A composite particle for treating floating algae in water, its preparation method and application

Abstract

This invention belongs to the field of environmental protection technology, and provides a composite particle for treating floating algae in water bodies, its preparation method, and its application. The preparation method includes the following steps: a) preparing core-active Gemini-type bisquaternary ammonium cationic polymer methanesulfonate; b) preparing a coating material; c) preparing composite particles: mixing the coating material from step b with castor oil and sodium bicarbonate, heating and stirring to obtain a coating solution, adding the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate prepared in step a, and obtaining composite particles; d) evaluating the performance of the composite particles. This invention uses a biodegradable and non-toxic natural polymer material as an outer coating to achieve the slow release and targeted release of quaternary ammonium salts. By coating quaternary ammonium salts in a complex formed by PVA and chitosan, controlling its release rate, and adjusting density to achieve floating or suspension, targeted treatment of cyanobacteria on the water surface is achieved.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to the preparation and application of quaternary ammonium salt composite particles for treating floating algae in water bodies. Background Technology

[0002] In the current process of treating cyanobacterial blooms in rivers, lakes, and other water bodies, traditional methods often rely on the direct addition of chemical agents to achieve rapid inhibition or sedimentation of algae, such as alum, cationic polymeric flocculants, and oxidative algicides. While these methods have some effect in the short term, they generally suffer from insufficient targeting, significant ecological disturbance, and limited duration of action. For example, alum can promote algal sedimentation through charge neutralization, but the aluminum ions it releases tend to accumulate in the water, especially under acidic conditions, exhibiting strong migration and leaching risks, causing long-term disturbance to aquatic ecosystems. Although cationic polyacrylamide can effectively accelerate the sedimentation of suspended particles, the byproducts formed during its degradation process are toxic, posing a potential threat to the survival environment of plankton and fish. While oxidants, such as hydrogen peroxide, can rapidly kill algae by releasing reactive oxygen species to disrupt algal cell structure, their high density, rapid diffusion, and short half-life cause them to easily settle to the bottom in still or slow-flowing water, making it difficult to maintain effective concentrations and significantly reducing their effectiveness. Furthermore, they can easily cause sudden drops in dissolved oxygen, drastic pH fluctuations, and even secondary pollution in localized water bodies. Therefore, this type of "extensive application and non-directional diffusion" approach to treatment is difficult to guarantee in complex and dynamic aquatic environments, hindering the sustainability, safety, and precision of the treatment.

[0003] This invention aims to overcome the aforementioned technical bottlenecks and propose a novel cyanobacteria control material and method with targeted identification, slow-release control, and eco-friendliness as its core features. This invention uses a self-synthesized modified quaternary ammonium salt compound as the main algicidal component, which exhibits excellent selective toxicity and the ability to rapidly lyse cyanobacterial cell membranes, while also possessing good aqueous stability and low ecotoxicity, ensuring high efficiency and safety in the control process. Structurally, this active ingredient is encapsulated in a porous, biodegradable polymer shell based on polyvinyl alcohol (PVA). A foaming nucleation process introduces closed air bubbles into the coating structure, maintaining the overall density of the resulting composite particles below that of the water body, ensuring they float on the surface and drift naturally with water flow and wind to the cyanobacteria aggregation area. Upon reaching the algal aggregation point, the outer PVA shell, through slow hydrolysis and pore structure regulation of the release rate, gradually releases the algicidal active component from the core, thereby achieving on-site elimination of algae. This composite material possesses excellent mechanical stability, buoyancy persistence, and release control. Compared with traditional direct application of agents, it not only significantly improves the identification and contact efficiency of cyanobacteria-rich areas but also reduces the amount of agent to be applied at one time, avoiding excessively high local concentrations and ecological disturbances caused by instantaneous release of agents, thus enhancing its adaptability and protective power for aquatic ecosystems.

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

[0005] This invention addresses the targeted remediation of floating algae pollution in aquatic bodies by proposing a composite particle for controlling floating algae, its preparation method, and its application. The composite particle, prepared by combining a modified polymeric quaternary ammonium salt as the core reagent with a green, eco-friendly coating material, serves as the remediation agent. This agent possesses the functional characteristics of highly efficient algae killing, slow-release and controlled-release, eco-friendliness, and floating on the water surface. It enables the agent to float with the water body and continuously release active ingredients, thereby achieving the precise control and elimination of floating algae.

