A sewage treatment composite purifying agent and a preparation method and application thereof

Abstract

The application discloses sewage treatment composite purifying agent and a preparation method and application thereof, and comprises the following steps: S1, nanometer aluminum powder is mixed with zeolite and is ball milled to obtain nanometer aluminum powder@zeolite inclusion compound; S2, chitosan is dissolved in acetic acid solution, and mercapto acetic acid is added to react to obtain mercapto chitosan; then the mercapto chitosan is dissolved in acetic acid solution, and a trivalent iron source solution is added dropwise to obtain mercapto chitosan-trivalent iron coordination gel; S3, tea saponin is mixed with beta-cyclodextrin to obtain tea saponin-beta-cyclodextrin inclusion compound; S4, porous ceramic granules, nanometer aluminum powder@zeolite inclusion compound, mercapto chitosan-trivalent iron coordination gel, microcrystalline cellulose and citric acid are uniformly mixed, water is added to granulate to obtain an inner core; S5, sulfur powder is melted, carbonate powder, maifanite powder and tea saponin-beta-cyclodextrin inclusion compound are added to obtain molten slurry, the inner core is added, and stirring is carried out to coat, so that the sewage treatment composite purifying agent is obtained; the sewage treatment composite purifying agent can stably remove various pollutants with high efficiency and can adapt to complex water bodies.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a composite wastewater treatment purifier, its preparation method, and its application. Background Technology

[0002] With rapid industrialization and urbanization, water pollution has become increasingly severe, particularly the complex problem of combined water pollution represented by domestic sewage, industrial wastewater, and agricultural non-point source pollution. Water bodies discharged from domestic sewage, industrial wastewater, and agricultural runoff generally contain a variety of pollutants such as suspended solids, organic matter, heavy metal ions, nitrate nitrogen, and phosphate, posing a serious threat to the ecological environment and human health. Single treatment technologies are insufficient to achieve efficient and economical simultaneous removal of pollutants.

[0003] Currently, commonly used technologies in wastewater treatment mainly include flocculation sedimentation, adsorption, membrane separation, and biological treatment. Among these, flocculation sedimentation (such as polyaluminum chloride and polyacrylamide) is effective in removing suspended solids and colloidal particles, but its ability to remove dissolved heavy metal ions and nitrates is limited. Adsorption (such as activated carbon and zeolite) can adsorb some organic matter and heavy metals, but it suffers from difficulties in regeneration after adsorption saturation and high treatment costs. Membrane separation produces high-quality effluent, but its investment and operating costs are high, and it is also susceptible to membrane fouling. Biological treatment (such as activated sludge) is effective in removing organic matter and nitrogen and phosphorus, but it is sensitive to heavy metal shock loads and has a long treatment cycle. In recent years, sulfur autotrophic denitrification technology has received widespread attention in the remediation of nitrate-contaminated water bodies due to its advantages such as not requiring external organic carbon sources and low sludge production.

[0004] Chinese patent CN115321680A, "A Maifan Stone-Doped Carbon-Sulfur Integrated Material and Its Preparation Method," discloses a Maifan stone-doped carbon-sulfur core-shell material. This material is prepared into core-shell structured particles using a melt-coating process with sulfur powder, carbonate powder, porous ceramsite, and Maifan stone powder. The material utilizes sulfur as an electron donor to achieve autotrophic denitrification, while sulfur reacts with heavy metal ions to form sulfide precipitates. The porous ceramsite and Maifan stone provide adsorption, and the carbonate powder acts as a pH buffer. However, this material primarily relies on physical filtration and adsorption, resulting in limited removal capacity for suspended solids and dissolved organic matter, slow sedimentation, and low solid-liquid separation efficiency. Furthermore, the removal of heavy metals depends solely on the sulfur precipitation mechanism; when the sulfur precipitation reaction is incomplete or the heavy metal concentration fluctuates, the effluent heavy metal concentration is difficult to consistently meet standards, and its adaptability to complex water bodies is severely insufficient.

[0005] Therefore, it is of great significance to develop a composite purifier for wastewater treatment that can efficiently and stably remove multiple pollutants and adapt to complex water bodies, as well as its preparation method and application. Summary of the Invention

[0006] The purpose of this invention is to provide a composite purifying agent for wastewater treatment, its preparation method, and its application, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a composite wastewater treatment purifier includes the following steps: S1. Mix nano-aluminum powder and zeolite at a mass ratio of 1:(6-10) and ball mill to obtain nano-aluminum powder@zeolite inclusion complex, which is ready for use; S2. Dissolve chitosan in acetic acid solution, add mercaptoacetic acid to react, take the precipitate, wash, freeze dry to obtain mercaptochitosan; then dissolve mercaptochitosan in acetic acid solution, add ferric iron source solution dropwise, gel, centrifuge, freeze dry, pulverize to obtain mercaptochitosan-ferric iron coordination gel, for later use; S3. Mix tea saponin with β-cyclodextrin, add hot water and stir, let stand at low temperature for 8-16 hours, take the precipitated crystals, filter, dry, and pulverize to obtain tea saponin-β-cyclodextrin inclusion complex for later use; S4. Mix the porous ceramsite, the nano-aluminum powder@zeolite inclusion complex obtained in S1, the mercapto-chitosan-trivalent iron coordination gel obtained in S2, microcrystalline cellulose, and citric acid evenly, add water and granulate to a particle size of 2-4 mm, and vacuum dry at 40-50℃ to a moisture content of ≤5% to obtain the core, which is ready for use. S5. Heat the sulfur powder to 115-120℃ to melt it, add carbonate powder, maifanite powder, and the tea saponin-β-cyclodextrin inclusion complex obtained in S3, keep it warm and stir to obtain a molten slurry, add the core obtained in S4 at this temperature, stir at 60-100 rpm for 3-5 minutes to coat it, cool naturally, crush and sieve, and take particles with a particle size of 3-6 mm to obtain the wastewater treatment composite purification agent.

