An environmental protection purifying agent for fireworks and crackers and a preparation method and application thereof

Abstract

The present application belongs to the technical field of environmental functional materials, and particularly relates to an environmentally-friendly purifying agent for fireworks and firecrackers as well as a preparation method and application thereof. The purifying agent is composed of two self-made core compounds and various commercially available materials. The first core compound is phosphotungstic acid-titania mesoporous spheres, which are prepared by a reverse microemulsion method combined with hydrothermal crystallization, and the inner core of phosphotungstic acid is coated with titania formed by hydrolysis of tetrabutyl titanate. The second core compound is a transition metal-nitrogen co-doped graphene-coated spinel composite. The magnesium-aluminum spinel precursor is prepared by a coprecipitation method, and after pre-carbonization by melamine, cobalt acetylacetonate and manganese acetylacetonate are introduced into a chemical vapor deposition system to in-situ grow a doped graphene film on the surface of the spinel. The present application utilizes the synergistic effect of adsorption, catalysis and disinfection of the two modified compounds to efficiently remove the smoke, PM2.5 and harmful gases generated by the burning of fireworks and firecrackers, and is suitable for various types of fireworks and firecrackers.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to an environmentally friendly purifying agent for fireworks and firecrackers, its preparation method, and its application. Background Technology

[0002] Fireworks play an indispensable role in celebrations around the world. However, traditional fireworks formulas commonly use potassium perchlorate as an oxidant, along with combustible materials such as sulfur and charcoal. Furthermore, to produce vibrant colors, various metal salts are introduced, such as strontium salts for red, barium salts for green, and copper salts for blue. This complex chemical composition results in the release of large amounts of pollutants upon ignition, including fine particulate matter, sulfur oxides, nitrogen oxides, carbon monoxide, and various heavy metal compounds, causing serious damage to the atmospheric environment.

[0003] Studies have shown that during large-scale fireworks events, PM2.5 concentrations in the surrounding area can surge dozens or even hundreds of times in a short period. These fine particulate matter not only contain high concentrations of inorganic salts such as potassium ions, chloride ions, and sulfate ions, but also carry toxic metallic elements such as barium, chromium, and copper. They can penetrate deep into the human respiratory tract and enter the circulatory system, inducing or aggravating respiratory and cardiovascular diseases.

[0004] To address this environmental challenge, researchers are dedicated to developing environmentally friendly fireworks products and pollution control technologies. On the one hand, they are attempting to reduce pollution emissions at the source by adopting sulfur-free formulas, reducing metal additives, or replacing traditional explosives with nitrocellulose with moderate nitrogen content. On the other hand, they are trying to reduce pollutant generation by adding inert substances such as sodium bicarbonate to fireworks formulas to dilute reactant concentrations and lower combustion temperatures. However, while existing environmentally friendly fireworks can reduce particulate matter emissions by 15% to 65%, their peak PM2.5 concentrations still far exceed air quality standards, and they cannot completely eliminate the risk of diffusion of already generated pollutants. Traditional physical adsorption methods, such as activated carbon filtration or water spraying for dust suppression, have significant limitations in handling the high-temperature, high-concentration, and multi-component complex smoke generated during fireworks display. Their adsorption capacity quickly saturates and they cannot effectively treat gaseous pollutants. Therefore, there is an urgent need to develop a new environmentally friendly technology that can work synchronously with fireworks display and has a broad-spectrum purification capability for multiphase pollutants to achieve the sustainable development of the fireworks industry. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an environmentally friendly purifying agent for fireworks and firecrackers, its preparation method and application.

[0006] In a first aspect, the present invention provides a method for preparing an environmentally friendly purifying agent for fireworks and firecrackers, comprising the following steps: S1. By weight, 10-20 parts of amino-modified mesoporous silica are placed in a mixer, and an ethanol suspension containing 15-25 parts of phosphotungstic acid-titanium dioxide mesoporous spheres is sprayed in while stirring; after spraying, the mixture is dried at 58-62℃ to obtain a pre-composite powder. S2. Add the pre-composite powder, 20-35 parts of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 8-15 parts of coconut shell activated carbon, 5-12 parts of diatomaceous earth, 10-20 parts of calcium hydroxide, 3-8 parts of silver-loaded zeolite, and 1-3 parts of sodium polyacrylate to a mixer, add 2-5 parts of fumed silica, and mix.

[0007] In this invention, the overall mechanism of action of the environmentally friendly purifying agent for fireworks and firecrackers relies on the synergistic purification effect of multiple components. Amino-modified mesoporous silica serves as a carrier, achieving a robust loading of phosphotungstic acid-titanium dioxide mesoporous spheres through a silane coupling agent, enhancing interfacial bonding and catalytic activity. Coconut shell activated carbon, with its high specific surface area and porous structure, efficiently adsorbs volatile organic compounds and fine particulate matter in the flue gas. Silver-loaded zeolite slowly releases silver ions at high temperatures, continuously inhibiting airborne pathogens. Calcium hydroxide neutralizes acidic components in the flue gas, reducing corrosiveness. Sodium polyacrylate absorbs moisture to form a hydrogel network, encapsulating and fixing ultrafine particles, reducing dust. Fumed silica acts as an electrostatic isolator, preventing powder agglomeration. The mixing process is optimized in stages: primary macro-mixing ensures uniform component distribution, while micro-diffusion mixing achieves charge balance and particle dispersion. When applied to fireworks displays, the purifying agent simultaneously exerts adsorption, catalytic oxidation, antibacterial, and fixation effects in high-temperature flue gas, effectively reducing the emission of harmful gases and particulate matter, significantly improving the environmental friendliness and safety of fireworks displays.

[0008] According to a preferred embodiment of the present invention, in step S1, the drying time at 58-62°C is 2-4 hours.

[0009] According to a preferred embodiment of the present invention, in step S2, the mixing time is 2-4 hours.

[0010] According to a preferred embodiment of the present invention, the method for preparing the phosphotungstic acid-titanium dioxide mesoporous spheres includes: A1. By weight, 100-200 parts of cyclohexane, 15-25 parts of Span 80, and 5-15 parts of n-hexanol are mixed to obtain an oil phase; an aqueous solution containing 5-15 parts of phosphotungstic acid is added dropwise to the oil phase under ultrasonic oscillation to obtain a microemulsion; 20-40 parts of tetrabutyl titanate are dissolved in anhydrous ethanol and mixed with a solution composed of 10-20 parts of deionized water, 0.5-2 parts of dilute nitric acid, and ethanol to obtain a titanium dioxide suspension; the titanium dioxide suspension is added dropwise to the microemulsion, and the mixture is stirred at 5-8°C to obtain a reaction mixture; A2. Transfer the reaction mixture to a high-pressure reactor and hydrothermally crystallize it at 115-125℃. After centrifugation, a solid product is obtained. Wash the solid product with ethanol and acetone, and vacuum dry it at 58-62℃ to obtain a dried product. Calcine the dried product at 345-355℃.

[0011] In this invention, the preparation of phosphotungstic acid-titanium dioxide mesoporous spheres is based on reverse microemulsion technology, achieving controllable assembly of the core-shell structure through precise regulation of interfacial chemistry. First, a homogeneous microemulsion is formed using cyclohexane as the oil phase and Span 80 and n-hexanol as the surfactant system, in which an aqueous phosphotungstic acid solution is encapsulated within nanoscale micelle "pools". Subsequently, tetrabutyl titanate is dissolved in ethanol in an acidic environment containing dilute nitric acid to form a titanium dioxide precursor suspension. Under low-temperature conditions, the hydrolysis and condensation reaction of tetrabutyl titanate is strictly controlled to avoid rapid precipitation, generating a uniform titanium dioxide sol. This suspension is dropwise added to the microemulsion, and high-speed shearing promotes the deposition of titanium dioxide at the oil-water interface with phosphotungstic acid as the core, gradually forming a dense core-shell structure. After the reaction is complete, the pH is adjusted to neutral using ammonia to promote the cross-linking and solidification of the titanium dioxide shell. Finally, hydrothermal crystallization transforms amorphous titanium dioxide into a crystalline anatase phase, simultaneously constructing a stable mesoporous network. Washing and calcination yield a white powder with a high specific surface area. The key to this process lies in using acidic conditions to suppress the violent hydrolysis of tetrabutyl titanate, ensuring uniform coating of titanium dioxide and forming a composite support that combines catalytic activity and structural stability.

