A hydrophobically modified molecular sieve / manganese sand functional material and its preparation method and application

Abstract

The present invention belongs to the field of environmental management materials and specifically discloses a hydrophobic modified molecular sieve / manganese sand functional material and its preparation method and application. The functional material has a core-shell structure, including natural manganese sand located in the core and a molecular sieve shell grown in situ on the surface of the natural manganese sand. The hydrophobicity of the molecular sieve from the core natural manganese sand to the shell is gradually enhanced to achieve directional discharge of water molecules while maintaining the transmission channel of ozone. The hydrophobic molecular sieve-natural manganese sand material prepared by the present invention can alleviate the corrosion of humid environments by improving the hydrophobicity and the stability of the hydrothermal environment of the molecular sieve. It can exhibit excellent catalytic activity in high humidity environments and can be widely used in air purification and water treatment systems.

Description

Technical Field

[0001] The present invention belongs to the field of air and water pollution environment treatment materials, and specifically relates to a hydrophobically modified molecular sieve / manganese sand functional material and a preparation method and application thereof. Background Art

[0002] Ultra-low concentrations of ozone (e.g., 0.02-0.05 ppm) may irritate the respiratory tract and cause minor headaches, dizziness, and difficulty concentrating. Prolonged exposure can impair sleep quality and cause fatigue. Treatment methods for ultra-low concentrations of ozone (<0.1 ppm) primarily include physical, chemical, and catalytic degradation technologies. Activated carbon adsorption, with its large surface area and rich pore structure, captures ozone through physical adsorption and catalytically decomposes it through its surface functional groups. However, activated carbon has a limited adsorption capacity and requires regular replacement or regeneration. Its treatment efficiency is significantly affected by air humidity and temperature. Catalytic decomposition uses catalysts (such as MnO2, CuO, TiO2, and Co3O4) to accelerate the decomposition of ozone into oxygen. Catalysts can be coated on supports (such as honeycomb ceramics, activated carbon, and alumina) to improve treatment efficiency. However, catalysts are sensitive to humidity and contaminants, which may affect degradation efficiency. Therefore, it is crucial to develop hydrophobic materials that can recognize, adsorb, and catalyze ultra-low concentrations of ozone.

[0003] Natural mineral catalysts have large reserves and low prices, and have unparalleled advantages over other catalysts in terms of cost of use. Natural manganese sand is widely distributed in nature, has abundant reserves, and is easy to obtain. Compared with some synthetic catalysts or precious metal catalysts, it has a lower cost, better economic efficiency, and is suitable for large-scale application. Natural manganese sand contains metal elements such as manganese. The metal active sites on its surface can adsorb ozone molecules and catalyze the decomposition of ozone into oxygen to a certain extent, which has an ozone removal effect. However, the catalytic decomposition effect of natural manganese sand on low-concentration ozone is limited, especially in outdoor atmospheric environments and high humidity conditions. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a hydrophobically modified molecular sieve / manganese sand functional material in response to the deficiencies of the existing technology, to improve the problem of efficient catalytic decomposition of low-concentration ozone by natural manganese sand, especially to show good catalytic effect in outdoor atmospheric environment and high humidity conditions, and to show good water resistance and long-term catalytic stability during the catalytic process, and to be able to maintain a high catalytic efficiency after long-term use.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0006] A hydrophobically modified molecular sieve / manganese sand functional material has a core-shell structure, including natural manganese sand located in the core and a molecular sieve shell grown in situ on the surface of the natural manganese sand; the hydrophobicity of the molecular sieve gradually increases from the natural manganese sand in the core to the outer shell to achieve directional discharge of water molecules while maintaining the transmission channel of ozone.

[0007] Among them, molecular sieves have become a popular material for ozone adsorption and catalysis due to their advantages such as efficient adsorption and catalytic performance, good stability and renewability. Molecular sieves have uniform pore size and large specific surface area, and can selectively adsorb ozone molecules based on the size and shape of the molecules. That is, by adjusting the pore size of the molecular sieve, it can selectively adsorb molecules of a specific size, such as ozone, thereby improving the catalytic efficiency. Its pore size is usually between 3-15 angstroms, which is comparable to the size of ozone molecules. Therefore, ozone molecules can smoothly enter the pores of the molecular sieve and be adsorbed. In addition, molecular sieves have a high affinity for polar molecules, and ozone molecules have a certain polarity, which also promotes their adsorption on the molecular sieve.

