N-Fe co-doped high titanium slag-based photocatalytic zeolite as well as preparation method and application thereof

Abstract

The invention relates to N-Fe co-doped high-titanium slag-based photocatalytic zeolite and a preparation method and application thereof.The preparation method comprises the following steps that high-titanium slag powder and ammonium salt are mixed and calcined at the temperature of 300-500 DEG C to obtain a calcined product, and then the calcined product is washed, dried and ground to obtain powder A; mixing the powder A with alkali to obtain powder B, uniformly mixing the powder B with water, and performing hydrothermal crystallization reaction, solid-liquid separation, washing and drying to obtain powder C; and mixing the powder C with an acidic iron source solution, and carrying out ultrasonic reaction, solid-liquid separation, washing and drying to obtain the N-Fe co-doped high titanium slag-based photocatalytic zeolite. According to the preparation method, the high titanium slag is taken as a main raw material and is mixed with the ammonium salt for high-temperature calcination, then is mixed with the alkali for hydrothermal crystallization, and then reacts with the iron source to prepare the N-Fe co-doped high titanium slag-based photocatalytic zeolite, so that resource utilization of industrial waste residues is realized, the preparation cost of the zeolite is reduced, and the prepared zeolite is good in photocatalytic performance and adsorption performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of zeolite, in particular to a N-Fe co-doped high-titanium slag-based photocatalytic zeolite, a preparation method and application thereof. BACKGROUND

[0002] High-titanium slag is a major by-product of vanadium-titanium magnetite smelting, with huge output and complex composition, lacking effective treatment methods. If disposed by stacking, not only a large amount of land is occupied, but also heavy metal elements such as cadmium and manganese contained therein may contaminate soil and groundwater through rainwater leaching. The most commonly used treatment method at present is to use high-titanium slag as cement and brick building materials. This method consumes a large amount, but the utilization value is low, and the high-value resource utilization of the large amount of titanium source contained in the high-titanium slag is a difficult problem to be solved in the metallurgical industry.

[0003] Traffic exhaust pollution has become one of the main sources of urban air pollution; automobile exhaust can be roughly divided into four categories: CO, HC, NO X and PM. At present, the automobile exhaust treatment technology based on asphalt pavement mainly focuses on photocatalytic technology, which introduces photocatalytic materials into asphalt pavement or coats them on the surface layer of the pavement to degrade exhaust pollutants by photocatalytic reaction. Among them, TiO2 becomes the most widely researched photocatalytic material due to its high catalytic activity and good chemical stability.

[0004] Although TiO2 photocatalytic technology has made certain progress in the field of road exhaust treatment, and high-titanium slag contains a relatively rich titanium source, the catalytic efficiency of the photocatalytic material prepared directly from high-titanium slag is still limited, which makes it difficult to meet the demand of actual exhaust degradation efficiency. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, provide a N-Fe co-doped high-titanium slag-based photocatalytic zeolite, a preparation method and application thereof, and solve 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 technical purpose, the technical solution provided by the present application is as follows: In a first aspect, the present application provides a preparation method of a 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 DEG C to obtain a calcined product, then washing, drying and grinding to obtain powder A; S2, mixing powder A with alkali to obtain powder B, and then uniformly mixing with water, and then performing hydrothermal crystallization reaction, solid-liquid separation, washing and drying to obtain powder C; S3, mixing powder C with an acidic iron source solution, and then performing ultrasonic reaction, solid-liquid separation, washing and drying to obtain a N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0007] Preferably, the high-titanium slag has a chemical composition of 15-45% TiO2, 15-40% CaO, 10-30% SiO2, 2-20% Al2O3, 5-15% MgO, and 0-5% Fe2O3, with the balance being other impurities.

[0008] Preferably, in step S1, the high-titanium slag powder is obtained by drying and grinding the high-titanium slag and then sieving the powder through a 100-200 mesh sieve; the ammonium salt is ammonium chloride or ammonium sulfate; the mass ratio of the high-titanium slag powder to the ammonium salt is 1:(0.2-0.6); and the calcination time is 1-4 hours.

[0009] Preferably, in step S2, the base is at least one of sodium hydroxide, potassium hydroxide, and ammonia water; the mass ratio of the powder A to the base is 1:(1-2); the solid-liquid ratio of the powder B to water is 1 g:(8-12) mL; the powder B is stirred with water for 0.1-2 hours after mixing; the hydrothermal crystallization reaction is performed at a temperature of 160-200°C for 12-24 hours.

