Efficient environment-friendly flocculant as well as preparation method and application thereof

Abstract

The invention discloses an efficient environment-friendly flocculant as well as a preparation method and application thereof, and relates to the technical field of water treatment. The high-efficiency environment-friendly flocculating agent prepared by the invention is obtained by mixing a carboxylated natural polymer material, a cationic monomer, inorganic acid, a stabilizer and pure water and then initiating polymerization by an efficient composite initiator. The high-efficiency environment-friendly flocculant prepared by the invention is environment-friendly and low in cost, and has a wide application range and high-efficiency flocculation performance.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a high-efficiency and environmentally friendly flocculant and a preparation method and application thereof. Background Art

[0002] Flocculants are chemical substances specially designed for use in sewage treatment processes. They condense tiny solute, colloid or suspended particles in aqueous solutions into larger flocs, making it easier to separate these particles from the water and purify the water. These flocculants can be inorganic substances such as polyaluminium chloride or organic substances such as polyacrylamide. They increase the cohesion between particles through different physical and chemical effects, such as electrochemistry, coagulation, adsorption and precipitation, and promote the aggregation of tiny particles into large flocs, which not only improves the water quality, removes turbidity, organic matter, bacteria and other suspended impurities in the water, and improves the transparency and cleanliness of the water, but also accelerates the sedimentation rate, saving processing time and cost, while promoting filtration efficiency and helping to form a uniform filter cake. Therefore, efficient and environmentally friendly flocculants and their technologies play a vital role in the field of water treatment and are of great significance to environmental protection and the sustainable use of water resources.

[0003] Swimming pools, sauna pools, and spa pools are places for people to exercise and entertain. The quality of their water hygiene directly affects human health. For pool water microbial indicators and most other physical and chemical indicators, most swimming places can meet national hygiene standards. However, for tiny suspended solids that mainly affect water turbidity and metal ions that affect water color, there are problems such as high difficulty in water treatment technology and a large amount of manpower and material resources to meet national hygiene standards. At present, the commonly used methods for removing impurities in water treatment mainly include inorganic coagulants, organic flocculants, and adsorbents. However, these reagents have some problems during use, such as large amounts of inorganic coagulants and large amounts of sludge produced; high costs of organic flocculants and possible secondary pollution; poor stability of adsorbents, etc. Therefore, it is of great practical significance to develop a new type of flocculant that is efficient, environmentally friendly, low-cost, and easy to use. Summary of the invention

[0004] The purpose of the present invention is to provide a high-efficiency and environmentally friendly flocculant and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A high-efficiency environmentally friendly flocculant is composed of the following raw materials: carboxylated natural polymer materials, cationic monomers, inorganic acids, stabilizers, high-efficiency composite initiators, and pure water.

[0007] As an optimization, the carboxylated natural polymer material is obtained by reacting the natural polymer material and chloroacetic acid in a sodium hydroxide solution.

[0008] A method for preparing an efficient and environmentally friendly flocculant comprises the following preparation steps:

[0009] (1) weighing a natural polymer material and chloroacetic acid in a mass ratio of 1:(5-7); mixing chloroacetic acid and ethanol in a mass ratio of 1:(10-12) to obtain a chloroacetic acid solution; mixing a natural polymer material and a 30wt% sodium hydroxide solution in a mass ratio of 1:(10-12), stirring for 1-2h, and after the stirring is completed, heating to 60-75°C, reacting for 4-5h, adjusting the pH to 7 with a 10wt% hydrochloric acid solution, filtering and vacuum drying at 50°C for 12h to obtain a carboxylated natural polymer material;

[0010] (2) Weigh the following raw materials: carboxylated natural polymer material, cationic monomer, inorganic acid, stabilizer, high-efficiency composite initiator, and pure water; mix the carboxylated natural polymer material, cationic monomer, inorganic acid, and stabilizer; add pure water and stir; then add the high-efficiency composite initiator to react, and obtain a high-efficiency and environmentally friendly flocculant.

[0011] As an optimization, the natural polymer material in step (1) is one of chitosan, starch and cellulose; the chitosan has a deacetylation degree of ≥90%; the starch is corn starch; and the cellulose is wood cellulose.

[0012] As an optimization, the degree of carboxyl substitution of the carboxylated natural polymer material in step (1) is ≥90%.

[0013] As an optimization, the amount of the raw materials used in step (2) is: by mass, 1-10 parts of carboxylated natural polymer material, preferably 1-5 parts; 50-200 parts of cationic monomer, preferably 50-70 parts; 20-40 parts of inorganic acid, 0.1-1.0 parts of stabilizer, 0.2-2.0 parts of high-efficiency composite initiator, and 50-70 parts of pure water.