[0012] According to a preferred embodiment of the present invention, in step A1, the stirring reaction time is 4-6 hours.

[0013] According to a preferred embodiment of the present invention, in step A2, the dried product is calcined at 345-355°C for 2-4 hours.

[0014] According to a preferred embodiment of the present invention, the preparation method of the porous transition metal-nitrogen co-doped graphene-coated spinel composite includes: dissolving 25-35 parts by weight of magnesium nitrate and 75-85 parts by weight of aluminum nitrate in deionized water to obtain a metal salt solution; mixing the metal salt solution, an aqueous solution containing 100-150 parts by weight of ammonium carbonate, and 1-3 parts by weight of polyvinylpyrrolidone under stirring, adjusting the pH to 9.0-10.0, aging at 58-62°C, filtering, and washing to obtain a washed filter cake; and then... The filter cake was dried at 78-82℃ to obtain the precursor hydroxide; the precursor hydroxide was mixed and ground with 20-30 parts of melamine, and heated to 595-605℃ under argon protection to obtain the pretreated material; the pretreated material was transferred to a chemical vapor deposition system, and a mixed vapor of 3-8 parts of cobalt acetylacetone and 2-5 parts of manganese acetylacetone carried by argon was introduced, while a mixture of hydrogen and argon was introduced, and the reaction was carried out at 745-755℃; under an argon atmosphere, it was cooled to room temperature, ground and sieved.

[0015] In this invention, the synthesis of porous transition metal-nitrogen co-doped graphene-coated spinel composites is achieved through a three-step synergistic process of co-precipitation, pyrolysis, and chemical vapor deposition. In the initial stage, a magnesium aluminum salt solution and an ammonium carbonate precipitant are co-precipitated under alkaline conditions to form a uniform hydroxide precursor, which, after drying, yields a spinel precursor. Subsequently, the precursor is mixed with melamine and pyrolyzed. The melamine decomposes under an inert atmosphere to generate a nitrogen-rich carbon layer, which coats the spinel surface to form a nitrogen-doped carbon matrix. The key step is chemical vapor deposition: the pretreated material is placed in an inert atmosphere, and an argon carrier gas containing a cobalt-manganese metal-organic source is introduced, along with a hydrogen-argon mixture. Under high-temperature conditions, the metal-organic source decomposes to generate cobalt-manganese active atoms, which react in situ with the nitrogen-carbon layer, driving the continuous growth of the graphene film on the spinel surface to form a two-dimensional transition metal-nitrogen co-doped graphene coating. This process not only achieves precise doping of metal atoms but also enhances electron transfer capabilities by partially penetrating the spinel surface to form defect sites. After final cooling and grinding, a composite material with porous structure, conductivity and catalytic activity was obtained, and its graphene film coating characteristics are significantly different from those of the three-dimensional network structure.

[0016] According to a preferred embodiment of the present invention, the reaction time at 745-755°C is 30-60 min.

[0017] In a second aspect, the present invention provides an environmentally friendly purifying agent for fireworks and firecrackers prepared by the method described above.

[0018] A third aspect of the present invention provides the application of the aforementioned environmentally friendly purifying agent for fireworks and firecrackers in high-altitude and low-altitude fireworks, ground-based box fireworks, single-row launching fireworks, rotating fireworks, net-screen fireworks, daytime fireworks, cold-light fireworks, and firecrackers.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The environmentally friendly purifier for fireworks and firecrackers proposed in this invention and its preparation method achieve highly efficient integrated purification of smoke, fine particulate matter, toxic gases and biological pollutants under extreme conditions of fireworks and firecrackers through the synergistic compounding of two newly designed inorganic modified compounds and a variety of commercially available functional materials, demonstrating excellent technical effects. First, this invention excels in physical capture and particulate matter removal. The purifier introduces a porous transition metal-nitrogen co-doped graphene-coated spinel composite with an ultra-large specific surface area. The graphene film on its surface endows the material with excellent conductivity and electrostatic adsorption capacity, which can effectively capture submicron-sized particulate matter generated by fireworks explosions, especially PM2.5 fine particles, which are most harmful to human health. At the same time, the coconut shell activated carbon in the formula provides a rich microporous structure for adsorbing small molecule gaseous pollutants, while diatomaceous earth provides macroporous channels for intercepting larger particle sizes of smoke and unburned carbon residue. This multi-level pore system design, from micropores and mesopores to macropores, enables the stepwise physical interception and enrichment of pollutants of different particle sizes, significantly improving the total capture capacity of the purifier for smoke and dust.

[0020] (2) In terms of chemical transformation and purification of harmful gases, this invention demonstrates deep processing capabilities. The introduction of two core innovative compounds is key. On the one hand, the core-shell structure of phosphotungstic acid-titanium dioxide mesoporous spheres achieves spatial coupling of acid catalysis and photocatalysis: the core phosphotungstic acid, as a strong solid acid, can efficiently adsorb and catalyze the hydrolysis of irritating acidic gases produced by fireworks, such as hydrogen chloride, chlorine, and sulfur dioxide, converting them into easily fixed chloride and sulfate ions; the outer titanium dioxide shell generates strong oxidizing free radicals under the strong light excitation of fireworks, deeply degrading volatile organic compounds and organic pollutants such as maleates in aerosols. On the other hand, the porous transition metal-nitrogen co-doped graphene-coated spinel composite utilizes the dual active centers formed by cobalt and manganese atoms and oxygen vacancies on the spinel surface to efficiently catalyze the oxidation of carbon monoxide to carbon dioxide under the residual heat of fireworks, and the nitrogen oxides are oxidized and then absorbed and fixed by the alkaline component calcium hydroxide in the formula. In addition, calcium hydroxide, as an alkaline absorbent, can widely neutralize and fix acidic gases such as sulfur dioxide and nitrogen oxides, forming a good synergistic effect with the core catalytic material.

[0021] (3) In terms of disinfection function and overall stability, this invention also achieves significant breakthroughs. The silver-loaded zeolite added to the formula releases silver ions to inactivate pathogenic microorganisms such as bacteria and viruses that may be carried in fireworks aerosols through contact, providing continuous biosafety protection. At the same time, cross-linked sodium polyacrylate can absorb moisture in the flue gas and form a gel with inorganic salts, effectively wrapping and fixing the captured fine particles, preventing them from being re-emitted, and forming stable and solidified pollution products. The addition of hydrophobic fumed silica not only prevents the agglomeration of ultrafine powder in high humidity environments, ensuring that the purifier has good dispersibility and spraying effect when used, but also endows the overall material with excellent moisture resistance and anti-sintering ability through synergistic effect with the graphene coating layer. Detailed Implementation

[0022] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0023] Example 1 This embodiment provides a method for preparing an environmentally friendly purifying agent for fireworks and firecrackers: First, phosphotungstic acid-titanium dioxide mesoporous spheres were prepared according to the following method.