[0010] Preferably, in step S3, the iron source is 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 the iron source with deionized water and adjusting the pH to 4.5-5.5; and the ultrasonic reaction is performed at a power of 60-100 W for 0.1-2 hours under ultrasonic oscillation at 60-80°C.

[0011] In a second aspect, the present application provides an N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared by the above method.

[0012] In a third aspect, the present application provides a spraying solution for treating automobile exhaust in asphalt pavement, which is obtained by mixing the N-Fe co-doped high-titanium slag-based photocatalytic zeolite with a silane hydrolysate.

[0013] In a fourth aspect, the present application provides a preparation method of a spraying solution for treating automobile exhaust in asphalt pavement, which comprises the following steps: mixing the N-Fe co-doped high-titanium slag-based photocatalytic zeolite with a silane hydrolysate, and stirring to obtain the spraying solution at 30-60°C.

[0014] Preferably, the silane hydrolysate is prepared by mixing an ethanol solution with γ-aminopropyl triethoxysilane and adjusting the pH to alkaline, and then performing a hydrolysis reaction; the concentration of the ethanol solution is 10-95%, and the amount of γ-aminopropyl triethoxysilane is 4-6% of the volume of the ethanol solution; the hydrolysis reaction is performed at a temperature of 20-60°C for 0.1-60 minutes; the solid-liquid ratio of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite to the silane hydrolysate is 1 g:(1-20) mL; and the stirring reaction is performed for 30-90 minutes.

[0015] In a fifth aspect, the present application provides a use of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite in preparing a material for synergistic adsorption and photocatalysis of pollutants.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application uses high-titanium slag as the main raw material, mixes with ammonium salt, and then performs high-temperature calcination, and then mixes with alkali to perform hydrothermal crystallization, and then reacts with an iron source to obtain the N-Fe co-doped high-titanium slag-based photocatalytic zeolite, thereby realizing the resource utilization of industrial waste slag and reducing the cost of zeolite preparation; the active components of the high-titanium slag are efficiently activated by optimizing the process, and the prepared zeolite has good photocatalytic and adsorption properties. Further, the N-Fe co-doped high-titanium slag-based photocatalytic zeolite provided by the present application is used as a raw material to prepare a spraying solution with a hydrolysis solution obtained by hydrolysis of silane, thereby realizing the high-value utilization of industrial waste slag and the efficient synergistic treatment of adsorption and photocatalysis of pollutants, and the environmental and economic benefits are taken into account, and the present application is easy to be mass-produced and popularized. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 is a SEM image and an EDS image of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite synthesized in Example 1 of the present application; 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; Figure 2 Fig. 2 is a schematic diagram of a preparation process of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite and the spraying solution of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0019] In view of the defects that the resource utilization efficiency of high-titanium slag is low and the catalytic efficiency of TiO2 photocatalytic treatment of automobile exhaust is limited, the present application provides a N-Fe co-doped high-titanium slag-based photocatalytic zeolite, a preparation method and an application, which can efficiently activate the active components of high-titanium slag, control the influence of impurities, obtain the N-Fe co-doped high-titanium slag-based photocatalytic zeolite, and prepare a spraying solution therefrom, and the spraying solution is applied to the treatment of automobile exhaust. The present application can not only solve the environmental protection problem of high-titanium slag stockpiling, but also provide a low-cost photocatalytic material to support the demand in the field of automobile exhaust treatment, and has significant environmental and economic benefits.

[0020] In a first aspect, the present application provides a preparation method of a N-Fe co-doped high-titanium slag-based photocatalytic zeolite, comprising the following steps: S1, mixing the high-titanium slag powder with an ammonium salt, calcining at 300-500 DEG C to obtain a calcined product, and then washing, drying and grinding to obtain powder A; S2, mixing the powder A with a base to obtain powder B, and then mixing with water uniformly, and performing hydrothermal crystallization reaction, solid-liquid separation, washing and drying to obtain powder C; S3, mixing the powder C with an acidic iron source solution, and performing ultrasonic reaction, solid-liquid separation, washing and drying to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0021] The present application uses high-titanium slag as the main raw material, mixes with an ammonium salt for high-temperature calcination, mixes with a base for hydrothermal crystallization, and then reacts with an iron source to prepare N-Fe co-doped high-titanium slag-based photocatalytic zeolite, realizes the resource utilization of industrial waste slag, and reduces the preparation cost of zeolite; through optimization of the process, the active components of high-titanium slag are activated efficiently, and the prepared zeolite has good photocatalytic performance and adsorption performance.

