N-Fe co-doped high-titanium slag-based photocatalytic zeolite, its preparation method and application

Abstract

This invention relates to an N-Fe co-doped high-titanium slag-based photocatalytic zeolite, its preparation method, and its application. The method includes the following steps: mixing high-titanium slag powder with ammonium salt and calcining at 300–500°C to obtain a calcined product; subsequently, washing, drying, and grinding to obtain powder A; mixing powder A with an alkali to obtain powder B, then mixing it uniformly with water, and undergoing hydrothermal crystallization, solid-liquid separation, washing, and drying to obtain powder C; mixing powder C with an acidic iron source solution, and undergoing ultrasonic reaction, solid-liquid separation, washing, and drying to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite. This invention uses high-titanium slag as the main raw material, mixes it with ammonium salt for high-temperature calcination, then mixes it with an alkali for hydrothermal crystallization, and subsequently reacts it with an iron source to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite. This achieves resource utilization of industrial waste, reduces zeolite preparation costs, and the prepared zeolite exhibits good photocatalytic and adsorption performance.

Description

Technical Field

[0001] This invention relates to the field of zeolites, specifically to an N-Fe co-doped high-titanium slag-based photocatalytic zeolite, its preparation method, and its application. Background Technology

[0002] High-titanium slag is a major byproduct of vanadium-titanium magnetite smelting, produced in huge quantities with complex composition, and lacking effective treatment methods. Stockpiling not only occupies large amounts of land, but the heavy metals it contains, such as cadmium and manganese, may also leach into the soil and groundwater through rainwater. Currently, the most common method is to use the high-titanium slag as building materials such as cement and bricks. This method consumes large quantities but has low utilization value, and the abundant titanium content in the slag is not fully utilized. The high-value resource utilization of this slag is a pressing problem that the metallurgical industry needs to solve.

[0003] Traffic exhaust pollution has become one of the main sources of urban air pollution; vehicle exhaust can be roughly divided into four categories: CO, HC, NO... X And PM. Currently, vehicle exhaust treatment technologies based on asphalt pavements mainly focus on photocatalysis, which involves introducing photocatalytic materials into asphalt pavements or coating them onto the pavement surface to degrade exhaust pollutants through photocatalytic reactions. Among these, TiO2 has become the most widely studied photocatalytic material due to its high catalytic activity and good chemical stability.

[0004] Although TiO2 photocatalysis technology has made some progress in the field of road exhaust gas treatment, and high-titanium slag contains relatively abundant titanium sources, the catalytic efficiency of photocatalytic materials prepared directly from high-titanium slag is still limited, making it difficult to meet the actual exhaust gas degradation efficiency requirements. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide an N-Fe co-doped high-titanium slag-based photocatalytic zeolite, its preparation method, and its application, thereby solving the technical problems of low resource utilization efficiency of high-titanium slag and limited catalytic efficiency of TiO2 photocatalytic treatment of automobile exhaust in the prior art.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite, comprising the following steps: S1, mixing high-titanium slag powder with ammonium salt and calcining at 300-500°C to obtain a calcined product, which is then washed, dried and ground to obtain powder A; S2, mixing powder A with alkali to obtain powder B, then mixing it evenly with water, and subjecting it to hydrothermal crystallization reaction, solid-liquid separation, washing and drying to obtain powder C; S3, mixing powder C with an acidic iron source solution, and subjecting it to ultrasonic reaction, solid-liquid separation, washing and drying to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0008] Preferably, the chemical composition of the high-titanium slag is as follows: TiO2 content 15-45%, CaO content 15-40%, SiO2 content 10-30%, Al2O3 content 2-20%, MgO content 5-15%, Fe2O3 content 0-5%, and the balance being other impurities.