[0006] The objective of this invention can be achieved through the following technical solutions:

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

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

[0009] b. Preparation of coating materials;

[0010] c. Preparation of composite particles: Castor oil is introduced as an auxiliary agent into the coating material in step b, and sodium bicarbonate is added 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 the microbubbles). The coating solution is then added to the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate 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 bisquaternary ammonium cationic polymer methanesulfonate in step a are as follows:

[0013] N,N-Dimethyl-1,2-ethylenediamine was dissolved in anhydrous ethanol, and allyl chloride was slowly added dropwise to the mixture in a three-necked flask while maintaining the temperature at 35-40°C and stirring for 4 hours to form the intermediate diallyl quaternary ammonium salt monomer structure. N,N'-methylenebisacrylamide (MBAA) was added to the reaction system as a crosslinking agent, and deionized water was added to dilute it evenly. Methanesulfonic acid (CH3SO3H) was then added for anion pairing, maintaining the pH at 5.5-6.0. Subsequently, potassium persulfate (K2S2O8) was added as an initiator, and... The polymer was subjected to polymerization in a constant temperature water bath at 55℃ 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 to precipitate, and washed three times with isopropanol to remove unreacted monomers and oligomers. The resulting white to pale yellow polymer precipitate was collected and vacuum dried to constant weight. The final product was a Gemini-type bisquaternary ammonium cationic polymer with methanesulfonic acid paired anions, namely, active Gemini-type bisquaternary ammonium cationic polymer methanesulfonate. It was ground by ball milling and set aside for later use.

[0014] Furthermore, the 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 bisquaternary ammonium cationic polymer methanesulfonate 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 was added to deionized water and stirred and heated at 90°C for 30 minutes to fully dissolve the PVA and form a homogeneous and transparent solution, thus obtaining a polyvinyl alcohol solution. Chitosan was dissolved in glacial acetic acid (concentration of 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 aims to enhance the mechanical strength and biodegradability of the coating layer. At the same time, its natural antibacterial properties help to improve the ecological safety of the treatment particles. After thorough and uniform mixing, the mixture was cooled to room temperature to obtain the coating material for later use.

[0018] Furthermore, the 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 polyvinyl alcohol has a molecular weight of 88,000 and a degree of alcoholysis of 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 bisquaternary ammonium cationic polymer methanesulfonate is 4:1.

[0022] Furthermore, in step c, the temperature for heating and stirring is 50-60℃, and the stirring speed is 700-900 rpm.

[0023] Furthermore, in step c, the temperature for heating and stirring is 55°C, and the stirring speed 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 above.

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

[0028] The beneficial effects of this invention are:

[0029] 1. This invention uses a self-synthesized modified quaternary ammonium salt compound as the main algicidal component. It exhibits excellent selective toxicity and the ability to rapidly lyse cyanobacterial cell membranes, while also possessing good aqueous stability and low ecotoxicity, ensuring high efficiency and safety in treatment. Structurally, this active ingredient is encapsulated in a porous, biodegradable polymer shell based on polyvinyl alcohol (PVA). A foaming nucleation process introduces closed air bubbles into the coating structure, maintaining the overall density of the resulting composite particles below that of the water body, ensuring they float on the surface and drift naturally with water flow and wind to the cyanobacteria aggregation area. Upon reaching the algal aggregation point, the outer PVA shell, through slow hydrolysis and pore structure regulation of the release rate, gradually releases the algicidal active component from the core, thereby achieving on-site elimination of algae. This composite material possesses excellent mechanical stability, buoyancy persistence, and release control. Compared with traditional direct application of agents, it not only significantly improves the identification and contact efficiency of cyanobacteria-rich areas but also reduces the amount of agent to be applied at one time, avoiding excessively high local concentrations and ecological disturbances caused by instantaneous release of agents, thus enhancing its adaptability and protective power for aquatic ecosystems.

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

[0031] 3. This invention uses a biodegradable and non-toxic natural polymer material as an outer coating to achieve the slow-release and targeted release of quaternary ammonium salts. The quaternary ammonium salt is coated in a complex formed from PVA and chitosan, controlling its release rate and adjusting its density to achieve floating or suspension, thus achieving targeted treatment of cyanobacteria on the water surface. This effectively extends the treatment time, improves treatment efficiency, and the material itself is ecologically safe, preventing the aggravation of eutrophication.

[0032] 4. Excellent ecological safety. All materials in this invention are biodegradable, low-toxicity, and environmentally friendly, with minimal impact on aquatic ecosystems. A systematic assessment of the materials' impact on indicators such as total nitrogen and total phosphorus confirms that they do not cause secondary pollution within the ecosystem. They can be applied long-term in the management of lakes, reservoirs, and urban rivers without altering the original ecological balance.

