A biodegradable scale inhibitor free of phosphorus and nitrogen

Abstract

The present invention relates to the field of scale inhibitors, and discloses a biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following raw materials in parts by weight: 25-35 parts of chitosan grafted acrylic acid copolymer, 8-12 parts of polyaspartic acid, 8-12 parts of gluconolactone, 7-13 parts of potassium citrate, 2-8 parts of propyl gallate, 9-11 parts of sodium lactate, 7-13 parts of polylysine, 3-7 parts of polycyclohexanedicarboxylic acid, and 5-15 parts of water; the biodegradable scale inhibitor proposed by the present invention further improves the scale inhibition performance, dispersion performance, thermal stability, shear resistance performance and service life, and at the same time maintains good biodegradability and environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the field of scale inhibitors, and more specifically, it relates to a biodegradable phosphorus-free and nitrogen-free scale inhibitor. Background Art

[0002] With the rapid development of industry, the problem of water pollution has become increasingly serious. Especially the scale problem in industrial equipment and pipelines not only affects the service life and efficiency of the equipment, but also causes waste of energy. Although traditional chemical scale inhibitors can effectively prevent the formation of scale, they are difficult to degrade themselves and will cause secondary pollution to the environment. Therefore, it is of great significance to develop a highly efficient and environmentally friendly biodegradable scale inhibitor. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following raw materials in parts by weight:

[0004] 25 - 35 parts of chitosan grafted acrylic acid copolymer, 8 - 12 parts of polyaspartic acid, 8 - 12 parts of gluconolactone, 7 - 13 parts of potassium citrate, 2 - 8 parts of propyl gallate, 9 - 11 parts of sodium lactate, 7 - 13 parts of polylysine, 3 - 7 parts of polycyclohexanedicarboxylic acid, 5 - 15 parts of water.

[0005] A biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following optimized raw materials in parts by weight:

[0006] 30 parts of chitosan grafted acrylic acid copolymer, 10 parts of polyaspartic acid, 10 parts of gluconolactone, 10 parts of potassium citrate, 5 parts of propyl gallate, 10 parts of sodium lactate, 10 parts of polylysine, 5 parts of polycyclohexanedicarboxylic acid, 10 parts of water.

[0007] A biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following optimized raw materials in parts by weight:

[0008] 25 parts of chitosan grafted acrylic acid copolymer, 8 parts of polyaspartic acid, 8 parts of gluconolactone, 7 parts of potassium citrate, 8 parts of propyl gallate, 11 parts of sodium lactate, 13 parts of polylysine, 7 parts of polycyclohexanedicarboxylic acid, 15 parts of water.

[0009] A biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following optimized raw materials in parts by weight:

[0010] 35 parts of chitosan grafted acrylic acid copolymer, 12 parts of polyaspartic acid, 12 parts of gluconolactone, 13 parts of potassium citrate, 2 parts of propyl gallate, 9 parts of sodium lactate, 7 parts of polylysine, 3 parts of polycyclohexanedicarboxylic acid, 5 parts of water.

[0011] A preparation method of a biodegradable phosphorus-free and nitrogen-free scale inhibitor, which comprises the following steps:

[0012] S1: Preparation of chitosan grafted acrylic acid copolymer;

[0013] Dissolve chitosan in dilute acetic acid solution, add initiator, heat up to 50 - 70 °C, slowly dropwise add acrylic acid monomer, and react for 5 - 7 hours;

[0014] After the reaction is completed, adjust the pH to 7.0, precipitate, filter, wash, and dry to obtain chitosan grafted acrylic acid copolymer.

[0015] S2: Preparation of polylysine and polyaspartic acid;

[0016] Dissolve lysine and aspartic acid in sodium bicarbonate buffer solution respectively, add enzyme catalyst, react at 35 - 39 °C for 24 hours, after the reaction is completed, dialyze to remove small molecular substances, and freeze-dry to obtain polylysine and polyaspartic acid.

[0017] S3: Compound of scale inhibitor;

[0018] According to the proportion, dissolve chitosan grafted acrylic acid copolymer, polylysine, polyaspartic acid, gluconolactone, propyl gallate, polycyclohexanedicarboxylic acid, potassium citrate, and sodium lactate in deionized water, stir evenly, adjust the pH to 7.0 - 8.0 to obtain scale inhibitor solution.

[0019] S4: Product preparation;

[0020] Spray-dry or vacuum-dry the scale inhibitor solution to obtain a solid powder product. Or directly package the scale inhibitor solution to prepare a liquid product.

[0021] Preferably: In step S1, dissolve chitosan in dilute acetic acid solution, add initiator, heat up to 60 °C, slowly dropwise add acrylic acid monomer, and react for 6 hours.

[0022] Preferably: In step S1, dissolve chitosan in dilute acetic acid solution, add initiator, heat up to 50 °C, slowly dropwise add acrylic acid monomer, and react for 7 hours.

[0023] Preferably: In step S1, dissolve chitosan in dilute acetic acid solution, add initiator, heat up to 70 °C, slowly dropwise add acrylic acid monomer, and react for 5 hours.

[0024] Preferably: In step S2, dissolve lysine and aspartic acid in sodium bicarbonate buffer solution respectively, add enzyme catalyst, and react at 37 °C for 24 hours.

[0025] Preferably: In step S4, adjust the pH to 7.5.

[0026] The beneficial effects of the present invention are as follows: For the biodegradable scale inhibitor proposed by the present invention, the amino and carboxyl groups in the chitosan-grafted acrylic acid copolymer can form hydrogen bonds with the amino and carboxyl groups in the polyaspartic acid, enhancing the intermolecular interaction of the scale inhibitor and improving the scale inhibition performance and dispersion performance.

[0027] In addition to forming hydrogen bonds, the amino group in the polylysine can also form electrostatic interactions with the carboxyl group in the chitosan-grafted acrylic acid copolymer, further enhancing the intermolecular force of the scale inhibitor and improving the scale inhibition performance and dispersion performance.

[0028] Glucono delta-lactone and propyl gallate both contain lactone structures, and can form supramolecular structures through hydrophobic interactions and π-π stacking interactions, enhancing the thermal stability and high-temperature resistance of the scale inhibitor. In addition to forming supramolecular structures through hydrophobic interactions and π-π stacking interactions, the phenolic hydroxyl group in propyl gallate can also form hydrogen bonds with the ester group in glucono delta-lactone, enhancing the thermal stability and high-temperature resistance of the scale inhibitor.

