium persulfate were added in sequence, and 3.6g itaconic acid was added after stirring for 15min, and the reaction was carried out for 0.5-1h; after the reaction was completed, 4g 2-acrylamido-2-methylpropanesulfonic acid and 3.6g itaconic acid were added in sequence, nitrogen was introduced, and then 0.82g isopropanol and 0.79g ammonium persulfate were added, the reaction was stirred for 2h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0037] A3, 10g of polysuccinimide was added to 1L of deionized water to form solution A, 9.6g of 4-aminophthalic acid was dissolved in 120mL of 10% sodium hydroxide solution a to form solution B, 8.5g of 2-aminoethanesulfonic acid was dissolved in 90mL of 10% sodium hydroxide solution b to form solution C, solution B and solution C were added dropwise to solution A, reacted at 40°C for 12h, adjusted to neutral after the reaction, then precipitated with anhydrous ethanol, separated from the solid and liquid, and dried to obtain a polyaspartic acid derivative;

[0038] A4. Add 13 g of modified sodium carboxymethyl cellulose-sulfur quantum dots and 7 g of polyaspartic acid derivative into 100 mL of deionized water and stir for 1 hour to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0039] Example 2

[0040] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0041] A1. 5.1 g of carboxymethyl cellulose and 8.1 g of sublimated sulfur powder were placed in 350 mL of a 5% sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen was introduced and the system temperature was raised to 100° C. for heating reaction for 36 h. After the reaction was completed, filtration, dialysis, and freeze-drying were performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0042] A2, 9g of sodium carboxymethyl cellulose-sulfur quantum dots were dispersed in 100mL of deionized water, nitrogen was introduced and the temperature was raised to 70°C, stirred for 1h, and then 1g of isopropanol and 1.3g of ammonium persulfate were added in sequence, and 3.6g of itaconic acid was added dropwise after stirring for 15min, and the reaction was carried out for 0.5h; after the reaction was completed, 4.2g of 2-acrylamido-2-methylpropanesulfonic acid and 4.2g of itaconic acid were added dropwise in sequence, nitrogen was introduced, and 1g of isopropanol and 0.9g of ammonium persulfate were added, and the reaction was stirred for 3h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0043] A3, 10g of polysuccinimide was added to 1.1L of deionized water to form solution A, 10.9g of 4-aminophthalic acid was dissolved in 160mL of a sodium hydroxide solution a having a mass concentration of 12% to form solution B, 9.4g of 2-aminoethanesulfonic acid was dissolved in 122mL of a sodium hydroxide solution b having a mass concentration of 12% to form solution C, solution B and solution C were added dropwise to solution A, and the mixture was reacted at 45°C for 15h. After the reaction was completed, the mixture was adjusted to neutral, and then precipitated with anhydrous ethanol, and then solid-liquid separation and drying were performed to obtain a polyaspartic acid derivative;

[0044] A4. Add 14 g of modified sodium carboxymethyl cellulose-sulfur quantum dots and 6 g of polyaspartic acid derivative into 100 mL of deionized water and stir for 2 h to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0045] Example 3

[0046] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0047] A1. 5.2 g of carboxymethyl cellulose and 8.2 g of sublimated sulfur powder were placed in 350 mL of a 6% sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen was introduced and the system temperature was raised to 110° C. for heating reaction for 36 h. After the reaction was completed, filtration, dialysis, and freeze-drying were performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0048] A2, 9.3g sodium carboxymethyl cellulose-sulfur quantum dots were dispersed in 120mL deionized water, nitrogen was introduced and the temperature was raised to 75°C, stirred for 1h, and then 1.27g isopropanol and 1.59g ammonium persulfate were added in sequence, stirred for 20min, 4.8g itaconic acid was added, and the reaction was carried out for 1h; after the reaction, 4.3g 2-acrylamido-2-methylpropanesulfonic acid and 3.2g itaconic acid were added in sequence, nitrogen was introduced, and then 1.03g isopropanol and 1.03g ammonium persulfate were added, the reaction was stirred for 4h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0049] A3, 10g of polysuccinimide was added to 1.3L of deionized water to form solution A, 12.3g of 4-aminophthalic acid was dissolved in 180mL of sodium hydroxide solution a having a mass concentration of 13% to form solution B, 9.4g of 2-aminoethanesulfonic acid was dissolved in 120mL of sodium hydroxide solution b having a mass concentration of 13% to form solution C, solution B and solution C were added dropwise to solution A, and the mixture was reacted at 50°C for 16h. After the reaction was completed, the mixture was adjusted to neutral, and then precipitated with anhydrous ethanol, and then solid-liquid separation and drying were performed to obtain a polyaspartic acid derivative;