[0008] Preferably, the ball milling in S1 is carried out under inert gas protection, with a rotation speed of 200-400 rpm and a time of 1-3 hours.

[0009] Preferably, the concentration of the acetic acid solution in S2 is 1-5 wt.%.

[0010] Preferably, the mass ratio of chitosan to mercaptoacetic acid in S2 is 1:(0.3-0.6).

[0011] Preferably, the reaction temperature in S2 is 50-70℃ and the reaction time is 3-6h.

[0012] Preferably, the reaction described in S2 further includes a step of adjusting the pH to 7.

[0013] Preferably, the mass ratio of the thiol chitosan to the trivalent iron source in S2 is (3-5):1.

[0014] Preferably, the trivalent iron source in S2 is one or more of ferric chloride, ferric sulfate, and ferric nitrate.

[0015] Preferably, the concentration of the trivalent iron source solution in S2 is 0.05-0.2 mol / L.

[0016] Preferably, the gel in S2 is a static gel that has been left to stand for 1-2 hours.

[0017] Preferably, the mass ratio of tea saponin to β-cyclodextrin in S3 is 1:(2-4).

[0018] Preferably, the hot water temperature in S3 is 50-70℃, and the stirring time is 1-2 hours.

[0019] Preferably, the low-temperature standing temperature in S3 is 2-8℃.

[0020] Preferably, the mass ratio of the porous ceramic particles, nano-aluminum powder@zeolite inclusion complex, and thiol chitosan-ferric coordination gel in S4 is (8-12):(1-2):(2-4).

[0021] Preferably, the amount of water added during the water-addition granulation process in step S4 is 8-12% of the total mass of the material.

[0022] Preferably, the mass ratio of sulfur powder, carbonate powder, maifanite powder, and tea saponin-β-cyclodextrin inclusion complex in S5 is (5-12):(10-20):(3-8):(3-8).

[0023] Preferably, the carbonate powder in S5 is one or more of calcium carbonate powder, limestone powder, eggshell powder, and seashell powder.

[0024] In addition, the present invention also provides a composite purifying agent for wastewater treatment.

[0025] A composite purifying agent for wastewater treatment, prepared according to any one of the above-mentioned methods.

[0026] In addition, the present invention also provides an application of a composite purifying agent for wastewater treatment.

[0027] A composite purifying agent for wastewater treatment.

[0028] Compared with the prior art, the beneficial effects of the present invention are: The wastewater treatment composite purifier of this invention has a core-shell structure, with porous ceramsite, nano-aluminum powder@zeolite inclusion complex, thiol-chitosan-ferric coordination gel, microcrystalline cellulose, and citric acid as the core. The porous ceramsite provides mechanical framework support and water flow channels for the particles, anchoring nano- and micron-sized functional components within millimeter-sized particles. This solves the problem of easy loss and difficulty in recycling of powdered functional materials when used directly. Simultaneously, its porous structure provides physical adsorption for suspended solids and some organic matter. In the nano-aluminum powder@zeolite inclusion complex, the nano-aluminum powder is physically passivated after being encapsulated by zeolite, allowing it to be stored in a dry state. The solution remains stable and, upon contact with water, synergistically produces gentle, continuous hydrogen microbubbles and aluminum hydroxide colloids with citric acid. As the bubbles rise, they carry suspended matter, forming flocs. The aluminum hydroxide colloids also have a flocculating effect, further capturing colloidal particles and some dissolved organic matter in the water, achieving rapid solid-liquid separation. Meanwhile, zeolite enriches pollutants from the aqueous phase onto the surface of the aluminum powder, efficiently adsorbing organic pollutants and assisting in the oxidative decomposition of nano-aluminum powder. Simultaneously, it controls the degradation reaction to occur within the zeolite channels, improving reaction efficiency through a localized high-concentration effect and extending the effective contact time of the aluminum powder, achieving "adsorption before degradation" and avoiding the spread of contaminants. Traditional adsorbents only transfer pollutants without completely removing them; the thiol chitosan-ferric coordination gel possesses a strong chelating ability for heavy metal ions such as lead, cadmium, and mercury, converting dissolved heavy metals into insoluble thiol metal complexes. Simultaneously, the slowly released ferric iron hydrolyzes to form ferric hydroxide flocs, which not only have their own flocculation effect but also form an aluminum-iron dual-flocculation system with aluminum hydroxide produced by the hydrolysis of aluminum powder, achieving highly efficient removal of heavy metal ions. Furthermore, microcrystalline cellulose provides plasticity and viscosity during wet granulation and can be slowly absorbed by microorganisms during long-term use. The degradation further increases the porosity of the particles, promoting the exposure and utilization of internal functional components. Citric acid, as a multidentate ligand, can form stable and soluble complexes with aluminum and iron ions through its carboxyl groups, ensuring the long-term stability of the activity of nano-aluminum powder@zeolite inclusion complex and mercapto-chitosan-ferric coordination gel. At the same time, it acts as a trigger to provide a local slightly acidic environment, promoting the dissolution of the oxide film on the surface of aluminum powder, so that the hydrogen production reaction can be smoothly started and continued. In addition, citric acid is also a biodegradable organic carbon source, which can promote the growth of microorganisms in wastewater treatment, enhance the biodegradation effect, and further improve the purification effect.

