Preparation method and application of Fe-MIL photocatalytic material with open pores and mixed valence

Abstract

The present invention discloses a preparation method and application of a Fe-MIL photocatalytic material with open pores and mixed valence. The preparation method specifically comprises the following steps: first, adding 0.5-2g of Fe-MIL original powder to a beaker with a volume of 40-80mL of organic alcohol and ultrasonicating it, then stirring it at room temperature for 3-9h, transferring the above solution to a high-pressure reactor, then placing it in an oven and keeping it warm for 6-18h, and finally centrifuging and washing it to obtain a Fe-MIL photocatalytic material with open pores and mixed valence. The Fe-MIL material modified by the present invention has a higher Fe content in its structure. 2+ / Fe 3+ The larger pore size, pore ratio and photocatalytic performance of the material can be improved, and it has a good removal efficiency for tetracycline.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, and in particular to a preparation method and application of a Fe-MIL photocatalytic material with open pores and mixed valence. Background Art

[0002] Antibiotics are a class of compounds that can inhibit bacterial growth and are widely used in the medical, agricultural, and veterinary fields. Tetracycline (TC) is a popular antibiotic drug that is widely used due to its excellent antibacterial activity and low price. Due to excessive use of tetracycline and inefficient wastewater treatment capabilities, it remains in large quantities in the environment, posing a huge risk to human health. Biodegradation, reverse osmosis, adsorption, etc. are all traditional methods for removing tetracycline from wastewater. Microbial problems associated with biodegradation and the high costs of reverse osmosis and adsorption limit their practical application. Due to its advantages such as low secondary pollution, low cost, and sufficient energy sources, photocatalytic technology is considered to be the most promising method for removing water pollutants. However, it is difficult for photocatalysts to be both highly active and environmentally friendly, which has become a major limiting factor in the use of photocatalytic technology for tetracycline degradation in the environment.

[0003] Metal-organic frameworks (MOFs) are novel porous materials composed of ligand-bound metal oxides and organic linkers. They possess high surface area, tunable pore size, and uniformly distributed active sites. Currently, MOFs are widely used in applications such as adsorption, gas storage, catalysis, photonics, capacitors, and drug delivery, with particular attention being paid to their applications in environmental remediation. Compared to traditional semiconductor materials, MOFs offer the flexibility to tailor organic ligands and inorganic units to achieve controllable band gaps. Surface functional groups can also be modified to selectively adsorb pollutants from water or improve visible light absorption. Among the various MOFs, iron-based MILs (MILs) with FeO₃ clusters, such as MIL-53, MIL-88B, MIL-101, and MIL-68, exhibit excellent visible light response. Furthermore, the coordinatively unsaturated iron sites in the MIL structure can serve as reactive sites, enhancing adsorption and catalytic performance. However, as with other MOFs, the rapid recombination of electron-hole pairs remains a limiting factor in the practical application of Fe-MILs. Therefore, how to reduce the band gap of Fe-MIL, increase the visible light response range, and accelerate the separation of electron-hole pairs are the main problems in the application of Fe-MIL materials in the degradation of environmental pollutants. At present, there are several methods to improve the photocatalytic performance of Fe-MIL, such as structural heterojunction, defect engineering, element doping, organic ligand modification, crystal structure and surface adjustment, etc. Among them, the control of the valence state of Fe at the metal node of Fe-MIL material, such as increasing the Fe 2+The proportion of Fe in the structure can improve the photocatalytic performance of the material. 2+ / Fe 3+ )Fe-MIL method is mainly vacuum heat treatment. The Fe 2+ The ratio is not high, and the metal-organic framework is easily destroyed at high temperatures, so new methods need to be developed. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems existing in the prior art and provide a preparation method and application of a Fe-MIL photocatalytic material with open pores and mixed valence.

[0005] To achieve the above-mentioned purpose, the technical solution provided by the present invention is: a method for preparing an Fe-MIL photocatalytic material with open pores and mixed valences, the preparation method specifically comprising the following steps: first, adding 0.5 to 2 g of Fe-MIL original powder to a beaker with a volume of 40 to 80 mL of organic alcohol and ultrasonicating it, then stirring it at room temperature for 3 to 9 hours, transferring the above solution to a high-pressure reactor, then placing it in an oven and keeping it warm for 6 to 18 hours, and finally centrifuging and washing it to obtain the Fe-MIL photocatalytic material with open pores and mixed valences.