[0050] A4. Add 14 g of modified sodium carboxymethyl cellulose-sulfur quantum dots and 6 g of polyaspartic acid derivative into 120 mL of deionized water and stir for 2 h to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0051] Example 4

[0052] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0053] A1. 5.2 g of carboxymethyl cellulose and 8.4 g of sublimed sulfur powder were placed in 360 mL of a 6% sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen was introduced and the system temperature was raised to 110° C. for heating reaction for 38 h. After the reaction was completed, filtration, dialysis, and freeze-drying were performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0054] A2, 9.6g sodium carboxymethyl cellulose-sulfur quantum dots were dispersed in 130mL deionized water, nitrogen was introduced and the temperature was raised to 80°C, stirred for 0.5h, and then 1.52g isopropanol and 1.92g ammonium persulfate were added in sequence, stirred for 25min, 4.9g itaconic acid was added, and the reaction was carried out for 0.5h; after the reaction, 4.6g 2-acrylamido-2-methylpropanesulfonic acid and 3.9g itaconic acid were added in sequence, nitrogen was introduced, and then 1.28g isopropanol and 1.28g ammonium persulfate were added, the reaction was stirred for 5h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0055] A3, 10g of polysuccinimide was added to 1.5L of deionized water to form solution A, 13.6g of 4-aminophthalic acid was dissolved in 200mL of 10% sodium hydroxide solution a to form solution B, 11.2g of 2-aminoethanesulfonic acid was dissolved in 145mL of 10% sodium hydroxide solution b to form solution C, solution B and solution C were added dropwise to solution A, reacted at 60°C for 12h, adjusted to neutral after the reaction, then precipitated with anhydrous ethanol, separated from the solid and liquid, and dried to obtain a polyaspartic acid derivative;

[0056] A4. Add 15 g of modified sodium carboxymethyl cellulose-sulfur quantum dots and 5 g of polyaspartic acid derivative into 100 mL of deionized water and stir for 3 h to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0057] Example 5

[0058] A method for preparing a high-hardness and high-sulfate water quality scale inhibitor comprises the following steps:

[0059] A1. 5.3 g of carboxymethyl cellulose and 8.6 g of sublimated sulfur powder were placed in 380 mL of 7% sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen was introduced and the system temperature was raised to 130° C. for heating reaction for 42 h. After the reaction was completed, filtration, dialysis, and freeze-drying were performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots;

[0060] A2, 10g sodium carboxymethyl cellulose-sulfur quantum dots were dispersed in 100mL deionized water, nitrogen was introduced and the temperature was raised to 80°C, stirred for 1h, and then 1.7g isopropanol and 2.06g ammonium persulfate were added in sequence, and 4.6g itaconic acid was added after stirring for 30min, and the reaction was carried out for 1h; after the reaction, 4.8g 2-acrylamido-2-methylpropanesulfonic acid and 4.6g itaconic acid were added in sequence, nitrogen was introduced, and then 1.42g isopropanol and 1.38g ammonium persulfate were added, and the reaction was stirred for 6h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots;

[0061] A3, 10g of polysuccinimide was added to 1.4L of deionized water to form solution A, 14.9g of 4-aminophthalic acid was dissolved in 180mL of 15% sodium hydroxide solution a to form solution B, 12.2g of 2-aminoethanesulfonic acid was dissolved in 155mL of 15% sodium hydroxide solution b to form solution C, solution B and solution C were added dropwise to solution A, reacted at 60°C for 18h, adjusted to neutral after the reaction, then precipitated with anhydrous ethanol, separated from the solid and liquid, and dried to obtain a polyaspartic acid derivative;

[0062] A4. Add 15 g of modified sodium carboxymethyl cellulose-sulfur quantum dots and 5 g of polyaspartic acid derivative into 100 mL of deionized water and stir for 3 h to obtain a high-hardness and high-sulfate water quality scale inhibitor.