[0009] Preferably, in step S1, the high-titanium slag powder is obtained by drying and grinding high-titanium slag and then passing it through a 100-200 mesh sieve; the ammonium salt includes ammonium chloride or ammonium sulfate; the mass ratio of high-titanium slag powder to ammonium salt is 1:(0.2-0.6); and the calcination time is 1-4 hours.

[0010] Preferably, in step S2, the alkali includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water; the mass ratio of powder A to alkali is 1:(1-2); the solid-liquid ratio of powder B to water is 1g:(8-12)mL; powder B is mixed with water and stirred for 0.1-2h; the temperature of the hydrothermal crystallization reaction is 160-200℃ and the time is 12-24h.

[0011] Preferably, in step S3, the iron source includes at least one of ferric chloride, ferric nitrate, and ferric sulfate; the mass ratio of powder C to iron source is 1:(0.1-2); the acidic iron source solution is prepared by mixing the iron source with deionized water and adjusting the pH value to 4.5-5.5; the ultrasonic reaction is carried out under ultrasonic conditions of 60-100W and oscillation reaction at 60-80℃ for 0.1-2h.

[0012] Secondly, the present invention provides an N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared by the above-mentioned preparation method.

[0013] Thirdly, the present invention provides a spraying solution for treating vehicle exhaust in asphalt pavements, which is obtained by mixing and reacting the above-mentioned N-Fe co-doped high-titanium slag-based photocatalytic zeolite with silane hydrolysate.

[0014] Fourthly, the present invention provides a method for preparing a spraying solution for treating vehicle exhaust gas on asphalt pavement, comprising the following steps: mixing N-Fe co-doped high-titanium slag-based photocatalytic zeolite with silane hydrolysate, and stirring the mixture at 30-60°C to obtain the spraying solution.

[0015] Preferably, the silane hydrolysate is prepared by mixing an ethanol solution with γ-aminopropyltriethoxysilane and adjusting the pH to alkaline, followed by a hydrolysis reaction; the concentration of the ethanol solution is 10-95%, and the amount of γ-aminopropyltriethoxysilane is 4-6% of the volume of the ethanol solution; the hydrolysis reaction temperature is 20-60℃, and the time is 0.1-60 min; the solid-liquid ratio of N-Fe co-doped high-titanium slag-based photocatalytic zeolite to the silane hydrolysate is 1 g: (1-20) mL; the stirring reaction time is 30-90 min.

[0016] Fifthly, the present invention provides an application of the above-mentioned N-Fe co-doped high-titanium slag-based photocatalytic zeolite in the preparation of materials with synergistic effects of pollutant adsorption and photocatalysis.

[0017] Compared with the prior art, the beneficial effects of the present invention include:

[0018] This invention uses high-titanium furnace slag as the main raw material, mixes it with ammonium salt for high-temperature calcination, then mixes it with alkali for hydrothermal crystallization, and subsequently reacts it with an iron source to obtain N-Fe co-doped high-titanium furnace slag-based photocatalytic zeolite. This achieves the resource utilization of industrial waste and reduces the cost of zeolite preparation. By optimizing the process, the active components of the high-titanium furnace slag are efficiently activated, resulting in zeolite with excellent photocatalytic and adsorption properties. Furthermore, using the N-Fe co-doped high-titanium furnace slag-based photocatalytic zeolite provided by this invention as a raw material, a spraying solution is prepared with the hydrolysate obtained from silane hydrolysis. This enables the high-value utilization of industrial waste and the efficient synergistic treatment of pollutants through adsorption and photocatalysis, balancing environmental and economic benefits, and is easy to scale up and promote. Attached Figure Description

[0019] Figure 1 These are SEM and EDS images of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite synthesized in Example 1 of this invention; wherein, (a) is the SEM image, (b) is the Ti element distribution, (c) is the N element distribution, and (d) is the Fe element distribution;