[0022] Specifically, the calcination temperature in step S1 includes but is not limited to 300 DEG C, 320 DEG C, 330 DEG C, 340 DEG C, 350 DEG C, 360 DEG C, 380 DEG C, 390 DEG C, 400 DEG C, 410 DEG C, 420 DEG C, 430 DEG C, 440 DEG C, 450 DEG C, 460 DEG C, 480 DEG C, 500 DEG C, etc.

[0023] In some embodiments, the chemical composition of the high-titanium slag is: 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 is other impurity components.

[0024] In some embodiments, in step S1, the high-titanium slag powder is prepared by drying and grinding the high-titanium slag and then passing through a 100-200 mesh sieve.

[0025] In some embodiments, in step S1, the ammonium salt includes ammonium chloride or ammonium sulfate; and the mass ratio of the high-titanium slag powder to the ammonium salt is 1:(0.2-0.6). Specifically, the mass ratio of the high-titanium slag powder to the ammonium salt includes but is not limited to 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, etc.

[0026] In some embodiments, in step S1, the calcination time is 1-4h. Specifically, the calcination time includes but is not limited to 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0027] In some embodiments, in step S1, the washing is washing the calcined product with deionized water until it is neutral.

[0028] In some embodiments, in step S2, the base includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water; and the mass ratio of the powder A to the base is 1:(1-2). Specifically, the mass ratio of the powder A to the base includes but is not limited to 1:1, 1:1.2, 1:1.5, 1:1.6, 1:1.8, 1:2, etc.

[0029] In some embodiments, in step S2, the solid-liquid ratio of the powder B to water is 1 g:(8-12) mL. Specifically, the solid-liquid ratio of the powder B to water includes but is not limited to 1 g:8 mL, 1 g:9 mL, 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, etc.

[0030] In some embodiments, in step S2, the powder B is stirred with water for 0.1-2 h after mixing. Specifically, the stirring time includes but is not limited to 0.1 h, 0.5 h, 1 h, 1.5 h, 2 h, etc.

[0031] In some embodiments, in step S2, the hydrothermal crystallization reaction is performed at a temperature of 160-200°C for a time of 12-24 h. 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 h, 12.5 h, 13 h, 15 h, 16 h, 18 h, 20 h, 22 h, 24 h, etc.

[0032] In some embodiments, in step S3, the iron source includes at least one of ferric chloride, ferric nitrate, and ferric sulfate; and the mass ratio of the powder C to the iron source is 1:(0.1-2). The mass ratio of the 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.

[0033] Further, 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. Specifically, the pH value includes but is not limited to 4.5, 4.8, 5.0, 5.2, 5.5, etc.

[0034] In some embodiments, in step S3, the ultrasonic reaction is performed at a power of 60-100 W under ultrasonic conditions, and the oscillation reaction is performed at a temperature of 60-80°C for a time of 0.1-2 h. 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 h, 0.5 h, 1 h, 1.5 h, 2 h, etc.

[0035] In a second aspect, the present application provides an N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared by the above preparation method.

[0036] In a third aspect, the present application provides a spraying solution for treating automobile exhaust in asphalt pavement, which is obtained by mixing and reacting the N-Fe co-doped high-titanium slag-based photocatalytic zeolite and the silane hydrolysate.

[0037] In this embodiment, the spraying solution is directly sprayed or coated on the surface of the asphalt pavement. After the solution is naturally dried, a coating layer with adsorption and photocatalytic functions is formed. The coating layer can efficiently adsorb automobile exhaust and degrade the automobile exhaust through photocatalytic reaction under light conditions, thereby achieving the synergistic treatment of automobile exhaust.

[0038] It should be noted that the use form of the spraying solution prepared by the present application includes but is not limited to "spraying" and "coating".