[0033] 5. Traditional algae removal methods, such as spraying chemicals, require ship-based spraying or costly construction of grid-type dosing systems, covering large water areas. These methods involve massive amounts of chemicals and are time-consuming. The algae remover provided by this invention floats to its designated location, allowing for single-trip application across the lake surface in the direction of the wind. It gathers automatically with the waves, synchronizing with the floating algae, achieving intelligent, adaptive algae removal. It proactively adapts to the distribution trends of algae, achieving on-site treatment through floating. This reduces the total amount of chemicals used, lowers labor costs, extends the effective period, and enhances the systematic nature of water body restoration. It achieves effective control of algae without causing ecological impact, representing a "low-disturbance, highly targeted, and sustainable" method for algae control. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

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

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

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

[0039] 20.0 mmol of N,N-dimethyl-1,2-ethylenediamine was dissolved in 30 mL of anhydrous ethanol, and 40.0 mmol of allyl chloride was slowly added dropwise while maintaining the temperature at 35-40 °C and stirring for 4 h to form the intermediate diallyl quaternary ammonium salt monomer structure. 10.0 mmol of N,N'-methylenebisacrylamide (MBAA) was added to the reaction system as a crosslinking agent, and 5.0 mL of deionized water was added to dilute it evenly. Then, 20.0 mmol of methanesulfonic acid (CH3SO3H) was added for anion pairing, maintaining the pH at 5.5-6.0. Subsequently, persulfuric acid was added... Potassium phosphate (K2S2O8) 0.2g was used as an initiator, and the polymer was subjected to polymerization in a constant temperature water bath at 55℃ for 6h 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 to precipitate, and washed three times with isopropanol to remove unreacted monomers and oligomers. The obtained white to pale yellow polymer precipitate was collected, vacuum dried to constant weight, and the product was obtained as a Gemini-type bisquaternary ammonium cationic polymer with methanesulfonic acid paired anions, with a solid content of 92%. It was ground by ball milling, sieved, and the particle size was controlled to be 50-200μm.

[0040] The physical properties of the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate reagent obtained by testing the above steps are shown in the table below:

[0041]

[0042] b. Preparation of coating materials:

[0043] 5.0 g of polyvinyl alcohol (PVA, molecular weight 88,000, degree of hydrolysis 98-99%) was added to 95 mL of deionized water and heated magnetically at 90 °C for 30 min to fully dissolve the PVA and form a homogeneous and transparent solution, thus 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 aims to enhance the mechanical strength and biodegradability of the coating layer, while its natural antibacterial properties help improve the ecological safety of the treatment particles. After thorough and uniform mixing, the mixture was cooled to room temperature to obtain the coating material for later use.

[0044] c. Preparation of composite particles:

[0045] To achieve a porous structure in the coating layer (ensuring the composite particle density is lower than that of water and has a slow-release function), 110g of the coating material from step b was mixed with 1.0g of castor oil as an additive and 0.5g of sodium bicarbonate as a chemical foaming agent. The mixture was stirred and heated appropriately. During the stirring process, sodium bicarbonate decomposed and released carbon dioxide gas, generating microporous bubbles that were evenly distributed in the coating solution (the coating solution had a certain viscosity, which trapped the microbubbles). The resulting coating solution was then added to the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate prepared in step a. The mass ratio of the coating solution to the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate was 4:1, resulting in composite particles.

[0046] To ensure stable bubble formation and prevent rupture, ultimately forming a porous honeycomb-like coating that effectively reduces particle density and achieves excellent flocculation performance, the optimal temperature (40-70℃) and stirring speed (500-1000rpm) were selected through the following tests under water sample pH conditions of 6-8. The test results are shown in the table below:

[0047]

[0048] As shown in Table 1, the composite particles prepared under the conditions of 55℃ temperature and 800rpm stirring speed (Group 4) exhibit the best overall performance. The bubbles are stably formed, the structure is uniformly honeycomb-like, and the density is suitable for floating on the water surface, while also maintaining controlled release performance. The particles have strong suspension properties, continuously floating for >72 hours. The coating layer structure is stable and does not expand or stratify in water. The effective ingredient is released steadily (41.8% release rate in 24 hours under pH 6-8 conditions), making it suitable for continuous application scenarios for targeted treatment of algal pollutants in water bodies.

[0049] d. Performance evaluation of composite particles

[0050] The structural stability, buoyancy, 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 and smooth surface. Under the microstructure, there is a uniform honeycomb porous layer with a porosity of 45-55%, which is conducive to the formation of slow-release channels.

