A rare earth composite antibacterial scale inhibitor and its preparation method

Abstract

This invention relates to the field of water treatment technology, and in particular to a rare earth composite antibacterial and scale inhibitor and its preparation method. The method involves mixing glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, and acrylic acid, adding a mixed solvent of deionized water and ethanol, stirring to dissolve, purging with nitrogen, adding azobisisobutyronitrile, and stirring at a constant temperature to obtain a quaternary copolymer solution. Trimethylamine hydrochloride is then added to the quaternary copolymer solution, and the mixture is heated and stirred to react. The pH is adjusted to neutral to obtain a cationized copolymer solution. This cationized copolymer solution is then added dropwise to a cerium nitrate solution, stirred at room temperature, centrifuged, washed, and freeze-dried to obtain the rare earth composite antibacterial and scale inhibitor. The antibacterial and scale inhibitor prepared by this invention has significant effects, can bind metal ions on the scale inhibitor and prevent the growth of scale crystals, and exhibits synergistic antibacterial activity between rare earth ions and the copolymer. Furthermore, it is durable, stable, and has good dispersibility, making it adaptable to complex environments.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a rare earth composite antibacterial scale inhibitor and its preparation method. Background Technology

[0002] Scale inhibitors are indispensable chemical agents in water treatment fields such as industrial circulating water, boiler water, and oilfield injection water. They mainly inhibit the formation of scale such as calcium carbonate and calcium sulfate through chelation, dispersion, and lattice distortion, ensuring the efficient and stable operation of equipment. Currently, most commonly used scale inhibitors are single-function agents such as organophosphonates and polycarboxylic acids. Although they have a certain scale inhibition effect, in complex aquatic environments, especially when there are a large number of bacteria and algae in the water, the growth of microorganisms can easily lead to the mixing and deposition of biological slime and scale, forming complex scale that is difficult to remove. This not only reduces the scale inhibition efficiency but also aggravates equipment corrosion and increases maintenance costs. At the same time, some traditional scale inhibitors have problems such as poor biodegradability and easy secondary pollution, making it difficult to meet environmental protection requirements.

[0003] However, rare earth composite antibacterial and scale inhibitors have attracted researchers' attention due to their combination of the special chemical activity of rare earth elements and the synergistic effect of composite components, exhibiting certain antibacterial properties while inhibiting scale growth. Rare earth elements can enhance scale inhibition by forming stable complexes with scale ions, and their unique 4f electron configuration can also disrupt bacterial cell membrane structures and inhibit microbial reproduction. However, existing rare earth composite antibacterial and scale inhibitors still have significant drawbacks: on the one hand, rare earth elements have poor compatibility with other functional components (such as antibacterial agents and dispersants), and simple physical mixing easily leads to component aggregation, making it difficult to fully exert scale inhibition and antibacterial properties, resulting in large fluctuations in effectiveness; on the other hand, most materials have a narrow antibacterial spectrum, with limited inhibitory effects on sulfate-reducing bacteria and iron bacteria commonly found in circulating water, and insufficient stability in high-hardness, high-pH water bodies, resulting in a significant decrease in scale inhibition efficiency. In addition, the preparation process of some composite materials is complex, and the utilization rate of rare earth elements is low, leading to high production costs, which limits their large-scale application and makes it difficult to meet the requirements for continuous and stable quality. Summary of the Invention

[0004] To address the problems mentioned in the background section, this invention provides a rare earth composite antibacterial scale inhibitor and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a rare earth composite antibacterial scale inhibitor includes the following steps:

[0007] S1. Glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, and acrylic acid are mixed and added to a mixed solvent of deionized water and ethanol. The mixture is stirred and dissolved under nitrogen protection. The nitrogen flow rate is maintained at 0.4-0.6 L / min throughout the reaction. Azobisisobutyronitrile is added and the mixture is stirred at a constant temperature to obtain a quaternary copolymer solution.

[0008] S2. Add trimethylamine hydrochloride to the quaternary copolymer solution, heat and stir. Trimethylamine hydrochloride reacts with the epoxy group of glycidyl methacrylate to form a ring-opening reaction, generating a quaternary ammonium salt cationic group. This reaction does not require a catalyst. During the dropwise addition, adjust the pH to 5.3-5.7 in real time with 1-0.5M nitric acid to obtain a cationic copolymer solution.