[0008] Natural manganese sand is widely distributed in nature, with abundant reserves and easy access. Compared to some synthetic catalysts or precious metal catalysts, it is relatively low-cost, has good economic benefits, and is suitable for large-scale application. Natural manganese sand contains metal elements such as manganese. The metal active sites on its surface can adsorb ozone molecules and, to a certain extent, catalyze the decomposition of ozone into oxygen, effectively removing ozone.

[0009] This invention combines molecular sieves with natural manganese sand to create a molecular sieve-natural manganese sand hydrophobic material. The MnOx in the natural manganese sand serves as the active site, utilizing its redox cycle to catalytically decompose adsorbed ozone. The molecular sieve layer provides numerous pores, allowing for the enrichment of ozone molecules. Furthermore, the molecular sieve surface possesses certain acidic, base, and polar functional groups, which interact with ozone through weak non-covalent interactions (such as van der Waals and dipole-dipole interactions), facilitating ozone capture. The hydrophobic modification reduces surface moisture on the catalyst, further ensuring that ozone molecules in the dry state more readily contact the active sites, improving overall adsorption and catalytic efficiency. Finally, by manipulating the pore size, surface functional groups, and hydrophobic / hydrophilic properties of the molecular sieve-natural manganese sand catalyst, the present invention aims to optimize the residence time of ultra-low-concentration ozone on the material surface, further enhancing its degradation efficiency and long-term stability.

[0010] Furthermore, the present invention also provides a method for preparing the above-mentioned hydrophobically modified molecular sieve / manganese sand functional material, comprising the following steps:

[0011] S1: Natural manganese sand pretreatment

[0012] Take natural manganese sand and wash it alternately with deionized water and anhydrous ethanol to remove surface dust and organic impurities; then immerse the manganese sand in an acid solution and stir it at room temperature to remove unstable impurities and part of the carbonate on the surface, and then repeatedly wash it with deionized water until it is neutral; finally, dry the washed manganese sand;

[0013] S2: In situ growth of molecular sieve shell

[0014] Deionized water, a silicon source, aluminum nitrate, and a structure-directing agent are uniformly mixed and the pH value is adjusted to obtain a precursor solution, the manganese sand obtained in step S1 is dispersed in the precursor solution, and the precursor solution is allowed to fully penetrate the surface of the manganese sand particles; then, after a hydrothermal reaction, the solid product is repeatedly washed with deionized water to remove the residual precursor solution and unreacted substances on the surface; finally, the product is calcined under an inert atmosphere to remove the structure-directing agent and form a pore structure of the shell molecular sieve;

[0015] S3: Hydrophobic surface modification

[0016] A hydrophobic agent solution is prepared, and then the product obtained in step S2 is immersed in the hydrophobic agent solution and stirred at room temperature to allow the hydrophobic functional groups to fully react with the surface of the molecular sieve to form a stable organic hydrophobic layer, which is then vacuum dried to obtain the product.

[0017] The present invention uses an in-situ growth method to grow molecular sieves on the surface of natural manganese sand, forming a core-shell structure similar to that of the natural manganese sand. This structure combines the shape selectivity and high specific surface area of ​​the molecular sieve with the catalytic activity and redox properties of natural manganese sand, demonstrating unique advantages in catalysis, adsorption, energy storage, and other fields.

[0018] The present invention modifies the material's hydrophobicity, creating a composite material with a gradual hydrophobicity gradient from the core to the shell. This allows for the targeted expulsion of water molecules while maintaining efficient ozone transmission. Furthermore, the present material has a wider range of applications, as the shell and core can be designed with varying hydrophobicity gradients. This allows for ozone removal not only from air in high-humidity environments but also from water.