[0029] Potassium citrate, sodium lactate and poly(cyclohexanedicarboxylic acid) can produce a synergistic effect. In addition to the chelating and dispersing effects of potassium citrate and sodium lactate, the carboxyl groups in poly(cyclohexanedicarboxylic acid) can form chelates with calcium and magnesium ions, and at the same time its hydrophobic cyclohexane structure can increase the dispersion of the scale inhibitor in water, synergistically enhancing the scale inhibition performance. In addition, poly(cyclohexanedicarboxylic acid) can also form a compound system with propyl gallate through hydrophobic interactions, further improving the comprehensive performance of the scale inhibitor.

[0030] The chitosan-grafted acrylic acid copolymer, polyaspartic acid and polylysine can produce a synergistic effect. In addition to the original electrostatic interaction, hydrogen bond interaction and chelation, the amino group in polylysine can also form amide bonds with the carboxyl group in polyaspartic acid, making the three form a cross-linked network structure, significantly enhancing the structural stability and shear resistance of the scale inhibitor. At the same time, this cross-linked network structure can also physically encapsulate other functional components such as glucono delta-lactone and propyl gallate, realizing the slow release and persistence of the functional components and improving the service life of the scale inhibitor.

[0031] The biodegradable scale inhibitor proposed by the present invention further improves the scale inhibition performance, dispersion performance, thermal stability, shear resistance and service life, while maintaining good biodegradability and environmental friendliness. Description of the Drawings

[0032] Figure 1 It is a graph of the scale inhibition performance test results in Example 5 of the present invention;

[0033] Figure 2 It is a graph of the dispersion performance test results in Example 5 of the present invention;

[0034] Figure 3 It is the Zeta potential test result graph in Example 6 of the present invention;

[0035] Figure 4 It is the scale inhibition performance test result graph in Example 6 of the present invention;

[0036] Figure 5 It is the dispersion performance test result graph in Example 6 of the present invention;

[0037] Figure 6 It is the DSC test result graph in Example 7 of the present invention;

[0038] Figure 7 It is the TGA test result graph in Example 7 of the present invention;

[0039] Figure 8 It is the XRD test result graph in Example 7 of the present invention;

[0040] Figure 9 It is the scale inhibition performance test result graph in Example 8 of the present invention;

[0041] Figure 10 It is the dispersion performance test result graph in Example 8 of the present invention;

[0042] Figure 11 It is the thermal stability test result graph in Example 8 of the present invention;

[0043] Figure 12 It is the high temperature resistance performance test result graph in Example 8 of the present invention;

[0044] Figure 13 It is the scale inhibition performance test result graph in Example 9 of the present invention;

[0045] Figure 14 It is the dispersion performance test result graph in Example 9 of the present invention;

[0046] Figure 15 It is the DMA test result graph in Example 9 of the present invention;

[0047] Figure 16 It is the scale inhibition performance test result graph in Example 10 of the present invention;

[0048] Figure 17 It is the dispersion performance test result graph in Example 10 of the present invention;

[0049] Figure 18 It is the thermal stability test result graph in Example 10 of the present invention;

[0050] Figure 19 It is the shear resistance performance test result graph in Example 10 of the present invention;

[0051] Figure 20 It is the graph of the service life test result in Embodiment 10 of the present invention;

[0052] Figure 21 It is the graph of the biodegradation performance test result in Embodiment 10 of the present invention;

[0053] Figure 22 It is the graph of the calcium ion chelating capacity test result in Embodiment 11 of the present invention;

[0054] Figure 23 It is the graph of the magnesium ion chelating capacity test result in Embodiment 10 of the present invention. Detailed implementation manners

[0055] Now, the subject matter described herein will be discussed with reference to exemplary embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the protection scope of the content of this specification, changes can be made to the functions and arrangements of the elements discussed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described relative to some examples can also be combined in other examples.

[0056] Embodiment 1

[0057] In this embodiment, a biodegradable phosphorus - and nitrogen - free scale inhibitor is proposed, which comprises the following raw materials in parts by weight:

[0058] 30 parts of chitosan - grafted acrylic acid copolymer, 10 parts of polyaspartic acid, 10 parts of gluconolactone, 10 parts of potassium citrate, 5 parts of propyl gallate, 10 parts of sodium lactate, 10 parts of polylysine, 5 parts of polycyclohexanedicarboxylic acid, and 10 parts of water.

[0059] Embodiment 2

[0060] In this embodiment, a biodegradable phosphorus - and nitrogen - free scale inhibitor is proposed, which comprises the following raw materials in parts by weight:

[0061] 25 parts of chitosan - grafted acrylic acid copolymer, 8 parts of polyaspartic acid, 8 parts of gluconolactone, 7 parts of potassium citrate, 8 parts of propyl gallate, 11 parts of sodium lactate, 13 parts of polylysine, 7 parts of polycyclohexanedicarboxylic acid, and 15 parts of water.

[0062] Embodiment 3

[0063] In this embodiment, a biodegradable phosphorus - and nitrogen - free scale inhibitor is proposed, which comprises the following raw materials in parts by weight:

[0064] 35 parts of chitosan grafted acrylic acid copolymer, 12 parts of polyaspartic acid, 12 parts of glucono delta-lactone, 13 parts of potassium citrate, 2 parts of propyl gallate, 9 parts of sodium lactate, 7 parts of polylysine, 3 parts of polycyclohexanedicarboxylic acid, 5 parts of water.

[0065] Example 4

[0066] In an embodiment of the present invention, a preparation method of a biodegradable scale inhibitor without phosphorus and nitrogen is proposed, including the following steps:

[0067] S1: Preparation of chitosan grafted acrylic acid copolymer;

[0068] Dissolve chitosan in a dilute acetic acid solution, add an initiator, heat up to 50 or 60 or 70 °C, slowly dropwise add acrylic acid monomer, and react for 5 or 6 or 7 hours; in this embodiment, heat up to 60 °C and react for 6 hours.

[0069] After the reaction is completed, adjust the pH to 7.0, precipitate, filter, wash, and dry to obtain chitosan grafted acrylic acid copolymer.

[0070] S2: Preparation of polylysine and polyaspartic acid;

[0071] Dissolve lysine and aspartic acid in a sodium bicarbonate buffer solution respectively, add an enzyme catalyst, react at 35 or 36 or 37 or 38 or 39 °C for 24 hours. After the reaction is completed, dialyze to remove small molecule substances, and freeze-dry to obtain polylysine and polyaspartic acid. In this embodiment, react at 37 °C for 24 hours.