[0009] S3. The cationic copolymer solution is added dropwise to the cerium nitrate solution, stirred at room temperature, and after centrifugation and washing, the precipitate is spread evenly on a freeze-drying tray with a thickness of ≤1 cm to obtain a rare earth composite antibacterial scale inhibitor.

[0010] Further, in step S1: the molar ratio of glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, and acrylic acid is 30:25:20:25; the volume ratio of deionized water to ethanol in the mixed solvent is 3:1; the ratio of the mixed solvent to the total mass of the monomer is 4:1; the amount of azobisisobutyronitrile is 0.6%-0.9% of the total mass of the monomer; the reaction temperature is 58-62℃; the reaction time is 7.5-8.5h; during the monomer dissolution process, ultrasonic dispersion with a power of 150-200W is required for 10-15min to ensure that there are no visible particles.

[0011] Further, in step S1: the nitrogen flow rate is 0.4-0.6 L / min, the aeration time is 25-35 min, to completely replace the air in the reaction system, the stirring speed is 220-280 rpm, the system needs to remain homogeneous and transparent during the reaction, without layering or precipitation, and the purity of the glycidyl methacrylate is ≥98%, the purity of vinylphosphonic acid is ≥95%, the purity of N-vinylthiourea is ≥97%, and the purity of acrylic acid is ≥99%.

[0012] Further, in step S2: the molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:1, and the purity of trimethylamine hydrochloride is ≥99%. A deionized water-ethanol mixed solvent with a volume ratio of 3:1 needs to be added to the reaction system so that the mass ratio of the quaternary copolymer-trimethylamine hydrochloride solute to the total solvent of the original mixed solvent-supplemented solvent is 1:6-1:8. The reaction temperature is 49-51℃, the reaction time is 3.8-4.2h, and the stirring speed is 160-190rpm.

[0013] Furthermore, in step S2: the pH adjustment uses a 0.5-0.1M NaOH solution, and the pH value after adjustment is 6.8-7.2. The solution must be clear and without layering. After the reaction is completed, it should be naturally cooled to 25-35℃ before pH adjustment to avoid the alkali solution from evaporating due to excessive temperature.

[0014] Further, in step S3: the cerium nitrate has the molecular formula Ce(NO3)3·6H2O, its purity is ≥99%, the solution concentration is 0.09-0.11M, and the pH is adjusted to 5.3-5.7 with 0.5-1M nitric acid. The cationic copolymer and Ce... 3+ The mass ratio is 10:1, and the rate of adding the cationic copolymer solution is 0.5-1 mL / min, corresponding to 1-2 drops / s.

[0015] Furthermore, in step S3: the stirring reaction time is 11-13 hours, the stirring speed is 120-140 rpm, the centrifugation speed is 7500-8500 rpm, the centrifugation time is 9-11 minutes, deionized water is used for washing, and the washing is performed 3 times. After each washing, the conductivity of the supernatant must be ≤5 μs / cm.

[0016] Furthermore, in step S3: the freeze-drying conditions are: pre-freezing temperature -22 to -18℃, pre-freezing time 1.5 to 2.5 h; drying temperature -45 to -50℃, vacuum degree 10 to 20 Pa, drying time 22 to 26 h. The dried product is a white powder with a particle size distribution D50 of 90 to 110 nm, and no obvious agglomeration is found when measured by a laser particle size analyzer.

[0017] Furthermore, in step S1, the reaction vessel must be a 500mL three-necked flask, with the flask neck connected to a nitrogen inlet tube, a stirrer, and a condenser, respectively. The condensate temperature should be 5-10℃. In step S2, a constant temperature water bath must be used to control the reaction temperature, with temperature fluctuations ≤ ±0.5℃. In step S3, the dropping process must be carried out under magnetic stirring, with the stir bar size matching the container, such as a 30mm long stir bar for a 500mL container.

[0018] According to another aspect of the present invention, a rare earth composite antibacterial scale inhibitor prepared by the above preparation method is provided.

