Composite particle for treating floating algae in water body as well as preparation method and application of composite particle

Abstract

The invention belongs to the technical field of environmental protection, and provides a composite particle for treating water floating algae and a preparation method and application thereof, the preparation method comprises the following steps: a, preparing intranuclear active Gemini type biquaternary ammonium cationic polymer mesylate; b, preparing a coating material; c, preparing composite particles: mixing the coating material in the step b with castor oil and sodium bicarbonate, heating and stirring to obtain a coating solution, and adding the Gemini type biquaternary ammonium cationic polymer mesylate prepared in the step a to obtain the composite particles; and d, evaluating the performance of the composite particles. According to the invention, a biodegradable and non-toxic natural polymer material is used as an outer coating, so that slow release and targeted release of quaternary ammonium salt are realized. Quaternary ammonium salt is coated in a compound formed by PVA and chitosan, the release rate of the quaternary ammonium salt is controlled, floating or suspension is realized through density adjustment, and targeted treatment of blue-green algae on the water surface is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to the preparation and application of quaternary ammonium salt composite particles for treating floating algae in water bodies. Background Art

[0002] Traditional methods for managing frequent algal blooms in rivers, lakes, and other water bodies rely on the direct addition of chemical agents to quickly suppress or settle algae. Representative examples include alum, cationic polymer flocculants, and oxidizing algaecides. While these approaches have some short-term effectiveness, they often suffer from issues such as insufficient targeting, significant ecological disturbance, and limited duration of action. For example, alum can induce algal sedimentation through electrical neutralization, but the aluminum ions it releases tend to accumulate in water, especially under acidic conditions, where they are highly mobile and have a risk of dissolution, causing long-term disruption to aquatic ecosystems. Cationic polyacrylamide, while effective in accelerating the settling of suspended particles, forms toxic byproducts during its degradation process, posing a potential threat to plankton and fish habitats. While oxidants like hydrogen peroxide can rapidly kill algae by releasing reactive oxygen species that damage algae cell structures, their high density, rapid diffusion rate, and short half-life make them easily sink to the bottom of the water in still or slow-flowing conditions, making it difficult to maintain an effective concentration and significantly reducing their effectiveness. Furthermore, they can easily cause a sudden drop in dissolved oxygen in localized water bodies, drastically fluctuate pH, and even induce secondary pollution. Therefore, this type of "extensive dosing and non-directional diffusion" treatment approach struggles to ensure sustainability, safety, and precision in complex, dynamic water environments.

[0003] The present invention aims to break through the above-mentioned technical bottleneck and propose a new type of cyanobacteria treatment material and method with targeted identification, slow-release control and eco-friendliness as the core features. The present invention uses a modified quaternary ammonium salt compound synthesized independently as the main algaecidal component, which has excellent selective toxicity and the ability to quickly lyse cyanobacterial cell membranes, while also having good aqueous phase stability and low ecotoxicity, ensuring the efficiency and safety of the treatment effect. In terms of structural design, this type of active ingredient is coated in a porous degradable polymer shell layer based on polyvinyl alcohol (PVA), and closed bubbles are introduced into the coating structure by introducing a foaming nucleation process, so that the overall density of the resulting composite particles remains lower than that of the water body, ensuring that it floats on the water surface and naturally drifts to the cyanobacteria aggregation area with the water flow and wind. After reaching the algae aggregation point, the outer PVA shell layer regulates the release rate through slow hydrolysis and pore structure, so that the algaecidal active components in the kernel are gradually released, thereby achieving on-site disinfecting of algae. This composite material has good mechanical stability, floating persistence and release control. Compared with the traditional direct addition of pesticides, it not only significantly improves the identification and contact efficiency of cyanobacteria-enriched areas, but also reduces the single application amount, avoiding local excessive concentration and ecological disturbance caused by instantaneous release of pesticides, and enhancing adaptability and protection to water ecology.

