A method for microemulsion-assisted synthesis of fe-mn oxide catalysts

Abstract

The application discloses a method for synthesizing Fe-Mn oxide catalysts with the assistance of microemulsion, which comprises the following steps: adding aminoalkoxysilane into anhydrous ethanol to prepare liquid A; dissolving a polyether surfactant in water, adding an acid regulator, an organic swelling agent and a salt additive, and forming a microemulsion through ultrasonic and stirring; adding iron salt, manganese salt and trimesic acid into the microemulsion according to a set molar ratio, and performing a solvothermal reaction under heating; centrifuging to obtain a micelle containing a metal organic framework material; washing with water and a polar organic solvent to remove unreacted raw materials and surfactants in the pores; adding liquid A and stirring to react, and then performing washing, centrifuging and drying to obtain an amine-modified three-dimensional porous spherical metal organic framework material. Further, the material is crosslinked with an aromatic dialdehyde compound and an aromatic triamine compound under the catalysis of an acid to prepare a three-dimensional porous spherical metal organic framework composite material coated with a covalent organic framework material.

Description

Technical Field

[0001] This invention belongs to the field of porous nanomaterials technology, and specifically discloses a method for the microemulsion-assisted synthesis of Fe-Mn oxide catalysts. Background Technology

[0002] Tetracycline antibiotics are among the most widely used antibiotic classes, employed extensively in clinical infection treatment and agricultural production. Tetracycline (TC), a typical tetracycline drug, can easily induce drug-resistant pathogens due to its environmental residues, posing a serious threat to human health and ecosystem balance. Excessive intake of tetracycline in humans can lead to kidney damage, functional abnormalities, and has potential mutagenic and teratogenic toxicities. In aquatic environments, tetracycline can also alter the structure and activity of microbial communities, disrupting ecological balance. Furthermore, tetracycline exhibits acute and chronic toxicity to algae, crustaceans, and other aquatic organisms. Under anaerobic conditions, tetracycline can have a lethal effect on microbial communities, inhibiting biogas production and chemical oxygen demand (COD) removal, ultimately leading to reactor deactivation. Therefore, developing efficient technologies for removing tetracycline from water bodies is of great significance.

[0003] Currently, various methods have been developed for the removal of tetracycline, including adsorption, biodegradation, ion exchange, membrane separation, and photocatalytic degradation. Among these, photocatalytic degradation technology is considered one of the most promising treatment strategies due to its advantages such as mild conditions, high efficiency, low cost, and no secondary pollution, and has shown good performance in the degradation of tetracycline.

[0004] Metal-organic frameworks (MOFs), assembled from metal nodes and organic ligands, possess tunable structures and highly porous structures. Their semiconductor properties have garnered significant attention in the field of photocatalysis. In MOFs, photoexcitation can be achieved through organic ligands or metal-oxygen clusters (SBUs), both of which can serve as photocatalytic active sites. Organic ligands act as "antennae," capturing light energy and transferring photogenerated charges to the metal nodes, thereby activating the metal active centers. Furthermore, the open porous structure of MOFs facilitates the loading of other active components, further enhancing photocatalytic efficiency. Currently, MOFs such as MILs and UiO have demonstrated potential in photocatalytic degradation of pollutants and photocatalytic water splitting, indicating that these materials offer significant advantages in structural regulation and performance design.

[0005] However, existing photocatalysis technologies still face several challenges: many metal oxides and sulfide semiconductors suffer from high photogenerated electron-hole recombination rates, poor stability, and limited light energy utilization, and some materials exhibit certain toxicity. Furthermore, achieving precise construction of MOFs with uniform mesopore sizes of 10–50 nm and improving low-yield yields remains a significant challenge, necessitating the development of innovative synthesis methods. Summary of the Invention

[0006] The purpose of this invention is to propose a method for the microemulsion-assisted synthesis of Fe-Mn oxide catalysts. The obtained three-dimensional porous spherical MIL-100 (Fe-Mn) coated with covalent organic framework material has adjustable pore size and highly open channels from the center to the surface. This invention uses a triblock polymer (F127) as a nanoemulsion stabilizer and a hydrophobic aromatic compound (1,3,5-trimethylbenzene) as a pore expander to prepare three-dimensional porous spherical MIL-100 (Fe-Mn), which is then modified with amine groups and coated with covalent organic framework material.