[0019] Specifically, in step S1, the natural manganese sand is cleaned with ultrasonic assistance when being cleaned with deionized water and anhydrous ethanol, and the ultrasonic cleaning time is 1 to 12 hours; the acid solution is a dilute hydrochloric acid aqueous solution with a concentration of 0.1 to 5 mM, and is stirred at room temperature for 1 to 24 hours.

[0020] Specifically, in step S2, the silicon source is ethyl silicate or sodium silicate; and the structure directing agent is selected from any one of tetrapropylammonium hydroxide, hexadecyltrimethylammonium bromide, and sodium diacetate.

[0021] Specifically, in step S2, the mass ratio of the treated manganese sand, silicon source, aluminum nitrate, and structure directing agent is 10: (1-5): (1-5): (0.1-2), and the pH value of the precursor solution is adjusted to 9-11.

[0022] Specifically, in step S2, the temperature of the hydrothermal reaction is 100-400° C., and the time is 12-72 h.

[0023] Specifically, in step S2, calcination is performed in a tubular furnace in a nitrogen atmosphere at a temperature of 300-800° C. for 12-24 hours.

[0024] Specifically, in step S3, a silane coupling agent is added to anhydrous toluene or ethanol, and the mixture is stirred to form a uniform solution to prepare a hydrophobic agent solution; the silane coupling agent is octamethylsilane or trifluoromethylsilane; and the mass ratio of the silane coupling agent to the product of step S2 is (0.1~2):1.

[0025] Specifically, in step S3, the vacuum drying temperature is 80-200° C., and the time is 2-24 h.

[0026] Furthermore, the present invention also claims the use of the above-mentioned hydrophobically modified molecular sieve / manganese sand functional material for catalytic decomposition of low-concentration ozone, wherein the concentration of the low-concentration ozone is not higher than 0.05 ppm.

[0027] Beneficial effects:

[0028] (1) The present invention improves the problem of efficient catalytic decomposition of low-concentration ozone by natural manganese sand, especially showing good catalytic effect in outdoor atmospheric environment and high humidity conditions, and showing good water resistance and long-term catalytic stability during the catalytic process, and can maintain a high catalytic efficiency after long-term use. It can also regulate the oxidation state of manganese sand through redox reactions to form abundant oxygen vacancies and active sites, thereby improving the adsorption and decomposition efficiency of ozone. In addition, the molecular sieve-natural manganese sand catalyst has good stability and catalytic activity under various environmental conditions (such as different humidity, high-speed airflow, etc.), and can cope with complex changes in the atmospheric environment. Finally, the molecular sieve-natural manganese sand catalyst prepared by the present invention can achieve efficient catalytic decomposition in an extremely low-concentration ozone environment, solving the problem that traditional catalysts fail under low-concentration ozone.

[0029] (2) The hydrophobic molecular sieve-natural manganese sand material prepared by the present invention can alleviate the corrosion of humid environment by improving the hydrophobicity and the stability of the hydrothermal environment of the molecular sieve. It can show excellent catalytic activity in high humidity environment and can be widely used in air purification and water treatment systems. In this composite catalyst, MnOx in natural manganese sand serves as the active center, and its redox cycle is used to catalytically decompose the adsorbed ozone. The molecular sieve layer provides a large number of pores, allowing ozone molecules to be enriched. At the same time, the molecular sieve surface has certain acidic, alkaline and polar functional groups, which can have weak non-covalent interactions with ozone, which helps to capture low-concentration ozone. It is suitable for the catalytic decomposition of low-concentration ozone (ppm level or ppb level) to meet the needs of daily air and water treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0031] Figure 1 This is the water contact angle test of ten groups of embodiments of the present invention.

[0032] Figure 2 The ozone removal efficiency of the ten groups of examples is 0.01 ppm, the relative humidity is 65%, and the reaction time is 48 h.

[0033] Figure 3 The ozone removal efficiency of the ten groups of examples is 0.03 ppm, the relative humidity is 80%, and the reaction time is 96 h.

[0034] Figure 4 The ozone removal efficiency of the ten groups of examples is shown when the ozone concentration is 0.05 ppm, the relative humidity is 85%, and the reaction time is 120 h.

