A targeted recognition core-shell structured nanoparticle flocculant and its preparation method

Abstract

This invention discloses a targeted recognition core-shell structured nanoparticle flocculant, comprising the following components by weight: 100 parts diallylamine; 115-120 parts ethyl chloroacetate; 175-180 parts chloroacetic acid; 100 parts SiO2 nanoparticles; 2-8 parts vinyltrimethoxysilane; 16-19 parts hydroxylamine hydrochloride; and 1-1.5 parts ammonium persulfate. This invention also discloses a method for preparing the above flocculant. This invention designs a SiO2-PDHAMDAC core-shell structured nanoparticle flocculant that targets and masks hydrophobic segments. It innovatively introduces a hydroxyoxime recognition group into the flocculant to enhance its recognition and adhesion to clay. The introduction of hydrophobic SiO2 nanoparticles masks the carbon chain structure of the flocculant, weakening the hydrophobic association with coal particles, reducing heterogeneous flocculation, and jointly promoting efficient and selective flocculation of clay, achieving efficient flotation of high-ash coal slime.

Description

Technical Field

[0001] This invention relates to the field of flocculant technology, and in particular to a targeted recognition core-shell structured nanoparticle flocculant and its preparation method. Background Technology

[0002] With the gradual depletion of high-quality coal resources and the continuous deterioration of coalfield geological conditions, coal quality is exhibiting characteristics of "high ash content and fine particle size." In the process of fine coal separation and upgrading, the non-selective flotation of clay and other fine mud contaminates the clean coal. During coal washing, high-ash fine mud such as clay enters the flotation foam through non-selective methods such as covering, entrainment, and coagulation, resulting in problems such as low clean coal yield, high ash content, high reagent consumption, and difficulty in dewatering, and even causing the entire production system to malfunction. Statistics show that due to inefficient separation, nearly 100 million tons of coal slime are lost annually, especially for strategic coal resources such as coking coal and fat coal.

[0003] Selective flocculation is an effective method to reduce the contamination of clean coal by fine slime. Under the action of flocculants, fine slime forms flocs, losing its colloidal properties and effectively reducing the chances of capping and entrainment, while maintaining the natural hydrophobicity of the coal slime, thus enhancing coal slime flotation. Currently commonly used traditional flocculants include polydimethyldiallyl ammonium chloride (PDMDAAC), polyacrylamide (PAM), polyethylene oxide (PEO), and sodium polyacrylate (PAAS). However, in using flocculants to improve coal slime flotation, the flocculation process suffers from drawbacks such as weak selectivity and unstable separation effects. This is because the interaction forces between traditional flocculants and coal and clay are not significantly different. On the one hand, the functional groups (quaternary ammonium, amide, carboxyl, hydroxyl, etc.) in traditional flocculants generate non-specific forces such as electrostatics and hydrogen bonds with both coal and clay; on the other hand, the flocculant backbone contains a large number of hydrophobic hydrocarbon chains (-CH2-CH2- structures), which flocculate coal particles through strong hydrophobic association. Furthermore, the complex spatial structure of flocculants leads to stronger non-selective effects such as netting and sweeping during flocculation. Most existing technologies utilize traditional flocculants, altering the coal slime flotation process, but cannot effectively control the problem of mixed flocs, resulting in unsatisfactory selective flocculation and hindering the development of coal slime ash reduction technology.

[0004] Therefore, it is urgent to modify traditional flocculants and develop a core-shell structured nanoparticle flocculant with targeted recognition to improve the selective flocculation effect of clay, strong flocculation ability and targeted recognition ability, and enhance coal slime flotation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a targeted recognition core-shell structured nanoparticle flocculant and its preparation method. Based on the traditional flocculant polydimethyldiallylammonium chloride (PDMDAAC), this invention introduces hydroxyoxime groups that specifically recognize metal ions on the surface of clay minerals into the structure. Hydrophobic SiO2 nanoparticles form the core, with PDHAMDAC micelles surrounding and fixed on the "core," forming a "core-shell micelle" structure, thereby achieving selective flocculation of clay. This invention weakens the intramolecular rigidity of the original flocculant, shields the hydrophobic interaction with coal particles, enhances hydrophilic properties, reduces the probability of coal particle flocculation, and enhances flocculation efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A targeted recognition core-shell structured nanoparticle flocculant, characterized in that it comprises the following components in parts by weight: Diallylamine (C6H) 11 N) 100 copies; Ethyl chloroethyl (C4H7ClO2) 115-120 parts; 175-180 parts of chloroacetic acid (C2H3ClO2); 100 parts of SiO2 nanoparticles; Vinyltrimethoxysilane (C5H) 12 2-8 parts of O3Si; Hydroxylamine hydrochloride 16-19 parts; 1 to 1.5 parts of ammonium persulfate.