[0020] Figure 2 This is a schematic diagram of the preparation process of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite and the spraying solution of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] To address the shortcomings of low resource utilization efficiency of high-titanium slag and limited catalytic efficiency of TiO2 photocatalysis in treating automobile exhaust, this invention provides an N-Fe co-doped high-titanium slag-based photocatalytic zeolite, its preparation method, and its application. This method can efficiently activate the active components of high-titanium slag, control the influence of impurities, and obtain an N-Fe co-doped high-titanium slag-based photocatalytic zeolite. This zeolite is then prepared into a spraying solution for application in automobile exhaust treatment. This invention not only solves the environmental problems associated with high-titanium slag stockpiling but also provides low-cost photocatalytic materials to support the needs of fields such as automobile exhaust treatment, demonstrating significant environmental and economic benefits.

[0023] In a first aspect, the present invention provides a method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite, comprising the following steps:

[0024] S1, high-titanium slag powder is mixed with ammonium salt and calcined at 300-500℃ to obtain calcined product, which is then washed, dried and ground to obtain powder A;

[0025] S2, mix powder A with alkali to obtain powder B, then mix it evenly with water, and after hydrothermal crystallization reaction, solid-liquid separation, washing and drying, obtain powder C;

[0026] S3. Powder C is mixed with an acidic iron source solution, and then subjected to ultrasonic reaction, solid-liquid separation, washing and drying to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0027] This invention uses high-titanium furnace slag as the main raw material, mixes it with ammonium salt for high-temperature calcination, then mixes it with alkali for hydrothermal crystallization, and subsequently reacts it with an iron source to obtain N-Fe co-doped high-titanium furnace slag-based photocatalytic zeolite. This realizes the resource utilization of industrial waste residue and reduces the cost of zeolite preparation. By optimizing the process, the active components of high-titanium furnace slag are efficiently activated, and the prepared zeolite has good photocatalytic and adsorption performance.

[0028] Specifically, the calcination temperature in step S1 includes, but is not limited to, 300℃, 320℃, 330℃, 340℃, 350℃, 360℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 480℃, and 500℃.

[0029] In some embodiments, the chemical composition of the high-titanium slag is as follows: TiO2 content 15-45%, CaO content 15-40%, SiO2 content 10-30%, Al2O3 content 2-20%, MgO content 5-15%, Fe2O3 content 0-5%, with the remainder being other impurities.

[0030] In some embodiments, in step S1, the high-titanium slag powder is obtained by drying and grinding high-titanium slag and then passing it through a 100-200 mesh sieve.

[0031] In some embodiments, in step S1, the ammonium salt includes ammonium chloride or ammonium sulfate; the mass ratio of high-titanium slag powder to ammonium salt is 1:(0.2-0.6). Specifically, the mass ratio of high-titanium slag powder to ammonium salt includes, but is not limited to, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, etc.

[0032] In some embodiments, the calcination time in step S1 is 1 to 4 hours. Specifically, the calcination time includes, but is not limited to, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, and 4 hours.

[0033] In some embodiments, in step S1, the calcined product is washed with deionized water until it becomes neutral.

[0034] In some embodiments, in step S2, the alkali includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water; the mass ratio of powder A to alkali is 1:(1-2). Specifically, the mass ratio of powder A to alkali includes, but is not limited to, 1:1, 1:1.2, 1:1.5, 1:1.6, 1:1.8, 1:2, etc.

[0035] In some embodiments, in step S2, the solid-liquid ratio of powder B to water is 1g:(8-12)mL. Specifically, the solid-liquid ratio of powder B to water includes, but is not limited to, 1g:8mL, 1g:9mL, 1g:10mL, 1g:11mL, 1g:12mL, etc.

[0036] In some embodiments, in step S2, powder B is mixed with water and stirred for 0.1 to 2 hours. Specifically, the stirring time includes, but is not limited to, 0.1 hours, 0.5 hours, 1 hour, 1.5 hours, and 2 hours.