[0035] Figure 5 This is the verification effect of the functional materials of Example 10 and the comparative example in removing ozone in water.

[0036] Figure 6 This is a scanning electron microscope image of the hydrophobically modified molecular sieve / manganese sand functional material prepared in Example 10. DETAILED DESCRIPTION

[0037] The present invention can be better understood with reference to the following examples.

[0038] Example 1

[0039] In this embodiment, the specific preparation method of the molecular sieve-natural manganese sand hydrophobic material is as follows:

[0040] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0041] (2) Add 2.5 g of ethyl silicate, 2.3 g of aluminum nitrate, and 0.3 g of tetrapropylammonium hydroxide to 50 ml of deionized water, and adjust the pH to 10 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 100 ° C and the time is 12 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate at a temperature of 300 ° C in a tubular furnace under a nitrogen atmosphere for 12 h to obtain a molecular sieve-natural manganese sand composite;

[0042] (3) Add 5 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 80-200 °C for 2-24 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0043] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0044] Example 2

[0045] (1) 10 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100 °C and dried to constant weight to obtain the treated manganese sand.

[0046] (2) Add 5.6 g of sodium silicate, 5.8 g of aluminum nitrate, and 0.9 g of sodium diacetate to 50 ml of deionized water, and adjust the pH to 9 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 hours. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 180 ° C and the time is 24 hours. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 300~800 ° C for 12~24 hours to obtain a molecular sieve-natural manganese sand composite;

[0047] (3) Add 5 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and then vacuum dry at 100 °C for 6 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0048] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0049] Example 3

[0050] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0051] (2) Add 3 g of ethyl silicate, 2 g of aluminum nitrate, and 0.5 g of tetrapropylammonium hydroxide to 50 ml of deionized water, and adjust the pH to 10 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 200 ° C and the time is 36 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate at a temperature of 400 ° C in a tubular furnace under a nitrogen atmosphere for 16 h to obtain a molecular sieve-natural manganese sand composite;

[0052] (3) Add 10 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 100 ° C for 6 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0053] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0054] Example 4

[0055] (1) 15 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 3 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0056] (2) Add 10 g of ethyl silicate, 5 g of aluminum nitrate, and 2 g of hexadecyltrimethylammonium bromide to 50 ml of deionized water, and adjust the pH to 11 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and perform the hydrothermal reaction at a temperature of 280 ° C for 48 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 550 ° C for 18 h to obtain a molecular sieve-natural manganese sand composite;

[0057] (3) Add 15 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction, wash with anhydrous ethanol and then vacuum dry at 90 °C for 13 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0058] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0059] Example 5

[0060] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 0.5 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0061] (2) Add 2.5 g of sodium silicate, 2.3 g of aluminum nitrate, and 0.3 g of hexadecyltrimethylammonium bromide to 50 ml of deionized water, and adjust the pH to 10 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and perform the hydrothermal reaction at a temperature of 180 ° C for 12 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 300 ° C for 12 h to obtain a molecular sieve-natural manganese sand composite;

[0062] (3) Add 5 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and then vacuum dry at 80 °C for 2 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0063] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0064] Example 6

[0065] (1) 18 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0066] (2) Add 5.6 g of sodium silicate, 5.8 g of aluminum nitrate, and 0.9 g of sodium diacetate to 50 ml of deionized water, and adjust the pH to 9 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 hours. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 180 ° C and the time is 24 hours. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 300~800 ° C for 12~24 hours to obtain a molecular sieve-natural manganese sand composite;

[0067] (3) Add 5 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and then vacuum dry at 100 °C for 6 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0068] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0069] Example 7

[0070] (1) 6 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 3 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0071] (2) Add 2.5 g of ethyl silicate, 2.3 g of aluminum nitrate, and 0.8 g of hexadecyltrimethylammonium bromide to 50 ml of deionized water, and adjust the pH to 9 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and perform the hydrothermal reaction at a temperature of 250 ° C for 36 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 500 ° C for 16 h to obtain a molecular sieve-natural manganese sand composite;

[0072] (3) Add 6 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and then vacuum dry at 120 °C for 15 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0073] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0074] Example 8