[0029] The wastewater treatment composite purifier of this invention has a core-shell structure, with sulfur powder, carbonate powder, maifanite powder, and tea saponin-β-cyclodextrin inclusion complex forming the outer shell. After cooling, the sulfur powder crystallizes and solidifies to form a dense sulfur shell, creating a protective barrier that slows the rate of wastewater penetration into the core and controls the release rate of active components within the core, thus providing a long-lasting purifier effect. Sulfur not only combines with heavy metal ions to form extremely insoluble metal sulfide precipitates, achieving initial removal of heavy metals, but also acts as an electron donor to support the growth and metabolism of sulfur-autotrophic denitrifying bacteria in the water, reducing nitrates to nitrogen. Furthermore, sulfur itself has antibacterial activity, inhibiting excessive growth of biofilm on the particle surface and preventing microbial blockage of pores that could lead to particle failure. This overcomes the "rapid release and rapid loss" defects of traditional adsorbents, achieving a tiered release and long-term stability of the purification function. The carbonate powder is dispersed in molten sulfur and, after solidification, is embedded within the sulfur shell. During wastewater treatment, it slowly dissolves in slightly acidic or neutral water, releasing CO2 and leaving micron-sized pores that allow wastewater to enter the core. This process addresses the problem of mass transfer obstruction caused by the dense sulfur shell, while simultaneously neutralizing the acid produced during the micro-electrolysis of nano-aluminum powder and the degradation of organic pollutants. It maintains the reaction system within a neutral to slightly alkaline range, acting as a pH buffer, which is beneficial for the precipitation and removal of heavy metal ions and the growth of microorganisms. Maifan stone powder, dispersed within the sulfur shell, exhibits excellent adsorption capacity for heavy metal ions, ammonia nitrogen, and organic pollutants. It captures pollutants in the initial stage of wastewater entering the particles, reducing the treatment load on the core. Simultaneously, it slowly releases trace elements to promote the activity of sulfur-autotrophic denitrifying bacteria in the water, further enhancing the ammonia nitrogen purification effect. The tea saponin-β-cyclodextrin inclusion complex slowly and continuously releases tea saponin, a natural surfactant that emulsifies and disperses oily pollutants in wastewater, continuously reducing interfacial tension, releasing bound water, assisting in the flotation and flocculation processes, increasing the oil-water interface area, and promoting the degradation of oily pollutants by microorganisms. It also has a good killing effect on common pathogens such as Escherichia coli and Staphylococcus aureus in wastewater, achieving a long-lasting solubilizing and antibacterial effect.

[0030] The wastewater treatment composite purifier of this invention has a core-shell structure. Wastewater is pretreated through the adsorption of maifanite in the outer shell and the antibacterial effects of sulfur powder and tea saponin, reducing the load on the core. Carbonates and tea saponin inclusion complexes dissolve and release upon contact with water, forming mass transfer channels and providing immediate antibacterial effects. After wastewater penetrates the core, microcrystalline cellulose gradually degrades, citric acid is slowly released, and the acidic conditions promote the dissolution of the oxide film on the surface of nano-aluminum powder, achieving controlled and slow release of aluminum powder. This generates hydrogen microbubbles and aluminum hydroxide colloids. The aluminum hydroxide colloids and ferric hydroxide colloids generated by the hydrolysis of ferric iron form an aluminum-iron dual flocculation system, flocculating the target pollutants. With the assistance of tea saponin reducing surface tension, the hydrogen microbubbles efficiently adhere to the floc surface and rapidly rise to the water surface, forming a scum layer, achieving rapid separation of suspended solids from water. As the outer shell is gradually wetted by water, the sulfur powder in the shell begins to slowly release sulfur ions and react with heavy metals in the water. The ions undergo a precipitation reaction, transforming dissolved heavy metals into extremely insoluble precipitates, thus achieving the main removal of heavy metals. The thiol chitosan in the core captures residual dissolved heavy metal ions, chelating them for deep purification. During long-term purification, maifanite and porous ceramsite continuously adsorb organic matter, sulfur powder acts as an electron donor, carbonate powder acts as a pH buffer, and trace elements released by maifanite act as microbial nutrients. Together, these three elements create an ideal growth environment for naturally occurring sulfur-autotrophic denitrifying bacteria in the water, efficiently and persistently reducing nitrate nitrogen to nitrogen gas. These mechanisms promote and complement each other, forming a relay-style purification chain in the wastewater treatment process. This gives the purifier both rapid response and long-term stability, enabling the simultaneous and efficient removal of multiple pollutants such as suspended solids, organic matter, heavy metals, and nitrate nitrogen from wastewater. It can adapt to complex water bodies and has good industrial application value. Detailed Implementation

[0031] To better illustrate the objectives, technical solutions, and advantages of this invention, the following embodiments are provided. Obviously, the following embodiments are only a part of the embodiments of this invention, and not all of them; these embodiments do not imply any limitation on this invention. Those skilled in the art should understand that these embodiments are only used to illustrate the technical effects of this invention, and not to limit the scope of protection of this invention.

[0032] Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. These examples are primarily intended to provide a better understanding of the analytical methods of this invention and do not exhaustively cover all possible procedures.