[0007] The preparation method includes the following steps: Includes the following steps: (1) Add aminoalkoxysilane to anhydrous ethanol and stir until homogeneous to obtain solution A; (2) Dissolve polyether surfactants in water, add acid regulators, organic swelling agents and salt additives, and form a microemulsion by sonication and stirring; (3) Add iron salt, manganese salt and pyromellitic acid to the microemulsion at a set molar ratio, stir until the solution is microemulsion, carry out a solvothermal reaction under heating conditions, and obtain micelles containing metal-organic framework materials by centrifugation. (4) Wash with water and polar organic solvent by centrifugation to remove unreacted raw materials and surfactants in the pores; (5) Add the A solution, stir and react, then wash, centrifuge and dry to obtain an amination-modified three-dimensional porous spherical metal-organic framework material; (6) The amino-modified three-dimensional porous spherical metal-organic framework material and the aromatic dialdehyde compound are added to a polar solvent and ultrasonically mixed. (7) Add aromatic triamine compound, dissolve by ultrasonication, and then add acid catalyst to carry out cross-linking reaction; (8) After centrifugation, washing and drying, a three-dimensional porous spherical metal-organic framework composite material coated with covalent organic framework material is obtained.

[0008] In step (1), the aminoalkoxysilane is at least one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0009] In step (2), the polyether surfactant is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer; preferably F127.

[0010] In step (2), the acidity regulator is glacial acetic acid; the organic swelling agent is at least one of 1,3,5-trimethylbenzene, cyclohexane, n-hexane or toluene; and the salt additive is at least one of perchlorate, chloride or sulfate.

[0011] In step (3), the molar ratio of iron salt, manganese salt and pyromellitic acid is 9:2:11.

[0012] In step (3), the temperature of the solvothermal reaction is 140-180℃ and the reaction time is 8-20h.

[0013] The iron salt is at least one of ferric nitrate, ferric chloride, or ferric sulfate; the manganese salt is at least one of manganese nitrate, manganese chloride, or manganese acetate.

[0014] The aromatic dialdehyde compound is at least one of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, terephthalaldehyde, or biphenyl dicarboxaldehyde; the aromatic triamine compound is at least one of 1,3,5-tris(4-aminophenyl)benzene, tris(4-aminophenyl)amine, or 1,3,5-tris(4-aminophenoxy)benzene; the molar ratio of the aromatic triamine compound to the aromatic dialdehyde compound is 1:1; the acid catalyst is at least one of glacial acetic acid, hydrochloric acid, or sulfuric acid; the polar solvent is at least one of acetonitrile, methanol, ethanol, or tetrahydrofuran; and the solvent used for washing is at least one of N,N-dimethylformamide, tetrahydrofuran, and anhydrous ethanol.

[0015] A three-dimensional porous spherical metal-organic framework composite material coated with a covalent organic framework material, prepared by the method described above.

[0016] Unlike existing technologies, the advantages of this invention are: it achieves the coating of MIL-100(Fe-Mn) with a covalent organic framework material while retaining 20-30 nm pores; the covalent organic framework material and MIL-100(Fe-Mn) work synergistically to improve the degradation efficiency and service life of tetracycline. Attached Figure Description

[0017] Figure 1 SEM image of three-dimensional porous spherical MIL-100 (Fe-Mn) coated with covalent organic framework material prepared by self-assembly guided by 1 nanometer emulsion for comparative example; Figure 2 SEM image of three-dimensional porous spherical MIL-100 (Fe-Mn) coated with covalent organic framework material prepared by nanoemulsion-guided self-assembly in Example 1; Figure 3 This image shows the effect of three-dimensional porous spherical MIL-100 (Fe-Mn) coated with covalent organic framework material prepared by nanoemulsion-guided self-assembly in Example 1 on the degradation of tetracycline. Detailed Implementation

[0018] The present application will now be described in detail with reference to specific embodiments. However, these embodiments do not limit the present application, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present application. The scope of protection of the present invention is not limited by the following embodiments.