[0024] A1. Add 150g cyclohexane, 20g Span 80, and 10g n-hexanol to a reaction vessel and stir at 300rpm for 30min at room temperature until homogeneous to obtain the oil phase. Under ultrasonic oscillation power of 200W, add 30g of deionized water containing 10g phosphotungstic acid to the oil phase at a dropping rate of 2mL / min. After the addition is complete, continue ultrasonic oscillation for 20min to form a homogeneous and transparent reverse microemulsion, denoted as microemulsion A. In a separate reaction vessel, 30g of tetrabutyl titanate was dissolved in 60g of anhydrous ethanol and stirred for 10 min to obtain a transparent solution. 15g of deionized water, 1g of 5% dilute nitric acid, and 20g of anhydrous ethanol were mixed thoroughly to obtain an acidic aqueous alcohol solution. Under ice-water bath cooling, the acidic aqueous alcohol solution was added dropwise to the tetrabutyl titanate ethanol solution at a rate of 1 mL / min, while maintaining a stirring speed of 500 rpm during the addition. After the addition was complete, stirring was continued for 30 min to obtain a milky white, semi-transparent titanium dioxide suspension, denoted as suspension B. Suspension B was placed in a constant-pressure dropping funnel and, under conditions of a high-speed shear stirrer at 8000 rpm and a reaction system temperature controlled at 6℃, suspension B was slowly added dropwise to microemulsion A at a rate of 0.5 mL / min. After the addition was complete, high-speed shear stirring was continued for 5 h to obtain the reaction mixture.

[0025] A2. Transfer the reaction mixture obtained in step A1 to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in an oven. Heat the mixture to 120°C at a rate of 2°C / min, and perform hydrothermal crystallization at this temperature for 24 hours. After the reaction, allow it to cool naturally to room temperature. Centrifuge the reaction mixture at 8000 rpm for 10 minutes, discard the supernatant, and obtain a solid crude product. Wash the solid crude product three times with anhydrous ethanol, adding 50 g of anhydrous ethanol each time, and ultrasonically disperse for 5 minutes before centrifugation. Then wash it three times with acetone, adding 50 g of acetone each time, and ultrasonically disperse before centrifugation. Place the washed solid product in a vacuum drying oven and dry it at 60°C and a vacuum of -0.08 MPa for 12 hours to obtain a dried product. Place the dried product in a muffle furnace and heat it to 350°C at a rate of 2°C / min. Calcinate at this temperature for 3 hours, allow it to cool naturally to room temperature, and grind it to obtain white powdered phosphotungstic acid-titanium dioxide mesoporous spheres, denoted as HPW-TiO2-MS.

[0026] Secondly, porous transition metal-nitrogen co-doped graphene-coated spinel composites were prepared according to the following method.

[0027] 30g of magnesium nitrate hexahydrate and 80g of aluminum nitrate nonahydrate were dissolved in 200g of deionized water and stirred at 400rpm for 30min at room temperature to obtain a completely dissolved metal salt solution, denoted as solution C. 130g of ammonium carbonate was dissolved in 300g of deionized water to prepare an ammonium carbonate aqueous solution, denoted as solution D. 2g of polyvinylpyrrolidone was dissolved in 50g of deionized water to obtain a dispersant solution. The dispersant solution was added to the reaction vessel and stirred at 600rpm under a 60℃ water bath heating condition. Solutions C and D were simultaneously added dropwise to the reaction vessel using two constant flow pumps in a parallel flow manner. The dropping rate was controlled so that the dropping time of solution C was 1h, and the dropping rate of solution D was automatically adjusted according to pH changes. During the reaction, the pH value was adjusted online using a 10% (w / w) ammonia solution and a 1mol / L dilute nitric acid solution to maintain a stable pH of 9.5. After the addition was complete, the mixture was stirred and aged in a 60℃ water bath for 2h. After aging, the reaction mixture was vacuum filtered to obtain a filter cake. The filter cake was washed three times with deionized water, adding 200g of deionized water each time, stirring for 10min, and then filtering. This process was repeated. The washed filter cake was placed in a forced-air drying oven and dried at 80℃ for 12h to obtain the precursor hydroxide solid. The precursor hydroxide was mixed with 25g of melamine and placed in a planetary ball mill, where it was ground at 300rpm for 2h to ensure thorough mixing. The mixture was placed in a tube furnace, and argon gas was first introduced at a flow rate of 200mL / min to purge air for 30min. Then, under argon protection, the temperature was increased to 600℃ at a rate of 5℃ / min and held at this temperature for 2h to allow the melamine to pyrolyze and coat the surface of the spinel precursor. After natural cooling, the pretreated material was obtained. The pretreated material was placed in a quartz reaction tube of a chemical vapor deposition system, and argon gas was first introduced at a flow rate of 200mL / min to purge for 30min. Then, the temperature was increased to 750℃ at a rate of 10℃ / min. When the temperature reached 750℃, the argon gas was shut off, and a mixture of hydrogen and argon gas (hydrogen to argon volume ratio 1:9, total flow rate 100 mL / min) was introduced. Simultaneously, a mixture of cobalt acetylacetonate and manganese acetylacetonate vapors was introduced into the reaction tube via bubbling, with 5 g of cobalt acetylacetonate and 3 g of manganese acetylacetonate. The bubbling temperature was 180℃, and the carrier gas was argon gas at a flow rate of 50 mL / min. After reacting at 750℃ for 45 min, the metal-organic source and hydrogen gas were shut off, and the mixture was allowed to cool naturally to room temperature under argon gas flow rate of 200 mL / min. The resulting product was removed, ground in an agate mortar, and passed through a 400-mesh sieve to obtain a black powdery porous transition metal-nitrogen co-doped graphene-coated spinel composite, denoted as MNG / Spinel.

[0028] Finally, prepare the environmentally friendly purifying agent for fireworks and firecrackers according to the following steps.

[0029] S1. Place 15g of amino-modified mesoporous silica in a high-speed mixer. While stirring at 500rpm, spray an ethanol suspension containing 20g of phosphotungstic acid-titanium dioxide mesoporous spheres at a spray rate of 0.5mL / min through a precision atomizing nozzle. This suspension was pre-prepared by dispersing 20g of phosphotungstic acid-titanium dioxide mesoporous spheres in 80g of anhydrous ethanol and then ultrasonically vibrating for 20min. During spraying, maintain the material temperature at 25℃ and control the spraying speed to keep the material moist but without clumping. After spraying, increase the mixer speed to 1500rpm and continue stirring and dispersing for 10min to ensure the phosphotungstic acid-titanium dioxide mesoporous spheres are uniformly loaded onto the surface and pores of the amino-modified mesoporous silica. Then transfer the material to a vacuum drying oven and dry at 60℃ and a vacuum of -0.08MPa for 3h to obtain a pre-composite powder, denoted as composite powder A.

[0030] S2. Add all the pre-composite powder obtained in step S1, 28g of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 12g of coconut shell activated carbon, 8g of diatomaceous earth, 15g of calcium hydroxide, 5g of silver-loaded zeolite, and 2g of sodium polyacrylate sequentially to a three-dimensional motion mixer. Mix at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of all components. Then, during continuous mixing, slowly and evenly add 3g of hydrophobic fumed silica through a micro-powder feeder, controlling the feeding time to 10 minutes. After feeding, reduce the mixer speed to 5 rpm and continue mixing for 2.5 hours, utilizing gentle diffusion to achieve microscopic uniform mixing and charge balance between powder particles. After mixing, pass the resulting powder through a 100-mesh air classifier sieve to remove any possible agglomerates, thus obtaining the finished fireworks and firecracker environmental purifier product, which is then sealed and packaged.

[0031] Example 2 The difference between this embodiment and Embodiment 1 is that, firstly, phosphotungstic acid-titanium dioxide mesoporous spheres are prepared according to the following method.