[0033] All raw materials used in the examples are commercially available; unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0034] Example 1 A method for preparing a composite wastewater treatment purifier includes the following steps: S1. Mix nano-aluminum powder and zeolite at a mass ratio of 1:8, purge with nitrogen, and ball mill at 300 rpm for 2 hours to obtain nano-aluminum powder@zeolite inclusion complex, which is ready for use. S2. Chitosan was dissolved in 2 wt.% acetic acid solution. Mercaptoacetic acid was added at a mass ratio of 1:0.5 (chitosan to mercaptoacetic acid). The mixture was reacted at 60°C for 4 hours. The pH was adjusted to 7. The precipitate was washed and freeze-dried to obtain mercapto-chitosan. Mercapto-chitosan was then dissolved in 2 wt.% acetic acid solution. 0.1 mol / L ferric chloride solution (mercapto-chitosan to ferric chloride mass ratio of 4:1) was added dropwise while stirring. After the addition was complete, the mixture was allowed to stand for 1 hour to form a dark brown coordination gel. The gel was centrifuged, freeze-dried, and pulverized through a 100-mesh sieve to obtain a mercapto-chitosan-ferric chloride coordination gel for later use. S3. Mix tea saponin and β-cyclodextrin at a mass ratio of 1:3, add to 60℃ hot water and stir for 2 hours, let stand at 4℃ for 12 hours to allow inclusion complex crystals to precipitate, take the precipitated crystals, filter, dry, pulverize and pass through a 200-mesh sieve to obtain tea saponin-β-cyclodextrin inclusion complex, for later use; S4. Add 50g of porous ceramsite, 8g of nano-aluminum powder@zeolite inclusion complex obtained in S1, 15g of thiol chitosan-trivalent iron coordination gel obtained in S2, 8g of microcrystalline cellulose, and 2g of citric acid into a three-dimensional mixer and mix evenly. Transfer the mixture to a disc granulator and spray in 10% of the total mass of the material while rotating. Add water and granulate until the particle size is 2-4mm. Vacuum dry at 45℃ until the moisture content is ≤5% to obtain the core. Set aside for use. S5. Heat 10g of sulfur powder to 118℃ to melt it, add 15g of limestone powder, 5g of maifanite powder, and 5g of the tea saponin-β-cyclodextrin inclusion complex obtained in S3. Keep the temperature in the range of 115-120℃ and stir at 80rpm for 10 minutes to obtain a molten slurry. At this temperature, add the core obtained in S4. The mass ratio of the core to the shell slurry is controlled at 1:0.4. Stir at 80rpm for 5 minutes to form a continuous shell with a thickness of about 0.5-1 mm. After the coating is completed, quickly discharge the material from the reactor, allow it to cool naturally, and send it to a double roller crusher for slight crushing. Pass it through a vibrating screen and take particles with a particle size of 3-6mm to obtain the wastewater treatment composite purification agent.

[0035] Example 2 A method for preparing a composite wastewater treatment purifier includes the following steps: S1. Mix nano-aluminum powder and zeolite at a mass ratio of 1:6, purge with nitrogen, and ball mill at 300 rpm for 2 hours to obtain nano-aluminum powder@zeolite inclusion complex, which is ready for use. S2. Chitosan was dissolved in 2 wt.% acetic acid solution. Mercaptoacetic acid was added at a mass ratio of 1:0.5 (chitosan to mercaptoacetic acid) and reacted at 60°C for 5 hours. The pH was adjusted to 7. The precipitate was washed and freeze-dried to obtain mercapto-chitosan. Mercapto-chitosan was then dissolved in 2 wt.% acetic acid solution, and 0.1 mol / L ferric chloride solution (mercapto-chitosan to ferric chloride mass ratio of 4:1) was added dropwise while stirring. After the addition was complete, the mixture was allowed to stand for 1 hour to form a dark brown coordination gel. The gel was centrifuged, freeze-dried, and pulverized through a 100-mesh sieve to obtain a mercapto-chitosan-ferric chloride coordination gel for later use. S3. Mix tea saponin and β-cyclodextrin at a mass ratio of 1:3, add to hot water at 66℃ and stir for 2 hours, let stand at 4℃ for 10 hours to allow inclusion complex crystals to precipitate, take the precipitated crystals, filter, dry, pulverize and pass through a 200-mesh sieve to obtain tea saponin-β-cyclodextrin inclusion complex, for later use; S4. Add 42g of porous ceramsite, 5g of nano-aluminum powder@zeolite inclusion complex obtained in S1, 10g of thiol chitosan-trivalent iron coordination gel obtained in S2, 6g of microcrystalline cellulose, and 1.2g of citric acid into a three-dimensional mixer and mix evenly. Transfer the mixture to a disc granulator and spray in 10% of the total mass of the material while rotating. Add water and granulate until the particle size is 2-4mm. Vacuum dry at 40℃ until the moisture content is ≤5% to obtain the core. Set aside for use. S5. Heat 6g of sulfur powder to 116℃ to melt it, add 12g of calcium carbonate powder, 5g of maifanite powder, and 3g of the tea saponin-β-cyclodextrin inclusion complex obtained in S3. Maintain the temperature within the range of 115-120℃ and stir at 80rpm for 12 minutes to obtain a molten slurry. At this temperature, add the core obtained in S4. The mass ratio of the core to the shell slurry is controlled at 1:0.4. Stir at 80rpm for 3 minutes to coat the core, forming a continuous shell with a thickness of about 0.5-1 mm. After coating, quickly discharge the material from the reactor, allow it to cool naturally, and send it to a double-roll crusher for slight crushing. Pass it through a vibrating screen and take particles with a particle size of 3-6mm to obtain the wastewater treatment composite purifying agent.