[0014] As an optimization, the cationic monomer in step (2) is a mixture of one or more of methacryloyloxyethyl trimethyl ammonium chloride, ethyl acrylate trimethyl ammonium chloride, and dimethyl diallyl ammonium chloride.

[0015] As an optimization, the stabilizer in step (2) is a mixture of one or more of sorbitol, ethylenediaminetetraacetic acid, and Tween 80; the inorganic acid is a mixture of one or more of dilute hydrochloric acid and dilute sulfuric acid; and the high-efficiency composite initiator is one of ammonium persulfate / sodium bisulfite and sodium sulfite / azobisisobutyramidine hydrochloride.

[0016] As an optimization, the reaction temperature in step (2) is 40-60°C and the reaction time is 1-3h.

[0017] As an optimization, the mass fraction of the inorganic acid is 3wt%-10wt%; the ammonium persulfate / sodium bisulfite is obtained by mixing ammonium persulfate and sodium bisulfite in a mass ratio of 1:1; the sodium sulfite / azobisisobutyramidine hydrochloride is obtained by mixing sodium sulfite and azobisisobutyramidine hydrochloride in a mass ratio of 1:1.

[0018] The present invention also provides an application of a flocculant prepared according to the preparation method of the high-efficiency and environmentally friendly composite flocculant in water treatment.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0020] (1) The composite flocculant of the present invention combines the advantages of natural polymer flocculants and organic polymer flocculants, has high-efficiency flocculation performance, and can quickly remove suspended matter, colloidal substances and organic matter in sewage; it uses natural polymer flocculants as the main raw materials, does not produce secondary pollution, and is environmentally friendly; the raw materials are easy to obtain, the preparation method is simple, the cost is low, and it has good economic benefits; it is suitable for various types of sewage, including commercial and leisure sewage, domestic sewage, industrial wastewater, etc.

[0021] (2) The carboxyl and hydroxyl groups on the modified natural polymer materials can effectively adsorb heavy metal ions in sewage; the presence of cationic monomers not only has good antibacterial properties, but can also adsorb negatively charged pollutants in sewage. The presence of efficient initiators can cause cationic monomers containing double bonds and modified natural polymer materials to undergo polymerization reactions to generate amphoteric polymers with specific structures, i.e., new high-efficiency and environmentally friendly flocculants.

[0022] (3) Since the new high-efficiency and environmentally friendly flocculant is a polymer with a specific structure and amphoteric properties, it quickly disperses and dissolves when added to water. The amphoteric flocculant has both positive and negative charge groups. Impurities in water are mostly negatively charged colloids or suspended matter. The cationic groups of the flocculant are first electrostatically attracted to them, neutralizing the charge to reduce the repulsive force and bring the impurity particles closer. Subsequently, the polymer chain stretches and entangles, and further aggregates small particles into large floccules by van der Waals forces and hydrogen bonds, significantly accelerating precipitation and separation. In domestic sewage treatment, it can efficiently remove suspended matter and colloids, reduce turbidity, and improve water clarity, creating conditions for subsequent deep treatment. The amphoteric characteristics give the flocculant a certain pH buffering capacity, maintaining a good flocculation effect in a wide pH range. Different water bodies have different pH values. This characteristic makes it suitable for complex water quality, such as acidic mine wastewater and alkaline printing and dyeing wastewater treatment, reducing pH adjustment operations and chemical agent consumption, stabilizing flocculation performance, ensuring continuous and efficient treatment processes, reducing treatment costs and operational complexity, and enhancing process versatility and environmental adaptability.

[0023] (4) The performance of flocculants when acting on filter media, represented by quartz sand. Quartz sand carries a negative charge in its natural state. The cationic group heads on the flocculants are adsorbed on the quartz sand, increasing the specific surface area of ​​the filter media. At the same time, the numerous functional chemical groups on the flocculants increase the adhesion of turbid particles on the filter media surface, thereby improving the flocculation performance. Amphoteric flocculants modify the surface of quartz sand to make it carry aldehyde functional groups that are more conducive to the adsorption of grease, thereby improving the efficiency of quartz sand filter media in filtering grease. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The deacetylation degree of chitosan used in the following examples and comparative examples is ≥90%; the starch is corn starch; the cellulose is wood cellulose; the ammonium persulfate / sodium bisulfite used is obtained by mixing ammonium persulfate and sodium bisulfite in a mass ratio of 1:1; the sodium sulfite / azobisisobutyramidine hydrochloride used is obtained by mixing sodium sulfite and azobisisobutyramidine hydrochloride in a mass ratio of 1:1.