[0004] In summary, the present invention has achieved systematic innovation in material design, mechanism of action and ecological synergy, providing a new solution for the treatment of cyanobacteria in water bodies that is more targeted, controllable and environmentally friendly. Summary of the Invention

[0005] This invention addresses the need for targeted treatment of floating algae pollution in water bodies and proposes a composite particle for treating floating algae in water bodies, as well as its preparation method and application. The composite particle, prepared by combining a modified polymeric quaternary ammonium salt as a core agent with a green, ecological coating material, serves as a treatment agent. This treatment agent exhibits highly effective algaecidal properties, sustained and controlled release, is eco-friendly, and floats on water surfaces. It floats with the water and continuously releases its active ingredient, thereby achieving precise control and control of floating algae.

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

[0007] A first aspect of the present invention provides a method for preparing composite particles for treating floating algae in water, comprising the following steps:

[0008] a. Preparation of core-active Gemini-type diquaternary ammonium cationic polymer mesylate;

[0009] b. preparing coating materials;

[0010] c. Preparing composite particles: The coating material in step b is added with castor oil as an auxiliary agent and sodium bicarbonate as a chemical foaming agent. The mixture is heated and stirred. The sodium bicarbonate decomposes and releases carbon dioxide gas, generating microporous bubbles that are evenly distributed in the coating solution (the coating solution has a certain viscosity to trap microbubbles). The coating solution is then added with the Gemini diquaternary ammonium cationic polymer mesylate prepared in step a to obtain composite particles.

[0011] d. Performance evaluation of composite particles.

[0012] Furthermore, the preparation steps of the core-active Gemini-type diquaternary ammonium cationic polymer mesylate in step a are as follows:

[0013] Dissolve N,N-dimethyl-1,2-ethylenediamine in anhydrous ethanol, slowly add allyl chloride dropwise in a three-necked flask, control the temperature at 35-40°C, and stir the reaction for 4 hours to form the intermediate bisallyl quaternary ammonium salt monomer structure; add N,N'-methylenebisacrylamide (MBAA) to the reaction system as a crosslinker, and add deionized water to dilute it evenly, then add methanesulfonic acid (CH3SO3H) for anion pairing, and maintain the pH at 5.5-6.0; then add potassium persulfate (K2S2O8) as an initiator, and The reaction was carried out in a constant temperature water bath at 55°C for 6 hours to form a Gemini-type cationic polymer with high charge density and good water solubility. After the reaction, the polymer product was poured into excess isopropanol for precipitation and washed three times with isopropanol to remove unreacted monomers and oligomers. The obtained white to light yellow polymer precipitate was collected and vacuum dried to constant weight. The final product was a Gemini-type diquaternary ammonium cationic polymer with a methanesulfonic acid paired anion, i.e., an active Gemini-type diquaternary ammonium cationic polymer methanesulfonate, which was ground by ball milling and set aside.

[0014] Furthermore, the usage ratio of N,N-dimethyl-1,2-ethylenediamine, anhydrous ethanol, allyl chloride, N,N'-methylenebisacrylamide, deionized water, methanesulfonic acid, and potassium persulfate is 20.0 mmol: 30 mL: 40.0 mmol: 10.0 mmol: 5.0 mL: 20.0 mmol: 0.2 g.

[0015] Furthermore, the particle size of the Gemini-type diquaternary ammonium cationic polymer mesylate after ball milling is 50-200 μm.

[0016] Furthermore, the preparation steps of the coating material in step b are as follows:

[0017] Polyvinyl alcohol is added to deionized water, and the mixture is stirred and heated at 90° C. for 30 minutes to fully dissolve the PVA to form a uniform transparent solution, thereby obtaining a polyvinyl alcohol solution; chitosan is dissolved in glacial acetic acid (at a concentration of 1%) and stirred to obtain a chitosan solution; subsequently, the chitosan solution is slowly added to the polyvinyl alcohol solution at 60° C. The addition of chitosan is intended to enhance the mechanical strength and biodegradability of the coating layer, and its natural antibacterial properties contribute to improving the ecological safety of the treated particles. After fully and evenly mixing, the mixture is cooled to room temperature to obtain a coating material for later use.

[0018] Furthermore, the usage ratio of polyvinyl alcohol, deionized water, chitosan and glacial acetic acid is 5.0 g:95 mL:1.5 g:20 mL, wherein the concentration of glacial acetic acid is 1%.

[0019] Furthermore, the molecular weight of the polyvinyl alcohol is 88,000, and the alcoholysis degree is 98-99%.

[0020] Furthermore, in step c, the mass ratio of the coating material, castor oil and sodium bicarbonate is 110:1.0:0.5.