[0072] S3: Compound of scale inhibitor;

[0073] According to the proportion, dissolve chitosan grafted acrylic acid copolymer, polylysine, polyaspartic acid, glucono delta-lactone, propyl gallate, polycyclohexanedicarboxylic acid, potassium citrate and sodium lactate in deionized water, stir evenly, and adjust the pH to 7.0 or 7.5 or 8.0 to obtain a scale inhibitor solution. In this embodiment, adjust the pH to 7.5.

[0074] S4: Product preparation;

[0075] Spray dry or vacuum dry the scale inhibitor solution to obtain a solid powder product. Or directly package the scale inhibitor solution to prepare a liquid product.

[0076] Example 5

[0077] Both chitosan-grafted acrylic acid copolymer and polyaspartic acid contain amino and carboxyl functional groups. When the two substances are mixed, intermolecular hydrogen bonds can form between the amino and carboxyl groups. Hydrogen bonds are a relatively strong intermolecular force, and their formation mechanism is the electrostatic attraction between the hydrogen atom in the amino or carboxyl group and the electronegative atom (such as oxygen or nitrogen atom) in another molecule.

[0078] In the mixed system of chitosan-grafted acrylic acid copolymer and polyaspartic acid, the amino and carboxyl groups on the copolymer molecular chain can form intermolecular hydrogen bonds with the amino and carboxyl groups on the polyaspartic acid molecular chain, binding the two substances tightly together. This hydrogen bond interaction can enhance the intermolecular interaction of the scale inhibitor molecules, increase the aggregation tendency of the scale inhibitor molecules in the solution, and thus more effectively prevent the formation and deposition of scale.

[0079] In addition, the hydrogen bond interaction can also improve the dispersion performance of the scale inhibitor molecules in the solution. Through the formation of hydrogen bonds, the molecular chains of chitosan-grafted acrylic acid copolymer and polyaspartic acid are intertwined with each other, forming a complex with a network-like structure. This structure can increase the steric hindrance effect of the scale inhibitor molecules in the solution, prevent molecular aggregation and precipitation, and thus improve the dispersion performance and stability of the scale inhibitor.

[0080] In this example, the influence of the hydrogen bond interaction on the scale inhibition performance and dispersion performance in the mixed system of chitosan-grafted acrylic acid copolymer and polyaspartic acid was studied to verify whether the hydrogen bond interaction can significantly improve the performance of the scale inhibitor.

[0081] I. Experimental materials

[0082] Chitosan-grafted acrylic acid copolymer (self-made, grafting degree 30%, molecular weight 50000).

[0083] Polyaspartic acid (purchased, molecular weight 10000).

[0084] Calcium carbonate (CaCO3, analytical pure).

[0085] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, etc.

[0086] II. Experimental methods

[0087] Prepare a mixed solution of chitosan-grafted acrylic acid copolymer and polyaspartic acid with a total concentration of 1000 mg / L, a mass ratio of the two components of 1:1, and adjust the pH to 7.0.

[0088] Use the static scale inhibition test method to evaluate the scale inhibition performance of the mixed solution. Test conditions: temperature 80 °C, pH 8.5, 200 mg / L CaCO3, stirring rate 100 rpm, duration 10 hours.

[0089] The dispersion performance of the mixed solution was tested by the wet sieving method under the following test conditions: temperature 25 °C, pH 7.0, 10 g / L CaCO3, sieve aperture 0.045 mm, and vibration time 10 minutes.

[0090] A blank control group and single-component control groups were set up to evaluate the influence of hydrogen bonding on the performance.

[0091] III. Experimental Results

[0092] See Table 1 in the appendix. Figure 1 The results of the scale inhibition performance test showed that the scale inhibition rate of the mixed solution was significantly higher than that of the single component, indicating that hydrogen bonding can effectively improve the scale inhibition performance.

[0093] See Table 2 in the appendix. Figure 2 The results of the dispersion performance test showed that the dispersion rate of the mixed solution was significantly higher than that of the single component, indicating that hydrogen bonding can significantly improve the dispersion performance.

[0094] IV. Analysis of Experimental Results

[0095] The results of the scale inhibition performance test showed that hydrogen bonding can significantly improve the scale inhibition performance of the scale inhibitor. This is because hydrogen bonding enhances the interaction between the scale inhibitor molecules, making the molecules more likely to aggregate, thus more effectively preventing the formation and deposition of scale.

[0096] The results of the dispersion performance test showed that hydrogen bonding can significantly improve the dispersion performance of the scale inhibitor. This is because the formation of hydrogen bonds causes the molecular chains of the scale inhibitor to entangle with each other, forming a complex with a network-like structure, increasing the steric hindrance effect of the molecules, and preventing molecular aggregation and precipitation.

[0097] Based on the test results of the scale inhibition performance and dispersion performance, it can be concluded that hydrogen bonding in the mixed system of chitosan grafted acrylic acid copolymer and polyaspartic acid can significantly improve the scale inhibition performance and dispersion performance of the scale inhibitor, verifying the important role of hydrogen bonding in improving the performance of the scale inhibitor.

[0098] Example 6

[0099] Polylysine is a cationic polymer with primary amino functional groups in its side chains. Under appropriate pH conditions of the solution, the primary amino groups can be protonated to form a positively charged ammonium salt structure (-NH3 + ). On the other hand, the carboxyl groups (-COOH) in the chitosan grafted acrylic acid copolymer will ionize in the solution to form negatively charged carboxylate ions (-COO - ).

[0100] When polylysine and chitosan-grafted acrylic acid copolymer are mixed, an electrostatic attraction will occur between the protonated primary amino groups and the ionized carboxyl groups, forming ion pairs or salt bridge structures. This electrostatic interaction can further enhance the force between the scale inhibitor molecules, making the molecular chains bind tightly and forming a more stable complex.

[0101] The mechanism of the electrostatic interaction in improving the scale inhibition performance and dispersion performance is as follows:

[0102] Scale inhibition performance: The electrostatic interaction makes the molecular chains of the scale inhibitor bind tightly, forming a denser adsorption layer, which can more effectively prevent the formation and deposition of scale crystals. In addition, the electrostatic interaction can also enhance the binding force between the scale inhibitor molecules and the surface of the scale crystals, further inhibiting the growth of scale.

[0103] Dispersion performance: The electrostatic interaction makes the molecular chains of the scale inhibitor form a cross-linked network structure, increasing the steric hindrance effect of the molecules. This structure can effectively disperse the scale crystals, prevent their aggregation and precipitation, thereby improving the dispersion performance and stability of the scale inhibitor.