[0075] (1) 8 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 2 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0076] (2) Add 4 g of sodium silicate, 3 g of aluminum nitrate, and 1 g of sodium diacetate to 50 ml of deionized water, and adjust the pH to 9 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 180 ° C and the time is 12 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate at a temperature of 400 ° C in a tubular furnace under a nitrogen atmosphere for 15 h to obtain a molecular sieve-natural manganese sand composite;

[0077] (3) Add 15 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 120 °C for 8 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0078] The prepared molecular sieve-natural manganese sand hydrophobic material is used in an ozone pollutant system in a humid environment to improve the removal ability of low-concentration ozone.

[0079] Example 9

[0080] (1) 8 g of natural manganese sand was ultrasonically cleaned with deionized water for 2 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 2 mM dilute hydrochloric acid solution and stirred at room temperature for 8 h. Subsequently, the treated manganese sand was repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100 °C and dried to constant weight to obtain the treated manganese sand.

[0081] (2) Add 2.4 g of sodium silicate, 2.4 g of aluminum nitrate, and 0.4 g of sodium diacetate to 50 ml of deionized water, and adjust the pH to 10 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 220 ° C and the time is 30 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate at a temperature of 450 ° C in a tubular furnace under a nitrogen atmosphere for 18 h to obtain a molecular sieve-natural manganese sand composite;

[0082] (3) Add 6 g of trifluoromethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 24 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 110 °C for 10 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0083] Example 10

[0084] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0085] (2) Add 2 g of sodium silicate, 2 g of aluminum nitrate, and 1 g of tetrapropylammonium hydroxide to 50 ml of deionized water, and adjust the pH to 11 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and the hydrothermal reaction temperature is 200 ° C and the time is 72 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate at a temperature of 600 ° C in a tubular furnace under a nitrogen atmosphere for 14 h to obtain a molecular sieve-natural manganese sand composite;

[0086] (3) Add 10 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 12 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 180 ° C for 17 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0087] Comparative Example 1

[0088] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0089] (2) Add 2.5 g of methyl orthosilicate and 0.3 g of tetrapropylammonium hydroxide to 50 ml of deionized water, and adjust the pH to 10 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the precursor solution and ultrasonically vibrate for 5 h. Transfer the mixed system to a high-pressure reactor, and perform the hydrothermal reaction at a temperature of 100 ° C for 12 h. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcine at 300 ° C for 12 h under a nitrogen atmosphere to obtain a molecular sieve-natural manganese sand composite;

[0090] (3) Add 10 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 12 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 180 ° C for 17 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0091] Comparative Example 2

[0092] (1) 5 g of natural manganese sand was ultrasonically cleaned with deionized water for 1 h, and then washed with anhydrous ethanol to remove surface dust and organic impurities. The treated manganese sand was then immersed in 50 ml of 1 mM dilute hydrochloric acid solution and stirred at room temperature for 6 h. It was then repeatedly washed with deionized water until the solution was neutral. The washed manganese sand was placed in an oven at 100°C and dried to constant weight to obtain the treated manganese sand.

[0093] (2) Add 5.8 g of aluminum nitrate and 0.9 g of sodium diacetate to 50 ml of deionized water, and adjust the pH to 9 with NaOH solution to make the solution uniform. Then disperse the treated manganese sand obtained in step (1) in the above precursor solution and ultrasonically vibrate for 5 hours. Transfer the mixed system to a high-pressure reactor, and perform the hydrothermal reaction at a temperature of 180 ° C for 24 hours. After the reaction is completed, cool to room temperature, take out the solid product, and wash it repeatedly with deionized water. Finally, calcinate in a tubular furnace under a nitrogen atmosphere at a temperature of 300 ° C for 12 hours to obtain a molecular sieve-natural manganese sand composite;

[0094] (3) Add 10 g of octamethylsilane to 100 ml of anhydrous ethanol and stir to form a uniform solution. Then, immerse the molecular sieve-natural manganese sand composite obtained in step (2) in the above solution and stir at room temperature for 12 h. After the reaction is completed, wash with anhydrous ethanol and vacuum dry at 180 ° C for 17 h. Finally, a molecular sieve-natural manganese sand hydrophobic material is formed.