[0026] Embodiment 1:

[0027] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0028] (1) weighing chitosan and chloroacetic acid in a mass ratio of 1:5; mixing chloroacetic acid and ethanol in a mass ratio of 1:10 to obtain a chloroacetic acid solution; mixing chitosan and 30 wt% sodium hydroxide solution in a mass ratio of 1:10, stirring for 2 hours, and after the stirring is completed, heating to 75° C., reacting for 5 hours, adjusting the pH to 7 with a 10 wt% hydrochloric acid solution, filtering and vacuum drying at 50° C. for 12 hours to obtain a carboxylated natural polymer material;

[0029] (2) Weigh the following raw materials: 1 part of carboxylated natural polymer material, 50 parts of ethyl acrylate trimethylammonium chloride, 20 parts of 5wt% dilute hydrochloric acid, 0.1 part of ethylenediaminetetraacetic acid, 0.2 parts of sodium sulfite / azobisisobutyramidine hydrochloride, and 50 parts of pure water, by mass. Mix the carboxylated natural polymer material, ethyl acrylate trimethylammonium chloride, 5wt% dilute hydrochloric acid and ethylenediaminetetraacetic acid, add pure water and stir, then add sodium sulfite / azobisisobutyramidine hydrochloride and react at 60°C for 3h to obtain a high-efficiency and environmentally friendly flocculant.

[0030] Embodiment 2:

[0031] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0032] (1) starch and chloroacetic acid are weighed in a mass ratio of 1:5; chloroacetic acid and ethanol are mixed in a mass ratio of 1:10 to obtain a chloroacetic acid solution; starch and a 30 wt % sodium hydroxide solution are mixed in a mass ratio of 1:10, stirred for 2 h, and after the stirring is completed, the temperature is raised to 75° C., reacted for 5 h, a 10 wt % hydrochloric acid solution is used to adjust the pH to 7, filtered and vacuum dried at 50° C. for 12 h to obtain a carboxylated natural polymer material;

[0033] (2) Weigh the following raw materials: 3 parts by mass of carboxylated natural polymer material, 60 parts by mass of methacryloyloxyethyl trimethyl ammonium chloride, 30 parts by mass of 7wt% dilute hydrochloric acid, 0.7 parts by mass of sorbitol, 1.4 parts by mass of ammonium persulfate / sodium bisulfite, and 60 parts by mass of pure water; mix the carboxylated natural polymer material, methacryloyloxyethyl trimethyl ammonium chloride, dilute hydrochloric acid and sorbitol; add pure water and stir; then add ammonium persulfate / sodium bisulfite and stir at 50°C for 2 hours to obtain a high-efficiency and environmentally friendly flocculant.

[0034] Embodiment 3:

[0035] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0036] (1) weighing cellulose and chloroacetic acid in a mass ratio of 1:(5-7); mixing chloroacetic acid and ethanol in a mass ratio of 1:(10-12) to obtain a chloroacetic acid solution; mixing cellulose and a 30wt% sodium hydroxide solution in a mass ratio of 1:(10-12), stirring for 1-2h, and after the stirring is completed, heating to 60-75°C, reacting for 4-5h, adjusting the pH to 7 with a 10wt% hydrochloric acid solution, filtering and vacuum drying at 50°C for 12h to obtain a carboxylated natural polymer material;

[0037] (2) Weigh the following raw materials: 5 parts by mass of carboxylated natural polymer material, 50 parts by mass of dimethyldimethylammonium chloride, 40 parts by mass of 3wt% dilute sulfuric acid, 1.0 part by mass of Tween 80, 2.0 parts by mass of sodium sulfite / azobisisobutylammonium hydrochloride, and 70 parts by mass of pure water; mix the carboxylated natural polymer material, dimethyldimethylammonium chloride, 3wt% dilute sulfuric acid, and Tween 80; add pure water and stir; then add sodium sulfite / azobisisobutylammonium hydrochloride and react at 40°C for 1 hour to obtain a highly efficient and environmentally friendly flocculant.