[0021] Furthermore, in step c, the mass ratio of the coating solution to the Gemini-type diquaternary ammonium cationic polymer mesylate is 4:1.

[0022] Furthermore, the temperature of the heating and stirring in step c is 50-60° C., and the stirring rate is 700-900 rpm.

[0023] Furthermore, the temperature of the heating and stirring in step c is 55° C., and the stirring rate is 800 rpm.

[0024] Furthermore, the particle size of the composite particles in step c is 0.5-2.0 mm.

[0025] Furthermore, the particle size of the composite particles in step c is 1 mm.

[0026] The second aspect of the present invention provides a composite particle for treating floating algae in water bodies, which is obtained by the preparation method described in the first aspect.

[0027] A third aspect of the present invention provides an application of composite particles for treating floating algae in water bodies.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention uses a modified quaternary ammonium salt compound synthesized independently as the main algaecidal component. It has excellent selective toxicity and the ability to quickly lyse cyanobacterial cell membranes, while also possessing good aqueous stability and low ecotoxicity, ensuring efficient and safe treatment effects. In terms of structural design, this type of active ingredient is coated in a porous, degradable polymer shell layer based on polyvinyl alcohol (PVA), and closed bubbles are introduced into the coating structure by introducing a foaming nucleation process, so that the overall density of the resulting composite particles remains lower than that of the water body, ensuring that it floats on the water surface and naturally drifts to the cyanobacteria aggregation area with the flow and wind. After reaching the algae aggregation point, the outer PVA shell layer regulates the release rate through slow hydrolysis and pore structure, so that the kernel algaecidal active component is gradually released, thereby achieving on-site disinfecting of algae. This composite material has good mechanical stability, floating persistence and release control. Compared with the traditional direct addition of pesticides, it not only significantly improves the identification and contact efficiency of cyanobacteria-enriched areas, but also reduces the single application amount, avoiding local excessive concentration and ecological disturbance caused by instantaneous release of pesticides, and enhancing adaptability and protection to water ecology.

[0030] 2. This invention uses modified polymeric quaternary ammonium salts as its core treatment component, achieving dual effects of efficient algae elimination and coagulation and sedimentation in water bodies. Unlike traditional inorganic flocculants or single algaecides, quaternary ammonium salt polymers selectively bind to the negatively charged surface of cyanobacteria and destroy their cell membranes, while simultaneously coagulating and settling them, effectively controlling their spread. This significantly improves algae removal rates while preventing secondary pollution such as heavy metal residues.

[0031] 3. The present invention uses a biodegradable and non-toxic natural polymer as an outer coating to achieve sustained and targeted release of quaternary ammonium salts. The quaternary ammonium salts are coated in a complex formed by PVA and chitosan, and their release rate is controlled. Density adjustment allows for floating or suspension, achieving targeted treatment of cyanobacteria on the water surface. This effectively extends treatment time and improves treatment efficiency. Furthermore, the material itself is ecologically safe, preventing increased eutrophication.

[0032] 4. Excellent ecological safety. All materials in this invention are biodegradable, low-toxic, and environmentally friendly, with minimal impact on aquatic ecosystems. Systematic assessments of their impact on indicators such as total nitrogen and total phosphorus confirm that they do not cause secondary pollution in the ecosystem. This allows for long-term application in water environment management in lakes, reservoirs, urban rivers, and other areas without altering the existing ecological balance.

[0033] 5. Traditional "spraying" algae removal methods require ship-based spraying or expensive grid-type dosing equipment, covering large water areas, requiring large dosages and taking a long time. The remover provided by this invention floats in place and can be added in a single voyage on the lake in the windward direction. Wind and waves gather the algae, synchronizing them with their floating behavior, achieving intelligent, dynamic algae removal. It can proactively adapt to the distribution trends of algae and achieve in-place treatment through floating, thereby reducing the total dosage, lowering labor costs, extending the effective period, and improving the systematic nature of water restoration. It effectively controls algae without causing ecological impacts, providing a "low-disturbance, highly targeted, and sustainable" algae control method. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment provides a composite particle for treating floating algae in water and a preparation method thereof

[0037] A method for preparing composite particles for treating floating algae in water bodies comprises the following steps:

[0038] a. Preparation of core-active Gemini-type diquaternary ammonium cationic polymer methanesulfonate reagent:

[0039] 20.0mmol of N,N-dimethyl-1,2-ethylenediamine was dissolved in 30mL of anhydrous ethanol, and 40.0mmol of allyl chloride was slowly added dropwise. The temperature was controlled at 35-40℃ and stirred for 4h to form the intermediate bisallyl quaternary ammonium salt monomer structure. 10.0mmol of N,N'-methylenebisacrylamide (MBAA) was added to the reaction system as a cross-linking agent. 5.0mL of deionized water was added to dilute the mixture. 20.0mmol of methanesulfonic acid (CH3SO3H) was added for anion pairing. The pH was maintained at 5.5-6.0. Persulfate was then added. The invention relates to a method for preparing a quaternary ammonium quaternary cationic polymer having a high charge density and good water solubility by adding 0.2 g of potassium sulfoxide (K2S2O8) as an initiator and placing the quaternary ammonium quaternary ammonium quaternary ammonium quaternary ammonium quaternary ammonium quaternary anion in a constant temperature water bath at 55°C for 6 hours. The quaternary ammonium quaternary ammonium quaternary ammonium quaternary anion is prepared by mixing the quaternary ammonium quaternary ammonium quaternary anion with the quaternary ammonium quaternary anion, wherein the quaternary ammonium quaternary ammonium quaternary anion is mixed with the quaternary ammonium ...

[0040] The physical property data of the Gemini type diquaternary ammonium cationic polymer mesylate reagent obtained by the above steps are shown in the following table:

[0041]

[0042] b. Preparation of coating materials:

[0043] 5.0 g of polyvinyl alcohol (PVA, molecular weight 88,000, alcoholysis degree 98-99%) was added to 95 mL of deionized water and heated at 90° C. with magnetic stirring for 30 minutes to fully dissolve the PVA to form a uniform transparent solution, thereby obtaining a polyvinyl alcohol solution. 1.5 g of chitosan was dissolved in 20 mL of glacial acetic acid (concentration 1%) and stirred to obtain a chitosan solution. Subsequently, the chitosan solution was slowly added to the polyvinyl alcohol solution at 60° C. The addition of chitosan is intended to enhance the mechanical strength and biodegradability of the coating layer. At the same time, its natural antibacterial properties contribute to improving the ecological safety of the treated particles. After thorough and uniform mixing, the mixture was cooled to room temperature to obtain a coating material for later use.

[0044] c. Preparation of composite particles:

[0045] To achieve a porous structure of the coating layer (ensuring that the density of the composite particles is lower than that of water and has a sustained-release function), 110 g of the coating material in step b is added with 1.0 g of castor oil as an adjuvant and 0.5 g of sodium bicarbonate as a chemical foaming agent, stirred and appropriately heated. During the stirring process, the sodium bicarbonate decomposes and releases carbon dioxide gas, generating microporous bubbles that are evenly distributed in the coating liquid (the coating liquid has a certain viscosity to trap tiny bubbles), obtaining a coating liquid, adding the Gemini-type diquaternary ammonium cationic polymer mesylate prepared in step a, and the mass ratio of the coating liquid to the Gemini-type diquaternary ammonium cationic polymer mesylate is 4:1 to obtain composite particles;

[0046] To ensure that bubbles are stably formed and not easily broken, ultimately forming a porous honeycomb envelope, effectively reducing particle density and achieving excellent floating performance, the temperature (40-70°C) and stirring speed (500-1000rpm) were regulated. Under the condition of a water sample pH value of 6-8, the optimal temperature and stirring speed were selected through the following tests. The test results are shown in the following table:

[0047]

[0048] The data in Table 1 show that the composite particles produced at 55°C and a stirring rate of 800 rpm (Group 4) exhibited the best overall performance, with stable bubble formation, a uniform honeycomb structure, and an appropriate density for floating on the water surface, while also ensuring controlled sustained-release performance. The particles exhibited strong suspension properties, with sustained buoyancy for >72 hours. The coating layer exhibited a stable structure, exhibited no swelling or stratification in water, and exhibited a steady sustained release of the active ingredient (41.8% release over 24 hours at a pH of 6-8), making them suitable for continuous release in targeted treatment of algal pollutants in water.