[0036] Example 3 A method for preparing a composite wastewater treatment purifier includes the following steps: S1. Mix nano-aluminum powder and zeolite at a mass ratio of 1:10, purge with nitrogen, and ball mill at 300 rpm for 2 hours to obtain nano-aluminum powder@zeolite inclusion complex, which is ready for use. S2. Chitosan was dissolved in 2 wt.% acetic acid solution. Mercaptoacetic acid was added at a mass ratio of 1:0.5 (chitosan to mercaptoacetic acid). The mixture was reacted at 60°C for 4 hours. The pH was adjusted to 7. The precipitate was washed and freeze-dried to obtain mercapto-chitosan. Mercapto-chitosan was then dissolved in 2 wt.% acetic acid solution. 0.1 mol / L ferric chloride solution (mercapto-chitosan to ferric chloride mass ratio of 4:1) was added dropwise while stirring. After the addition was complete, the mixture was allowed to stand for 1 hour to form a dark brown coordination gel. The gel was centrifuged, freeze-dried, and pulverized through a 100-mesh sieve to obtain a mercapto-chitosan-ferric chloride coordination gel for later use. S3. Mix tea saponin and β-cyclodextrin at a mass ratio of 1:3, add to hot water at 65℃ and stir for 2 hours, let stand at 4℃ for 15 hours to allow inclusion complex crystals to precipitate, take the precipitated crystals, filter, dry, pulverize and pass through a 200-mesh sieve to obtain tea saponin-β-cyclodextrin inclusion complex, for later use; S4. Add 58g of porous ceramsite, 10g of nano-aluminum powder@zeolite inclusion complex obtained in S1, 20g of thiol chitosan-trivalent iron coordination gel obtained in S2, 8g of microcrystalline cellulose, and 2g of citric acid into a three-dimensional mixer and mix evenly. Transfer the mixture to a disc granulator and spray in 10% of the total mass of the material while rotating. Add water and granulate until the particle size is 2-4mm. Vacuum dry at 45℃ until the moisture content is ≤5% to obtain the core. Set aside for use. S5. Heat 10g of sulfur powder to 117℃ to melt it, add 15g of shell powder, 5g of maifanite powder, and 7g of the tea saponin-β-cyclodextrin inclusion complex obtained in S3. Keep the temperature in the range of 115-120℃ and stir at 80rpm for 15 minutes to obtain a molten slurry. At this temperature, add the core obtained in S4. The mass ratio of the core to the shell slurry is controlled at 1:0.4. Stir at 80rpm for 5 minutes to form a continuous shell layer with a thickness of about 0.5-1 mm. After the coating is completed, quickly discharge the material from the reactor, allow it to cool naturally, and send it to a double roller crusher for slight crushing. Pass it through a vibrating screen and take particles with a particle size of 3-6mm to obtain the wastewater treatment composite purification agent.

[0037] Comparative Example 1 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: This comparative example does not add nano-aluminum powder@zeolite inclusion complex; instead, porous ceramsite is used to make up to the same mass.

[0038] Comparative Example 2 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: This comparative example does not contain thiol-chitosan-ferric coordination gel; the mass is supplemented with porous ceramic particles to achieve the same level.

[0039] Comparative Example 3 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: This comparative example does not contain citric acid and is made up to equal mass using porous ceramsite.

[0040] Comparative Example 4 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: This comparative example does not contain tea saponin-β-cyclodextrin inclusion complex; the amount is made up to equal mass with carbonate powder.

[0041] Comparative Example 5 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: This comparative example does not add maifanite powder, but uses carbonate powder to make up to the same mass.

[0042] Comparative Example 6 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, nano-aluminum powder and zeolite were mixed at a mass ratio of 1:4 in step S1.

[0043] Comparative Example 7 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, in step S1, nano-aluminum powder and zeolite are mixed at a mass ratio of 1:12.

[0044] Comparative Example 8 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, step S4 involves vacuum drying at 35°C until the moisture content is ≤5%.

[0045] Comparative Example 9 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, step S4 involves vacuum drying at 55°C until the moisture content is ≤5%.

[0046] Comparative Example 10 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, the sulfur powder heating temperature in step S5 is 110℃.

[0047] Comparative Example 11 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, the sulfur powder was heated at 125°C in step S5.

[0048] Comparative Example 12 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, the sulfur coating time in step S5 was 2 minutes.

[0049] Comparative Example 13 A method for preparing a wastewater treatment and purification agent, the steps not specifically described are generally the same as in Example 1, the difference being: In this comparative example, the sulfur coating time in step S5 was 10 minutes.

[0050] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-13, and the specific test methods are as follows: (1) Chemical oxygen demand (COD) was determined according to the "Determination of Chemical Oxygen Demand in Water - Dichromate Method" (HJ 828-2017). The test water sample was the effluent from the primary sedimentation tank of a municipal sewage treatment plant, with an initial COD concentration of approximately 320 mg / L. 800 mL of the test water sample was added to a 1 L beaker, and the purification agent samples prepared in each example and comparative example were added at a dosage of 3 g / L. First, the mixture was stirred rapidly at 200 rpm for 5 minutes to fully disperse the purification agent, followed by slow stirring at 50 rpm for 30 minutes, and then allowed to settle for 30 minutes. The supernatant was taken, and potassium dichromate standard solution and sulfuric acid-silver sulfate solution were added. The mixture was refluxed at 165 °C for 2 hours for digestion, and after cooling, it was titrated with ferrous ammonium sulfate standard solution. Each batch of samples was measured in triplicate, and a blank experiment was performed simultaneously.