[0038] Embodiment 4:

[0039] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0040] (1) weighing cellulose and chloroacetic acid in a mass ratio of 1:7; mixing chloroacetic acid and ethanol in a mass ratio of 1:12 to obtain a chloroacetic acid solution; mixing cellulose and a 30 wt % sodium hydroxide solution in a mass ratio of 1:12, stirring for 1 hour, and after the stirring is completed, heating to 60° C., reacting for 4 hours, adjusting the pH to 7 with a 10 wt % hydrochloric acid solution, filtering and vacuum drying at 50° C. for 12 hours to obtain a carboxylated natural polymer material;

[0041] (2) Weigh the following raw materials: 2 parts of carboxylated natural polymer material, 70 parts of dimethyldiallyl ammonium chloride, 23 parts of 10wt% dilute hydrochloric acid, 0.2 parts of sorbitol, 0.4 parts of ethylenediaminetetraacetic acid, 0.5 parts of sodium sulfite / azobisisobutylammonium hydrochloride, and 52 parts of pure water, by mass; mix sorbitol and ethylenediaminetetraacetic acid to obtain a stabilizer; mix the carboxylated natural polymer material, dimethyldiallyl ammonium chloride, 10wt% dilute hydrochloric acid and the stabilizer, add pure water and stir, then add sodium sulfite / azobisisobutylammonium hydrochloride and react at 43°C for 2h to obtain a high-efficiency and environmentally friendly flocculant.

[0042] Embodiment 5:

[0043] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0044] (1) weighing chitosan and chloroacetic acid in a mass ratio of 1:5.4; mixing chloroacetic acid and ethanol in a mass ratio of 1:11 to obtain a chloroacetic acid solution; mixing chitosan and 30 wt% sodium hydroxide solution in a mass ratio of 1:10.5, stirring for 1.3 h, and after the stirring, heating to 70° C., reacting for 4.3 h, adjusting the pH to 7 with a 10 wt% hydrochloric acid solution, filtering and vacuum drying at 50° C. for 12 h to obtain a carboxylated natural polymer material;

[0045] (2) Weigh the following raw materials: 4 parts by mass of carboxylated natural polymer material, 30 parts by mass of methacryloyloxyethyl trimethyl ammonium chloride, 24 parts by mass of ethyl acrylate trimethyl ammonium chloride, 34 parts by mass of 5 wt% dilute sulfuric acid, 0.3 parts by mass of ethylenediaminetetraacetic acid, 0.8 parts by mass of sodium sulfite / azobisisobutyramidine hydrochloride, and 63 parts by mass of pure water; mix methacryloyloxyethyl trimethyl ammonium chloride and ethyl acrylate trimethyl ammonium chloride to obtain a cationic monomer; mix the carboxylated natural polymer material, the cationic monomer, 5 wt% dilute sulfuric acid and ethylenediaminetetraacetic acid, add pure water and stir, then add sodium sulfite / azobisisobutyramidine hydrochloride and react at 46°C for 2.5 hours to obtain a high-efficiency and environmentally friendly flocculant.

[0046] Embodiment 6:

[0047] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0048] (1) starch and chloroacetic acid are weighed in a mass ratio of 1:6; chloroacetic acid and ethanol are mixed in a mass ratio of 1:11 to obtain a chloroacetic acid solution; starch and a 30 wt % sodium hydroxide solution are mixed in a mass ratio of 1:11.5, stirred for 1.5 h, and after the stirring is completed, the temperature is raised to 63° C., reacted for 4.5 h, a 10 wt % hydrochloric acid solution is used to adjust the pH to 7, filtered and vacuum dried at 50° C. for 12 h to obtain a carboxylated natural polymer material;

[0049] (2) Weigh the following raw materials: 3 parts by mass of carboxylated natural polymer material, 60 parts by mass of dimethyldiallyl ammonium chloride, 10 parts by mass of 3wt% dilute hydrochloric acid, 21 parts by mass of 6wt% dilute sulfuric acid, 0.6 parts by mass of sorbitol, 1.3 parts by mass of sodium sulfite / azobisisobutylammonium hydrochloride, and 67 parts by mass of pure water; mix 3wt% dilute hydrochloric acid and 6wt% dilute sulfuric acid to obtain an inorganic acid; mix the carboxylated natural polymer material, dimethyldiallyl ammonium chloride, the inorganic acid and sorbitol, add pure water and stir, then add sodium sulfite / azobisisobutylammonium hydrochloride and react at 55°C for 3h to obtain a high-efficiency and environmentally friendly flocculant.