[0037] In some embodiments, in step S2, the temperature of the hydrothermal crystallization reaction is 160–200°C, and the time is 12–24 hours. Specifically, the temperature of the hydrothermal crystallization reaction includes, but is not limited to, 160°C, 165°C, 170°C, 175°C, 180°C, 190°C, 200°C, etc., and the time includes, but is not limited to, 12 hours, 12.5 hours, 13 hours, 15 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.

[0038] In some embodiments, in step S3, the iron source includes at least one of ferric chloride, ferric nitrate, and ferric sulfate; the mass ratio of powder C to the iron source is 1:(0.1-2). The mass ratio of powder C to the iron source includes, but is not limited to, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc.

[0039] Furthermore, the acidic iron source solution is prepared by mixing an iron source with deionized water and adjusting the pH value to 4.5–5.5. Specifically, the pH value includes, but is not limited to, 4.5, 4.8, 5.0, 5.2, and 5.5.

[0040] In some embodiments, in step S3, the ultrasonic reaction is performed under ultrasonic conditions with a power of 60-100W, at a temperature of 60-80°C, for 0.1-2 hours. Specifically, the temperature includes, but is not limited to, 60°C, 65°C, 70°C, 75°C, 80°C, etc., and the time includes, but is not limited to, 0.1 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, etc.

[0041] Secondly, the present invention provides an N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared by the above-mentioned preparation method.

[0042] Thirdly, the present invention provides a spraying solution for treating vehicle exhaust in asphalt pavements, which is obtained by mixing and reacting the above-mentioned N-Fe co-doped high-titanium slag-based photocatalytic zeolite with silane hydrolysate.

[0043] In this embodiment, the above-mentioned spraying solution is directly sprayed or coated onto the surface of the asphalt pavement. After the solution dries naturally, a coating with both adsorption and photocatalytic functions is formed. This coating can efficiently adsorb vehicle exhaust gas in vehicle exhaust gas and degrade vehicle exhaust gas through photocatalytic reaction under light conditions, thereby achieving synergistic treatment of vehicle exhaust gas.

[0044] It should be noted that the spraying solution prepared by this invention can be used in forms including but not limited to "spraying" and "coating".

[0045] Fourthly, the present invention provides a method for preparing a spraying solution for treating vehicle exhaust gas on asphalt pavement, comprising the following steps: mixing N-Fe co-doped high-titanium slag-based photocatalytic zeolite with silane hydrolysate, and stirring the mixture at 30-60°C to obtain the spraying solution.

[0046] In some embodiments, the silane hydrolysate is prepared by mixing an ethanol solution with γ-aminopropyltriethoxysilane, adjusting the pH to alkaline, and then performing a hydrolysis reaction.

[0047] Furthermore, the volume concentration of the ethanol solution is 10–95%, and the amount of γ-aminopropyltriethoxysilane used is 4–6% of the volume of the ethanol solution; the pH value is adjusted to 8–12; the hydrolysis reaction temperature is 20–60℃, and the time is 0.1–60 min. Specifically, the volume concentration of the ethanol solution includes, but is not limited to, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 80%, 90%, and 95%; the amount of γ-aminopropyltriethoxysilane used includes, but is not limited to, 4%, 4.5%, 5%, 5.5%, and 6%; the pH value is adjusted to, but is not limited to, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, and 12; the temperature of the hydrolysis reaction includes, but is not limited to, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, and 60℃; and the time includes, but is not limited to, 0.1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 50 min, 55 min, and 60 min.

[0048] In some embodiments, the solid-liquid ratio of N-Fe co-doped high-titanium slag-based photocatalytic zeolite to silane hydrolysate is 1 g: (1-20) mL; the stirring reaction time is 30-90 min.

[0049] Fifthly, the present invention provides an application of the above-mentioned N-Fe co-doped high-titanium slag-based photocatalytic zeolite in the preparation of materials with synergistic effects of pollutant adsorption and photocatalysis.

[0050] In some embodiments, the contaminants include one or more of methylene blue, CO, propane, and NO.