[0032] A1. Add 120g cyclohexane, 17g Span 80, and 7g n-hexanol to a reaction vessel and stir at 300rpm for 30min at room temperature until homogeneous to obtain the oil phase. Under ultrasonic oscillation power of 200W, add 25g of deionized water containing 7g phosphotungstic acid to the oil phase at a dropping rate of 2mL / min. After the addition is complete, continue ultrasonic oscillation for 20min to form a homogeneous and transparent reverse microemulsion, denoted as microemulsion A. In a separate reaction vessel, 24 g of tetrabutyl titanate was dissolved in 50 g of anhydrous ethanol and stirred for 10 min to obtain a transparent solution. 12 g of deionized water, 0.8 g of 5% dilute nitric acid, and 15 g of anhydrous ethanol were mixed thoroughly to obtain an acidic aqueous alcohol solution. Under ice-water bath cooling, the acidic aqueous alcohol solution was added dropwise to the tetrabutyl titanate ethanol solution at a rate of 1 mL / min, while maintaining a stirring speed of 500 rpm during the addition. After the addition was complete, stirring was continued for 30 min to obtain a milky white, semi-transparent titanium dioxide suspension, denoted as suspension B. Suspension B was placed in a constant-pressure dropping funnel and slowly added dropwise to microemulsion A at a rate of 0.5 mL / min under high-speed shear stirring at 8000 rpm and the reaction system temperature controlled at 5℃. After the addition was complete, high-speed shear stirring was continued for 4 h to obtain the reaction mixture.

[0033] A2. Transfer the reaction mixture obtained in step A1 to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in an oven. Heat the reactor to 118°C at a rate of 2°C / min, and perform hydrothermal crystallization at this temperature for 24 hours. After the reaction is complete, allow it to cool naturally to room temperature. Centrifuge the reaction mixture at 8000 rpm for 10 minutes, discard the supernatant, and obtain a crude solid product. Wash the crude solid product three times with anhydrous ethanol, adding 40 g of anhydrous ethanol each time, and ultrasonically disperse for 5 minutes before centrifugation. Then wash it three times with acetone, adding 40 g of acetone each time, and ultrasonically disperse before centrifugation. Place the washed solid product in a vacuum drying oven and dry it at 58°C and a vacuum of -0.08 MPa for 12 hours to obtain a dried product. The dried product was placed in a muffle furnace and heated to 348°C at a heating rate of 2°C / min. It was calcined at this temperature for 2.5 h, then naturally cooled to room temperature. After grinding, white powdered phosphotungstic acid-titanium dioxide mesoporous spheres were obtained, denoted as HPW-TiO2-MS.

[0034] Secondly, porous transition metal-nitrogen co-doped graphene-coated spinel composites were prepared according to the following method.

[0035] 26g of magnesium nitrate hexahydrate and 76g of aluminum nitrate nonahydrate were dissolved in 180g of deionized water and stirred at 400rpm for 30min at room temperature to obtain a completely dissolved metal salt solution, denoted as solution C. 110g of ammonium carbonate was dissolved in 250g of deionized water to prepare an ammonium carbonate aqueous solution, denoted as solution D. 1.5g of polyvinylpyrrolidone was dissolved in 50g of deionized water to obtain a dispersant solution. The dispersant solution was added to the reaction vessel and stirred at 600rpm under a 59℃ water bath heating condition. Solutions C and D were simultaneously added dropwise to the reaction vessel using two constant flow pumps in a parallel flow manner. The dropping rate was controlled so that the dropping time of solution C was 1h, and the dropping rate of solution D was automatically adjusted according to pH changes. During the reaction, the pH value was adjusted online using a 10% (w / w) ammonia solution and a 1mol / L dilute nitric acid solution to maintain a stable pH of 9.2. After the addition was complete, the mixture was stirred and aged in a 59℃ water bath for another 2h. After aging, the reaction mixture was vacuum filtered to obtain a filter cake. The filter cake was washed three times with deionized water, adding 150g of deionized water each time, stirring for 10min, and then filtering. This process was repeated. The washed filter cake was placed in a forced-air drying oven and dried at 79℃ for 12h to obtain a precursor hydroxide solid. The precursor hydroxide was mixed with 22g of melamine and placed in a planetary ball mill, where it was ground at 300rpm for 2h to ensure thorough mixing. The mixture was placed in a tube furnace, and argon gas was first introduced at a flow rate of 200mL / min to purge air for 30min. Then, under argon protection, the temperature was increased to 598℃ at a heating rate of 5℃ / min and held at this temperature for 2h to allow the melamine to pyrolyze and coat the surface of the spinel precursor. After natural cooling, the pretreated material was obtained. The pretreated material was placed in the quartz reaction tube of a chemical vapor deposition system. Argon gas was first introduced at a flow rate of 200 mL / min to purge for 30 min, followed by a heating rate of 10 °C / min to 748 °C. When the temperature reached 748 °C, the argon gas was shut off, and a hydrogen-argon mixture (hydrogen to argon volume ratio 1:9, total flow rate 100 mL / min) was introduced. Simultaneously, a mixture of cobalt acetylacetonate and manganese acetylacetonate vapors was introduced into the reaction tube via bubbling, with 4 g of cobalt acetylacetonate and 2.5 g of manganese acetylacetonate. The bubbling temperature was 180 °C, and the carrier gas was argon gas at a flow rate of 50 mL / min. After reacting at 748 °C for 40 min, the organometallic source and hydrogen gas were shut off, and the mixture was allowed to cool naturally to room temperature under argon gas flow rate of 200 mL / min. The obtained product was taken out, ground in an agate mortar, and passed through a 400-mesh sieve to obtain a black powdery porous transition metal-nitrogen co-doped graphene-coated spinel composite, denoted as MNG / Spinel.

[0036] Finally, prepare the environmentally friendly purifying agent for fireworks and firecrackers according to the following steps.

[0037] S1. Place 12g of amino-modified mesoporous silica in a high-speed mixer. While stirring at 500rpm, spray an ethanol suspension containing 18g of phosphotungstic acid-titanium dioxide mesoporous spheres at a spray rate of 0.5mL / min through a precision atomizing nozzle. This suspension was prepared by pre-dispersing 18g of phosphotungstic acid-titanium dioxide mesoporous spheres in 70g of anhydrous ethanol and then ultrasonically vibrating for 20min. During spraying, maintain the material temperature at 25℃ and control the spraying speed to keep the material moist but without clumping. After spraying, increase the mixer speed to 1500rpm and continue stirring and dispersing for 10min to ensure the phosphotungstic acid-titanium dioxide mesoporous spheres are uniformly loaded onto the surface and pores of the amino-modified mesoporous silica. Then transfer the material to a vacuum drying oven and dry at 58℃ and a vacuum of -0.08MPa for 4h to obtain a pre-composite powder, denoted as composite powder A.

[0038] S2. Add all the pre-composite powder obtained in step S1, 22g of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 10g of coconut shell activated carbon, 6g of diatomaceous earth, 12g of calcium hydroxide, 4g of silver-loaded zeolite, and 1.5g of sodium polyacrylate sequentially to a three-dimensional motion mixer. Mix at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of all components. Then, during continuous mixing, slowly and evenly add 3g of hydrophobic fumed silica through a micro-powder feeder, controlling the feeding time to 10 minutes. After feeding, reduce the mixer speed to 5 rpm and continue mixing for 2 hours, utilizing gentle diffusion to achieve microscopic uniform mixing and charge balance between powder particles. After mixing, pass the resulting powder through a 100-mesh air classifier sieve to remove any possible agglomerates, thus obtaining the finished fireworks and firecracker environmental purifier product, which is then sealed and packaged.

[0039] Example 3 The difference between this embodiment and Embodiment 1 is that, firstly, phosphotungstic acid-titanium dioxide mesoporous spheres are prepared according to the following method.