[0007] Preferably, the diameter of the SiO2 nanoparticles is 80–100 nm.

[0008] Preferably, the flocculant of the present invention comprises the following components: Diallylamine (C6H) 11 N) 100g; Ethyl chloroacetate (C4H7ClO2) 118g; 180g of chloroacetic acid (C2H3ClO2); 100g of SiO2 nanoparticles; Vinyltrimethoxysilane (C5H) 12 5g of O3Si; 18g of hydroxylamine hydrochloride; 1.2g of ammonium persulfate.

[0009] This invention also discloses a method for preparing a targeted recognition core-shell structured nanoparticle flocculant, comprising the following steps: (1) Using diallylamine as a raw material, in the presence of inorganic base and polar aprotic organic solvent, it undergoes a nucleophilic substitution reaction with ethyl chloroacetate. The reaction temperature is 50-70℃ and the reaction time is 10-15 hours. After the reaction is completed, it is cooled to room temperature, filtered, concentrated under reduced pressure to remove the solvent, and the residue is extracted by liquid-liquid extraction, washed, dried and concentrated to obtain (N,N-diallylamino)ethyl acetate. (N,N-diallylamino)ethyl acetate was hydrolyzed in an aqueous sodium hydroxide solution at a temperature of 50-60°C for 0.5-2 hours. Sodium diallylaminoacetate was obtained after the reaction was completed. Adjust the pH of the solution to 8-9, add chloroacetic acid to sodium diallylaminoacetate, heat to 55-60℃, react for 1-2 hours, and filter after precipitation to obtain dicarboxymethyl diallyl ammonium chloride monomer. (2) Add SiO2 nanoparticles to a piranha solution, heat to 50-65℃, react for 0.5-1 h, then rinse with ultrapure water until neutral to obtain treated SiO2 nanoparticles; immerse the treated SiO2 nanoparticles in C5H 12 O3Si-toluene solution was reacted at 70-80℃ under N2 atmosphere for 6-8 hours, and then washed and dried with ultrapure water to obtain hydrophobic SiO2 nanoparticles. (3) Dicarboxymethyl diallyl ammonium chloride monomer and hydrophobic SiO2 nanoparticles were mixed and ammonium persulfate initiator was added to carry out free radical polymerization to prepare SiO2-PDCMDAAC with different molecular weights; hydroxylamine hydrochloride was added to SiO2-PDCMDAAC to carry out oxime reaction, the temperature was raised to 30-45℃, the reaction time was 4-6h, and the product was washed and acidified to pH = 3.5-4.0 to obtain SiO2-PDHAMDAC core-shell structured nanoparticle flocculant.

[0010] The inorganic base, polar aprotic organic solvent, sodium hydroxide aqueous solution, piranha solution, toluene, etc., in the preparation method of this invention are process aids. They are auxiliary substances used in the reaction but are removed at the end and are not structural components. Dilute hydrochloric acid (acid-base regulator / acid-binding agent) is used to adjust the pH value. After the reaction, they are converted into inorganic salts or water. These inorganic salts are washed away during purification or exist as trace impurities and do not participate in the formation of the polymer backbone structure of the flocculant.

[0011] Preferably, in step (1), the molar ratio of diallylamine, ethyl chloroacetate and inorganic base is 1: (1.0~1.2): (1.0~1.5).

[0012] Preferably, the sodium hydroxide aqueous solution in step (1) is a 10 wt% sodium hydroxide aqueous solution.