[0049] d. Performance evaluation of composite particles

[0050] The structural stability, floatation, sustained release and degradation behavior of the composite particles obtained in the above steps were tested, and the test results are as follows:

[0051] 1) Appearance and structure observation: The particles are white to light yellow spherical, with a dense surface and overall smoothness. The microstructure has a uniform honeycomb porous layer with a porosity of 45-55%, which is conducive to the formation of sustained-release channels.

[0052] 2) Floatability test: 1.000g of composite particles were placed in 100mL of static deionized water and the floating and sinking states were observed. The particles quickly floated up and continued to float without any obvious sinking within 72 hours, indicating that their density was lower than that of water (<1.0g / cm 3 ), excellent floating properties.

[0053] 3) Evaluation of sustained-release performance: In the experiment, 1.000 g of the composite particles were placed in 100 mL of deionized water. The concentration of the active ingredient (polyquaternium salt) released from the composite particles in static water at 25°C was measured by ultraviolet absorption. The particles released 41.8% within 24 hours, 62.5% within 48 hours, and 87.4% within 96 hours, meeting the controlled-release requirements. The fitted release curve showed first-order kinetics, indicating that the diffusion-controlled release mechanism was dominant.

[0054] 4) Aqueous Stability and Degradability Assessment: 1.000 g of the composite particles were placed in deionized water (pH = 7.0) and the coating morphology and mass loss were observed. Within 72 hours, the coating showed no significant disintegration and the structure remained intact. After 120 hours, the coating softened at the edges, with a mass loss rate of 18.2%. The complete biodegradation period was estimated to be 7-15 days, which is suitable for the entire process of administration-release-natural degradation.

[0055] The composite particles for treating floating algae in water bodies are prepared by the above steps.

[0056] application

[0057] In order to verify the actual treatment performance of the "composite particles for targeted treatment of floating algae in water bodies" described in the present invention, a eutrophic lake area was selected as the experimental simulated water area, and the experimental area was demarcated with an area of 100m×100m and a water depth of 2m to form a closed control water body with a volume of 20000m 3 The experimental area is enclosed by PVC floats to avoid water exchange and ensure experimental stability and data controllability.

[0058] The initial environmental parameters of the water body are shown in the following table:

[0059] project Initial value water temperature 25±1℃ pH 7.8 Dissolved oxygen (DO) 6.4mg / L Total nitrogen (TN) 2.35mg / L Total phosphorus (TP) 0.38mg / L Chemical oxygen demand (COD) 23.5mg / L Cyanobacteria abundance <![CDATA[1.3×10 6 cells / mL (mainly Microcystis) Water status Eutrophication, early stages of algal blooms

[0060] The algae in the experimental area showed obvious algal blooms, which is representative of good targeted treatment.

[0061] The following further describes the specific embodiments:

[0062] Example 2

[0063] Test on the removal effect of composite particles on cyanobacteria at different dosages

[0064] The effect of different dosages (0, 5, 10, 20, 30 g / m 3 ) to verify its effective dosage range and environmental safety, and test the corresponding indicators. The results are shown in Table 1:

[0065] Table 1

[0066]

[0067]

[0068] From the data in Table 1, it can be seen that the composite particles showed good dose dependence. The higher the dosage, the more obvious the decrease in cyanobacteria abundance. 3 Under these conditions, the number of algal cells decreased by more than 80%. Since the polymeric quaternary ammonium salt is a nitrogen-containing cationic polymer, the total nitrogen in the water body increased slightly after addition, with the highest increase value (30g / m 3 ) was +0.81 mg / L. At medium and high doses, algae inhibition led to a decrease in photosynthesis, but no obvious DO reduction was observed. On the contrary, some groups slightly increased, indicating that hypoxia was not induced in the short term. Because some particles adsorbed and carried suspended phosphorus, the cyclic release of phosphorus by algae was also inhibited, which had a synergistic dephosphorization effect.

[0069] In summary, the recommended usage is 10-20g / m 3 It can kill 60-75% of blue algae and prevent the total nitrogen from rising too quickly.