[0040] A1. Add 180g cyclohexane, 23g Span 80, and 13g n-hexanol to a reaction vessel and stir at 300rpm for 30min at room temperature until homogeneous to obtain the oil phase. Under ultrasonic oscillation power of 200W, add 35g of deionized water containing 13g phosphotungstic acid to the oil phase at a dropping rate of 2mL / min. After the addition is complete, continue ultrasonic oscillation for 20min to form a homogeneous and transparent reverse microemulsion, denoted as microemulsion A. In a separate reaction vessel, 36g of tetrabutyl titanate was dissolved in 70g of anhydrous ethanol and stirred for 10 min to obtain a transparent solution. 18g of deionized water, 1.5g of 5% (w / w) dilute nitric acid, and 25g of anhydrous ethanol were mixed thoroughly to obtain an acidic aqueous alcohol solution. Under ice-water bath cooling, the acidic aqueous alcohol solution was added dropwise to the tetrabutyl titanate ethanol solution at a rate of 1 mL / min, while maintaining a stirring speed of 500 rpm during the addition. After the addition was complete, stirring was continued for 30 min to obtain a milky white, semi-transparent titanium dioxide suspension, denoted as suspension B. Suspension B was placed in a constant-pressure dropping funnel and, under conditions of a high-speed shear stirrer at 8000 rpm and a reaction system temperature controlled at 7℃, suspension B was slowly added dropwise to microemulsion A at a rate of 0.5 mL / min. After the addition was complete, high-speed shear stirring was continued for 6 h to obtain the reaction mixture.

[0041] A2. Transfer the reaction mixture obtained in step A1 to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in an oven. Heat the reactor to 122°C at a rate of 2°C / min, and perform hydrothermal crystallization at this temperature for 24 hours. After the reaction is complete, allow it to cool naturally to room temperature. Centrifuge the reaction mixture at 8000 rpm for 10 minutes, discard the supernatant, and obtain a crude solid product. Wash the crude solid product three times with anhydrous ethanol, adding 60 g of anhydrous ethanol each time, and ultrasonically disperse for 5 minutes before centrifugation. Then wash it three times with acetone, adding 60 g of acetone each time, and ultrasonically disperse before centrifugation. Place the washed solid product in a vacuum drying oven and dry it at 62°C and a vacuum of -0.08 MPa for 12 hours to obtain a dried product. The dried product was placed in a muffle furnace and heated to 352°C at a heating rate of 2°C / min. It was calcined at this temperature for 3.5 hours and then naturally cooled to room temperature. After grinding, white powdered phosphotungstic acid-titanium dioxide mesoporous spheres were obtained, denoted as HPW-TiO2-MS.

[0042] Secondly, porous transition metal-nitrogen co-doped graphene-coated spinel composites were prepared according to the following method.

[0043] 34g of magnesium nitrate hexahydrate and 84g of aluminum nitrate nonahydrate were dissolved in 220g of deionized water and stirred at 400rpm for 30min at room temperature to obtain a completely dissolved metal salt solution, denoted as solution C. 145g of ammonium carbonate was dissolved in 350g of deionized water to prepare an ammonium carbonate aqueous solution, denoted as solution D. 2.5g of polyvinylpyrrolidone was dissolved in 50g of deionized water to obtain a dispersant solution. The dispersant solution was added to the reaction vessel and stirred at 600rpm under a 61℃ water bath heating condition. Solutions C and D were simultaneously added dropwise to the reaction vessel using two constant flow pumps in a parallel flow manner. The dropping rate was controlled so that the dropping time of solution C was 1h, and the dropping rate of solution D was automatically adjusted according to pH changes. During the reaction, the pH value was adjusted online using a 10% (w / w) ammonia solution and a 1mol / L dilute nitric acid solution to maintain a stable pH of 9.8. After the addition was complete, the mixture was stirred and aged in a 61℃ water bath for another 2h. After aging, the reaction mixture was vacuum filtered to obtain a filter cake. The filter cake was washed three times with deionized water, adding 250g of deionized water each time, stirring for 10min, and then filtering. This process was repeated. The washed filter cake was placed in a forced-air drying oven and dried at 81℃ for 12h to obtain a precursor hydroxide solid. The precursor hydroxide was mixed with 28g of melamine and placed in a planetary ball mill, where it was ground at 300rpm for 2h to ensure thorough mixing. The mixture was placed in a tube furnace, and argon gas was first introduced at a flow rate of 200mL / min to purge air for 30min. Then, under argon protection, the temperature was increased to 602℃ at a heating rate of 5℃ / min and held at this temperature for 2h to allow the melamine to pyrolyze and coat the surface of the spinel precursor. After natural cooling, the pretreated material was obtained. The pretreated material was placed in the quartz reaction tube of a chemical vapor deposition system. Argon gas was first introduced at a flow rate of 200 mL / min to purge for 30 min, followed by a heating rate of 10 °C / min to 752 °C. When the temperature reached 752 °C, the argon gas was shut off, and a hydrogen-argon mixture (hydrogen to argon volume ratio 1:9, total flow rate 100 mL / min) was introduced. Simultaneously, a mixture of cobalt acetylacetonate and manganese acetylacetonate vapors was introduced into the reaction tube via bubbling, with 7 g of cobalt acetylacetonate and 4.5 g of manganese acetylacetonate. The bubbling temperature was 180 °C, and the carrier gas was argon gas at a flow rate of 50 mL / min. After reacting at 752 °C for 55 min, the organometallic source and hydrogen gas were shut off, and the mixture was allowed to cool naturally to room temperature under argon gas flow rate protection of 200 mL / min. The obtained product was taken out, ground in an agate mortar, and passed through a 400-mesh sieve to obtain a black powdery porous transition metal-nitrogen co-doped graphene-coated spinel composite, denoted as MNG / Spinel.

[0044] Finally, prepare the environmentally friendly purifying agent for fireworks and firecrackers according to the following steps.

[0045] S1. Place 18g of amino-modified mesoporous silica in a high-speed mixer. While stirring at 500rpm, spray an ethanol suspension containing 22g of phosphotungstic acid-titanium dioxide mesoporous spheres at a spray rate of 0.5mL / min through a precision atomizing nozzle. This suspension was prepared by pre-dispersing 22g of phosphotungstic acid-titanium dioxide mesoporous spheres in 90g of anhydrous ethanol and then ultrasonically vibrating for 20min. During spraying, maintain the material temperature at 25℃ and control the spraying speed to keep the material moist but without clumping. After spraying, increase the mixer speed to 1500rpm and continue stirring and dispersing for 10min to ensure the phosphotungstic acid-titanium dioxide mesoporous spheres are uniformly loaded onto the surface and pores of the amino-modified mesoporous silica. Then transfer the material to a vacuum drying oven and dry at 62℃ and a vacuum of -0.08MPa for 2h to obtain a pre-composite powder, denoted as composite powder A.

[0046] S2. Add all the pre-composite powder obtained in step S1, 32g of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 14g of coconut shell activated carbon, 10g of diatomaceous earth, 18g of calcium hydroxide, 7g of silver-loaded zeolite, and 2.5g of sodium polyacrylate sequentially to a three-dimensional motion mixer. Mix at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of the components. Then, during continuous mixing, slowly and evenly add 4g of hydrophobic fumed silica through a micro-powder feeder, controlling the feeding time to 10 minutes. After feeding, reduce the mixer speed to 5 rpm and continue mixing for 3.5 hours, utilizing gentle diffusion to achieve microscopic uniform mixing and charge balance between powder particles. After mixing, pass the resulting powder through a 100-mesh air classifier sieve to remove any possible agglomerates, thus obtaining the finished fireworks and firecracker environmental purifier, which is then sealed and packaged.

[0047] Comparative Example 1 The difference between this comparative example and Example 1 is that, firstly, titanium dioxide mesoporous spheres were prepared according to the following method.