[0019] Example 1 Add 300 μL of APTES (3-aminopropyltriethoxysilane) to 10 mL of anhydrous ethanol and stir well to form solution A. Add 500 mg of polyether F127 (PEO) to the solution. 106 PPO 70 PEO 106 Dissolve the compound in 40 mL of deionized water. Then, add 1 mL of glacial acetic acid, 10 mL of 1,3,5-trimethylbenzene, and 1.5 g of NaClO4 to the above solution. Sonicate for 5-20 min and magnetically stir for 2 hours at room temperature to form a microemulsion. Then, add 0.909 g of Fe(NO3)3·9H2O, 0.126 g of Mn(NO3)2·4H2O, and 0.578 g of trimesic acid H3BTC in a molar ratio of 9:2:11 to the microemulsion. Stir for 30-60 min until the solution becomes microemulsion-like and react at 160 °C for 10-16 h. Centrifuge to obtain micelles containing the organic framework material MIL-100 (Fe-Mn). Wash several times with water and N,N-dimethylformamide to remove unreacted raw materials and remove polyether F127 from the pores of the organic framework material. Add solution A and continue stirring for 2 hours. h, then the product was repeatedly washed with deionized water and anhydrous ethanol, and the precipitate was separated by high-speed centrifugation; the obtained product was dried in a vacuum drying oven at room temperature to obtain amination-modified three-dimensional porous spherical MIL-100 (Fe-Mn).

[0020] Amination-modified three-dimensional porous spherical MIL-100 (Fe-Mn) and DMTP (2,5-dimethoxybenzene-1,4-dicarboxaldehyde) were added to centrifuge tubes, followed by 37.5 mL of acetonitrile. The mixture was sonicated for 10 min until completely fused. TAPB (1,3,5-tris(4-aminophenyl)benzene) was weighed and added to the mixture, and sonicated for 5 min. 12M glacial acetic acid was added to the mixture to initiate a cross-linking reaction. Finally, the precipitate was separated by high-speed centrifugation and repeatedly washed with DMF (N,N-dimethylamide), THF (tetrahydrofuran), and anhydrous ethanol. The mixture was then vacuum-dried for 12 h to obtain the sample, namely the three-dimensional porous spherical MIL-100 (Fe-Mn) coated with a covalent organic framework material. The molar ratio of TAPB to DMTP was 1:1.

[0021] Comparative Example 1 500mg of polyether P123 (PEO) 20 PPO 70 PEO 20 Dissolve the compound in 40 mL of deionized water, then add 1 mL of glacial acetic acid and 10 mL of 1,3,5-trimethylbenzene to the above solution, sonicate for 5-20 min, and magnetically stir for 2 hours at room temperature to form a microemulsion for later use. Subsequently, add 0.909 g of Fe(NO3)3·9H2O, 0.126 g of Mn(NO3)2·4H2O and 0.578 g of trimesic acid H3BTC in a molar ratio of 9:2:11 to the microemulsion, stir for 30-60 min until the solution is in a microemulsion state, and react at 160 °C for 10-16 h. By centrifugation, micelles containing organic framework material MIL-100 (Fe-Mn) are obtained, and washed several times with water and N,N-dimethylformamide to remove unreacted raw materials and remove polyether P123 from the pores of the organic framework material to obtain three-dimensional porous spherical MIL-100 (Fe-Mn).

[0022] The morphology of three-dimensional porous spherical MIL-100(Fe-Mn) was observed using ultra-high resolution scanning electron microscopy. The three-dimensional porous spherical MIL-100(Fe-Mn) possesses macropores with a pore size of 40 nm. Using the three-dimensional porous spherical MIL-100(Fe-Mn) prepared in Comparative Example 1, further modification of the amino groups with APTES was performed. After coating with a covalent organic framework material, solid spherical MIL-100(Fe-Mn) coated with the covalent organic framework material was obtained. Figure 1 As shown. Example 1 uses polyether F127 to prepare amino-modified three-dimensional porous spherical MIL-100 (Fe-Mn) with macropores of 60-70 nm. After further coating with a covalent organic framework material, it still retains pores of 20-30 nm. Figure 2 As shown.