[0051] The main mechanism of action and advantages of this invention are as follows:

[0052] (1) Realize the high-value utilization of high-titanium slag: Functional zeolite is prepared by using high-titanium slag as the main raw material, which effectively disposes of industrial solid waste, solves the problem of extensive and low added value of traditional high-titanium slag utilization, reduces the raw material cost of zeolite preparation, and has significant environmental and economic benefits.

[0053] (2) Excellent photocatalytic and adsorption performance: By mixing and calcining high-titanium slag powder with ammonium salt, the ammonium salt decomposes at high temperature to generate weak acid radical ions and nitrogen-containing substances such as ammonia. Among them, weak acid radical ions combine with a small amount of impurities such as calcium and magnesium, which are removed by water washing after calcination. The nitrogen-containing substances are doped in zeolite, thereby achieving N doping and impurity removal effects. Then, through hydrothermal crystallization and Fe doping, N-Fe co-doped high-titanium slag-based photocatalytic zeolite is formed. This invention efficiently activates the active components in high-titanium slag through N-Fe co-doping modification and optimization process. The prepared zeolite has good photocatalytic activity and automobile exhaust adsorption performance. N-Fe co-doping can regulate the electronic structure of titanium active sites, broaden the light response range, and improve the visible light utilization efficiency.

[0054] (3) Excellent coating stability and durability: γ-aminopropyltriethoxysilane is introduced during the preparation of the spraying solution. Its hydrolysis products can enhance the compatibility and adhesion between zeolite and asphalt pavement, and enhance its stability in complex environments.

[0055] (4) Easy to scale up production and promotion: The preparation steps of this invention are simple and mild, the required equipment is conventional, the raw material cost is low, the spraying construction is convenient, and there is no need to make major modifications to the existing asphalt pavement construction process, which is conducive to industrial production and large-scale engineering application.

[0056] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0057] The chemical composition of the high-titanium slag used in the following examples and comparative examples is as follows: TiO2 content 20%, CaO content 21%, SiO2 content 27%, Al2O3 content 17%, MgO content 8%, and other components 7%. All reagents used were commercially available analytical grade.

[0058] The chemical composition of the fly ash used in the following comparative examples is as follows: SiO2 content 43%, Al2O3 content 34%, CaO content 7%, Fe2O3 content 5%, TiO2 content 2%, K2O content 1%, MgO content 1%, and other components 7%. All reagents used were commercially available analytical grade.

[0059] Example 1

[0060] A method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite includes the following steps:

[0061] (1) Nitrogen doping and impurity removal: High-titanium slag was dried, ground, and passed through a 200-mesh sieve to obtain high-titanium slag powder; the high-titanium slag powder was mixed with ammonium chloride at a mass ratio of 1:0.4, ground into powder, and placed in a muffle furnace for calcination at 400°C for 2 hours. After natural cooling to room temperature, the calcined product was obtained. The calcined product was washed with deionized water until neutral, dried, and ground into powder to obtain powder A.

[0062] (2) Hydrothermal crystallization: Powder A and sodium hydroxide were mixed at a mass ratio of 1:1 and ground into powder B. Deionized water was added, and the solid-liquid ratio of powder B to deionized water was 1:10 (g / mL). The mixture was stirred with a magnetic stirrer for 1 hour. After thorough mixing, the mixture was placed in a reaction vessel for hydrothermal crystallization at a temperature of 180℃ for 12 hours. After crystallization, the solid product was collected by filtration and repeatedly washed with deionized water until neutral. The washed solid was dried and ground into powder to obtain powder C.

[0063] (3) Fe doping: Take 5g of ferric chloride powder, add 50mL of deionized water and stir to dissolve. Adjust the pH to 5 with HCl solution to obtain an acidic iron source solution. Then add 5g of powder C and react with 80W ultrasonic waves at 60℃ for 1h. After the reaction is complete, filter and wash until neutral, dry and grind into powder to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0064] Example 2

[0065] Compared with Example 1, the only difference is that the mesh size in step (1) is adjusted to 100 mesh; the other steps and conditions are the same as in Example 1.