[0052] 2) Flotation test: 1.000g of composite particles were added to 100mL of deionized water and the buoyancy was observed. The particles floated rapidly and continued to float for 72 hours without significant sinking, indicating that their density was lower than that of water (<1.0g / cm³). 3 It has excellent buoyancy.

[0053] 3) Evaluation of sustained-release performance: In the experiment, 1.000g of composite particles were placed in 100mL of deionized water. The concentration of the effective component (polyquaternary ammonium salt) released by the composite particles in still water at 25℃ was detected by ultraviolet absorption method. The particles released 41.8% within 24 hours, 62.5% within 48 hours, and 87.4% within 96 hours, which met the requirements for controlled release. The fitted release curve was a first-order kinetic, indicating that the diffusion-controlled release mechanism was dominant.

[0054] 4) Stability and degradability assessment in water: 1.000g of composite particles were placed in deionized water (pH=7.0) and the coating morphology and mass loss were observed. The coating did not disintegrate significantly within 72 hours and the structure remained intact. After 120 hours, the edge structure softened and the mass loss rate was 18.2%. It is estimated that the complete biodegradation cycle is 7-15 days, which is applicable to the entire process of release-natural degradation.

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

[0056] application

[0057] To verify the actual treatment performance of the "floating algae-targeting composite particles" described in this invention, a eutrophic lake area was selected as the experimental simulation water area. The experimental area was defined as 100m × 100m with a water depth of 2m, forming a closed control water body with a volume of 20,000 m³. 3 The experimental area is enclosed with PVC pontoons to prevent water exchange and ensure experimental stability and data controllability.

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

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

[0060] The algae in the experimental area showed obvious algal blooms, making it a good representative area for targeted treatment.

[0061] The following detailed embodiments further illustrate the following:

[0062] Example 2

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

[0064] The study investigated the effects of different dosages (0, 5, 10, 20, 30 g / m³) of the compound treatment granules. 3 The treatment effect of the drug was evaluated, its effective dosage range and environmental safety were verified, and the relevant indicators were tested. The results are shown in Table 1.

[0065] Table 1

[0066]

[0067]

[0068] As can be seen from the data in Table 1, the composite particles exhibit a good dose-dependent effect; the higher the dosage, the more significant the decrease in cyanobacterial abundance. (30 g / m³) 3 Under these conditions, the number of algal cells decreased by more than 80%. Because polymeric quaternary ammonium salts are nitrogen-containing cationic polymers, the total nitrogen in the water increased slightly after addition, with the highest increase being 30 g / m³. 3 The concentration was +0.81 mg / L. At medium and high doses, algal inhibition led to a decrease in photosynthesis, but no significant decrease in DO was observed. On the contrary, some groups showed a slight increase, indicating that hypoxia was not induced in the short term. This is because some particles adsorbed and carried suspended phosphorus, which also inhibited the cyclic release of phosphorus by algae, thus having a synergistic dephosphorization effect.

[0069] In summary, the recommended dosage is 10-20 g / m³. 3 It can kill 60-75% of cyanobacteria while avoiding a rapid increase in total nitrogen.

[0070] Example 3

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

[0072] 1) Evaluate the impact 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 are the same except for the coating. Four groups of different coating structures are set up, as shown in Table 2:

[0073] Table 2

[0074]

[0075]

[0076] 2) Coated quaternary ammonium salt composite particles with different ratios were added to experimental waters under the same environmental background. The density of cyanobacterial cells, 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 the chitosan content significantly affects the algae control effect of the particles. Group C, with a higher chitosan content, exhibited the best algae control effect, reducing the cyanobacterial cell density to 10% of the original level after 14 days. Group D, without chitosan, showed poor algae control; insufficient particle stability led to rapid release and weakened effect. Chitosan coating enhanced the mechanical strength and slow-release properties of the particles, while also improving ecological safety. The results demonstrate that optimizing the coating material ratio is crucial for treatment performance.

[0080] Example 4

[0081] The effect of coating thickness on the sustained-release performance and treatment effect of composite particles

[0082] 1) In this embodiment, a fixed quaternary ammonium salt nucleus dose of 20 g / m² is used. 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 coating Single-layer coating, 10μm thickness B Medium coating thickness Double coating, 30μm thickness C Thick coating Three-layer coating, 50μm thickness

[0085] 2) Composite quaternary ammonium salt particles with different coating thicknesses were added to the experimental water bodies, with each group being added at a rate of 20 g / m³. 3 The relevant data for monitoring 0, 3, 7, and 14 days after the addition are shown in Table 5:

[0086] Table 5

[0087]

[0088] As shown in Tables 4-5, the coating thickness significantly affects the release rate and treatment effect of the quaternary ammonium salt composite particles. Thick-coated particles exhibit the best slow-release performance and sustained algae-killing effect, with the lowest cyanobacterial cell density after 14 days. Thin-coated particles release more quickly and show significant algae-killing effect in the initial stage, but the effect decreases in the later stage. A coating thickness of 30 μm is the most reasonable choice, achieving the best comprehensive balance between treatment effect, ecological safety, cost control, and engineering feasibility.