[0013] Preferably, the C5H 12 O3Si-toluene solution is C5H with a mass ratio of 1:(10~20). 12 O3Si and toluene solution.

[0014] Preferably, in step (3), the mass ratio of dicarboxymethyl diallyl ammonium chloride monomer to hydrophobic SiO2 nanoparticles is (3-4):1.

[0015] Preferably, the free radical polymerization reaction in step (3) is carried out at pH 10 to 11, at a temperature of 52 to 55°C, and for a reaction time of 1 to 1.5 h.

[0016] Preferably, in step (3), the product is washed with methanol and acidified with dilute hydrochloric acid.

[0017] Theoretically, dilute sulfuric acid, nitric acid, or phosphoric acid can be used to adjust the pH of the solution, but these will introduce impurities such as sulfate ions. To maintain the purity of the product, dilute hydrochloric acid is preferred in this embodiment of the invention. More preferably, the mass fraction of dilute hydrochloric acid is 5% to 15%.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention can reduce the non-specific adsorption between flocculants and coal particles: because the hydrophobic segments of PDHAMDAC in the core-shell structure of the flocculant SiO2-PDHAMDAC are shielded, the interaction between the flocculant and the hydrophobic coal surface is greatly weakened, thereby effectively preventing coal particles from being entrained into clay flocs and reducing the phenomenon of mixed flocculation.

[0019] 2. This invention can enhance the selective adhesion to clay minerals: by replacing the methyl structure in the original flocculant with a hydroxyoxime functional group, it can specifically recognize metal ions on the clay surface, while the quaternary ammonium group enhances adsorption through electrostatic interaction. The two work together to improve the flocculation efficiency and selectivity of clay.

[0020] 3. This invention enhances flocculation efficiency and floc strength: Utilizing the micronucleus effect of SiO2 particles, clay particles can rapidly form mesoscale flocs around the flocculation nucleus, thereby enhancing flocculation efficiency. Furthermore, the "weighting effect" of SiO2 particles increases floc inertia, reducing the likelihood of flocs entering the clean coal under water flow, thus contributing to further reduction of clean coal ash content.

[0021] This invention designs a SiO2-PDHAMDAC core-shell structured nanoparticle flocculant that targets and masks hydrophobic segments. It innovatively introduces a recognition group, hydroxyoxime, into the flocculant to enhance its recognition and adhesion to clay. The introduction of hydrophobic SiO2 nanoparticles masks the carbon chain structure of the flocculant, weakens the hydrophobic association with coal particles, reduces heterogeneous flocculation, and jointly promotes efficient and selective flocculation of clay, thereby achieving efficient flotation of high-ash coal slime.

[0022] This invention utilizes the selective flocculation effect of a novel flocculant to regulate the interaction forces between the flocculant and coal and clay. This enables the flocculant to recognize clay during flocculation and weakens the non-specific forces between the flocculant and coal particles, thereby improving the selective flocculation efficiency of clay and enhancing coal slime flotation. This invention improves the selective flocculation efficiency of clay, enhances the adhesion of the flocculant to clay, and strengthens coal slime flotation. It effectively reduces the probability of coal particle flocculation, enhances flocculation efficiency, and provides a more efficient pathway for upgrading the flotation of low-quality coal. Attached Figure Description

[0023] Figure 1 This is a TEM image of the SiO2-PDHAMDAC core-shell structured nanoparticle flocculant prepared in Example 1; Figure 2 This is a TEM image of the hydrophilic-SiO2 / PDHAMDAC physical mixture obtained in Comparative Example 2. Figure 3 This is the infrared spectrum of ethyl acetate (N,N-diallylamino) intermediate in Example 1; Figure 4 This is the infrared spectrum of sodium diallyl aminoacetate, the intermediate in Example 1. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments. However, it should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0025] In the embodiments, all original reagent materials are commercially available, and experimental methods not specified are conventional methods and conditions well known in the field, or according to the conditions recommended by the instrument manufacturer.