[0066] Example 3

[0067] Compared with Example 1, the only difference is that the nitrogen source in step (1) is ammonium sulfate, and the ammonium sulfate is calcined with high titanium slag; the other steps and conditions are the same as in Example 1.

[0068] Example 4

[0069] Compared with Example 1, the only difference is that the calcination time in step (1) is adjusted to 4 hours; the other steps and conditions are the same as in Example 1.

[0070] Example 5

[0071] Compared with Example 1, the only difference is that the amount of sodium hydroxide in step (2) is adjusted, and powder A is mixed with sodium hydroxide at a mass ratio of 1:1.5; the other steps and conditions are the same as in Example 1.

[0072] Comparative Example 1

[0073] Compared with Example 1, the only difference is that the ammonium chloride added in step (1) is removed and the high-titanium slag powder is directly calcined; the other steps and conditions are the same as in Example 1.

[0074] Comparative Example 2

[0075] Compared with Example 1, the only difference is that the ferric chloride added in step (3) is removed, and powder C is directly placed in a hydrochloric acid solution with a pH of 5 for shaking reaction; the other steps and conditions are the same as in Example 1.

[0076] Comparative Example 3

[0077] Compared with Example 1, the only difference is that the high-titanium slag in step (1) is replaced with fly ash; the other steps and conditions are the same as in Example 1.

[0078] Application Example 1

[0079] A method for preparing a spraying solution for treating vehicle exhaust fumes on asphalt pavements includes the following steps:

[0080] (1) Silane hydrolysis: Take a 30% volume concentration ethanol solution and 5% volume of γ-aminopropyltriethoxysilane in the ethanol solution and put them in a beaker. Adjust the pH value to 10 with ammonia water. Under the stirring condition of magnetic stirrer, carry out the hydrolysis reaction at 30℃ for 30 min to obtain silane hydrolysate.

[0081] (2) Preparation of spraying solution: Take the N-Fe co-doped high titanium slag-based photocatalytic zeolite prepared in Example 1 and silane hydrolysate and stir for 60 min at a solid-liquid ratio of 1:10 (g / mL) at a reaction temperature of 30℃.

[0082] Performance testing

[0083] (1) SEM and EDS images of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite synthesized in Example 1 are shown below. Figure 1 As shown, the zeolite prepared by this invention has a granular morphology, and the EDS results show that nitrogen and iron elements were successfully doped into the zeolite.

[0084] (2) Zeolite adsorption and photocatalytic performance test method: 0.1g of zeolite sample was added to 50ml of methylene blue solution with a concentration of 50ml / g, and placed in a photocatalytic reactor equipped with a magnetic stirrer. The mixture was first subjected to physical adsorption in the dark for 1h, and then to photocatalytic reaction in the light environment for 3h. The UV lamp power was 500W. After the reaction was completed, the supernatant was taken and analyzed by a UV spectrophotometer.

[0085] The zeolites obtained in Examples 1-2 and Comparative Examples 1-3 were tested for zeolite adsorption and photocatalytic performance, and the results are shown in Table 1. The methylene blue removal rate under dark conditions reflects the physical adsorption performance of the zeolite, while the methylene blue removal rate under light conditions reflects the photocatalytic performance of the zeolite.

[0086] Table 1. Test results of zeolite adsorption and photocatalytic performance

[0087]

[0088] As shown in Table 1, the zeolite prepared in the embodiments of the present invention has good adsorption effect and photocatalytic activity for methylene blue. It can achieve a removal rate of more than 15.8% in a dark environment for 1 hour, and can achieve a removal rate of more than 90% when placed in a light environment.