[0063] Comparative Example 1

[0064] Compared with Example 3, no polyaspartic acid derivative was added in Comparative Example 1, and other steps and raw materials were the same as those in Example 3.

[0065] Comparative Example 2

[0066] Compared with Example 3, polyaspartic acid was used to replace the polyaspartic acid derivative in Comparative Example 2, and other steps and raw materials were the same as those in Example 3.

[0067] Comparative Example 3

[0068] Compared with Example 3, the polyaspartic acid derivative in Comparative Example 3 is not grafted with 4-aminophthalic acid, and the other steps and raw materials are the same as those in Example 3.

[0069] Comparative Example 4

[0070] Compared with Example 3, no modified sodium carboxymethyl cellulose-sulfur quantum dots were added in Comparative Example 4, and other steps and raw materials were the same as those in Example 3.

[0071] Comparative Example 5

[0072] Compared with Example 3, in Comparative Example 5, sodium carboxymethyl cellulose-sulfur quantum dots are used to replace modified sodium carboxymethyl cellulose-sulfur quantum dots, and other steps and raw materials are the same as those in Example 3.

[0073] Comparative Example 6

[0074] Compared with Example 3, in Comparative Example 6, sodium carboxymethyl cellulose is directly reacted with itaconic acid and 2-acrylamido-2-methylpropanesulfonic acid, and the obtained product is used to replace the modified sodium carboxymethyl cellulose-sulfur quantum dots, and the other steps and raw materials are synchronized with Example 3.

[0075] Performance Testing

[0076] The performance of the scale inhibitors prepared in Examples 1-5 and Comparative Examples 1-6 was studied, and the results are shown in Table 1.

[0077] According to the method of GB / T 16632-2019 "Calcium Carbonate Deposition Method for Evaluation of Scale Inhibition Performance of Water Treatment Agents", water was prepared for static scale inhibition experiments. In the calcium carbonate scale inhibition experiment, the calcium ion concentration was 300 mg / L, the bicarbonate ion concentration was 915 mg / L, and the scale inhibitor concentration was 10 mg / L; in the calcium sulfate scale inhibition experiment, the calcium ion concentration was 1000 mg / L, the sulfate ion concentration was 19000 mg / L, and the scale inhibitor concentration was 10 mg / L; the test temperature was 80°C and 150°C, and after 12 hours, the scale inhibition rate was determined. The results are shown in Table 1.

[0078] Table 1

[0079]

[0080]

[0081] It can be seen from the results in Table 1 that the scale inhibitor prepared by the present invention has excellent scale inhibition efficiency for high hardness and high sulfate water quality, and has good high temperature resistance. It can be seen from the data of Comparative Example 3 and Comparative Example 1 that the scale inhibition rate of the scale inhibitor is significantly reduced due to the absence of the addition of polyaspartic acid derivatives. It can be seen from the data of Comparative Example 3 and Comparative Example 2 that the scale inhibition rate and temperature resistance are both reduced due to the lack of grafting modification of polyaspartic acid. It can be seen from the data of Comparative Example 3 and Comparative Example 3 that the scale inhibition rate and temperature resistance are both reduced due to the lack of grafting of 4-aminophthalic acid on the molecular chain of the polyaspartic acid derivative. It can be seen from the data of Comparative Example 3 and Comparative Example 4 that the scale inhibitor does not contain modified sodium carboxymethyl cellulose-sulfur quantum dots, but only contains polyaspartic acid derivatives, which leads to a decrease in scale inhibition rate and temperature resistance, indicating that there is a synergistic effect between modified sodium carboxymethyl cellulose-sulfur quantum dots and polyaspartic acid derivatives. Comparing the data of Example 3 and Comparative Example 5, it can be seen that grafting modification of sodium carboxymethyl cellulose-sulfur quantum dots can improve the scale inhibition rate and temperature resistance of the scale inhibitor. Comparing the data of Example 3 and Comparative Example 6, it can be seen that the scale inhibition rate and temperature resistance of the scale inhibitor are reduced due to the absence of sulfur quantum dots.