[0019] The beneficial effects of this invention are:

[0020] 1. In the technical solution of the present invention, the rare earth composite antibacterial scale inhibitor is prepared by reacting a quaternary copolymer with cerium nitrate after cationization. The quaternary copolymer contains a variety of functional monomers, which are polymerized to form a molecular chain with multiple groups. Then, by introducing cationic groups and combining them with rare earth ions, a stable composite structure is constructed.

[0021] 2. In the technical solution of the present invention, the polar groups such as phosphonic acid group and carboxyl group on the molecular chain can combine with metal ions such as calcium and magnesium in water through coordination, thereby reducing the material basis for scale formation; at the same time, the flexibility and steric hindrance effect of the molecular chain can be adsorbed on the surface of scale crystals, preventing crystal growth and aggregation, destroying its regular structure, and effectively inhibiting scale adhesion.

[0022] 3. In the technical solution of the present invention, rare earth ions are stably combined with the copolymer, which can both disrupt the integrity of the bacterial cell membrane through interaction with it and interfere with bacterial metabolism and genetic material replication by means of thiourea groups and other groups on the copolymer molecular chain. The two work together to enhance the bactericidal and bacteriostatic ability. In addition, the electrostatic attraction between the cationic groups and the bacterial cell membrane increases the concentration of antibacterial components at the target site, further improving the antibacterial efficiency.

[0023] 4. In the technical solution of this invention, the coordination bonds between rare earth ions and copolymers prevent the rapid loss of effective components and prolong the action time; the interaction between polar groups on the molecular chain and water molecules and the characteristics of the nanoscale structure enable it to be uniformly dispersed in water, ensuring full contact with ions and microorganisms in the water, thereby giving full play to its performance and providing strong support for its application in industrial circulating water, water treatment equipment and other fields. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0026] Preparation Example 1

[0027] A rare earth composite antibacterial scale inhibitor and its preparation method include the following steps:

[0028] S1. A 500mL three-necked flask was selected as the reaction vessel, with a nitrogen inlet tube, a stirrer, and a condenser (cooling water temperature controlled at 7℃) connected to the flask. Glycidyl methacrylate (98% purity), vinylphosphonic acid (95% purity), N-vinylthiourea (97% purity), and acrylic acid (99% purity) were mixed in a molar ratio of 30:25:20:25. A mixed solvent of deionized water and ethanol in a volume ratio of 3:1 (mixed solvent to total monomer mass ratio of 4:1) was added, and the mixture was ultrasonically dispersed for 12 minutes at a power of 150-200W to ensure no visible particles. Nitrogen gas was then introduced at a flow rate of 0.5L / min for 30 minutes to completely replace the air in the system. Azobisisobutyronitrile (0.75% of the total monomer mass) was added, and the mixture was stirred at 250rpm at 60℃ for 8 hours, maintaining a homogeneous and transparent system to obtain a quaternary copolymer solution.

[0029] S2. Add trimethylamine hydrochloride (99% purity) to the quaternary copolymer solution, wherein the molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:1. Add a deionized water-ethanol mixed solvent with a volume ratio of 3:1 to bring the mass ratio of the quaternary copolymer-trimethylamine hydrochloride solute to the total solvent in the reaction system to 1:7. Maintain the reaction temperature at 50℃ (temperature fluctuation ≤ ±0.5℃) using a constant temperature water bath and stir at 175 rpm for 4 hours. After the reaction is complete, allow it to cool naturally to 30℃, and adjust the pH to 7.0 with 0.3M NaOH solution to ensure the solution is clear and does not separate into layers, thus obtaining the cationic copolymer solution.

[0030] S3. Prepare a 0.1M cerium nitrate (Ce(NO3)3·6H2O, 99% purity) solution, and adjust the pH to 5.5 with 0.7M nitric acid. Place a 30mm long stir bar in a 500mL container and, under magnetic stirring, add the cationic copolymer solution dropwise into the cerium nitrate solution at a rate of 0.75mL / min (approximately 1.5 drops / s). (The cationic copolymer reacts with Ce...) 3+ The mass ratio of the additives was 10:1. After the addition was complete, the mixture was stirred at 130 rpm for 12 hours. After the reaction, the mixture was centrifuged at 8000 rpm for 10 minutes, and the precipitate was collected. It was washed three times with deionized water, and the conductivity of the supernatant after each wash was ≤5 μS / cm. The washed precipitate was then freeze-dried: first pre-frozen at -20℃ for 2 hours, and then dried at -47℃ under a vacuum of 15 Pa for 24 hours to obtain a white powder product. The particle size distribution D50 of the powder was measured by a laser particle size analyzer to be 100 nm, with no obvious agglomeration. This product is a rare earth composite antibacterial and scale inhibitor.