[0051] COD removal rate is calculated using the following formula: COD removal rate (%) = (initial COD concentration - final COD concentration) / initial COD concentration × 100%.

[0052] (2) Suspended solids (SS) were determined according to the "Determination of Suspended Solids in Water - Gravimetric Method" (GB 11901-89). The test water sample was the same as that for COD, and the initial SS concentration was approximately 180 mg / L. After adding the purifying agent, stirring, and allowing it to stand under the same conditions, 100 mL of the supernatant was taken and filtered through a 0.45 μm filter membrane that had been dried to constant weight at 103-105 °C. The filter membrane was washed with a small amount of distilled water, and the filter membrane along with the precipitate was placed in a weighing bottle and dried in an oven at 103-105 °C for 1 hour. After being removed and cooled to room temperature in a desiccator, it was weighed, and the drying process was repeated until constant weight was achieved. Each batch of samples was measured in parallel three times. During the settling process, the interface height between the supernatant and the precipitate was recorded every 5 minutes, and the settling velocity (the distance the interface height decreased divided by the time) was calculated.

[0053] The SS removal rate is calculated using the following formula: SS removal rate (%) = (initial SS concentration - final SS concentration) / initial SS concentration × 100%.

[0054] (3) Heavy metal ions (Pb) 2+ The determination of copper, zinc, lead and cadmium in water was carried out according to the standard "Determination of Copper, Zinc and Lead in Water by Atomic Absorption Spectrophotometry" (GB7475-87). The test water sample was simulated heavy metal wastewater prepared by adding lead nitrate standard solution to deionized water. 2+ The initial concentration was 0.8 mg / L. The purifying agent sample was added at a dosage of 3 g / L, stirred rapidly at 200 rpm for 5 minutes, then stirred slowly at 50 rpm for 30 minutes, and allowed to stand for 30 minutes. The supernatant was filtered through a 0.45 μm filter membrane, acidified with 1.5 mL of nitric acid, and diluted to 50 mL. The determination was performed using an atomic absorption spectrophotometer, with the wavelength set to 283.3 nm and the flame type set to air-acetylene, according to the instrument's operating conditions. A standard series of 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.80 mg / L, and 1.00 mg / L was prepared by serially diluting lead standard stock solution (1000 mg / L), and a standard curve was plotted. Each batch of samples was measured in triplicate, and a blank experiment was performed simultaneously.

[0055] The removal rate of heavy metal ions is calculated using the following formula: Pb 2+ Removal rate (%) = (Pb) 2+ Initial concentration - Pb 2+ (final concentration) / Pb 2+ Initial concentration × 100%.

[0056] (4) Nitrate nitrogen (NO3) --N) was determined according to the "Determination of Nitrate Nitrogen in Water - Ultraviolet Spectrophotometry" (HJ / T 346-2007). The test water sample was a simulated nitrate-containing wastewater prepared by adding potassium nitrate standard solution to deionized water and inoculating it with returned sludge from a municipal wastewater treatment plant (the inoculum amount was approximately 5% of the test water sample volume). NO3 - The initial NO3- concentration was 50 mg / L. The purifying agent sample was added at a dosage of 5 g / L and incubated statically at room temperature for 11 days under sealed conditions. The supernatant was collected on day 1 and day 11, filtered through a 0.45 μm filter, and the absorbance was measured at wavelengths of 220 nm and 275 nm. NO3- was calculated based on the standard curve. - -N concentration. Each batch of samples was measured in triplicate.

[0057] The initial reduction rate is calculated using the following formula: Initial reduction rate (mg / L·d) = (initial concentration - day 1 concentration) / day.

[0058] The cumulative removal rate is calculated using the following formula: NO3 - -N removal rate (%) = (initial concentration - concentration on day 11) / initial concentration × 100%.

[0059] The hydrogen production rate was determined using the water displacement method, based on the principles outlined in "Determination of Gas Volume in Gas Analysis - Volumetric Method". The test water sample was deionized water, and the water temperature was controlled at 25±2℃. 300mL of deionized water was added to a 500mL three-necked flask, followed by the addition of the purifying agent sample at a dosage of 3g / L. The flask was then quickly sealed, and the generated gas was collected using the water displacement method. The gas production rate was recorded every 5 minutes for 60 minutes.

[0060] The hydrogen production rate is calculated using the following formula: Hydrogen production rate (mL / min·g) = Gas production volume during the time period (mL) / Time during the time period (min) / Mass of purifying agent (g).

[0061] Record the peak hydrogen production rate and total hydrogen production. Each batch of samples was measured in triplicate, and the arithmetic mean was taken.