[0050] Comparative Example 1:

[0051] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0052] (1) Weigh the following raw materials: 3 parts by mass of starch, 60 parts by mass of methacryloyloxyethyl trimethyl ammonium chloride, 30 parts by mass of 7wt% dilute hydrochloric acid, 0.7 parts by mass of sorbitol, 1.4 parts by mass of ammonium persulfate / sodium bisulfite, and 60 parts by mass of pure water; mix the carboxylated natural polymer material, methacryloyloxyethyl trimethyl ammonium chloride, dilute hydrochloric acid and sorbitol; add pure water and stir; then add ammonium persulfate / sodium bisulfite and stir at 50°C for 2 hours to obtain a highly efficient and environmentally friendly flocculant.

[0053] Comparative Example 2:

[0054] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0055] (1) starch and chloroacetic acid are weighed in a mass ratio of 1:5; chloroacetic acid and ethanol are mixed in a mass ratio of 1:10 to obtain a chloroacetic acid solution; starch and a 30 wt % sodium hydroxide solution are mixed in a mass ratio of 1:10, stirred for 2 h, and after the stirring is completed, the temperature is raised to 75° C., reacted for 5 h, a 10 wt % hydrochloric acid solution is used to adjust the pH to 7, filtered and vacuum dried at 50° C. for 12 h to obtain a carboxylated natural polymer material;

[0056] (2) Weigh the following raw materials: 3 parts by mass of carboxylated natural polymer material, 30 parts by mass of 7wt% dilute hydrochloric acid, 0.7 parts by mass of sorbitol, 1.4 parts by mass of ammonium persulfate / sodium bisulfite, and 60 parts by mass of pure water; mix the carboxylated natural polymer material, methacryloyloxyethyl trimethylammonium chloride, dilute hydrochloric acid and sorbitol; add pure water and stir; then add ammonium persulfate / sodium bisulfite and stir at 50°C for 2 hours to obtain a high-efficiency and environmentally friendly flocculant.

[0057] Comparative Example 3:

[0058] A method for preparing a high-efficiency environmentally friendly flocculant, the method comprising the following steps:

[0059] (1) starch and chloroacetic acid are weighed in a mass ratio of 1:5; chloroacetic acid and ethanol are mixed in a mass ratio of 1:10 to obtain a chloroacetic acid solution; starch and a 30 wt % sodium hydroxide solution are mixed in a mass ratio of 1:10, stirred for 2 h, and after the stirring is completed, the temperature is raised to 75° C., reacted for 5 h, a 10 wt % hydrochloric acid solution is used to adjust the pH to 7, filtered and vacuum dried at 50° C. for 12 h to obtain a carboxylated natural polymer material;

[0060] (2) Weigh the following raw materials: 3 parts by mass of carboxylated natural polymer material, 60 parts by mass of methacryloyloxyethyl trimethyl ammonium chloride, 30 parts by mass of 7 wt% dilute hydrochloric acid, 0.7 parts by mass of sorbitol, and 60 parts by mass of pure water; mix the carboxylated natural polymer material, methacryloyloxyethyl trimethyl ammonium chloride, dilute hydrochloric acid and sorbitol; add pure water and stir; react at 50°C for 2 hours to obtain a highly efficient and environmentally friendly flocculant.

[0061] Test Example 1:

[0062] Flocculation performance test:

[0063] Test method: The flocculation experiment uses pool water from a swimming pool with a dosage of 1 mg / L. The water is added near the pool return outlet and enters the swimming pool's filtration circulation system. The pool water is circulated and filtered for 3.5 cycles.

[0064] The suspended solids concentration of the pool water before and after the addition of the flocculants prepared in the examples and comparative examples was measured by the water sample filter membrane weight method, and the suspended solids removal rate was calculated. The results are shown in Table 1.

[0065] According to standard HJ828-2017, the chemical oxygen demand (COD) of the pool water before and after the addition of the flocculants prepared in the examples and comparative examples was measured, and the COD removal rate was calculated. The results are shown in Table 1.

[0066] According to the standard GB11903-89, the chromaticity of the pool water before and after the addition of the flocculants prepared in the examples and comparative examples was measured, and the chromaticity removal rate was calculated. The results are shown in Table 1.

[0067] Table 1

[0068] Suspended matter removal rate (%) COD removal rate Chroma removal rate (%) Example 1 94.43 87.24 97.93 Example 2 95.37 88.19 98.45 Example 3 95.51 88.23 98.62 Example 4 94.51 87.63 98.23 Example 5 94.73 87.54 98.75 Example 6 95.02 88.06 98.30 Comparative Example 1 80.14 75.31 54.12 Comparative Example 2 82.46 75.24 85.47 Comparative Example 3 61.23 60.84 78.21

[0069] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the water treatment filter material prepared by the present invention has good flocculation performance.