[0104] This example studies the influence of the electrostatic interaction on the scale inhibition performance and dispersion performance in the mixed system of polylysine and chitosan-grafted acrylic acid copolymer, and verifies whether the electrostatic interaction can significantly improve the performance of the scale inhibitor.

[0105] I. Experimental materials

[0106] Chitosan-grafted acrylic acid copolymer (self-made, grafting degree 30%, molecular weight 50000)

[0107] Polylysine (purchased, molecular weight 5000)

[0108] Calcium carbonate (CaCO3, analytical pure)

[0109] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, etc.

[0110] II. Experimental methods

[0111] Prepare a mixed solution of chitosan-grafted acrylic acid copolymer and polylysine with a total concentration of 1000 mg / L, a molar ratio of the two components of 1:1, and adjust the pH to 6.0 (the optimal pH for polylysine protonation).

[0112] Use a Zeta potential analyzer to measure the Zeta potential of the mixed solution to evaluate the electrostatic interaction in the system.

[0113] Adopt the static scale inhibition test method to evaluate the scale inhibition performance of the mixed solution. Test conditions: temperature 80 °C, pH 8.5, 200 mg / L CaCO3, stirring rate 100 rpm, duration 10 hours.

[0114] The wet sieve method was used to test the dispersion performance of the mixed solution. The test conditions were as follows: temperature 25°C, pH 7.0, 10 g / L CaCO3, sieve mesh aperture 0.045 mm, and vibration time 10 minutes.

[0115] A blank control group and single-component control groups were set up to evaluate the influence of electrostatic interaction on the performance.

[0116] III. Experimental Results

[0117] See Table 3 in the appendix Figure 3 The Zeta potential test results showed that the Zeta potential of the mixed solution was between those of the two single components, and the absolute value decreased significantly, indicating that there was an electrostatic interaction in the system and a neutral complex was formed.

[0118] See Table 4 in the appendix Figure 4 The scale inhibition performance test results showed that the scale inhibition rate of the mixed solution was significantly higher than that of the single components, indicating that the electrostatic interaction could effectively improve the scale inhibition performance.

[0119] See Table 5 in the appendix Figure 5 The dispersion performance test results showed that the dispersion rate of the mixed solution was significantly higher than that of the single components, indicating that the electrostatic interaction could significantly improve the dispersion performance.

[0120] IV. Analysis of Experimental Results

[0121] The Zeta potential test confirmed the existence of electrostatic interaction in the mixed system of polylysine and chitosan-grafted acrylic acid copolymer, and a neutral complex was formed.

[0122] The scale inhibition performance test results showed that the electrostatic interaction could significantly improve the scale inhibition performance of the scale inhibitor. This was because the electrostatic interaction enhanced the force between the scale inhibitor molecules, making the molecular chains bind tightly and forming a denser adsorption layer, thus more effectively preventing the formation and deposition of scale.

[0123] The dispersion performance test results showed that the electrostatic interaction could significantly improve the dispersion performance of the scale inhibitor. This was because the electrostatic interaction made the scale inhibitor molecular chains form a cross-linked network structure, increasing the steric hindrance effect of the molecules and effectively dispersing the scale crystals to prevent their aggregation and precipitation.

[0124] Based on the test results of Zeta potential, scale inhibition performance, and dispersion performance, it can be concluded that the electrostatic interaction in the mixed system of polylysine and chitosan-grafted acrylic acid copolymer can significantly improve the scale inhibition performance and dispersion performance of the scale inhibitor, verifying the important role of electrostatic interaction in improving the performance of the scale inhibitor.

[0125] Example 7

[0126] Both glucono delta-lactone and propyl gallate are compounds containing a lactone structure. A lactone is a cyclic ester structure formed by the condensation of a carboxyl group and an adjacent hydroxyl group, and it has strong hydrophobicity and rigidity. When glucono delta-lactone and propyl gallate are mixed, their lactone structures can form a supramolecular structure through hydrophobic interactions and π-π stacking interactions.

[0127] Hydrophobic interaction refers to the mutual attraction between non-polar groups, and it is an important intermolecular force. The alkyl and aromatic groups in the lactone structure belong to hydrophobic groups, and they can aggregate together through hydrophobic interactions to form a hydrophobic region.

[0128] π-π stacking interaction refers to the face-to-face arrangement between aromatic rings, and it is a special intermolecular force. Propyl gallate contains the trihydroxybenzene ring structure of gallic acid, which belongs to an aromatic ring compound. When propyl gallate molecules aggregate, the benzene rings can form an ordered face-to-face arrangement through π-π stacking interactions.

[0129] The synergistic effect of hydrophobic interaction and π-π stacking interaction can enable glucono delta-lactone and propyl gallate to form a stable supramolecular structure. This supramolecular structure can enhance the thermal stability and high-temperature resistance of the scale inhibitor for the following reasons:

[0130] The supramolecular structure forms a tight physical cross-linking network between the scale inhibitor molecules, improving the rigidity and heat resistance of the material.

[0131] The formation of the hydrophobic region can hinder the penetration of water molecules and other small molecules, reducing the degradation and decomposition of the scale inhibitor at high temperatures.

[0132] The π-π stacking interaction makes the aromatic rings form an ordered arrangement, increasing the crystallinity and thermal stability of the scale inhibitor molecules.

[0133] In addition to hydrophobic interaction and π-π stacking interaction, the phenolic hydroxyl group in propyl gallate can also form intermolecular hydrogen bonds with the ester group in glucono delta-lactone. Hydrogen bond is a relatively strong intermolecular force, which can further enhance the stability of the supramolecular structure and improve the high-temperature resistance of the scale inhibitor.

[0134] This example studies the influence of the supramolecular interaction between glucono delta-lactone and propyl gallate on the thermal stability and high-temperature resistance of the scale inhibitor, and verifies whether the supramolecular interaction can significantly improve the heat resistance of the scale inhibitor.

[0135] I. Experimental Materials

[0136] Glucono delta-lactone (purchased, purity ≥ 98%).

[0137] Propyl gallate (purchased, purity ≥ 95%).

[0138] Chitosan grafted acrylic acid copolymer (self-made, grafting degree 30%, molecular weight 50000).

[0139] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, etc.

[0140] II. Experimental methods

[0141] Prepare a mixed solution of glucono delta-lactone and propyl gallate with a total concentration of 1000 mg / L and a molar ratio of the two components of 1:1.

[0142] Mix the mixed solution with chitosan grafted acrylic acid copolymer according to a mass ratio of 9:1 to prepare a scale inhibitor sample.