[0031] Example 1

[0032] S1, glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, acrylic acid molar ratio 30:25:20:25; mixed solvent (deionized water: ethanol = 3:1) to total monomer mass ratio 4:1; ultrasonic power 150W, dispersion for 10min; nitrogen flow rate 0.4L / min, aeration for 25min; azobisisobutyronitrile (AIBN) amount 0.6% of total monomer mass; reaction temperature 58℃, stirring speed 220rpm, reaction time 7.5h.

[0033] S2, the molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:1; the mass ratio of solute to total solvent is 1:6; the reaction temperature is 49℃, the stirring speed is 160rpm, and the reaction time is 3.8h; after cooling to 25℃, the pH is adjusted to 6.8 with 0.1M NaOH.

[0034] S3, cerium nitrate solution concentration 0.09M, pH adjusted to 5.3 with 0.5M nitric acid; cationic copolymer and Ce 3+ The mass ratio was 10:1; the dropping rate was 0.5 mL / min; the reaction was stirred for 11 h at a speed of 120 rpm; the centrifugation speed was 7500 rpm for 9 min; the freeze-drying pre-freezing temperature was -22℃ for 1.5 h; the drying temperature was -50℃, the vacuum degree was 10 Pa, and the time was 22 h. The product was a white powder with a D50 of 90 nm.

[0035] Example 2

[0036] S1, glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, acrylic acid molar ratio 30:25:20:25; mixed solvent (deionized water: ethanol = 3:1) to total monomer mass ratio 4:1; ultrasonic power 175W, dispersion 12.5min; nitrogen flow rate 0.5L / min, aeration 30min; azobisisobutyronitrile amount is 0.75% of total monomer mass; reaction temperature 60℃, stirring speed 250rpm, reaction time 8h.

[0037] S2, the molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:1; the mass ratio of solute to total solvent is 1:7; the reaction temperature is 50℃, the stirring speed is 175rpm, and the reaction time is 4h; after cooling to 30℃, the pH is adjusted to 7.0 with 0.3M NaOH.

[0038] S3, cerium nitrate solution concentration 0.1M, pH adjusted to 5.5 with 0.75M nitric acid; cationic copolymer and Ce 3+The mass ratio was 10:1; the dropping rate was 0.75 mL / min; the reaction was stirred for 12 h at a speed of 130 rpm; the centrifugation speed was 8000 rpm for 10 min; the freeze-drying pre-freezing temperature was -20℃ for 2 h; the drying temperature was -47℃, the vacuum degree was 15 Pa, and the time was 24 h. The product was a white powder with a D50 of 100 nm.

[0039] Example 3

[0040] S1, glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, acrylic acid molar ratio 30:25:20:25; mixed solvent (deionized water: ethanol = 3:1) to total monomer mass ratio 4:1; ultrasonic power 200W, dispersion 15min; nitrogen flow rate 0.6L / min, aeration 35min; azobisisobutyronitrile dosage 0.9% of total monomer mass; reaction temperature 62℃, stirring speed 280rpm, reaction time 8.5h.

[0041] S2, the molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:1; the mass ratio of solute to total solvent is 1:8; the reaction temperature is 51℃, the stirring speed is 190rpm, and the reaction time is 4.2h; after cooling to 35℃, the pH is adjusted to 7.2 with 0.5M NaOH.

[0042] S3, cerium nitrate solution concentration 0.11M, pH adjusted to 5.7 with 1M nitric acid; cationic copolymer and Ce 3+ The mass ratio was 10:1; the dropping rate was 1 mL / min; the reaction was stirred for 13 h at a speed of 140 rpm; the centrifugation speed was 8500 rpm for 11 min; the freeze-drying pre-freezing temperature was -18℃ for 2.5 h; the drying temperature was -45℃, the vacuum degree was 20 Pa, and the time was 26 h. The product was a white powder with a D50 of 110 nm.