[0070] By comparison, the suspended solids removal rate, COD removal rate, and chromaticity removal rate of Examples 1 to 3 are greater than those of Comparative Examples 1 to 3, indicating that the carboxyl and hydroxyl groups on the modified natural polymer material can effectively adsorb heavy metal ions in sewage; the presence of the cationic monomer not only has good antibacterial properties, but can also adsorb negatively charged pollutants in sewage. The presence of the efficient initiator can cause the cationic monomer containing double bonds and the modified natural polymer material to undergo a polymerization reaction to generate amphoteric polymers of a specific structure, i.e., a new type of efficient and environmentally friendly flocculant; the amphoteric characteristics give the flocculant the characteristics of effective and efficient flocculation performance in a wide pH range, making it adaptable to complex water quality and improving flocculation efficiency.

[0071] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A highly efficient and environmentally friendly flocculant, characterized in that: The high-efficiency and environmentally friendly flocculant is composed of the following raw materials: carboxylated natural polymer materials, cationic monomers, inorganic acids, stabilizers, high-efficiency composite initiators, and pure water; The carboxylated natural macromolecular material is obtained by reacting the natural macromolecular material with chloroacetic acid in a sodium hydroxide solution.

2. A method for preparing a highly efficient and environmentally friendly flocculant, characterized in that: The method comprises the following preparation steps: (1) weighing a natural polymer material and chloroacetic acid in a mass ratio of 1:(5-7); mixing chloroacetic acid and ethanol in a mass ratio of 1:(10-12) to obtain a chloroacetic acid solution; mixing a natural polymer material and a 30wt% sodium hydroxide solution in a mass ratio of 1:(10-12), stirring for 1-2h, and after the stirring is completed, heating to 60-75°C, reacting for 4-5h, adjusting the pH to 7 with a 10wt% hydrochloric acid solution, filtering and vacuum drying at 50°C for 12h to obtain a carboxylated natural polymer material; (2) Weigh the following raw materials: carboxylated natural polymer material, cationic monomer, inorganic acid, stabilizer, high-efficiency composite initiator, and pure water; mix the carboxylated natural polymer material, cationic monomer, inorganic acid, and stabilizer; add pure water and stir; then add the high-efficiency composite initiator to react, and obtain a high-efficiency and environmentally friendly flocculant.

3. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The natural polymer material in step (1) is one of chitosan, starch and cellulose; the chitosan has a deacetylation degree of ≥90%; the starch is corn starch; and the cellulose is wood cellulose.

4. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The carboxyl substitution degree of the carboxylated natural polymer material in step (1) is ≥90%.

5. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The amount of the raw materials used in step (2) is: by mass, 1-10 parts of carboxylated natural polymer material, preferably 1-5 parts; 50-200 parts of cationic monomer, preferably 50-70 parts; 20-40 parts of inorganic acid, 0.1-1.0 parts of stabilizer, 0.2-2.0 parts of high-efficiency composite initiator, and 50-70 parts of pure water.

6. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The cationic monomer in step (2) is a mixture of one or more of methacryloyloxyethyl trimethyl ammonium chloride, ethyl acrylate trimethyl ammonium chloride, and dimethyl diallyl ammonium chloride.

7. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The stabilizer in step (2) is a mixture of one or more of sorbitol, ethylenediaminetetraacetic acid, and Tween 80; the inorganic acid is a mixture of one or more of dilute hydrochloric acid and dilute sulfuric acid; and the high-efficiency composite initiator is one of ammonium persulfate / sodium bisulfite and sodium sulfite / azobisisobutyramidine hydrochloride.

8. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 2, characterized in that: The reaction temperature in step (2) is 40-60° C. and the reaction time is 1-3 h.

9. The method for preparing a high-efficiency and environmentally friendly flocculant according to claim 5, characterized in that: The mass fraction of the inorganic acid is 3wt%-10wt%; the ammonium persulfate / sodium bisulfite is obtained by mixing ammonium persulfate and sodium bisulfite in a mass ratio of 1:1; the sodium sulfite / azobisisobutyramidine hydrochloride is obtained by mixing sodium sulfite and azobisisobutyramidine hydrochloride in a mass ratio of 1:

1.

10. Use of a flocculant prepared by the method for preparing a high-efficiency and environmentally friendly composite flocculant according to any one of claims 2 to 9 in water treatment.