[0039] In a fourth aspect, the present application provides a preparation method of a spraying solution for treating automobile exhaust in asphalt pavement, which comprises the following steps: mixing the N-Fe co-doped high-titanium slag-based photocatalytic zeolite and the silane hydrolysate, and stirring and reacting at 30-60°C to obtain the spraying solution.

[0040] In some embodiments, the silane hydrolysate is obtained by mixing an ethanol solution and γ-aminopropyl triethoxysilane and adjusting the pH value to alkaline, and then through hydrolysis reaction.

[0041] Further, the volume concentration of the ethanol solution is 10-95%, the amount of γ-aminopropyl triethoxysilane is 4-6% of the volume of the ethanol solution, the pH value is adjusted to 8-12, the temperature of the hydrolysis reaction is 20-60°C, 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%, 95%, etc.; the amount of γ-aminopropyl triethoxysilane includes but is not limited to 4%, 4.5%, 5%, 5.5%, 6%, etc.; the adjusted pH value includes but is not limited to 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, etc.; the temperature of the hydrolysis reaction includes but is not limited to 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc., 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, 60 min, etc.

[0042] In some embodiments, the solid-liquid ratio of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite and the silane hydrolysate is 1g: (1-20)mL, and the stirring reaction time is 30-90 min.

[0043] In a fifth aspect, the present application provides a use of the above-mentioned N-Fe co-doped high-titanium slag-based photocatalytic zeolite in preparation of a material with synergistic effects of pollutant adsorption and photocatalysis.

[0044] In some embodiments, the pollutants include one or more of methylene blue, CO, propane, and NO.

[0045] The main mechanism and advantages of the present application are as follows: (1) Realizing high-value utilization of high-titanium slag: the functional zeolite is prepared by using high-titanium slag as the main raw material, which effectively absorbs industrial solid waste and solves the problems of extensive utilization and low added value of traditional high-titanium slag, thereby reducing the raw material cost of zeolite preparation and achieving significant environmental and economic benefits; (2) Excellent photocatalytic and adsorption performance: the high-titanium slag powder is mixed with ammonium salt and calcined, the ammonium salt is decomposed into weak acid ions and nitrogen-containing substances such as ammonia gas at high temperature, the weak acid ions combine with a small amount of impurities such as calcium and magnesium, and are removed through the calcination and water washing steps, and the nitrogen-containing substances are doped in the zeolite, thereby realizing N-doping and impurity removal effect; then, through hydrothermal crystallization and Fe-doping, the N-Fe co-doped high-titanium slag-based photocatalytic zeolite is formed; through N-Fe co-doping modification and optimization process, the present application efficiently activates the active components in the high-titanium slag, and the prepared zeolite has good photocatalytic activity and automobile exhaust adsorption performance; the N-Fe co-doping can adjust the electronic structure of titanium active sites, broaden the light response range, and improve the visible light utilization efficiency; (3) Excellent coating stability and durability: during the preparation of the spraying solution, γ-aminopropyl triethoxysilane is introduced, and the hydrolysis product thereof can enhance the compatibility and adhesion of the zeolite with the asphalt pavement, and enhance the stability of the zeolite in complex environments; (4) Easy to scale production and popularization: the preparation steps of the present application are simple, the conditions are mild, the required equipment is conventional, the raw material cost is low, and the spraying construction is convenient, without the need to greatly modify the existing asphalt pavement construction process, which is convenient for industrialized production and large-area engineering application.

[0046] The present application will be further described in detail below in conjunction with specific embodiments, but the scope of protection of the present application is not limited thereto.

[0047] The chemical composition results of the high-titanium slag used in the following examples and comparative examples are as follows: TiO2 content 20%, CaO content 21%, SiO2 content 27%, Al2O3 content 17%, MgO content 8%, and other component content 7%. The reagents used are all commercially available analytical pure.

[0048] The chemical composition of 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 content 7%. The reagents used are all commercially available analytical pure.

[0049] Example 1 A preparation method of N-Fe co-doped high-titanium slag-based photocatalytic zeolite, comprising the following steps: (1) N-doping and impurity removal: dry and grind the high-titanium slag to pass through a 200-mesh screen to obtain high-titanium slag powder; mix the high-titanium slag powder with ammonium chloride at a mass ratio of 1:0.4, grind into powder, and place in a muffle furnace for calcination at 400°C for 2h, and then naturally cool to room temperature to obtain a calcined product. Wash the calcined product with deionized water until neutral, dry and grind into powder to obtain powder A.