[0143] Use differential scanning calorimetry (DSC) to test the thermal stability of the scale inhibitor sample. Test conditions: nitrogen atmosphere, heating rate 10 °C / min, temperature range 30 - 500 °C.

[0144] Use thermogravimetric analysis (TGA) to test the high-temperature resistance of the scale inhibitor sample. Test conditions: nitrogen atmosphere, heating rate 10 °C / min, temperature range 30 - 800 °C.

[0145] Use X-ray diffraction analysis (XRD) to characterize the crystallinity of the scale inhibitor sample. Test conditions: Cu Kα ray, 2θ range 5 - 60°, scanning speed 5° / min.

[0146] Set up a blank control group (pure chitosan grafted acrylic acid copolymer) and single-component control groups to evaluate the influence of supramolecular interactions on the performance.

[0147] III. Experimental results

[0148] See Figure 6 Table 6 in. The DSC test results show that both the glass transition temperature and the thermal decomposition temperature of the mixed scale inhibitor are significantly higher than those of the blank control group and the single-component ones, indicating that the supramolecular interaction improves the thermal stability of the scale inhibitor.

[0149] See Figure 7 Table 7 in. The TGA test results show that the weight loss temperature of the mixed scale inhibitor is significantly higher than that of the blank control group and the single-component ones, indicating that the supramolecular interaction improves the high-temperature resistance of the scale inhibitor.

[0150] See Figure 8 Table 8 in. The XRD test results show that the crystallinity of the mixed scale inhibitor is significantly higher than that of the blank control group and the single-component ones, indicating that the supramolecular interaction improves the crystallinity of the scale inhibitor and enhances its thermal stability.

[0151] IV. Analysis of experimental results

[0152] The DSC and TGA test results indicate that the supramolecular interaction between glucono delta-lactone and propyl gallate can significantly improve the thermal stability and high-temperature resistance of the scale inhibitor. This is because the supramolecular structure enhances the interaction between the scale inhibitor molecules, forms a tight physical crosslinking network, and improves the rigidity and heat resistance of the material.

[0153] The XRD test results show that the supramolecular interaction can increase the crystallinity of the scale inhibitor. This is because the π-π stacking interaction makes the aromatic rings form an ordered arrangement, increasing the molecular regularity and crystallization tendency. The increase in crystallinity further improves the thermal stability of the scale inhibitor.

[0154] Based on the comprehensive DSC, TGA, and XRD test results, it can be concluded that the supramolecular interaction between glucono delta-lactone and propyl gallate, including hydrophobic interaction, π-π stacking interaction, and hydrogen bonding interaction, can significantly improve the thermal stability and high-temperature resistance of the scale inhibitor, verifying the important role of supramolecular interaction in improving the performance of the scale inhibitor.

[0155] Example 8

[0156] Potassium citrate, sodium lactate, and poly(cyclohexane-1,4-dicarboxylic acid) are all compounds containing carboxyl groups, and they can produce a synergistic effect in the scale inhibitor to improve the scale inhibition performance.

[0157] First of all, potassium citrate and sodium lactate are both commonly used chelating agents and dispersants. The carboxyl groups in them can form stable chelates with calcium and magnesium ions in water, thus inhibiting the crystallization and deposition of calcium and magnesium ions. At the same time, potassium citrate and sodium lactate also have good dispersing properties and can adsorb on the surface of scale crystals to prevent the aggregation and growth of scale crystals.

[0158] Poly(cyclohexane-1,4-dicarboxylic acid) is a dicarboxylic acid compound, and the two carboxyl groups in it can form more stable chelates with calcium and magnesium ions, further enhancing the scale inhibition effect. In addition, poly(cyclohexane-1,4-dicarboxylic acid) contains a hydrophobic cyclohexane structure, which can increase the dispersibility of the scale inhibitor molecules in water and prevent molecular aggregation and precipitation. The introduction of hydrophobic groups also helps the adsorption of scale inhibitor molecules at the solid-liquid interface to form a denser protective layer.

[0159] The synergistic effect of potassium citrate, sodium lactate, and poly(cyclohexane-1,4-dicarboxylic acid) can enhance the scale inhibition performance in the following aspects:

[0160] The synergistic effect of multiple chelating groups improves the chelating ability and chelating stability towards calcium and magnesium ions.

[0161] The introduction of hydrophobic groups increases the dispersibility of the scale inhibitor molecules in water and the adsorption at the solid-liquid interface.

[0162] The compounding of different types of scale inhibitors molecules forms a multi-component synergistic scale inhibition system, which improves the broad-spectrum and applicability of the scale inhibition effect.

[0163] In addition, poly(cyclohexane-1,4-dicarboxylic acid) can also form a compounding system with propyl gallate through hydrophobic interaction. Propyl gallate contains a hydrophobic aromatic ring and ester group, which can undergo hydrophobic-hydrophobic interaction with the cyclohexyl group in poly(cyclohexane-1,4-dicarboxylic acid) to form a more stable supramolecular structure. This compounding system can further improve the thermal stability, high-temperature resistance and shear resistance of the scale inhibitor, and also contribute to improving the comprehensive performance and synergistic effect of the scale inhibitor.

[0164] This example studies the synergistic scale inhibition effect of potassium citrate, sodium lactate and poly(cyclohexane-1,4-dicarboxylic acid), and evaluates the influence of different components on the scale inhibition performance.

[0165] Study the compounding effect of poly(cyclohexane-1,4-dicarboxylic acid) and propyl gallate, and evaluate the influence of the compounding system on the comprehensive performance of the scale inhibitor.

[0166] I. Experimental materials

[0167] Potassium citrate (purchased, purity ≥ 99%).

[0168] Sodium lactate (purchased, purity ≥ 98%).

[0169] Poly(cyclohexane-1,4-dicarboxylic acid) (purchased, molecular weight 1000).

[0170] Propyl gallate (purchased, purity ≥ 95%).

[0171] Chitosan grafted acrylic acid copolymer (self-made, grafting degree 30%, molecular weight 50000).

[0172] Calcium carbonate (CaCO3, analytical pure).

[0173] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, etc.

[0174] II. Experimental methods

[0175] Prepare a mixed solution of potassium citrate, sodium lactate and poly(cyclohexane-1,4-dicarboxylic acid) with a total concentration of 1000 mg / L and a molar ratio of the three components of 1:1:1.

[0176] Mix the mixed solution with chitosan grafted acrylic acid copolymer according to a mass ratio of 9:1 to prepare a scale inhibitor sample.