[0070] Example 3

[0071] Effects of different coating structures on the controlled release and cyanobacteria killing effects of composite particles

[0072] 1) Evaluate the effects of different coating structures (formulation differences) on the sustained-release performance, cyanobacteria removal efficiency, and environmental indicators of the composite particles, and select the coating system with better overall performance. The formulations of each group were the same except for the coating. Four groups with different coating structures were set up, as shown in Table 2:

[0073] Table 2

[0074]

[0075]

[0076] 2) Different ratios of coated quaternary ammonium salt composite particles were added to the experimental waters under the same environmental background. The cyanobacterial cell density, total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), and chemical oxygen demand (COD) were monitored. The experimental results are shown in Table 3:

[0077] Table 3

[0078]

[0079] Table 2-3 shows that chitosan content significantly affects the algaecide efficacy of the granules. Group C, which contained a higher chitosan content, exhibited the best algaecide efficacy, reducing the cyanobacteria cell density to 10% of its original value after 14 days. Group D, which lacked chitosan, showed poor algaecide efficacy. This was attributed to insufficient granule stability, which resulted in rapid release and reduced effectiveness. Chitosan coating enhanced the granules' mechanical strength and sustained release, while also improving their ecological safety. These results demonstrate that optimizing the coating material ratio is crucial for effective algaecide control.

[0080] Example 4

[0081] Effect of coating thickness on sustained-release properties and treatment effects of composite particles

[0082] 1) This embodiment uses a fixed quaternary ammonium salt core dosage of 20g / m 3 Based on the coating composition ratio (chitosan 1.5g, PVA 5.0g), the effect of coating thickness on the sustained-release performance and treatment effect of the composite particles was studied. The thickness is shown in Table 4:

[0083] Table 4

[0084] Group Coating thickness description Remark A Thin layer coating Single layer coating, 10μm thickness B Medium coating thickness Double-layer coating, 30μm thickness C Thick coating Three-layer coating, 50μm thickness

[0085] 2) Add the composite quaternary ammonium salt particles with different coating thicknesses to the experimental waters, with the dosage of each group being 20 g / m 3 , the relevant data of monitoring 0, 3, 7, and 14 days after addition are shown in Table 5:

[0086] Table 5

[0087]

[0088] Tables 4-5 show that coating thickness significantly affects the release rate and treatment efficacy of quaternary ammonium salt composite granules. Thick-coated granules exhibit the best sustained-release performance and sustained algaecide, with the lowest cyanobacterial cell density after 14 days. Thin-coated granules release more quickly and achieve significant algaecide initially, but the effect declines later. A coating thickness of 30 μm is the most reasonable choice, achieving the optimal balance between treatment efficacy, ecological safety, cost control, and engineering feasibility.

[0089] Example 5

[0090] Treatment efficiency of different particle sizes

[0091] 1) Under the same coating thickness (30 μm) and effective dose (20 g / m3), the effects of different particle sizes (0.5 mm, 1.0 mm, and 2.0 mm) on cyanobacteria control efficiency, release behavior, and water environmental parameters were investigated to screen the optimal particle size range. Four groups were set, as shown in Table 6:

[0092] Table 6

[0093]

[0094] 2) Composite particles of different particle sizes were tested on day 0, day 7, and day 14. The test results are shown in Table 7:

[0095] Table 7

[0096]

[0097]

[0098] As shown in Table 6-7, the 1.0 mm particle size (Group B) reduced the abundance of cyanobacteria to 2.2 × 10 4 cells / mL, achieving the best results. While the 0.5mm release rate was rapid and initially effective in killing algae, there was a slight rebound in the latter stages. The 2.0mm release rate was slower, and the overall algae killing rate was slightly lower than that of Group B. Total nitrogen levels in all groups increased slightly, but the magnitude was within an acceptable range (<0.15 mg / L). Group B had a moderate release rate, balanced nitrogen release, and the best control effect. All treatment groups showed a significant decrease in COD and an increase in dissolved oxygen, indicating significant improvements in the water ecosystem. Group B achieved the most significant improvement, demonstrating the best overall performance.

[0099] In summary, the most reasonable composite particle size is 1.0 mm, which performs superior in algaecidal efficiency, ecological impact, and improvement of water indicators, and has good buoyancy and slow-release stability. It is the recommended particle size standard for engineering applications.