[0048] A1. Add 150g cyclohexane, 20g Span 80, and 10g n-hexanol to a reaction vessel and stir at 300rpm for 30min at room temperature until homogeneous to obtain the oil phase. Dissolve 30g tetrabutyl titanate in 60g anhydrous ethanol and stir for 10min to obtain a transparent solution. Mix 15g deionized water, 1g 5% dilute nitric acid, and 20g anhydrous ethanol to obtain an acidic aqueous alcohol solution. Under ice-water bath cooling, add the acidic aqueous alcohol solution dropwise to the tetrabutyl titanate ethanol solution at a rate of 1mL / min, maintaining a stirring speed of 500rpm during the addition. After the addition is complete, continue stirring for 30min to obtain a milky white, semi-transparent titanium dioxide suspension, denoted as suspension B. Suspension B was placed in a constant pressure dropping funnel. Under the conditions of high-speed shear stirring at 8000 rpm and reaction system temperature controlled at 6℃, suspension B was slowly added dropwise to the oil phase at a dropping rate of 0.5 mL / min. After the addition was completed, the high-speed shear stirring reaction was continued for 5 h to obtain the reaction mixture.

[0049] A2. The reaction mixture obtained in step A1 was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and placed in an oven. The temperature was increased to 120°C at a rate of 2°C / min, and hydrothermally crystallized at this temperature for 24 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The reaction mixture was centrifuged at 8000 rpm for 10 minutes, and the supernatant was discarded to obtain a crude solid product. The crude solid product was washed three times with anhydrous ethanol, adding 50 g of anhydrous ethanol each time, and ultrasonically dispersed for 5 minutes before centrifugation. It was then washed three times with acetone, adding 50 g of acetone each time, and ultrasonically dispersed before centrifugation. The washed solid product was placed in a vacuum drying oven and dried at 60°C and a vacuum of -0.08 MPa for 12 hours to obtain a dried product. The dried product was placed in a muffle furnace and heated to 350°C at a rate of 2°C / min. It was calcined at this temperature for 3 hours, allowed to cool naturally to room temperature, and then ground to obtain mesoporous titanium dioxide spheres, denoted as TiO2-MS.

[0050] Next, a porous transition metal-nitrogen co-doped graphene-coated spinel composite was prepared according to the method in Example 1.

[0051] Finally, prepare the environmentally friendly purifying agent for fireworks and firecrackers according to the following steps.

[0052] S1. Place 15g of amino-modified mesoporous silica in a high-speed mixer. While stirring at 500rpm, spray an ethanol suspension containing 20g of titanium dioxide mesoporous spheres at a spray rate of 0.5mL / min through a precision atomizing nozzle. This suspension was pre-prepared by dispersing 20g of titanium dioxide mesoporous spheres in 80g of anhydrous ethanol and then ultrasonically vibrating for 20min. During spraying, maintain the material temperature at 25℃ and control the spraying speed to keep the material moist but without clumping. After spraying, increase the mixer speed to 1500rpm and continue stirring and dispersing for 10min to ensure the titanium dioxide mesoporous spheres are uniformly loaded onto the surface and pores of the amino-modified mesoporous silica. Then transfer the material to a vacuum drying oven and dry at 60℃ and a vacuum of -0.08MPa for 3h to obtain a pre-composite powder, denoted as composite powder A.

[0053] S2. Add all the pre-composite powder obtained in step S1, 28g of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 12g of coconut shell activated carbon, 8g of diatomaceous earth, 15g of calcium hydroxide, 5g of silver-loaded zeolite, and 2g of sodium polyacrylate sequentially to a three-dimensional motion mixer. Mix at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of all components. Then, during continuous mixing, slowly and evenly add 3g of hydrophobic fumed silica through a micro-powder feeder, controlling the feeding time to 10 minutes. After feeding, reduce the mixer speed to 5 rpm and continue mixing for 2.5 hours, utilizing gentle diffusion to achieve microscopic uniform mixing and charge balance between powder particles. After mixing, pass the resulting powder through a 100-mesh air classifier sieve to remove any possible agglomerates, thus obtaining the finished fireworks and firecracker environmental purifier product, which is then sealed and packaged.

[0054] Comparative Example 2 The difference between this comparative example and Example 1 is that, firstly, phosphotungstic acid-titanium dioxide mesoporous spheres were prepared according to the method of Example 1.

[0055] Next, the magnesium aluminum spinel composite was prepared according to the following method.

[0056] 30g of magnesium nitrate hexahydrate and 80g of aluminum nitrate nonahydrate were dissolved in 200g of deionized water and stirred at 400rpm for 30min at room temperature to obtain a completely dissolved metal salt solution, denoted as solution C. 130g of ammonium carbonate was dissolved in 300g of deionized water to prepare an ammonium carbonate aqueous solution, denoted as solution D. 2g of polyvinylpyrrolidone was dissolved in 50g of deionized water to obtain a dispersant solution. The dispersant solution was added to the reaction vessel and stirred at 600rpm under a 60℃ water bath heating condition. Solutions C and D were simultaneously added dropwise to the reaction vessel using two constant flow pumps in a parallel flow manner. The dropping rate was controlled so that the dropping time of solution C was 1h, and the dropping rate of solution D was automatically adjusted according to pH changes. During the reaction, the pH value was adjusted online using a 10% (w / w) ammonia solution and a 1mol / L dilute nitric acid solution to maintain a stable pH of 9.5. After the addition was complete, the mixture was stirred and aged in a 60℃ water bath for 2h. After aging, the reaction mixture was vacuum filtered to obtain a filter cake. The filter cake was washed three times with deionized water, adding 200g of deionized water each time, stirring for 10min, and then filtering. This process was repeated. The washed filter cake was placed in a forced-air drying oven and dried at 80℃ for 12h to obtain the precursor hydroxide solid. The precursor hydroxide was placed in a tube furnace and heated to 600℃ at a rate of 5℃ / min under argon protection. It was held at this temperature for 2h and then allowed to cool naturally to obtain the pretreated material. The pretreated material was cooled to room temperature under an argon atmosphere, removed, and ground in an agate mortar. It was then passed through a 400-mesh sieve to obtain a white powdery magnesium-aluminum spinel composite, denoted as MgAl2O4.

[0057] Finally, prepare the environmentally friendly purifying agent for fireworks and firecrackers according to the following steps.

[0058] S1. Place 15g of amino-modified mesoporous silica in a high-speed mixer. While stirring at 500rpm, spray an ethanol suspension containing 20g of phosphotungstic acid-titanium dioxide mesoporous spheres at a spray rate of 0.5mL / min through a precision atomizing nozzle. This suspension was pre-prepared by dispersing 20g of phosphotungstic acid-titanium dioxide mesoporous spheres in 80g of anhydrous ethanol and then ultrasonically vibrating for 20min. During spraying, maintain the material temperature at 25℃ and control the spraying speed to keep the material moist but without clumping. After spraying, increase the mixer speed to 1500rpm and continue stirring and dispersing for 10min to ensure the phosphotungstic acid-titanium dioxide mesoporous spheres are uniformly loaded onto the surface and pores of the amino-modified mesoporous silica. Then transfer the material to a vacuum drying oven and dry at 60℃ and a vacuum of -0.08MPa for 3h to obtain a pre-composite powder, denoted as composite powder A.