[0026] The raw materials used in the embodiments of this invention are as follows: Diallylamine (C6H) 11 N), ethyl chloroacetate (C4H7ClO2), chloroacetic acid (C2H3ClO2), hydroxylamine hydrochloride, ammonium persulfate, and vinyltrimethoxysilane (VTMS) were all commercially available analytical grade.

[0027] SiO2 nanoparticles (average particle size 90 nm) were purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0028] Kaolinite is a commercially available reagent.

[0029] The coal slime sample was taken from the flotation feed of the coal preparation plant of Fanggezhuang Mining Branch of Kailuan Energy Chemical Co., Ltd., with an ash content of 29.5%.

[0030] The clay minerals are mainly kaolinite, montmorillonite and illite.

[0031] To address the issue of fine clay and other slime contaminating the flotation concentrate during coal slime flotation by entering the froth through non-selective means such as covering, entrainment, and coagulation, traditional flocculants, which exhibit relatively similar interaction forces with coal and clay, suffer from weak selectivity and unstable separation effects. Furthermore, the presence of numerous hydrophobic hydrocarbon chains (-CH2-CH2- structures) in the flocculant backbone leads to strong hydrophobic association and flocculation of coal particles, causing severe heterogeneous flocculation problems. This invention proposes a targeted, core-shell structured nanoparticle flocculant, comprising the following components by weight: Diallylamine (C6H) 11 N) 100 copies; Ethyl chloroethyl (C4H7ClO2) 115-120 parts; 175-180 parts of chloroacetic acid (C2H3ClO2); 100 parts of SiO2 nanoparticles; Vinyltrimethoxysilane (C5H) 12 2-8 parts of O3Si; Hydroxylamine hydrochloride 16-19 parts; 1 to 1.5 parts of ammonium persulfate.

[0032] In some embodiments, the diameter of the SiO2 nanoparticles is 80–100 nm. More preferably, the average particle size of the SiO2 nanoparticles is 90 nm.

[0033] The preparation method of the above-mentioned targeted recognition core-shell structured nanoparticle flocculant includes the following steps: (1) Using diallylamine as a raw material, in the presence of inorganic base and polar aprotic organic solvent, it undergoes a nucleophilic substitution reaction with ethyl chloroacetate. The reaction temperature is 50-70℃ and the reaction time is 10-15 hours. After the reaction is completed, it is cooled to room temperature, filtered, concentrated under reduced pressure to remove the solvent, and the residue is extracted by liquid-liquid extraction, washed, dried and concentrated to obtain (N,N-diallylamino)ethyl acetate. (N,N-diallylamino)ethyl acetate was hydrolyzed in an aqueous sodium hydroxide solution at a temperature of 50-60°C for 0.5-2 hours. Sodium diallylaminoacetate was obtained after the reaction was completed. Adjust the pH of the solution to 8-9, add chloroacetic acid to sodium diallylaminoacetate, heat to 55-60℃, react for 1-2 hours, and filter after precipitation to obtain dicarboxymethyl diallyl ammonium chloride monomer. (2) Add SiO2 nanoparticles to a piranha solution, heat to 50-65℃, react for 0.5-1 h, then rinse with ultrapure water until neutral to obtain treated SiO2 nanoparticles; immerse the treated SiO2 nanoparticles in C5H 12 O3Si-toluene solution was reacted at 70-80℃ under N2 atmosphere for 6-8 hours, and then washed and dried with ultrapure water to obtain hydrophobic SiO2 nanoparticles. (3) Dicarboxymethyl diallyl ammonium chloride monomer and hydrophobic SiO2 nanoparticles were mixed and ammonium persulfate initiator was added to carry out free radical polymerization to prepare SiO2-PDCMDAAC with different molecular weights; hydroxylamine hydrochloride was added to SiO2-PDCMDAAC to carry out oxime reaction, the temperature was raised to 30-45℃, the reaction time was 4-6h, and the product was washed and acidified to pH = 3.5-4.0 to obtain SiO2-PDHAMDAC core-shell structured nanoparticle flocculant.