[0177] Prepare a compounding solution of poly(cyclohexane-1,4-dicarboxylic acid) and propyl gallate with a total concentration of 1000 mg / L and a molar ratio of the two components of 1:1.

[0178] Mix the compound solution and chitosan grafted acrylic acid copolymer in a mass ratio of 9:1 to prepare a compound scale inhibitor sample.

[0179] Adopt the static scale inhibition test method to evaluate the scale inhibition performance of different scale inhibitor samples. Test conditions: temperature 80°C, pH 8.5, 200 mg / L CaCO3, stirring rate 100 rpm, duration 10 hours.

[0180] Adopt the wet screening method to test the dispersion performance of different scale inhibitor samples. Test conditions: temperature 25°C, pH 7.0, 10 g / L CaCO3, sieve aperture 0.045 mm, vibration time 10 minutes.

[0181] Use differential scanning calorimetry (DSC) to test the thermal stability of the compound scale inhibitor sample. Test conditions: nitrogen atmosphere, heating rate 10°C / min, temperature range 30 - 500°C.

[0182] Use thermogravimetric analysis (TGA) to test the high temperature resistance performance of the compound scale inhibitor sample. Test conditions: nitrogen atmosphere, heating rate 10°C / min, temperature range 30 - 800°C.

[0183] Set up a blank control group and a single component control group to evaluate the influence of the synergistic effect and compound action on the performance.

[0184] III. Experimental Results

[0185] See Figure 9 Table 9 in Figure 10 Table 10 in Figure 11 Table 11 in Figure 12 Table 12 in

[0186] IV. Analysis of Experimental Results

[0187] The results of the scale inhibition performance test show that the mixed system of potassium citrate, sodium lactate and polycyclohexanedicarboxylic acid has a significant synergistic scale inhibition effect, and the scale inhibition rate is much higher than that of the single component. This is because the synergistic effect of multiple chelating groups improves the chelating ability for calcium and magnesium ions, and at the same time the hydrophobic groups increase the dispersion of the scale inhibitor molecules in water and the adsorption on the solid-liquid interface.

[0188] The results of the dispersion performance test show that the mixed system of potassium citrate, sodium lactate and polycyclohexanedicarboxylic acid has excellent dispersion effect, and the dispersion rate is significantly higher than that of the single component. This benefits from the improved dispersion of the scale inhibitor molecules in water and the adsorption on the surface of the scale crystals.

[0189] The test results of thermal stability and high temperature resistance show that the compound system of poly(cyclohexanedicarboxylic acid) and propyl gallate has higher thermal stability and high temperature resistance, and the glass transition temperature, thermal decomposition temperature and weight loss temperature are all significantly increased. This is because the hydrophobic-hydrophobic interaction forms a more stable supramolecular structure, enhancing the heat resistance and anti-degradation ability of the scale inhibitor molecules.

[0190] Based on the comprehensive test results of scale inhibition performance, dispersion performance, thermal stability and high temperature resistance, the conclusion can be drawn that potassium citrate, sodium lactate and poly(cyclohexanedicarboxylic acid) have significant synergistic scale inhibition effects, and the compound action of poly(cyclohexanedicarboxylic acid) and propyl gallate can further improve the comprehensive performance of the scale inhibitor.

[0191] Example 9

[0192] Chitosan grafted acrylic acid copolymer, polyaspartic acid and polylysine are all functional polymers containing amino and carboxyl groups, which can produce multiple synergistic effects in the scale inhibitor, improving the performance and stability of the scale inhibitor.

[0193] First of all, the amino and carboxyl groups in the chitosan grafted acrylic acid copolymer can form intermolecular hydrogen bonds and electrostatic interactions with the amino and carboxyl groups in polyaspartic acid and polylysine, enhancing the intermolecular forces between the scale inhibitor molecules. At the same time, these functional groups can also form stable chelates with calcium and magnesium ions in water, improving the chelating ability and scale inhibition performance of the scale inhibitor.

[0194] In addition to these effects, the amino group in polylysine can also undergo a condensation reaction with the carboxyl group in polyaspartic acid to form an amide bond. The amide bond is a covalent bond, which is more stable and firm than hydrogen bonds and electrostatic interactions. Through the formation of amide bonds, chitosan grafted acrylic acid copolymer, polyaspartic acid and polylysine can crosslink into a network structure. This crosslinked network structure has the following advantages:

[0195] Significantly improves the structural stability and shear resistance of the scale inhibitor. The crosslinked network structure forms strong chemical bonding between the scale inhibitor molecules, preventing the sliding and breaking of the molecular chains and improving the mechanical strength and tolerance of the material.

[0196] A large number of micropores and voids are formed in the crosslinked network structure, and other functional components such as gluconolactone and propyl gallate can be coated inside through physical coating. These functional components can be protected and fixed in the crosslinked network structure, avoiding their leakage and loss.

[0197] The functional components are encapsulated in the cross-linked network structure, which can achieve slow release and persistent effects. When the scale inhibitor is added to water, the cross-linked network structure can control the release rate of the functional components, enabling them to function over a longer period and improving the service life and persistence of the scale inhibitor.

[0198] The cross-linked network structure can also improve the thermal stability and high-temperature resistance of the scale inhibitor. Chemical cross-linking enhances the heat resistance and anti-degradation ability of the material, allowing the scale inhibitor to be used at higher temperatures and with a wider application range.

[0199] This example studies the synergistic scale inhibition effect of chitosan-grafted acrylic acid copolymer, polyaspartic acid, and polylysine, and evaluates the influence of different components on the scale inhibition performance.

[0200] Study the mechanism of the formation of the cross-linked network structure of chitosan-grafted acrylic acid copolymer, polyaspartic acid, and polylysine, and evaluate the influence of the cross-linked network structure on the performance of the scale inhibitor.

[0201] I. Experimental Materials

[0202] Chitosan-grafted acrylic acid copolymer (self-made, grafting degree 30%, molecular weight 50000).

[0203] Polyaspartic acid (purchased, molecular weight 10000).

[0204] Polylysine (purchased, molecular weight 5000).

[0205] Glucono delta-lactone (purchased, purity ≥98%).

[0206] Propyl gallate (purchased, purity ≥95%).

[0207] Calcium carbonate (CaCO3, analytical pure)

[0208] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, thionyl chloride, etc.

[0209] II. Experimental Methods

[0210] Prepare a mixed solution of chitosan-grafted acrylic acid copolymer, polyaspartic acid, and polylysine with a total concentration of 1000 mg / L and a molar ratio of the three components of 1:1:1.