[0089] A comparison of Examples 1 and 2 shows that the particle size of the high-titanium slag powder affects the adsorption and photocatalytic properties of the obtained zeolite. A comparison of Examples 1 and 3 shows that the system of the present invention using ammonium chloride as the nitrogen source is more effective. Furthermore, Examples 4 and 5 show that, within the scope of the present invention, appropriately extending the calcination time and increasing the amount of sodium hydroxide does not significantly promote the photocatalytic properties of the obtained zeolite.

[0090] In Comparative Example 1, the removal of ammonium chloride negatively impacted the adsorption and photocatalytic properties of the resulting zeolite. Similarly, in Comparative Example 2, the removal of ferric chloride also reduced the photocatalytic properties of the resulting zeolite. This demonstrates that the present invention, by adding ammonium chloride as a nitrogen source and a small amount of ferric chloride as an iron source, can form N-Fe co-doped high-titanium slag-based photocatalytic zeolite and produce a synergistic effect.

[0091] (3) Test method for photocatalytic performance of spray solution: Apply the spray solution to the cut 100mm×100mm×50mm asphalt concrete rut slab specimen with a brush, with a coating amount of 10g / m 2 The coated specimens were then allowed to air dry indoors for 24 hours. The coated specimens were then placed in a photocatalytic reaction apparatus. The initial concentration of CO in the apparatus was 1.0% vol, and the initial concentrations of propane and NO were both 200 ppm. The UV lamp power was 500 W, and the reaction time was 3 hours.

[0092] The main pollutants in automobile exhaust can be divided into four categories: carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). CO is a gaseous pollutant produced by the incomplete combustion of automobile fuel. Propane is stable and can effectively simulate the common structure and reaction characteristics of hydrocarbons (HC) in automobile exhaust, making it a commonly used model compound in the laboratory to replace complex HC mixtures. NO is a nitrogen oxide (NOx) in automobile exhaust. XThese three substances (CO, propane, and NO) are the main forms of pollutants in automobile exhaust and are the core gaseous pollutants most representative of automobile exhaust, as well as the main targets of exhaust pollution control technology research and development. Meanwhile, the actual composition of automobile exhaust is complex and easily affected by factors such as fuel quality, engine operating conditions, and environmental impurities, making it difficult to achieve precise control of experimental variables. This invention simulates the treatment effect on automobile exhaust by examining the concentration changes of CO, propane, and NO. Using these three pure substances allows for flexible adjustment of the concentration, ratio, and reaction conditions of each pollutant, effectively eliminating interference from irrelevant factors.

[0093] The photocatalytic performance of the spray solutions of Examples 1-2 and Comparative Examples 1-3 (the preparation steps and conditions of the spray solutions of the products obtained in Examples 2 and Comparative Examples 1-3 are the same as those in Application Example 1) was tested, and the results are shown in Table 2.

[0094] Table 2. Test results of photocatalytic performance of the sprayed solution

[0095]

[0096] As shown in Table 2, the zeolite obtained in the embodiments of the present invention, when prepared into a spraying solution, has a uniform and good removal effect on CO, propane and NO, indicating that the spraying solution of the present invention can be used for automobile exhaust treatment and has a good effect.

[0097] In summary, as Figure 2 As shown, this invention uses high-titanium furnace slag as the main raw material, mixes it with ammonium salts such as ammonium chloride for high-temperature calcination, then mixes it with sodium hydroxide for hydrothermal crystallization, and subsequently reacts it with ferric chloride to obtain N-Fe co-doped high-titanium furnace slag-based photocatalytic zeolite. This achieves the resource utilization of industrial waste and reduces the cost of zeolite preparation. By optimizing the process, the active components of the high-titanium furnace slag are efficiently activated, resulting in zeolite with good photocatalytic and adsorption properties. Furthermore, using the N-Fe co-doped high-titanium furnace slag-based photocatalytic zeolite provided by this invention as a raw material, it is combined with silane hydrolysate obtained from silane hydrolysis to prepare a spray solution for treating automobile exhaust. This solution can be applied to asphalt pavements to treat automobile exhaust with good results. Therefore, this invention provides a low-cost material for the synergistic treatment of automobile exhaust through physical adsorption and photocatalytic degradation, exhibiting significant environmental and economic benefits and being easy to scale up and promote.