[0034] The inorganic base, polar aprotic organic solvent, sodium hydroxide aqueous solution, piranha solution, toluene, etc., in the preparation method of this invention are process aids. They are auxiliary substances used in the reaction but are removed at the end and are not structural components. Dilute hydrochloric acid (acid-base regulator / acid-binding agent) is used to adjust the pH value. After the reaction, they are converted into inorganic salts or water. These inorganic salts are washed away during purification or exist as trace impurities and do not participate in the formation of the polymer backbone structure of the flocculant.

[0035] In some embodiments, the molar ratio of diallylamine, ethyl chloroacetate and inorganic base in step (1) is 1:(1.0~1.2):(1.0~1.5).

[0036] In some embodiments, the sodium hydroxide aqueous solution in step (1) is a 10 wt% sodium hydroxide aqueous solution.

[0037] In some embodiments, the C5H 12 O3Si-toluene solution is C5H with a mass ratio of 1:(10~20). 12 O3Si and toluene solution.

[0038] In some embodiments, the mass ratio of dicarboxymethyl diallyl ammonium chloride monomer to hydrophobic SiO2 nanoparticles in step (3) is (3-4):1.

[0039] In some embodiments, the free radical polymerization reaction in step (3) is carried out at pH 10 to 11, at a temperature of 52 to 55°C, and for a reaction time of 1 to 1.5 h.

[0040] In some embodiments, the product in step (3) is washed with methanol and acidified with dilute hydrochloric acid.

[0041] Theoretically, dilute sulfuric acid, nitric acid, or phosphoric acid can be used to adjust the pH of the solution, but these will introduce impurities such as sulfate ions. To maintain the purity of the product, dilute hydrochloric acid is preferred in this embodiment of the invention. More preferably, the mass fraction of dilute hydrochloric acid is 5% to 15%.

[0042] To better illustrate the formation mechanism of the SiO2-PDHAMDAC "core-shell micelle" structure, the targeted recognition function of the hydroxyoxime functional group, and the effect of hydrophobic association on the hydrophobicity of the masked coal particles, the following examples 1 and comparative examples 1-2 further illustrate this.

[0043] Example 1 A method for preparing a targeted recognition core-shell structured nanoparticle flocculant includes the following steps: (1) 100 g diallylamine, 118 g ethyl chloroacetate, 170 g potassium carbonate (as an acid-binding agent) and 500 mL acetonitrile (as a solvent) were added to a reaction vessel and reacted at a reaction temperature of 60 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, concentrated under reduced pressure to remove acetonitrile, and the residue was extracted, washed, dried and concentrated to obtain ethyl (N,N-diallylamino)acetate. The infrared spectrum of the intermediate (N,N-diallylamino)ethyl acetate is shown in the figure below. Figure 3 As shown.

[0044] Then, 480 g of a 10% sodium hydroxide aqueous solution was added to the ethyl (N,N-diallylamino)acetate, and the hydrolysis reaction was carried out at a reaction temperature of 55°C for 1 h. After the reaction was completed, sodium diallylaminoacetate was obtained. The infrared spectrum of the intermediate sodium diallyl aminoacetate is shown below. Figure 4 As shown.

[0045] The solution pH was then adjusted to 8, and 180 g of chloroacetic acid was added and reacted at 58°C for 1.5 h. After precipitation, the mixture was filtered to obtain dicarboxymethyl diallyl ammonium chloride monomer. (2) 100g of SiO2 nanoparticles were added to 200g of piranha solution and reacted at 60℃ for 0.5h. Then, the mixture was washed with ultrapure water until neutral to obtain treated SiO2 nanoparticles. The treated SiO2 nanoparticles were then immersed in 55g of C5H 12Hydrophobic SiO2 nanoparticles were obtained by reacting O3Si-toluene solution (mass ratio 1:10) at 75℃ under N2 atmosphere for 7 hours, followed by washing with ultrapure water and drying. (3) The above dicarboxymethyl diallyl ammonium chloride monomer was mixed with hydrophobic SiO2 nanoparticles, 1.2 g of ammonium persulfate was added, and polymerization was carried out at pH=10.5 and 55℃ for 1.2 h. Then, it was oximated with 18 g of hydroxylamine hydrochloride at 42℃ for 5 h. After washing with methanol and acidifying with dilute hydrochloric acid to pH=3.8, SiO2-PDHAMDAC core-shell structured nanoparticle flocculant was obtained.