[0100] Example 6

[0101] Preliminary safety assessment of ecological impact

[0102] The ecological impact of the composite particles of the present invention on non-target organisms (zooplankton, benthic animals, small fish, etc.) in the water body and the fluctuation of water quality indicators during the treatment of cyanobacteria were evaluated to preliminarily judge their environmental safety. In the experimental waters, the composite particles of the present invention were added once at a dosage of 20g / m 3 The reference group was a blank control group (no drug was added), and the zooplankton, benthic animals, and small fish were observed for 21 consecutive days. The test results are shown in Table 8:

[0103] Table 8

[0104]

[0105]

[0106] As shown in Table 8, the survival rate of various non-target aquatic organisms in the composite particle treatment group exceeded 90%, and no acute toxicity was observed. Behavioral observations revealed no abnormalities in feeding, swimming, or aggregation. This demonstrates that the composite particles of the present invention, at the recommended dose, have minimal impact on aquatic ecosystems and demonstrate good initial environmental safety.

[0107] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0108] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing composite particles for treating floating algae in water, characterized in that: The following steps are involved: a. Preparation of core-active Gemini-type diquaternary ammonium cationic polymer mesylate; b. preparing coating materials; c. Preparation of composite particles: Mix the coating material in step b with castor oil and sodium bicarbonate, heat and stir to obtain a coating solution, add the Gemini type diquaternary ammonium cationic polymer mesylate prepared in step a to obtain composite particles; d. Performance evaluation of composite particles.

2. The method for preparing composite particles for treating floating algae in water according to claim 1, characterized in that: The preparation steps of the core active Gemini type diquaternary ammonium cationic polymer mesylate in step a are as follows: N,N-dimethyl-1,2-ethylenediamine was dissolved in anhydrous ethanol, allyl chloride was added dropwise, and the mixture was stirred and reacted at 35-40°C for 4 hours. N,N'-methylenebisacrylamide and deionized water were added, and then methanesulfonic acid was added to maintain the pH at 5.5-6.

0. Potassium persulfate was added and the mixture was polymerized at 55°C for 6 hours. After the reaction, the mixture was precipitated, washed, and collected, and vacuum dried to constant weight to obtain an active Gemini-type diquaternary ammonium cationic polymer methanesulfonate.

3. The method for preparing composite particles for treating floating algae in water according to claim 2, characterized in that: The usage ratio of N,N-dimethyl-1,2-ethylenediamine, anhydrous ethanol, allyl chloride, N,N'-methylenebisacrylamide, deionized water, methanesulfonic acid, and potassium persulfate is 20.0 mmol: 30 mL: 40.0 mmol: 10.0 mmol: 5.0 mL: 20.0 mmol: 0.2 g.

4. The method for preparing composite particles for treating floating algae in water according to claim 1, characterized in that: The preparation steps of the coating material in step b are as follows: Polyvinyl alcohol was added to deionized water and stirred at 90°C for 30 minutes to obtain a polyvinyl alcohol solution; chitosan was dissolved in glacial acetic acid and stirred to obtain a chitosan solution; then, the chitosan solution was added to the polyvinyl alcohol solution at 60°C, mixed evenly, and cooled to room temperature to obtain a coating material.

5. The method for preparing composite particles for treating floating algae in water according to claim 4, characterized in that: The usage ratio of polyvinyl alcohol, deionized water, chitosan and glacial acetic acid is 5.0 g:95 mL:1.5 g:20 mL, wherein the concentration of glacial acetic acid is 1%.

6. The method for preparing composite particles for treating floating algae in water according to claim 1, characterized in that: In step c, the mass ratio of the coating material, castor oil and sodium bicarbonate is 110:1.0:0.5; the mass ratio of the coating solution to the Gemini-type diquaternary ammonium cationic polymer mesylate is 4:

1.

7. The method for preparing composite particles for treating floating algae in water according to claim 1, characterized in that: The temperature for heating and stirring in step c is 50-60° C., and the stirring rate is 700-900 rpm.

8. The method for preparing composite particles for treating floating algae in water according to claim 1, characterized in that: The particle size of the composite particles in step c is 0.5-2.0 mm.

9. A composite particle for treating floating algae in water, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the composite particles for treating floating algae in water bodies as claimed in claim 9 in treating floating algae in water bodies.

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