[0098] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite, characterized in that, Includes the following steps: S1, high-titanium slag powder is mixed with ammonium salt and calcined at 300-500℃ to obtain calcined product, which is then washed, dried and ground to obtain powder A; S2, mix powder A with alkali to obtain powder B, then mix it evenly with water, and after hydrothermal crystallization reaction, solid-liquid separation, washing and drying, obtain powder C; S3. Powder C is mixed with an acidic iron source solution, and then subjected to ultrasonic reaction, solid-liquid separation, washing and drying to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

2. The method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite according to claim 1, characterized in that, The chemical composition of the high-titanium slag is as follows: TiO2 content 15-45%, CaO content 15-40%, SiO2 content 10-30%, Al2O3 content 2-20%, MgO content 5-15%, Fe2O3 content 0-5%, with the remainder being other impurities.

3. The method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite according to claim 1, characterized in that, In step S1, the high-titanium slag powder is obtained by drying and grinding high-titanium slag and then passing it through a 100-200 mesh sieve. The ammonium salt includes ammonium chloride or ammonium sulfate; the mass ratio of the high-titanium slag powder to the ammonium salt is 1:(0.2-0.6). The calcination time is 1 to 4 hours.

4. The method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite according to claim 1, characterized in that, In step S2, the alkali includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water; the mass ratio of powder A to the alkali is 1:(1-2). The solid-liquid ratio of powder B to water is 1g:(8-12)mL; The powder B is mixed with the water and stirred for 0.1 to 2 hours; The hydrothermal crystallization reaction is carried out at a temperature of 160–200°C for 12–24 hours.

5. The method for preparing N-Fe co-doped high-titanium slag-based photocatalytic zeolite according to claim 1, characterized in that, In step S3, the iron source includes at least one of ferric chloride, ferric nitrate, and ferric sulfate; the mass ratio of the powder C to the iron source is 1:(0.1-2). The acidic iron source solution is prepared by mixing an iron source with deionized water and adjusting the pH value to 4.5–5.

5. The ultrasonic reaction is performed under ultrasonic conditions with a power of 60-100W, with an oscillation reaction at 60-80℃ for 0.1-2 hours.

6. N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared by the preparation method according to any one of claims 1-5.

7. A spraying solution for treating vehicle exhaust fumes on asphalt pavements, characterized in that, It is obtained by mixing and reacting the N-Fe co-doped high-titanium slag-based photocatalytic zeolite described in claim 6 with silane hydrolysate.

8. The method for preparing the spraying solution as described in claim 7, characterized in that, The process includes the following steps: mixing N-Fe co-doped high-titanium slag-based photocatalytic zeolite with silane hydrolysate and stirring the mixture at 30–60°C to prepare a spraying solution.

9. The method for preparing the spraying solution according to claim 8, characterized in that, The silane hydrolysate is prepared by mixing an ethanol solution with γ-aminopropyltriethoxysilane, adjusting the pH to alkaline, and then carrying out a hydrolysis reaction. The concentration of the ethanol solution is 10-95%, and the amount of γ-aminopropyltriethoxysilane used is 4-6% of the volume of the ethanol solution; the hydrolysis reaction temperature is 20-60℃, and the time is 0.1-60 min. The solid-liquid ratio of N-Fe co-doped high-titanium slag-based photocatalytic zeolite to silane hydrolysate is 1 g: (1-20) mL; the stirring reaction time is 30-90 min.

10. The application of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite as described in claim 6 in the preparation of materials with synergistic effects of pollutant adsorption and photocatalysis.

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