[0023] The materials obtained in Example 1 and Comparative Example 1 were used to test the tetracycline degradation effect. 20 mg of sample was dispensed into 50 mL of a 20 ppm tetracycline solution. Samples were taken every 5 minutes to measure their UV absorption, and the tetracycline degradation effect at different times was calculated based on the absorption intensity. Figure 3 As shown, the catalyst prepared in Example 1 achieved a tetracycline degradation efficiency of over 90% within 1 hour, and after 5 cycles, the tetracycline degradation still reached 89%.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the microemulsion-assisted synthesis of Fe-Mn oxide catalysts, characterized in that, Includes the following steps: (1) Add aminoalkoxysilane to anhydrous ethanol and stir until homogeneous to obtain solution A; (2) Dissolve polyether surfactants in water, add acid regulators, organic swelling agents and salt additives, and form a microemulsion by sonication and stirring; (3) Add iron salt, manganese salt and pyromellitic acid to the microemulsion at a set molar ratio, stir until the solution is microemulsion, carry out a solvothermal reaction under heating conditions, and obtain micelles containing metal-organic framework materials by centrifugation. (4) Wash with water and polar organic solvent by centrifugation to remove unreacted raw materials and surfactants in the pores; (5) Add the A solution, stir and react, then wash, centrifuge and dry to obtain an amination-modified three-dimensional porous spherical metal-organic framework material; (6) The amino-modified three-dimensional porous spherical metal-organic framework material and the aromatic dialdehyde compound are added to a polar solvent and ultrasonically mixed. (7) Add aromatic triamine compound, dissolve by ultrasonication, and then add acid catalyst to carry out cross-linking reaction; (8) After centrifugation, washing and drying, a three-dimensional porous spherical metal-organic framework composite material coated with covalent organic framework material is obtained.

2. The method according to claim 1, characterized in that: In step (1), the aminoalkoxysilane is at least one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

3. The method according to claim 1, characterized in that: In step (2), the polyether surfactant is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer; preferably F127.

4. The method according to claim 1, characterized in that: In step (2), the acidity regulator is glacial acetic acid; the organic swelling agent is at least one of 1,3,5-trimethylbenzene, cyclohexane, n-hexane or toluene; and the salt additive is at least one of perchlorate, chloride or sulfate.

5. The method according to claim 1, characterized in that: In step (3), the molar ratio of iron salt, manganese salt and pyromellitic acid is 9:2:

11.

6. The method according to claim 1, characterized in that: In step (3), the temperature of the solvothermal reaction is 140-180℃ and the reaction time is 8-20h.

7. The method according to claim 1, characterized in that: The iron salt is at least one of ferric nitrate, ferric chloride, or ferric sulfate; the manganese salt is at least one of manganese nitrate, manganese chloride, or manganese acetate.

8. The method according to claim 1, characterized in that: In step (4), the polar organic solvent is at least one of N,N-dimethylformamide, N,N-diethylformamide, or dimethyl sulfoxide.

9. The method according to claim 1, characterized in that: The aromatic dialdehyde compound is at least one of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, terephthalaldehyde, or biphenyl dicarboxaldehyde; the aromatic triamine compound is at least one of 1,3,5-tris(4-aminophenyl)benzene, tris(4-aminophenyl)amine, or 1,3,5-tris(4-aminophenoxy)benzene; the molar ratio of the aromatic triamine compound to the aromatic dialdehyde compound is 1:1; the acid catalyst is at least one of glacial acetic acid, hydrochloric acid, or sulfuric acid; the polar solvent is at least one of acetonitrile, methanol, ethanol, or tetrahydrofuran; and the solvent used for washing is at least one of N,N-dimethylformamide, tetrahydrofuran, and anhydrous ethanol.

10. A three-dimensional porous spherical metal-organic framework composite material coated with covalent organic framework material, prepared by the method according to any one of claims 1 to 9.

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