[0050] (2) Hydrothermal crystallization: mix powder A with sodium hydroxide at a mass ratio of 1:1 to obtain powder B, add deionized water, and the solid-liquid ratio of powder B to deionized water is 1:10 (g / mL), stir with a magnetic stirrer for 1h, and then place in a reaction kettle for hydrothermal crystallization reaction at a temperature of 180°C for 12h. After the crystallization is completed, filter and collect the solid product, and repeatedly wash the solid product with deionized water until neutral. Dry and grind the washed solid into powder to obtain powder C.

[0051] (3) Fe-doping: take 5g of iron chloride powder, add 50mL of deionized water to dissolve by stirring, adjust the pH to 5 with an HCl solution to obtain an acidic iron source solution, and then add 5g of powder C, and perform ultrasonic oscillation reaction at 80W and 60°C for 1h. After the reaction is completed, filter and wash until neutral, dry and grind into powder to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite.

[0052] Example 2 Compared with Example 1, the only difference is that the mesh size in step (1) is adjusted to 100 meshes; the other steps and conditions are the same as those in Example 1.

[0053] Example 3 Compared with Example 1, the only difference is that the nitrogen source in step (1) is ammonium sulfate, and ammonium sulfate is calcined with high-titanium slag; the other steps and conditions are the same as those in Example 1.

[0054] Example 4 Compared with Example 1, the only difference is that the calcination time in step (1) is adjusted to 4h; the other steps and conditions are the same as those in Example 1.

[0055] Example 5 The difference compared with Example 1 is only 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; other steps and conditions are the same as those in Example 1.

[0056] Comparative Example 1 The difference compared with Example 1 is only that: the added ammonium chloride in step (1) is removed, and the high-titanium slag powder is directly calcined; other steps and conditions are the same as those in Example 1.

[0057] Comparative Example 2 The difference compared with Example 1 is only that: the added iron chloride in step (3) is removed, and powder C is directly placed in a hydrochloric acid solution with a pH value of 5 for oscillation reaction; other steps and conditions are the same as those in Example 1.

[0058] Comparative Example 3 The difference compared with Example 1 is only that: the high-titanium slag in step (1) is replaced by fly ash; other steps and conditions are the same as those in Example 1.

[0059] Application Example 1 A preparation method of a spraying solution for treating automobile exhaust in asphalt pavement, comprising the following steps: (1) Silane hydrolysis: take a 30% volume concentration of ethanol solution and 5% of the volume of the ethanol solution of γ-aminopropyl triethoxysilane in a beaker, adjust the pH value to 10 with ammonia water, and hydrolyze at 30°C for 30 min under the condition of magnetic stirring to obtain a silane hydrolysis solution.

[0060] (2) Preparation of the spraying solution: take the N-Fe co-doped high-titanium slag-based photocatalytic zeolite prepared in Example 1 and the silane hydrolysis solution to stir for 60 min at a solid-liquid ratio of 1:10 (g / mL) and a reaction temperature of 30°C.

[0061] Performance test (1) The SEM and EDS images of the N-Fe co-doped high-titanium slag-based photocatalytic zeolite synthesized in Example 1 are shown in Figure 1 The zeolite prepared by the application has a granular morphology, and from the EDS results, it can be seen that nitrogen and iron elements are successfully doped on the zeolite.

[0062] (2) Zeolite adsorption and photocatalytic performance test method: 0.1 g of the zeolite sample is added to 50 ml of a 50 ml / g methylene blue solution, and placed in a photocatalytic reactor with a magnetic stirrer for stirring, first physically adsorbed for 1 h in a dark environment, and then photocatalyzed for 3 h in a light environment, with a UV lamp power of 500 w. After the reaction is completed, the supernatant is analyzed by ultraviolet spectrophotometry.

[0063] The zeolite obtained in Example 1-2 and Comparative Example 1-3 was subjected to zeolite adsorption and photocatalytic performance test, and the results are shown in Table 1. The methylene blue removal rate in dark environment can reflect the physical adsorption performance of the zeolite, and the methylene blue removal rate in light environment can reflect the photocatalytic performance of the zeolite.

[0064] Table 1: Results of zeolite adsorption and photocatalytic performance test

[0065] As can be seen from Table 1, the zeolite prepared in the examples has good adsorption effect and photocatalytic property for methylene blue, and can achieve a removal rate of more than 15.8% in dark environment for 1 h, and a removal rate of more than 90% in light environment.