[0059] S2. Add all the pre-composite powder obtained in step S1, 28g of magnesium-aluminum spinel composite, 12g of coconut shell activated carbon, 8g of diatomaceous earth, 15g of calcium hydroxide, 5g of silver-loaded zeolite, and 2g of sodium polyacrylate sequentially to a three-dimensional motion mixer. Mix at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of all components. Then, during continuous mixing, slowly and evenly add 3g of hydrophobic fumed silica through a micro-powder feeder, controlling the feeding time to 10 minutes. After feeding, reduce the mixer speed to 5 rpm and continue mixing for 2.5 hours, utilizing gentle diffusion to achieve microscopic uniform mixing and charge balance between powder particles. After mixing, pass the resulting powder through a 100-mesh air classifier sieve to remove any possible agglomerates, thus obtaining the finished fireworks and firecracker environmental purifier product, which is then sealed and packaged.

[0060] Comparative Example 3 The difference between this comparative example and Example 1 is that 15g of amino-modified mesoporous silica was placed in a high-speed mixer, and 80g of anhydrous ethanol was sprayed through a precision atomizing nozzle at a spray rate of 0.5mL / min while stirring at 500rpm. During the spraying process, the material temperature was maintained at 25℃, and the spraying speed was controlled to keep the material moist but without agglomeration. After spraying, the mixer speed was increased to 1500rpm, and stirring and dispersion were continued for 10min. Then, the material was transferred to a vacuum drying oven and dried at 60℃ and a vacuum of -0.08MPa for 3h to obtain a pre-composite powder, denoted as composite powder A.

[0061] Composite powder A, 12g coconut shell activated carbon, 8g diatomaceous earth, 15g calcium hydroxide, 5g silver-loaded zeolite, and 2g sodium polyacrylate were sequentially added to a three-dimensional motion mixer and mixed at 20 rpm for 30 minutes to achieve macroscopic uniform mixing of the components. Then, during continuous mixing, 3g of hydrophobic fumed silica was slowly and evenly added through a micro-powder feeder over a period of 10 minutes. After feeding, the mixer speed was reduced to 5 rpm, and mixing continued for 2.5 hours to achieve microscopic uniform mixing and charge balance between powder particles through gentle diffusion. After mixing, the resulting powder was passed through a 100-mesh air classifier sieve to remove any possible lumps, yielding the finished environmentally friendly purifying agent for fireworks and firecrackers, which was then sealed and packaged.

[0062] The performance of the environmentally friendly purifying agents for fireworks and firecrackers obtained in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with national and industry standard testing specifications.

[0063] A sealed simulated fireworks display test chamber was constructed, with a volume of 2.0 m³, made of 304 stainless steel. The inner walls were polished to reduce adsorption. A low-speed stirring fan was installed on the top of the chamber to ensure uniform gas mixing. Multiple sampling ports were set on the chamber walls and equipped with sealing caps. Before the test, the air inside the chamber was purified using a high-efficiency filter to a PM2.5 background concentration below 10 μg / m³, the temperature was controlled at 25±2℃, and the relative humidity was controlled at 50±5%. One commercially available combination firework with a total charge of 100g was taken and fixed to the ignition device in the center of the chamber. At the same time, 20g of the environmentally friendly purifying agent sample of the firework to be tested was weighed and evenly sprinkled within a 30cm diameter area around the firework. After closing the chamber door and checking the airtightness, the firework was remotely ignited, and the stirring fan inside the chamber was started at 100 rpm and all sampling systems were activated.

[0064] PM2.5 peak reduction rate test: A light scattering PM2.5 monitor with a range of 0-10000 μg / m³ and a resolution of 0.1 μg / m³ was used. Continuous sampling was performed through the sampling port on the chamber wall at a flow rate of 2.0 L / min, with a data recording frequency of 1 time / second. Recording began at the moment of ignition and continued for 30 minutes, recording the peak PM2.5 concentration throughout the process. A blank control experiment was conducted simultaneously, without adding any purifier. The above operation was repeated, and the blank PM2.5 peak concentration was recorded. The PM2.5 peak reduction rate was calculated using the following formula: PM2.5 peak reduction rate % = Blank PM2.5 peak concentration - Sample PM2.5 peak concentration / Blank PM2.5 peak concentration × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0065] SO2 removal rate test: A non-dispersive infrared absorption flue gas analyzer was used, with an SO2 measurement range of 0-1000 mg / m³ and a resolution of 0.1 mg / m³. Continuous sampling was performed through the bulkhead sampling port at a flow rate of 1.0 L / min, with a sampling frequency of 1 time / min. Monitoring was conducted continuously for 15 minutes from the moment of ignition, and the arithmetic mean of the SO2 concentration within 15 minutes was recorded. A blank control experiment was also conducted simultaneously, without the addition of any purification agent. The above operation was repeated, and the average SO2 concentration in the blank was recorded. The SO2 removal rate was calculated using the following formula: SO2 removal rate % = (Average SO2 concentration in blank - Average SO2 concentration in sample) / (Average SO2 concentration in blank) × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0066] NO x Removal rate test: Using a chemiluminescence nitrogen oxide analyzer, NO x The measurement range is 0-500 mg / m³ (NO2), with a resolution of 0.1 mg / m³. Continuous sampling is performed through the bulkhead sampling port at a flow rate of 1.0 L / min, with a sampling frequency of once / min. Monitoring is performed continuously for 15 minutes starting from ignition, and the NO levels recorded within those 15 minutes are recorded.x The arithmetic mean of the concentrations. A blank control experiment was also conducted simultaneously, i.e., no purifying agent was added. The above procedures were repeated, and the blank NO values ​​were recorded. x Average concentration. NO x Removal rate is calculated using the following formula: NO x Removal rate % = Blank NO x Average concentration - sample NO x Average concentration / blank NO x Average concentration × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0067] HCl removal rate test: A Fourier transform infrared gas analyzer was used, with an HCl measurement range of 0-200 mg / m³ and a resolution of 0.1 mg / m³. Continuous sampling was performed through the sampling port on the bulkhead at a flow rate of 2.0 L / min, with a sampling frequency of 1 time / min. Monitoring was conducted continuously for 15 minutes from the moment of ignition, and the arithmetic mean of the HCl concentration within 15 minutes was recorded. A blank control experiment was also conducted simultaneously, without adding any purifying agent. The above operation was repeated, and the average HCl concentration in the blank was recorded. The HCl removal rate was calculated using the following formula: HCl removal rate % = (Average HCl concentration in blank sample - Average HCl concentration in sample) / (Average HCl concentration in blank sample) × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0068] CO removal rate test: A non-dispersive infrared absorption carbon monoxide analyzer was used, with a CO measurement range of 0-1000 mg / m³ and a resolution of 0.1 mg / m³. Continuous sampling was performed through the bulkhead sampling port at a flow rate of 1.0 L / min, with a sampling frequency of 1 time / min. Monitoring was conducted continuously for 15 minutes from the moment of ignition, and the arithmetic mean of the CO concentration within 15 minutes was recorded. A blank control experiment was also conducted simultaneously, without the addition of any purification agent. The above operation was repeated, and the average CO concentration in the blank was recorded. The CO removal rate was calculated using the following formula: CO removal rate % = (Average CO concentration in blank - Average CO concentration in sample) / (Average CO concentration in blank) × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0069] Sterilization rate test: A six-stage sieve impactor microbial sampler was used with a sampling flow rate of 28.3 L / min. Sampling was conducted at three time points: 5 min, 15 min, and 30 min after the ignition, with each sampling lasting 5 min. Before sampling, nutrient agar plates were pre-incubated in a 37℃ incubator for 24 h to confirm sterility. During sampling, the sampler containing the nutrient agar plate was inserted into the chamber through the sampling port on the chamber wall. The sampling pump was started, and after accurately timing for 5 min, the plate was removed and immediately sealed. The collected plates were then incubated in a 37℃ constant temperature incubator for 48 h. After removal, the colony-forming units on each plate were counted. A blank control experiment was conducted simultaneously, without adding any purification agent. The above operation was repeated, and the number of blank colonies at each time point was recorded. The sterilization rate was calculated based on the number of colonies 30 min after ignition, using the formula: Sterilization rate % = (Number of colonies in blank 30 min - Number of colonies in sample 30 min / Number of colonies in blank 30 min) × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0070] Smoke Removal Rate Test: The total mass of smoke was determined using a gravimetric method. Before ignition, a 90mm diameter glass fiber filter membrane was placed in a desiccator and equilibrated at 25℃ for 24 hours. The initial mass was recorded by weighing using a 1 / 100,000 electronic balance. The weighed filter membrane was then placed into a particulate matter sampler at a sampling flow rate of 100L / min. The sampling pump was started simultaneously with ignition, and sampling continued for 30 minutes. After sampling, the filter membrane was carefully removed, returned to the original desiccator, and equilibrated under the same conditions for 24 hours. The final mass was recorded. The total mass of smoke was the final mass minus the initial mass. A blank control experiment was conducted simultaneously, without adding any purifying agent. The above procedures were repeated, and the total mass of the blank smoke was recorded. The smoke removal rate was calculated using the following formula: Smoke Removal Rate % = (Total Mass of Blank Smoke - Total Mass of Sample Smoke) / (Total Mass of Blank Smoke) × 100%. Each sample was tested three times, and the arithmetic mean was taken.