[0095] Figure 1 The test data of the water contact angle of the molecular sieve-natural manganese sand hydrophobic material prepared in the above ten examples are as follows. The test method is to measure the water contact angle of the membrane using a dynamic contact angle meter, and take several test points on each membrane to measure and calculate the average value. Figure 1 It can be seen that Example 10 has the best effect. Through the mesoporous structure of the silica-alumina molecular sieve, the hydrophobic silane (octamethylsilane in Example 10) is directionally anchored on the surface of the manganese sand to form a hydrophobic layer, which reduces the competitive adsorption of water molecules. The hydrophobic layer only covers the non-catalytic area, and the manganese active sites (such as Mn³⁺ / Mn 4 ⁺Redox couple) are still exposed inside the pores, realizing the intelligent response structure of "hydrophobic shell + hydrophilic catalytic core".

[0096] The molecular sieve-natural manganese sand hydrophobic materials prepared in the ten examples above were applied to an ozone pollution system in a humid environment to improve its ability to remove low-concentration ozone. Specifically, a gas chromatograph (equipped with an electron capture detector (ECD)) was used to analyze ozone concentrations before and after degradation and calculate the degradation rate.

[0097] Figure 2 It is the ozone degradation efficiency after 48 h of reaction at an ozone concentration of 0.01 ppm and a relative humidity of 65%.

[0098] Figure 3 It is the ozone degradation efficiency after 96 h of reaction at an ozone concentration of 0.03 ppm and a relative humidity of 80%.

[0099] Figure 4 It is the ozone degradation efficiency after 120 h of reaction at an ozone concentration of 0.05 ppm and a relative humidity of 85%.

[0100] It can be seen that the degradation effect of Example 10 is optimal under all conditions. The present invention significantly improves the ozone degradation efficiency of the material under various environmental conditions through the optimization of the molecular sieve loading structure, the regulation of active sites and the hydrophobic-catalytic synergistic mechanism. It is significantly superior to traditional manganese sand and single molecular sieve materials in ozone degradation rate, environmental adaptability and long-term stability, especially under high humidity and low concentration conditions.

[0101] Figure 5 Here are the experimental results for verifying the effect of removing ozone in water:

[0102] The removal efficiency was calculated by measuring the change in dissolved ozone concentration in water before and after treatment with the material using indigo disulfonate (IDS) spectrophotometry. A blank control group, a control group with activated carbon added, and experimental groups with materials prepared according to Example 10, Comparative Example 1, and Comparative Example 2 of the patent were set up. The results showed that the silicon-aluminum composite molecular sieve prepared in Example 10 had a more complete structure, a larger specific surface area, and a stronger catalytic effect than pure silicon molecular sieves and pure aluminum molecular sieves. Compared with activated carbon, the silicon-aluminum hybrid molecular sieve effectively avoided competitive adsorption between water molecules and internal manganese active sites. After repeated use for five times, the efficiency only decreased by 0.7%, and the stability was better than that of activated carbon (attenuation of 26.5%).

[0103] Figure 6 This is a scanning electron microscope image of the hydrophobically modified molecular sieve / manganese sand functional material prepared in Example 10. It can be seen that the material presents clear core-shell stratification, and the interface between the core and the shell is tightly bonded without peeling or cracks, indicating that the preparation process can stably construct a composite structure, the shell thickness is uniform, and the coating is complete, verifying the controllable growth of molecular sieve on the surface of manganese sand. The shell layer has a uniform porous structure, which is consistent with the typical characteristics of molecular sieves and provides enrichment and transmission channels for ozone molecules. The surface dense area (possibly related to hydrophobic modification) shows no pore blockage phenomenon, indicating that the hydrophobic treatment does not destroy the molecular sieve pores and maintains the functionality of the material. The porous shell structure can significantly improve the adsorption capacity of ozone (compared with activated carbon). The core manganese sand transfers active sites to the shell through interfacial contact, combined with the shape-selective enrichment effect of the molecular sieve, to enhance the catalytic decomposition efficiency of low-concentration ozone. The gradient hydrophobicity of the core-shell structure (from the core to the shell) is indirectly reflected through the surface morphology, supporting the stable performance of the material under high humidity (see Figure 2-5 experimental data).