[0043] Comparative Example 1

[0044] In this comparative example, the monomer molar ratio in step S1 was adjusted to 40:20:15:25 (deviating from 30:25:20:25), and the other parameters were the same as in Example 2.

[0045] Comparative Example 2

[0046] In this comparative example, the cationic copolymer in step S3 and Ce 3+ The mass ratio was adjusted to 8:1 (deviating from 10:1), and the other parameters were the same as in Example 2.

[0047] Comparative Example 3

[0048] In this comparative example, the reaction temperature in step S2 is 55℃ (deviating from 49-51℃), and the other parameters are the same as in Example 2.

[0049] Nutrient broth culture medium was prepared and sterilized according to the procedure of the antibacterial rate test standard "GB / T 21844-2008 Method for Evaluation of Antibacterial Performance"; Escherichia coli and Staphylococcus aureus bacterial suspensions were activated to a concentration of 1.2 × 10⁻⁶. 7 CFU / mL; the sample was prepared into a 10 g / L stock solution using sterile PBS buffer, and then dispersed by sonication and filtered; the stock solution was mixed with the bacterial suspension and reacted at 37℃ for 2 h, with blank, positive and negative control groups included; after the reaction, the bacterial suspension was serially diluted, plated and incubated for 24 h, colonies were counted and the inhibition rate was calculated. The results are shown in Table 1:

[0050] Table 1. Comparison of antibacterial effects between Examples 1-3 and Comparative Examples 1-3

[0051]

[0052] The scale inhibition rate was tested according to the standard GB / T 16632-2008 "Determination of Scale Inhibition Performance of Water Treatment Agents" for preparing a Ca-containing solution. 2+ HCO 3- Simulated hard water was prepared by adding sample solution to achieve a concentration of 5 mg / L; after reacting at 60℃ for 10 h, the solution was filtered, and the filtrate was titrated with EDTA to determine the Ca content. 2+ Concentration was used to calculate the scale inhibition rate; the sample was dissolved in water, ultrasonically dispersed, and then the particle size was measured using a laser particle size analyzer (Example D 50 95-102nm, Comparative Example 118-130nm). Agglomeration was observed by centrifugation. The results are shown in Table 2.

[0053] Table 2. Comparison of scale inhibition and dispersion effects between Examples 1-3 and Comparative Examples 1-3

[0054]

[0055] As shown in Table 1, Examples 1-3 exhibit superior antibacterial effects because they strictly adhere to the preparation process. The thiourea groups provided by N-vinylthiourea in the quaternary copolymer can interfere with bacterial metabolism, and the cationic groups introduced after the cationization of glycidyl methacrylate can target and bind to the bacterial cell membrane through electrostatic attraction, thereby increasing the rare earth Ce content. 3+ The enrichment concentration of Ce on the bacterial surface 3+ The interaction with bacterial cell membranes disrupts their integrity, and the thiourea group forms a synergistic antibacterial effect, maintaining an inhibition rate of over 93% against both *Escherichia coli* and *Staphylococcus aureus*. In contrast, the comparative examples showed poorer antibacterial effects. In Comparative Example 1, the reduced proportion of N-vinylthiourea due to adjusting the monomer molar ratio led to a decrease in the number of thiourea groups, weakening its ability to interfere with bacterial metabolism, resulting in an inhibition rate of 82%-84%. In Comparative Example 2, the cationic copolymer and Ce... 3+ The mass ratio deviates from 10:1, Ce 3+Excessive proportion leads to unstable binding and easy aggregation, reducing the contact efficiency with bacteria and decreasing the antibacterial rate to 85%-87%. In Comparative Example 3, the reaction temperature in step S2 was too high, resulting in incomplete reaction between trimethylamine hydrochloride and glycidyl methacrylate, and insufficient number of cationic groups, which reduced the targeted adsorption of bacteria, and the antibacterial rate was only 80%-83%.