[0066] As can be seen from the comparison between Example 1 and Example 2, the particle size of high-titanium slag powder has an effect on the adsorption and photocatalytic property of the obtained zeolite. As can be seen from the comparison between Example 1 and Example 3, the effect of using ammonium chloride as a nitrogen source in the system of the present application is better. At the same time, as can be seen from Examples 4-5, within the scope of the present application, appropriately extending the calcination time and increasing the amount of sodium hydroxide have no obvious promoting effect on the photocatalytic property of the obtained zeolite.

[0067] In Comparative Example 1, the ammonium chloride is removed, which has an adverse effect on the adsorption and photocatalytic property of the obtained zeolite. In Comparative Example 2, the ferric chloride is removed, which also reduces the photocatalytic property of the obtained zeolite, which indicates that the addition of ammonium chloride as a nitrogen source and a small amount of ferric chloride as an iron source in the present application can form N-Fe co-doped high-titanium slag-based photocatalytic zeolite and produce a synergistic effect.

[0068] (3) Photocatalytic performance test method of spraying solution: the spraying solution was applied to the cut 100mmx100mmx50mm asphalt concrete rutting plate test piece with a brush, the application amount was 10g / m 2 , and it was placed in the indoor natural air for 24h. The coated test piece was placed in a photocatalytic reaction device, the initial concentration of CO in the reaction device was 1.0%vol, the initial concentration of propane and NO was 200ppm, the ultraviolet lamp power was 500w, and the reaction time was 3h.

[0069] 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 incomplete combustion of automobile fuel, propane has stable properties and can effectively simulate the common structure and reaction characteristics of hydrocarbons (HC) in automobile exhaust, and is a commonly used model compound for replacing complex HC mixtures in the laboratory; NO is a nitrogen oxide (NO X), which are the most representative core gaseous pollutants in automobile exhaust and the main objects of research and development of exhaust pollution control technology. Meanwhile, the actual automobile exhaust composition is complex and is easily disturbed by factors such as fuel quality, engine working condition and environmental impurities, and it is difficult to accurately control the experimental variables. The present application simulates the treatment effect on automobile exhaust by investigating the concentration changes of CO, propane and NO, and the three pure substances can be used to flexibly control the concentration, ratio and reaction conditions of each pollutant, effectively excluding the interference of irrelevant factors.

[0070] The photocatalytic performance of the sprayed solutions (the sprayed solutions of the products of Examples 2 and Comparative Examples 1-3 were prepared according to the preparation steps and conditions of the sprayed solution of Example 1) of Examples 1-2 and Comparative Examples 1-3 was tested, and the results are shown in Table 2.

[0071] Table 2: Test results of the photocatalytic performance of the sprayed solutions

[0072] As can be seen from the results in Table 2, the zeolite obtained in the examples has good removal effect on CO, propane and NO when prepared into a sprayed solution, indicating that the sprayed solution of the present application can be used for automobile exhaust treatment and has good effect.

[0073] In summary, as shown in Figure 2 The present application uses high-titanium slag as the main raw material, mixes with ammonium chloride and other ammonium salts, and then performs high-temperature calcination, and then mixes with sodium hydroxide to perform hydrothermal crystallization, and then reacts with ferric chloride to obtain N-Fe co-doped high-titanium slag-based photocatalytic zeolite, which realizes the resource utilization of industrial waste slag and reduces the preparation cost of zeolite. Through optimization of the process, the active components of high-titanium slag are activated efficiently, and the prepared zeolite has good photocatalytic and adsorption properties. The N-Fe co-doped high-titanium slag-based photocatalytic zeolite provided by the present application is used as the raw material to prepare a sprayed solution for treating automobile exhaust with the silane hydrolysis solution obtained by hydrolysis of silane, which can be applied to asphalt pavement and can treat automobile exhaust with good treatment effect. Therefore, the present application provides a low-cost material for synergistically treating automobile exhaust through physical adsorption and photocatalytic degradation, which has significant environmental and economic benefits and is easy to mass-produce and popularize.

[0074] The specific embodiments of the present application described above do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made in accordance with the technical concept of the present application shall be included in the scope of protection of the claims of the present application.

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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