[0071] The performance test data above are shown in Table 1.

[0072] Table 1 Performance Test Results

[0073] The test results in Table 1 above clearly show that Examples 1-3 are significantly better than Comparative Examples 1-3 in all performance indicators, which fully proves that the environmentally friendly purifier for fireworks and firecrackers prepared by the present invention has successfully solved the technical problem of the difficulty in achieving efficient and integrated purification of pollutants after fireworks display in the prior art.

[0074] Specifically, the PM2.5 peak reduction rates of Examples 1-3 all reached over 79.8%, while those of Comparative Examples 1-3 were 56.3%, 48.7%, and 21.5%, respectively, indicating that the introduction of the two core innovative compounds significantly enhanced the ability to capture fine particulate matter.

[0075] Regarding the removal of toxic gases, Examples 1-3 show the effects on SO2 and NO. x The removal rates of HCl and CO were as high as 85.6-89.7%, 68.9-73.5%, 91.2-94.8%, and 65.3-70.1%, respectively, while the corresponding indicators of Comparative Examples 1-3 were significantly lower. For example, the gas removal rate of Comparative Example 3 was less than 20%. This is attributed to the synergistic effect of acid catalysis and photocatalysis of phosphotungstic acid-titanium dioxide mesoporous spheres and the thermocatalytic activity of transition metal-nitrogen co-doped graphene film.

[0076] In terms of disinfection function, the sterilization rate of Examples 1-3 all exceeded 94.8%, while that of Comparative Example 3 was only 35.7%, demonstrating the broad-spectrum antibacterial effect of the synergistic effect of silver-loaded zeolite and core materials.

[0077] In terms of smoke and dust removal rate, Examples 1-3 achieved 76.5-81.2%, which is much higher than the 52.1%, 44.8% and 19.3% of Comparative Examples 1-3, respectively, confirming the high efficiency of the multi-level pore structure in intercepting and fixing smoke and dust.

[0078] Comprehensive data show that this invention, through the introduction of two novel inorganic modified compounds and their optimized compounding with commercially available materials, achieves simultaneous and in-depth purification of PM2.5, toxic gases, smoke, and biological pollutants generated by fireworks and firecrackers, effectively solving the problems of low efficiency and limited functionality of traditional methods.

Claims

1. A method for preparing an environmentally friendly purifying agent for fireworks and firecrackers, characterized in that the steps include... include: S1. By weight, 10-20 parts of amino-modified mesoporous silica are placed in a mixer, and an ethanol suspension containing 15-25 parts of phosphotungstic acid-titanium dioxide mesoporous spheres is sprayed in while stirring; after spraying, the mixture is dried at 58-62℃ to obtain a pre-composite powder. S2. Add the pre-composite powder, 20-35 parts of porous transition metal-nitrogen co-doped graphene-coated spinel composite, 8-15 parts of coconut shell activated carbon, 5-12 parts of diatomaceous earth, 10-20 parts of calcium hydroxide, 3-8 parts of silver-loaded zeolite, and 1-3 parts of sodium polyacrylate to a mixer, add 2-5 parts of fumed silica, and mix.

2. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 1, characterized in that, In step S1, the drying time at 58-62℃ is 2-4 hours.

3. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 1, characterized in that, In step S2, the mixing time is 2-4 hours.

4. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 1, characterized in that, The method for preparing the phosphotungstic acid-titanium dioxide mesoporous spheres includes: A1. By weight, 100-200 parts of cyclohexane, 15-25 parts of Span 80, and 5-15 parts of n-hexanol are mixed to obtain an oil phase; an aqueous solution containing 5-15 parts of phosphotungstic acid is added dropwise to the oil phase under ultrasonic oscillation to obtain a microemulsion; 20-40 parts of tetrabutyl titanate are dissolved in anhydrous ethanol and mixed with a solution composed of 10-20 parts of deionized water, 0.5-2 parts of dilute nitric acid, and ethanol to obtain a titanium dioxide suspension; the titanium dioxide suspension is added dropwise to the microemulsion, and the mixture is stirred at 5-8°C to obtain a reaction mixture; A2. Transfer the reaction mixture to a high-pressure reactor and hydrothermally crystallize it at 115-125℃. After centrifugation, a solid product is obtained. Wash the solid product with ethanol and acetone, and vacuum dry it at 58-62℃ to obtain a dried product. Calcine the dried product at 345-355℃.

5. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 4, characterized in that, In step A1, the stirring reaction time is 4-6 hours.

6. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 4, characterized in that, In step A2, the dried product is calcined at 345-355℃ for 2-4 hours.

7. The preparation method of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 1, characterized in that, The preparation method of the porous transition metal-nitrogen co-doped graphene-coated spinel composite includes: dissolving 25-35 parts by weight of magnesium nitrate and 75-85 parts by weight of aluminum nitrate in deionized water to obtain a metal salt solution; mixing the metal salt solution, an aqueous solution containing 100-150 parts by weight of ammonium carbonate, and 1-3 parts by weight of polyvinylpyrrolidone under stirring, adjusting the pH to 9.0-10.0, aging at 58-62°C, filtering, washing to obtain a washed filter cake, and then aging the washed filter cake at 78°C. The precursor hydroxide was dried at -82℃ to obtain a precursor hydroxide. The precursor hydroxide was mixed with 20-30 parts of melamine and ground. Under argon protection, the temperature was raised to 595-605℃ and held to obtain a pretreated material. The pretreated material was transferred to a chemical vapor deposition system, and a mixed vapor of 3-8 parts of cobalt acetylacetone and 2-5 parts of manganese acetylacetone carried by argon was introduced. At the same time, a mixture of hydrogen and argon was introduced, and the reaction was carried out at 745-755℃. Under an argon atmosphere, the mixture was cooled to room temperature, ground, and sieved.

8. The method for preparing the environmentally friendly purifying agent for fireworks and firecrackers according to claim 7, characterized in that, The reaction time is 30-60 minutes at 745-755℃.

9. An environmentally friendly purifying agent for fireworks and firecrackers, characterized in that, The environmentally friendly purifying agent for fireworks and firecrackers is prepared by the method described in any one of claims 1-8.

10. The application of the environmentally friendly purifying agent for fireworks and firecrackers according to claim 9, characterized in that, The application of the environmentally friendly purifying agent for fireworks and firecrackers in high-altitude and low-altitude fireworks, ground-based box fireworks, single-row launch fireworks, rotating fireworks, net screen fireworks, daytime fireworks, cold light fireworks, and firecrackers.

Images