[0062] The specific test results of Examples 1-3 and Comparative Examples 1-13 are shown in the table below: Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-13 As shown in Table 1, the wastewater treatment composite purifiers of Examples 1-3 of this invention achieve controlled and slow release of aluminum powder through nano-aluminum powder@zeolite inclusion complex. Upon contact with water, it synergistically generates smooth and continuous hydrogen microbubbles with citric acid. During the upward movement of these bubbles, suspended matter is carried to form flocs, achieving rapid solid-liquid separation. Simultaneously, the aluminum hydroxide generated by the hydrolysis of aluminum powder has a flocculation effect, which can further capture colloidal particles and some dissolved organic matter in the water. Therefore, the COD removal rate reaches over 80%, and the SS removal rate reaches over 90%. Furthermore, the thiol groups (-SH) in the thiol-chitosan-ferric coordination gel have a strong chelating ability for lead ions, which can convert dissolved lead into insoluble chelates. At the same time, the slow release of ferric iron hydrolyzes to generate ferric hydroxide flocs, which assist in flocculation and adsorption of trace amounts of lead. The two work synergistically to reduce Pb 2+ The removal rate can reach 96.5%. The shell is composed of sulfur powder, carbonate, maifanite, and tea saponin-β-cyclodextrin inclusion complex. Sulfur acts as an electron donor to support the growth and metabolism of sulfur-autotrophic denitrifying bacteria. Maifanite releases trace elements to promote microbial activity, and carbonate neutralizes the acidity produced during denitrification. The three work synergistically to reduce NO3. - The removal rate of -N reaches over 98%, while the tea saponin-β-cyclodextrin inclusion complex can slowly release tea saponin, continuously reduce interfacial tension, release bound water, and assist in the flotation and flocculation processes. This allows the resulting composite wastewater treatment agent to efficiently and stably remove multiple pollutants, adapt to complex water bodies, and has good industrial promotion value.

[0063] Comparative Example 1, without the addition of nano-aluminum powder@zeolite inclusion complex, lacks hydrogen-producing components in its core. Suspended solids are removed solely through physical filtration and gravity sedimentation, resulting in a significant decrease in SS removal rate to 72.2% and COD removal rate to 60.1%. Comparative Example 2, without the addition of thiol-chitosan-ferric coordination gel, lacks heavy metal chelation and iron flocculation functions in its core. Heavy metal ions are removed solely through sulfide precipitation generated from sulfur powder in the shell and physical adsorption by porous ceramsite and maifanite. Pb... 2+ The removal rate dropped to 80.0%; Comparative Example 3, without citric acid, lacked a trigger in the core, resulting in a slow reaction between aluminum powder and water, a low initial hydrogen production rate, and a reaction concentrated in the middle and late stages, leading to unstable flotation performance. The SS removal rate was 89.8%, the COD removal rate was 77.1%, and the hydrogen production rate was 3.58 mL / min·g; Comparative Example 4, without tea saponin-β-cyclodextrin inclusion complex, lacked a surfactant in the shell, causing some organic matter to be encapsulated within the flocs and unable to be fully removed, resulting in a COD removal rate of 76.9%; Comparative Example 5, without maifanite powder, lacked adsorption and promotion of microbial activity, significantly reducing nitrogen removal efficiency, and NO3... -The initial reduction rate of -N decreased to 6.44 mg / L·d, and the cumulative removal rate decreased to 76.6%. In Comparative Example 6, the ratio of aluminum powder to zeolite was 1:4, resulting in insufficient zeolite encapsulation and exposure of a large amount of free aluminum powder. Upon contact with water, the reaction was extremely vigorous, with a hydrogen production rate as high as 5.89 mL / min·g. This led to rapid aggregation of bubbles into large bubbles, localized increases in water temperature, and accelerated thermal decomposition of thiol-chitosan, while also posing a safety risk of hydrogen combustion or explosion. In Comparative Example 7, the ratio of aluminum powder to zeolite was 1:12. Excessive zeolite resulted in excessively high aluminum powder dispersion, with the particle surface overly coated by zeolite. This significantly reduced the contact area between the aluminum powder and water, leading to a low hydrogen production rate. With a drying rate of only 1.23 mL / min·g, a large amount of suspended solids could not be effectively carried to the surface, resulting in a SS removal rate of 82.0% and a COD removal rate of 70.5%. In Comparative Example 8, the core drying temperature was 35℃, which was insufficient and prolonged the drying time, making it difficult to reduce the core moisture content to below 5%. The residual moisture vaporized during the molten sulfur coating process, forming a large number of bubbles and pores in the shell, which destroyed the continuity and density of the shell. The hydrogen production reaction of the nano-aluminum powder was out of control, and the overall performance decreased. In Comparative Example 9, the core drying temperature was 55℃, which was too high and caused the thiol groups in the thiol chitosan to undergo thermal oxidation and decomposition, resulting in a decrease in chelation ability and Pb removal. 2+ The removal rate dropped to 87.2%; in Comparative Example 10, the sulfur powder was heated to 110℃, which is below the complete melting temperature of sulfur. At this temperature, sulfur is still in a semi-molten state, with excessively high viscosity and extremely poor fluidity, making it difficult to uniformly coat the core particles. A large number of cores are exposed, leading to uncontrolled hydrogen production. At the same time, the lack of a sulfur shell results in heavy metal precipitation and impaired denitrification function, significantly reducing overall performance. In Comparative Example 11, the sulfur powder was heated to 125℃. Sulfur underwent a thermal polymerization reaction at high temperature, causing a sharp increase in viscosity. High-viscosity molten sulfur also made it difficult to uniformly coat the core, and the impurities produced by oxidation damaged the chemical stability of the shell. The overall performance decline was more severe than in Comparative Example 10. In addition, some sulfur was oxidized by oxygen in the air to produce sulfur dioxide, generating an irritating odor. In Comparative Example 12, the molten sulfur powder was heated to 125℃. Sulfur underwent a thermal polymerization reaction at high temperature, causing a sharp increase in viscosity. High-viscosity molten sulfur also made it difficult to uniformly coat the core, and the impurities produced by oxidation damaged the chemical stability of the shell. The overall performance decline was more severe than in Comparative Example 10. At the same time, some sulfur was oxidized by oxygen in the air to produce sulfur dioxide, generating an irritating odor. The sulfur coating time was 2 minutes, which was too short. The contact time between the molten sulfur and the core particles was insufficient, and the sulfur slurry failed to spread and wet the core surface. The shell thickness was uneven, and some areas had too thin a shell or even exposed points. The hydrogen production rate and the stability of heavy metal removal were affected. In Comparative Example 13, the molten sulfur coating time was 10 minutes, which was too long. The core particles were heated in molten sulfur at 115-120℃ for a long time. The nano-aluminum powder in the core underwent surface oxidation or even reacted with water vapor prematurely. The thiol chitosan underwent thermal decomposition. In addition, the long-term stirring caused collisions and friction between the core particles, and some particles broke. The broken core fragments were mixed into the shell slurry, resulting in uneven particle size distribution. Some particles lost their core-shell structure, and the overall performance decreased.