[0211] Add thionyl chloride to the mixed solution, adjust the pH to 8.0, and react at room temperature for 24 hours to prepare a cross-linked scale inhibitor sample.

[0212] Prepare a mixed solution of glucono delta-lactone and propyl gallate with a total concentration of 1000 mg / L and a molar ratio of the two components of 1:1.

[0213] A mixed solution of glucono delta-lactone and propyl gallate was mixed with the crosslinked scale inhibitor sample in a mass ratio of 9:1 to prepare a coated scale inhibitor sample.

[0214] The scale inhibition performance of different scale inhibitor samples was evaluated by the static scale inhibition test method. The test conditions were as follows: temperature 80 °C, pH 8.5, 200 mg / L CaCO3, stirring rate 100 rpm, and duration 10 hours.

[0215] The storage modulus and loss factor of the crosslinked scale inhibitor sample were tested using dynamic thermomechanical analysis (DMA) to evaluate the shear resistance of the material.

[0216] A blank control group and a single-component control group were set up to evaluate the synergistic effect and the influence of the crosslinked network structure on the performance.

[0217] IV. Experimental Results

[0218] See Figure 13 Table 13 in Figure 14 Table 14 in Figure 15 Table 15 in

[0219] IV. Analysis of Experimental Results

[0220] The test results of scale inhibition performance and dispersion performance showed that chitosan grafted acrylic acid copolymer, polyaspartic acid, and polylysine had a significant synergistic scale inhibition effect, and the compounding of the three could greatly improve the scale inhibition rate and dispersion rate. The performance of the crosslinked scale inhibitor and the coated scale inhibitor was further improved, confirming the promoting effect of the crosslinked network structure and functional component coating on the scale inhibition performance.

[0221] The DMA test results showed that the crosslinked network structure significantly improved the shear resistance and structural stability of the scale inhibitor, which benefited from the inhibitory effect of chemical crosslinking on the sliding and breaking of molecular chains.

[0222] Example 10

[0223] In this example, through comparative tests with similar scale inhibitors, the advantages of the biodegradable scale inhibitor of the present invention in terms of scale inhibition performance, dispersion performance, thermal stability, shear resistance, service life, and biodegradability were evaluated, and the effectiveness and environmental friendliness of the present invention were verified.

[0224] I. Experimental Materials

[0225] The biodegradable scale inhibitor in Example 1 (prepared according to the method in Example 4).

[0226] Commercial chemical scale inhibitor A (purchased).

[0227] Commercial chemical scale inhibitor B (purchased).

[0228] Commercial environmental scale inhibitor C (purchased).

[0229] Calcium carbonate (CaCO3, analytical reagent).

[0230] Other reagents: sodium chloride, sodium hydroxide, hydrochloric acid, etc.

[0231] II. Experimental methods

[0232] The scale inhibition performance of different scale inhibitors was evaluated by the static scale inhibition test method. Test conditions: temperature 80°C, pH 8.5, 200 mg / L CaCO3, stirring rate 100 rpm, duration 10 hours.

[0233] The dispersion performance of different scale inhibitors was tested by the wet screening method. Test conditions: temperature 25°C, pH 7.0, 10 g / L CaCO3, sieve aperture 0.045 mm, vibration time 10 minutes.

[0234] The thermal stability of different scale inhibitors was tested by differential scanning calorimetry (DSC). Test conditions: nitrogen atmosphere, heating rate 10°C / min, temperature range 30 - 500°C.

[0235] The shear resistance performance of different scale inhibitors was tested using a rotational rheometer. Test conditions: temperature 25°C, shear rate range 0.1 - 100 s-1.

[0236] The service life of different scale inhibitors was evaluated by the continuous dosing test. Test conditions: temperature 80°C, pH 8.5, 200 mg / L CaCO3, scale inhibitor concentration 10 mg / L, continuous dosing for 30 days, and the scale inhibition rate was measured daily.

[0237] The biodegradability of different scale inhibitors was evaluated by the biochemical oxygen demand (BOD) test. Test conditions: temperature 25°C, dissolved oxygen ≥ 2 mg / L, inoculated with activated sludge, and the BOD value was measured for 28 days.

[0238] IV. Experimental results

[0239] See See Figure 16 Table 16 in Figure 17 Table 17 in Figure 18 Table 18 in Figure 19 Table 19 in Figure 20 Table 20 in Figure 21 Table 21 in

[0240] IV. Analysis of experimental results

[0241] The test results of scale inhibition performance and dispersion performance show that the scale inhibition rate and dispersion rate of the optimized biodegradable scale inhibitor are better than those of commercial chemical scale inhibitors and environmental scale inhibitors, confirming the significant improvement of scale inhibition performance by formula optimization.

[0242] The results of the thermal stability test show that the thermal decomposition temperature of the optimized biodegradable scale inhibitor is significantly higher than that of other scale inhibitors, indicating its better high-temperature resistance and thermal stability.

[0243] The results of the shear resistance test show that the optimized biodegradable scale inhibitor has the lowest apparent viscosity decline rate, confirming its excellent shear resistance and mechanical stability.

[0244] The results of the service life test show that the optimized biodegradable scale inhibitor maintains a high scale inhibition rate during long-term continuous use, confirming its good long-term effectiveness and service life.

[0245] The results of the biodegradability test show that the biodegradation rate of the optimized biodegradable scale inhibitor is much higher than that of commercial chemical scale inhibitors and slightly higher than that of commercial environmentally friendly scale inhibitors, confirming its excellent environmental friendliness and biodegradability.

[0246] Example 11

[0247] In this example, the chelating capacity test was carried out to evaluate the chelating ability of the biodegradable scale inhibitor of the present invention for calcium and magnesium ions, and it was compared with similar scale inhibitors to verify the influence of the present invention on the chelating performance.

[0248] I. Experimental materials

[0249] The biodegradable scale inhibitor of the present invention (prepared by the method in Example 4).

[0250] Commercial chemical scale inhibitor A (purchased).

[0251] Commercial chemical scale inhibitor B (purchased).

[0252] Commercial environmentally friendly scale inhibitor C (purchased).

[0253] Calcium chloride (CaCl2, analytical pure).

[0254] Magnesium chloride (MgCl2, analytical pure).

[0255] EDTA standard solution (0.01mol / L).

[0256] Indicators: Eriochrome Black T, Calcon.

[0257] II. Experimental method

[0258] Prepare a 200mg / L scale inhibitor solution and adjust the pH to 8.5.

[0259] Prepare 500mg / L CaCl2 and MgCl2 solutions respectively.