[0046] TEM images of the prepared SiO2-PDHAMDAC core-shell structured nanoparticle flocculant are shown below. Figure 1 As shown.

[0047] Comparative Example 1 A method for preparing a flocculant is the same as in Example 1, but the hydrochloric acid hydroxylamine oxime reaction in step (3) is omitted. That is, the polymer backbone of the obtained product does not contain hydroxyl oxime groups, but only quaternary ammonium groups and methyl side chains. The product is denoted as SiO2-PDMDAAC.

[0048] Comparative Example 2 A method for preparing a flocculant is the same as in Example 1, but step (2) of hydrophobic modification of SiO2 is omitted, and the original hydrophilic SiO2 nanoparticles are directly used to participate in the polymerization to obtain a physical mixture product: hydrophilic-SiO2 / PDHAMDAC.

[0049] TEM images of the prepared physical mixture product hydrophilic-SiO2 / PDHAMDAC are shown below. Figure 2 As shown.

[0050] Structural characterization and performance testing (1) Core-shell structure verification The SiO2-PDHAMDAC core-shell structured nanoparticle flocculant prepared in Example 1 was subjected to TEM testing, and its structure is as follows: Figure 1 As shown, the core consists of spherical SiO2 particles with high electron density (approximately 400 nm in diameter), surrounded by a low-density organic layer approximately 50 nm thick, exhibiting a typical core-shell morphology. The zeta potential is determined by the hydrophobic SiO2... The voltage increased from 15 mV to +38 mV, indicating that the surface was covered by a cationic polymer.

[0051] In contrast, the TEM image of the hydrophilic SiO2 / PDHAMDAC physical mixture obtained in Comparative Example 2 is as follows: Figure 2 As shown, there is no continuous coating layer, indicating that the polymer is not effectively fixed to the particle surface.

[0052] (2) Verification of the effect of hydroxyoxime group The SiO2-PDHAMDAC core-shell nanoparticle flocculant prepared in Example 1 and the SiO2-PDMDAAC flocculant prepared in Comparative Example 1 were used for flocculation experiments of kaolinite suspensions. 5.0 g of kaolinite (2% solid content in both cases) was weighed and placed in a 250 mL beaker, and deionized water was added to prepare a suspension. Then, the flocculant was added at a dosage of 20 g / t (based on dry solids mass), and the mixture was rapidly stirred at 200 rpm for 30 s. After stirring, a sample was immediately taken from the bottom third of the liquid surface, and the apparent particle size distribution was determined using a laser particle size analyzer. The remaining suspension was then transferred to a 250 mL graduated cylinder and allowed to settle. After 60 s, the supernatant was collected, and its turbidity was measured using a turbidimeter to evaluate the flocculation and clarification effect. The results are shown in Table 1.

[0053] Table 1. Flocculation performance of flocculants in kaolinite systems As can be seen from the experimental results in Table 1, the introduction of hydroxyoxime groups significantly enhances the flocculant's ability to recognize, adsorb, and flocculate clay.

[0054] (3) Actual coal slime flotation test results 80 g of the above-mentioned coal slime sample (solid content 10%) was weighed and 20 g / t of flocculant (based on dry coal mass) was added. A laboratory flotation test was conducted in a flotation cell. The flotation conditions were as follows: aeration rate of 0.2 m³ / h, collector of kerosene (80 g / t), frother of methyl isobutyl methanol (MIBC, 40 g / t), and flotation time of 5 min. After flotation, the clean coal and tailings products were collected separately, dried, and their ash content was determined to evaluate the effect of the flocculant on flotation selectivity and upgrading effect. The results are shown in Table 2.