[0056] As shown in Table 2, Examples 1-3 exhibit superior scale inhibition and dispersion performance. This is because the phosphonic acid groups (from vinylphosphonic acid) and carboxyl groups (from acrylic acid) in the quaternary copolymers are in a suitable ratio, allowing for efficient binding of calcium in the water through coordination. 2+ Mg 2 + This reduces the material basis for scale formation, and the steric hindrance effect of the molecular chain effectively prevents the growth and aggregation of scale crystals, achieving a scale inhibition rate of over 87%. Furthermore, proper control of the freeze-drying process ensures that the product particle size distribution (D50) is within the range of 90-110 nm, with no significant agglomeration, guaranteeing uniform dispersion in water and sufficient contact with ions, further enhancing the scale inhibition effect. In contrast, the comparative examples exhibited poor scale inhibition and dispersion performance. Comparative Example 1, due to changes in the monomer molar ratio and the altered proportions of vinylphosphonic acid and acrylic acid, resulted in a decrease in the number of phosphonic acid and carboxyl groups, reducing their binding ability with metal ions and lowering the scale inhibition rate to 78.6%. Moreover, changes in the molecular chain structure affected dispersibility, increasing the particle size to 125.6 nm and causing a small amount of agglomeration. In Comparative Example 2, Ce... 3+ If the ratio is too high, the coordination balance with the copolymer is broken, and the resulting complex is prone to agglomeration (particle size 130.8 nm), which reduces the contact area with ions in water, and the scale inhibition rate drops to 80.2%. In Comparative Example 3, due to improper reaction temperature in step S2, the copolymer cationization was incomplete, the polar groups of the molecular chain were unevenly distributed, the interaction with water molecules was weakened, and the dispersibility was poor (particle size 118.9 nm). At the same time, it affected the adsorption capacity for scale crystals, and the scale inhibition rate was only 76.8%.

[0057] In summary, rare earth composite antibacterial and scale inhibitors possess significant performance advantages. By strictly controlling the preparation process parameters, the appropriate proportion of functional groups can be ensured, allowing thiourea groups, cationic groups, phosphonic acid groups, and carboxyl groups to exert synergistic effects. This not only enhances the antibacterial effect, effectively inhibiting bacteria such as Escherichia coli and Staphylococcus aureus, but also efficiently binds to metal ions in water, preventing the growth of scale crystals and exhibiting excellent scale inhibition performance. Furthermore, the material exhibits stable binding with rare earth ions and good dispersibility, with no significant agglomeration, allowing for full contact with the target organism and further improving antibacterial and scale inhibition efficiency. This fully demonstrates the importance of the synergistic effect of each component, providing strong support for its application in industrial circulating water, water treatment equipment, and other fields.

[0058] In the description of this specification, the terms "preparation example," "example," "various examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that example or preparation example, which are included in at least one example or preparation example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same example or preparation example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more examples or preparation examples.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a rare earth composite antibacterial scale inhibitor, characterized in that, Includes the following steps: S1. Glycidyl methacrylate, vinylphosphonic acid, N-vinylthiourea, and acrylic acid are mixed in a molar ratio of 30:25:20:

25. A mixed solvent of deionized water and ethanol is added, and the mixture is stirred and dissolved under nitrogen protection. The nitrogen flow rate is maintained at 0.4-0.6 L / min throughout the reaction. Azobisisobutyronitrile is added, and the reaction is carried out at a constant temperature of 58-62℃ with stirring to obtain a quaternary copolymer solution. S2. Add trimethylamine hydrochloride to the quaternary copolymer solution, heat and stir. The molar ratio of trimethylamine hydrochloride to glycidyl methacrylate is 1.2:

1. Trimethylamine hydrochloride reacts with the epoxy groups of glycidyl methacrylate to form quaternary ammonium salt cationic groups. The reaction does not require a catalyst. The reaction temperature is 49-51℃. During the dropwise addition, the pH is adjusted to 5.3-5.7 in real time with 1-0.5M nitric acid to obtain a cationic copolymer solution. S3. Add the cationic copolymer solution dropwise to the cerium nitrate solution. The cationic copolymer reacts with Ce. 3+ The mass ratio was 10:

1. The mixture was stirred at room temperature, centrifuged and washed, and the precipitate was spread evenly on a freeze-drying tray with a thickness of ≤1 cm to obtain a rare earth composite antibacterial scale inhibitor.