[0089] Example 5

[0090] Treatment efficiency of different particle sizes

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

[0092] Table 6

[0093]

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

[0095] Table 7

[0096]

[0097]

[0098] As shown in Tables 6-7, the 1.0 mm particle size (Group B) reduced the cyanobacteria abundance to 2.2 × 10⁻⁶ within 14 days. 4 The optimal algae control rate was achieved at [number of cells / mL]. While 0.5 mm algae release was rapid and initially effective, it showed a slight rebound later. 2.0 mm algae release was slow, resulting in a slightly lower overall algae control rate compared to group B. Total nitrogen levels increased slightly in all groups, but the increases were within acceptable limits (<0.15 mg / L). Group B exhibited a moderate release rate and balanced nitrogen release, resulting in the best control effect. All treatment groups showed a significant decrease in COD and an increase in dissolved oxygen, indicating a significant improvement in the aquatic ecosystem. Group B showed the most significant improvement and demonstrated the best overall performance.

[0099] In summary, the most reasonable particle size for composite particles is 1.0 mm. It performs well in terms of algae removal efficiency, ecological impact, and improvement of water quality 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 and water quality fluctuations of the composite particles of this invention on non-target organisms (zooplankton, benthic animals, small fish, etc.) in the water body during cyanobacteria control were evaluated to preliminarily determine its environmental safety. In the experimental water body, the composite particles of this invention were added in a single application at a dosage of 20 g / m³. 3 The control group served as a blank control group (without any medication). Observations were conducted for 21 consecutive days, focusing on zooplankton, benthic animals, and small fish. 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 was above 90%, and no acute toxicity was observed. No abnormalities were found in feeding, swimming, or aggregation during behavioral observation. Therefore, the composite particles of this invention have minimal impact on the aquatic ecosystem at the recommended dosage and possess good preliminary environmental safety.

[0107] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly 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 bodies, characterized in that, Includes the following steps: a. Preparation of core-active Gemini-type bisquaternary ammonium cationic polymer methanesulfonate: N,N-dimethyl-1,2-ethylenediamine was dissolved in anhydrous ethanol, allyl chloride was added dropwise, and the mixture was stirred at 35-40°C for 4 h. N,N'-methylenebisacrylamide and deionized water were added, followed by methanesulfonic acid, maintaining the pH at 5.5-6.

0. Potassium persulfate was added, and the polymerization reaction was carried out at 55°C for 6 h. After the reaction was completed, the precipitate was precipitated, washed, collected, and vacuum dried to constant weight to obtain the active Gemini-type bisquaternary ammonium cationic polymer methanesulfonate. b. Preparation of coating materials; c. Preparation of composite particles: The coating material in step b is mixed with castor oil and sodium bicarbonate, heated and stirred to obtain a coating solution, and the Gemini-type bisquaternary ammonium cationic polymer methanesulfonate prepared in step a is added to obtain composite particles; d. Performance evaluation of composite particles.

2. The method for preparing composite particles for treating floating algae in water bodies according to claim 1, characterized in that, The 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.

3. The method for preparing composite particles for treating floating algae in water bodies 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 min to obtain a polyvinyl alcohol solution. Chitosan was dissolved in glacial acetic acid and stirred to obtain a chitosan solution. Subsequently, the chitosan solution was added to the polyvinyl alcohol solution at 60°C, mixed evenly, and then cooled to room temperature to obtain a coating material.

4. The method for preparing composite particles for treating floating algae in water bodies according to claim 3, characterized in that, The ratio of polyvinyl alcohol, deionized water, chitosan and glacial acetic acid is 5.0g:95mL:1.5g:20mL, with the concentration of glacial acetic acid being 1%.

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

1.

6. The method for preparing composite particles for treating floating algae in water bodies according to claim 1, characterized in that, In step c, the temperature for heating and stirring is 50-60℃, and the stirring speed is 700-900 rpm.

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

8. A composite granule for treating floating algae in water bodies, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the composite particles for treating floating algae in water bodies as described in claim 8 in the treatment of floating algae in water bodies.

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