[0055] Table 2. Comprehensive separation indexes of each scheme in actual coal slime flotation. As can be seen from Table 2, Example 1 significantly reduced the ash content of clean coal while maintaining a high clean coal yield, indicating that the SiO2-PDHAMDAC core-shell structure effectively reduced the interference of fine mud and improved the sorting efficiency.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A targeted recognition core-shell structured nanoparticle flocculant, characterized in that, Includes the following components by weight: Diallylamine (C6H) 11 N) 100 copies; Ethyl chloroethyl (C4H7ClO2) 115-120 parts; 175-180 parts of chloroacetic acid (C2H3ClO2); 100 parts of SiO2 nanoparticles; Vinyltrimethoxysilane (C5H) 12 2-8 parts of O3Si; Hydroxylamine hydrochloride 16-19 parts; 1 to 1.5 parts of ammonium persulfate.

2. The targeted recognition core-shell structured nanoparticle flocculant according to claim 1, characterized in that, The diameter of the SiO2 nanoparticles is 80–100 nm.

3. The targeted recognition core-shell structured nanoparticle flocculant according to claim 1, characterized in that, Includes the following components: Diallylamine (C6H) 11 N) 100g; Ethyl chloroacetate (C4H7ClO2) 118g; 180g of chloroacetic acid (C2H3ClO2); 100g of SiO2 nanoparticles; Vinyltrimethoxysilane (C5H) 12 5g of O3Si; 18g of hydroxylamine hydrochloride; 1.2g of ammonium persulfate.

4. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant as described in claim 1, characterized in that, Includes the following steps: (1) Using diallylamine as a raw material, in the presence of inorganic base and polar aprotic organic solvent, it undergoes a nucleophilic substitution reaction with ethyl chloroacetate. The reaction temperature is 50-70℃ and the reaction time is 10-15 hours. After the reaction is completed, it is cooled to room temperature, filtered, concentrated under reduced pressure to remove the solvent, and the residue is extracted by liquid-liquid extraction, washed, dried and concentrated to obtain (N,N-diallylamino)ethyl acetate. (N,N-diallylamino)ethyl acetate was hydrolyzed in an aqueous sodium hydroxide solution at a temperature of 50-60°C for 0.5-2 hours. Sodium diallylaminoacetate was obtained after the reaction was completed. Adjust the pH of the solution to 8-9, add chloroacetic acid to sodium diallylaminoacetate, heat to 55-60℃, react for 1-2 hours, and filter after precipitation to obtain dicarboxymethyl diallyl ammonium chloride monomer. (2) Add SiO2 nanoparticles to a piranha solution, heat to 50-65℃, react for 0.5-1 h, then rinse with ultrapure water until neutral to obtain treated SiO2 nanoparticles; immerse the treated SiO2 nanoparticles in C5H 12 O3Si-toluene solution was reacted at 70-80℃ under N2 atmosphere for 6-8 hours, and then washed and dried with ultrapure water to obtain hydrophobic SiO2 nanoparticles. (3) Dicarboxymethyl diallyl ammonium chloride monomer and hydrophobic SiO2 nanoparticles were mixed and ammonium persulfate initiator was added to carry out free radical polymerization to prepare SiO2-PDCMDAAC with different molecular weights; hydroxylamine hydrochloride was added to SiO2-PDCMDAAC to carry out oxime reaction, the temperature was raised to 30-45℃, the reaction time was 4-6h, and the product was washed and acidified to pH = 3.5-4.0 to obtain SiO2-PDHAMDAC core-shell structured nanoparticle flocculant.

5. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, The molar ratio of diallylamine, ethyl chloroacetate and inorganic base in step (1) is 1 : (1.0~1.2) : (1.0~1.5).

6. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, The sodium hydroxide aqueous solution in step (1) is a 10 wt% sodium hydroxide aqueous solution.

7. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, The C5H 12 O3Si-toluene solution is C5H with a mass ratio of 1:(10~20). 12 O3Si and toluene solution.

8. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, In step (3), the mass ratio of dicarboxymethyl diallyl ammonium chloride monomer to hydrophobic SiO2 nanoparticles is (3-4):

1.

9. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, In step (3), the free radical polymerization reaction is carried out at pH 10 to 11, at a temperature of 52 to 55°C, and for a reaction time of 1 to 1.5 h.

10. The method for preparing a targeted recognition core-shell structured nanoparticle flocculant according to claim 4, characterized in that, In step (3), the product is washed with methanol and acidified with dilute hydrochloric acid.

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