2. The method for preparing rare earth composite antibacterial and scale inhibitor according to claim 1, characterized in that, In step S1: The volume ratio of deionized water to ethanol in the mixed solvent is 3:1, the ratio of the mixed solvent to the total mass of the monomer is 4:1, the amount of azobisisobutyronitrile is 0.6%-0.9% of the total mass of the monomer, the reaction time is 7.5-8.5h, and the monomer needs to be dispersed with ultrasonic assistance at a power of 150-200W for 10-15min during the monomer dissolution process to ensure that there are no visible particles.

3. The method for preparing rare earth composite antibacterial and scale inhibitor according to claim 1, characterized in that, In step S1: The nitrogen flow rate is 0.4-0.6 L / min, and the aeration time is 25-35 min to completely replace the air in the reaction system. The stirring speed is 220-280 rpm. During the reaction, the system must remain homogeneous and transparent, without layering or precipitation. The purity of the glycidyl methacrylate is ≥98%, the purity of vinylphosphonic acid is ≥95%, the purity of N-vinylthiourea is ≥97%, and the purity of acrylic acid is ≥99%.

4. The method for preparing rare earth composite antibacterial and scale inhibitor according to claim 1, characterized in that, In step S2: The purity of the trimethylamine hydrochloride is ≥99%. The reaction system needs to be supplemented with a deionized water-ethanol mixed solvent with a volume ratio of 3:1, so that the mass ratio of the quaternary copolymer-trimethylamine hydrochloride solute to the total solvent of the original mixed solvent-supplemented solvent in the reaction system is 1:6-1:

8. The reaction time is 3.8-4.2h, and the stirring speed is 160-190rpm.

5. The method for preparing rare earth composite antibacterial and scale inhibitor according to claim 1, characterized in that, In step S2: The pH is adjusted using a 0.5-0.1M NaOH solution, resulting in a pH of 6.8-7.

2. The solution should be clear and free of stratification. After the reaction is complete, allow it to cool naturally to 25-35℃ before adjusting the pH to avoid excessively high temperatures that could cause the alkali solution to evaporate.

6. The method for preparing the rare earth composite antibacterial scale inhibitor according to claim 1, characterized in that, In step S3: The cerium nitrate has the molecular formula Ce(NO3)3·6H2O, a purity ≥99%, a solution concentration of 0.09-0.11M, and the pH is adjusted to 5.3-5.7 with 0.5-1M nitric acid. The cationic copolymer solution is added at a rate of 0.5-1mL / min, corresponding to 1-2 drops / s.

7. The method for preparing rare earth composite antibacterial scale inhibitor according to claim 1, characterized in that, In step S3: The stirring reaction time is 11-13 hours, the stirring speed is 120-140 rpm, the centrifugation speed is 7500-8500 rpm, and the centrifugation time is 9-11 minutes. Deionized water is used for washing, and the washing is performed 3 times. After each washing, the conductivity of the supernatant should be ≤5 μs / cm.

8. The method for preparing rare earth composite antibacterial scale inhibitor according to claim 1, characterized in that, In step S3: The freeze-drying conditions were as follows: pre-freezing temperature -22 to -18℃, pre-freezing time 1.5 to 2.5 h; drying temperature -45 to -50℃, vacuum degree 10 to 20 Pa, drying time 22 to 26 h. The dried product was a white powder with a particle size distribution D50 of 90 to 110 nm. No obvious agglomeration was found when measured by a laser particle size analyzer.

9. The method for preparing rare earth composite antibacterial scale inhibitor according to claim 1, characterized in that, In step S1, the reaction vessel must be a 500mL three-necked flask, with the flask neck connected to a nitrogen inlet tube, a stirrer, and a condenser, respectively. The condensate temperature should be 5-10℃. In step S2, a constant temperature water bath must be used to control the reaction temperature, with temperature fluctuations ≤ ±0.5℃. In step S3, the dropwise addition process must be carried out under magnetic stirring, with the stir bar size matching the container.

10. A rare earth composite antibacterial scale inhibitor prepared by the method for preparing a rare earth composite antibacterial scale inhibitor as described in any one of claims 1-9.

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