[0064] In summary, the wastewater treatment composite purifier of this invention has a core-shell structure, with porous ceramsite, nano-aluminum powder@zeolite inclusion complex, thiol chitosan-ferric trivalent coordination gel, microcrystalline cellulose, and citric acid as the core, and sulfur powder, carbonate powder, maifanite powder, and tea saponin-β-cyclodextrin inclusion complex as the outer shell. Wastewater is pretreated through the adsorption of maifanite in the outer shell and the antibacterial effects of sulfur powder and tea saponin, reducing the load on the core. The carbonate and tea saponin inclusion complex dissolve and release upon contact with water, forming mass transfer channels and providing immediate antibacterial effects. After wastewater penetrates the core, microcrystalline cellulose gradually degrades and citric acid is slowly released, maintaining the long-term effectiveness of the active components in the core. Deep purification is achieved through ion exchange of zeolite, coordination chelation of thiol groups, anion adsorption of ferric trivalents, and oxidative degradation of aluminum powder. This gives the purifier both rapid response and long-term stability, enabling the simultaneous and efficient removal of multiple pollutants such as suspended solids, organic matter, heavy metals, and ammonia nitrogen from wastewater. It can adapt to complex water bodies and has good industrial application value.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite wastewater treatment purifying agent, characterized in that, Includes the following steps: S1. Mix nano-aluminum powder and zeolite at a mass ratio of 1:(6-10) and ball mill to obtain nano-aluminum powder@zeolite inclusion complex, which is ready for use; S2. Dissolve chitosan in acetic acid solution, add mercaptoacetic acid to react, take the precipitate, wash, freeze dry to obtain mercaptochitosan; then dissolve mercaptochitosan in acetic acid solution, add ferric iron source solution dropwise, gel, centrifuge, freeze dry, pulverize to obtain mercaptochitosan-ferric iron coordination gel, for later use; S3. Mix tea saponin with β-cyclodextrin, add hot water and stir, let stand at low temperature for 8-16 hours, take the precipitated crystals, filter, dry, and pulverize to obtain tea saponin-β-cyclodextrin inclusion complex for later use; S4. Mix the porous ceramsite, the nano-aluminum powder@zeolite inclusion complex obtained in S1, the mercapto-chitosan-trivalent iron coordination gel obtained in S2, microcrystalline cellulose, and citric acid evenly, add water and granulate to a particle size of 2-4 mm, and vacuum dry at 40-50℃ to a moisture content of ≤5% to obtain the core, which is ready for use. S5. Heat the sulfur powder to 115-120℃ to melt it, add carbonate powder, maifanite powder, and the tea saponin-β-cyclodextrin inclusion complex obtained in S3, keep it warm and stir to obtain a molten slurry, add the core obtained in S4 at this temperature, stir at 60-100 rpm for 3-5 minutes to coat it, cool naturally, crush and sieve, and take particles with a particle size of 3-6 mm to obtain the wastewater treatment composite purification agent.

2. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The ball milling described in S1 is carried out under inert gas protection, with a rotation speed of 200-400 rpm and a time of 1-3 hours.

3. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The mass ratio of chitosan to mercaptoacetic acid in S2 is 1:(0.3-0.6); the mass ratio of mercaptochitosan to trivalent iron source in S2 is (3-5):

1.

4. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The trivalent iron source mentioned in S2 is one or more of ferric chloride, ferric sulfate, and ferric nitrate.

5. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The mass ratio of tea saponin to β-cyclodextrin in S3 is 1:(2-4).

6. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The hot water temperature in S3 is 50-70℃; the low-temperature settling temperature in S3 is 2-8℃.

7. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The mass ratio of the porous ceramic particles, nano-aluminum powder@zeolite inclusion complex, and thiol chitosan-ferric coordination gel in S4 is (8-12):(1-2):(2-4).

8. The method for preparing a composite wastewater treatment purifier according to claim 1, characterized in that: The mass ratio of sulfur powder, carbonate powder, maifanite powder, and tea saponin-β-cyclodextrin inclusion complex in S5 is (5-12):(10-20):(3-8):(3-8).

9. A composite purifying agent for wastewater treatment, characterized in that: The wastewater treatment composite purification agent is prepared according to any one of claims 1-8.

10. The application of the composite purifying agent for wastewater treatment according to claim 9, characterized in that: Used for wastewater treatment.

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