[0260] Take 25 mL of the scale inhibitor solution and place it in a conical flask. Add 25 mL of CaCl2 or MgCl2 solution and mix well.

[0261] Add 2 - 3 drops of indicator to the solution (Eriochrome Black T for calcium ions and Calcon for magnesium ions).

[0262] Titrate with 0.01 mol / L EDTA standard solution until the color of the solution changes, and record the amount of EDTA used.

[0263] Calculate the chelating capacity (mmol / g) of the scale inhibitor for calcium and magnesium ions based on the amount of EDTA used.

[0264] Repeat steps 3 - 6, and measure each sample in parallel 3 times, then take the average value.

[0265] III. Experimental Results

[0266] See Figure 22 the test results of the calcium ion chelating capacity in Figure 23 and the test results of the magnesium ion chelating capacity in

[0267] IV. Analysis of Experimental Results

[0268] The test results of the calcium ion chelating capacity show that the biodegradable scale inhibitor of the present invention has the highest chelating capacity for calcium ions, reaching 6.28 mmol / g, which is significantly higher than that of commercial chemical scale inhibitors and environmentally friendly scale inhibitors, confirming its excellent calcium chelating ability.

[0269] The test results of the magnesium ion chelating capacity show that the biodegradable scale inhibitor of the present invention also has the highest chelating capacity for magnesium ions, reaching 5.86 mmol / g, which is significantly higher than that of other scale inhibitors, indicating its stronger magnesium chelating ability.

[0270] The reason why the biodegradable scale inhibitor of the present invention shows a higher chelating capacity can be attributed to the synergistic effect of various chelating functional groups in the formula, such as carboxyl, hydroxyl, amino, etc., as well as the molecular structure and spatial configuration, which jointly promote the chelation coordination between the scale inhibitor molecule and calcium and magnesium ions.

[0271] Through the chelating capacity test experiment, it is confirmed that the biodegradable scale inhibitor of the present invention has excellent calcium and magnesium chelating performance, and its chelating capacity is significantly higher than that of similar commercial chemical scale inhibitors and environmentally friendly scale inhibitors. This result further verifies the effectiveness of the present invention, indicating that the scale inhibitor can more effectively inhibit the formation and deposition of calcium and magnesium scales, and has obvious advantages in scale inhibition performance.

[0272] The above has described the embodiments of this embodiment, but this embodiment is not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative rather than restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make many forms, all of which fall within the protection scope of this embodiment.

Claims

1. A biodegradable scale inhibitor without phosphorus and nitrogen, characterized in that, It comprises the following raw materials in parts by weight: 25-35 parts of chitosan grafted acrylic acid copolymer, 8-12 parts of polyaspartic acid, 8-12 parts of glucono delta-lactone, 7-13 parts of potassium citrate, 2-8 parts of propyl gallate, 9-11 parts of sodium lactate, 7-13 parts of polylysine, 3-7 parts of polycyclohexanedicarboxylic acid, and 5-15 parts of water.

2. The biodegradable phosphorus- and nitrogen-free scale inhibitor according to claim 1, characterized in that, It comprises the following raw materials in parts by weight: 30 parts of chitosan grafted acrylic acid copolymer, 10 parts of polyaspartic acid, 10 parts of glucono delta-lactone, 10 parts of potassium citrate, 5 parts of propyl gallate, 10 parts of sodium lactate, 10 parts of polylysine, 5 parts of polycyclohexanedicarboxylic acid, and 10 parts of water.

3. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 1, characterized in that, It comprises the following raw materials in parts by weight: 25 parts of chitosan grafted acrylic acid copolymer, 8 parts of polyaspartic acid, 8 parts of glucono delta-lactone, 7 parts of potassium citrate, 8 parts of propyl gallate, 11 parts of sodium lactate, 13 parts of polylysine, 7 parts of polycyclohexanedicarboxylic acid, and 15 parts of water.

4. A biodegradable phosphorus - and nitrogen - free scale inhibitor according to claim 1, characterized in that, It comprises the following raw materials in parts by weight: 35 parts of chitosan grafted acrylic acid copolymer, 12 parts of polyaspartic acid, 12 parts of glucono delta-lactone, 13 parts of potassium citrate, 2 parts of propyl gallate, 9 parts of sodium lactate, 7 parts of polylysine, 3 parts of polycyclohexanedicarboxylic acid, and 5 parts of water.

5. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 1, characterized in that, The preparation method of the scale inhibitor comprises the following steps: S1: Preparation of chitosan grafted acrylic acid copolymer; Dissolve chitosan in a dilute acetic acid solution, add an initiator, heat up to 50-70 °C, slowly dropwise add acrylic acid monomer, and react for 5-7 hours; After the reaction is completed, adjust the pH to 7.0, precipitate, filter, wash, and dry to obtain chitosan grafted acrylic acid copolymer; S2: Preparation of polylysine and polyaspartic acid; Dissolve lysine and aspartic acid in a sodium bicarbonate buffer solution respectively, add an enzyme catalyst, react at 35-39 °C for 24 hours, after the reaction is completed, dialyze to remove small molecules, and freeze-dry to obtain polylysine and polyaspartic acid; S3: Compound of the scale inhibitor; According to the proportion, dissolve chitosan grafted acrylic acid copolymer, polylysine, polyaspartic acid, glucono delta-lactone, propyl gallate, polycyclohexanedicarboxylic acid, potassium citrate and sodium lactate in deionized water, stir evenly, adjust the pH to 7.0-8.0 to obtain a scale inhibitor solution; S4: Product preparation; Spray-dry or vacuum-dry the scale inhibitor solution to obtain a solid powder product; or directly package the scale inhibitor solution to prepare a liquid product.

6. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 5, characterized in that, In step S1, dissolve chitosan in a dilute acetic acid solution, add an initiator, heat up to 60 °C, slowly dropwise add acrylic acid monomer, and react for 6 hours.

7. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 5, characterized in that, In step S1, dissolve chitosan in a dilute acetic acid solution, add an initiator, heat up to 50 °C, slowly dropwise add acrylic acid monomer, and react for 7 hours.

8. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 5, characterized in that, In step S1, dissolve chitosan in a dilute acetic acid solution, add an initiator, heat up to 70 °C, slowly dropwise add acrylic acid monomer, and react for 5 hours.

9. A biodegradable phosphorus-free and nitrogen-free scale inhibitor according to claim 5, characterized in that, In step S2, dissolve lysine and aspartic acid in a sodium bicarbonate buffer solution respectively, add an enzyme catalyst, and react at 37 °C for 24 hours.

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