[0104] The molecular sieve structure formed in this application is a mixed structure of silicon ions and aluminum ions. The skeleton of the silicon-aluminum molecular sieve has no hydrophilic acidic sites and is naturally hydrophobic. The composite material with a gradual hydrophobicity change from the core to the shell can achieve directional discharge of water molecules while maintaining efficient transmission of ozone.

[0105] The present invention provides a hydrophobically modified molecular sieve / manganese sand functional material, its preparation method, and its application. There are many methods and approaches to implement this technical solution. The above is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention. Any components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a hydrophobically modified molecular sieve / manganese sand functional material, characterized in that: The steps include: S1: Natural manganese sand pretreatment Take natural manganese sand and wash it alternately with deionized water and anhydrous ethanol to remove surface dust and organic impurities; then immerse the manganese sand in an acid solution and stir it at room temperature to remove unstable impurities and part of the carbonate on the surface, and then repeatedly wash it with deionized water until it is neutral; finally, dry the washed manganese sand; S2: In situ growth of molecular sieve shell Deionized water, a silicon source, aluminum nitrate, and a structure-directing agent are uniformly mixed and the pH value is adjusted to obtain a precursor solution, the manganese sand obtained in step S1 is dispersed in the precursor solution, and the precursor solution is allowed to fully penetrate the surface of the manganese sand particles; then, after a hydrothermal reaction, the solid product is repeatedly washed with deionized water to remove the residual precursor solution and unreacted substances on the surface; finally, the product is calcined under an inert atmosphere to remove the structure-directing agent and form a pore structure of the shell molecular sieve; S3: Hydrophobic surface modification A hydrophobic agent solution is prepared, and then the product obtained in step S2 is immersed in the hydrophobic agent solution and stirred at room temperature to allow the hydrophobic functional groups to fully react with the surface of the molecular sieve to form a stable organic hydrophobic layer, which is then vacuum dried to obtain the product.

2. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, wherein: In step S1, the natural manganese sand is cleaned with ultrasonic assistance when being cleaned with deionized water and anhydrous ethanol, and the ultrasonic cleaning time is 1 to 12 hours; the acid solution is a dilute hydrochloric acid aqueous solution with a concentration of 0.1 to 5 mM, and is stirred at room temperature for 1 to 24 hours.

3. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, wherein: In step S2, the silicon source is ethyl silicate or sodium silicate; and the structure directing agent is selected from any one of tetrapropylammonium hydroxide, hexadecyltrimethylammonium bromide, and sodium diacetate.

4. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, wherein: In step S2, the mass ratio of the treated manganese sand, silicon source, aluminum nitrate, and structure directing agent is 10:(1-5):(1-5):(0.1-2), and the pH value of the precursor solution is adjusted to 9-11.

5. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, wherein: In step S2, the temperature of the hydrothermal reaction is 100-400°C, and the time is 12-72 hours.

6. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, characterized in that: In step S2, calcination is performed in a tubular furnace in a nitrogen atmosphere at a temperature of 300-800° C. for 12-24 h.

7. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, characterized in that: In step S3, a silane coupling agent is added to anhydrous toluene or ethanol, and the mixture is stirred to form a uniform solution to prepare a hydrophobic agent solution; the silane coupling agent is octamethylsilane or trifluoromethylsilane; and the mass ratio of the silane coupling agent to the product of step S2 is (0.1-2):

1.

8. The method for preparing the hydrophobically modified molecular sieve / manganese sand functional material according to claim 1, characterized in that: In step S3, the vacuum drying temperature is 80-200° C. and the time is 2-24 h.

9. The hydrophobically modified molecular sieve / manganese sand functional material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the hydrophobically modified molecular sieve / manganese sand functional material according to claim 9 for catalytic decomposition of low-concentration ozone, characterized in that: The low-concentration ozone concentration is not higher than 0.05 ppm.

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