[0082] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0083] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-hardness and high-sulfate water quality scale inhibitor, characterized in that: The following steps are involved: A1. Carboxymethyl cellulose and sublimated sulfur powder are placed in a sodium hydroxide solution, stirred evenly to obtain a dispersion, and then oxygen is introduced and the system temperature is raised to 90-130° C. for heating reaction. After the reaction is completed, filtration, dialysis, and freeze-drying are performed in sequence to obtain sodium carboxymethyl cellulose-sulfur quantum dots; A2, sodium carboxymethyl cellulose-sulfur quantum dots are dispersed in deionized water, nitrogen is introduced and the temperature is raised to 70-80°C, stirred for 0.5-1h, and then isopropanol and ammonium persulfate are added in sequence, stirred for 15-30min, and itaconic acid is added dropwise, and the reaction is carried out for 0.5-1h; after the reaction is completed, 2-acrylamido-2-methylpropanesulfonic acid and the remaining itaconic acid are added dropwise in sequence, nitrogen is introduced, and the remaining isopropanol and the remaining ammonium persulfate are added, and the reaction is stirred for 2-6h, washed with ethanol, filtered, and dried to obtain modified sodium carboxymethyl cellulose-sulfur quantum dots; A3, adding polysuccinimide to deionized water to form solution A, dissolving 4-aminophthalic acid in sodium hydroxide solution a to form solution B, dissolving 2-aminoethanesulfonic acid in sodium hydroxide solution b to form solution C, adding solution B and solution C dropwise to solution A, reacting at 40-60° C. for 12-18 hours, adjusting to neutrality after the reaction, then precipitating with anhydrous ethanol, and then solid-liquid separation and drying to obtain a polyaspartic acid derivative; A4. Add modified sodium carboxymethyl cellulose-sulfur quantum dots and polyaspartic acid derivatives into deionized water and stir for 1-3 hours to obtain a high-hardness and high-sulfate water quality scale inhibitor.

2. The method for preparing a high-hardness and high-sulfate water quality scale inhibitor according to claim 1, characterized in that: In the step A1, the heating reaction time is 30-42 hours.

3. The method for preparing a high-hardness and high-sulfate water-quality scale inhibitor according to claim 1, characterized in that: In the step A1, the usage ratio of carboxymethyl cellulose, sublimated sulfur powder and sodium hydroxide solution is (5-5.3) g: (7.9-8.6) g: (330-380) mL.

4. The method for preparing a high-hardness and high-sulfate water quality scale inhibitor according to claim 1, characterized in that: In the step A2, the mass ratio of sodium carboxymethyl cellulose-sulfur quantum dots, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, isopropanol and ammonium persulfate is (2.2-2.5): (1.8-2.3): (1-1.2): (0.42-0.78): (0.48-0.86).

5. The method for preparing a high-hardness and high-sulfate water-quality scale inhibitor according to claim 1, characterized in that: In the step A2, the mass ratio of the itaconic acid added twice is (1-1.5):(1-1.5).

6. The method for preparing a high-hardness and high-sulfate water quality scale inhibitor according to claim 1, characterized in that: In the step A2, the mass ratio of the isopropanol added twice is (0.9-1.2):(0.8-1); the mass ratio of the ammonium persulfate added twice is (1-1.2):(0.7-0.9).

7. The method for preparing a high-hardness and high-sulfate water-quality scale inhibitor according to claim 1, characterized in that: In the step A3, the molar ratio of polysuccinimide, 4-aminophthalic acid and 2-aminoethanesulfonic acid is 1:(0.7-1.1):(0.9-1.3).

8. The method for preparing a high-hardness and high-sulfate water quality scale inhibitor according to claim 1, characterized in that: In the step A3, the mass concentration of the sodium hydroxide solution a and the sodium hydroxide solution b is 10-15%.

9. The method for preparing a high-hardness and high-sulfate water-quality scale inhibitor according to claim 1, characterized in that: In step A3, the usage ratio of 4-aminophthalic acid and sodium hydroxide solution a is (1-1.2) g: (12-15) mL; the usage ratio of 2-aminoethanesulfonic acid and sodium hydroxide solution b is (1-1.2) g: (10-13) mL.

10. The method for preparing a high-hardness and high-sulfate water quality scale inhibitor according to claim 1, characterized in that: In the step A4, the mass ratio of modified sodium carboxymethyl cellulose-sulfur quantum dots to polyaspartic acid derivatives is (65-75): (25-35).

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