[0006] Preferably, the Fe-MIL raw powder may be any one of MIL-53 powder, MIL-88B (Fe) powder and MIL-101 (Fe) powder.

[0007] Preferably, the organic alcohol is one or more of ethylene glycol and glycerol, and the purity is analytical grade.

[0008] Preferably, the oven temperature is 90-180°C.

[0009] The present invention also discloses an application of a Fe-MIL photocatalytic material with open pores and mixed valences, including the Fe-MIL photocatalytic material with open pores and mixed valences prepared by the above-mentioned method for preparing the Fe-MIL photocatalytic material with open pores and mixed valences, which can be used in the field of photocatalytic degradation of antibiotics.

[0010] Beneficial effects of the present invention:

[0011] 1. Compared with the original material, the modified Fe-MIL material structure has higher Fe 2+ / Fe 3+ Compared with the conventional method, the photocatalytic performance of the material can be improved, and the removal efficiency of tetracycline is very good.

[0012] 2. Compared with other methods for obtaining mixed-valence Fe-MIL, the present invention can not only obtain mixed-valence Fe-MIL materials, but also obtain a metal framework with an open pore structure and oxygen vacancies.

[0013] 3. Compared with the existing methods of modifying the photocatalytic performance of Fe-MIL, the present invention has the advantages of simple preparation and low cost, and Fe-MIL can maintain a high degree of crystallinity and strong photocatalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] Figure 1 XRD diffraction patterns of all photocatalysts obtained in Examples 1 to 6;

[0016] Figure 2 The activity diagram of the photocatalyst obtained in Examples 1 to 6 towards tetracycline under darkness and light;

[0017] Figure 3 This is the high-resolution X-ray photoelectron spectrum of Fe element on the surface of the photocatalyst in step S1 and step S4 in Example 1. DETAILED DESCRIPTION

[0018] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0019] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0020] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0021] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0022] Reference Figure 1-Figure 3 A preferred embodiment of the present invention provides a method for preparing an Fe-MIL photocatalytic material having open pores and mixed valences. The method specifically comprises the following steps: first, adding 0.5 to 2 g of Fe-MIL raw powder to a beaker with a volume of 40 to 80 mL of organic alcohol and ultrasonicating the mixture; then, stirring the mixture at room temperature for 3 to 9 hours; transferring the solution to an autoclave; then, preserving the mixture in an oven for 6 to 18 hours; and finally, centrifuging and washing the mixture to obtain the Fe-MIL photocatalytic material having open pores and mixed valences.

[0023] In this embodiment, the Fe-MIL original powder may be any one of MIL-53 powder, MIL-88B (Fe) powder and MIL-101 (Fe) powder.

[0024] In this embodiment, the organic alcohol is one or more of ethylene glycol and glycerol, and the purity is analytical grade.

[0025] In this embodiment, the oven temperature is 90-180°C.

[0026] The present invention also discloses an application of a Fe-MIL photocatalytic material with open pores and mixed valences, including the Fe-MIL photocatalytic material with open pores and mixed valences prepared by the above-mentioned method for preparing the Fe-MIL photocatalytic material with open pores and mixed valences, which can be used in the field of photocatalytic degradation of antibiotics.

[0027] according to Figure 1 This method can improve the degradation performance of the original MIL-53(Fe) photocatalyst for tetracycline, with the photocatalytic activity reaching its maximum at a reaction temperature of 150°C. Furthermore, this method is also effective in improving the photocatalytic degradation performance of other Fe-MILs. Figure 2 In the study, after secondary solvent treatment, when the reaction temperature was above 120°C, the strongest diffraction peak changed and the diffraction angle shifted. According to literature reports, the raw material was modified to produce Fe-MIL materials with open pores and mixed valence. Figure 3 The results also further illustrate that the modified Fe-MIL improves the 2+ Table 1 further illustrates the modified MIL materials, which have larger pore size and pore volume.

[0028] The present invention uses organic alcohol to perform secondary solvent thermal treatment on Fe-MIL powder to increase the Fe content in the metal organic framework.2+ / Fe3+ molar ratio, opening the closed gaps in MOF, thereby significantly improving the photocatalytic performance of the material.

[0029] As a preferred embodiment of the present invention, it may also have the following additional technical features:

[0030] Example 1:

[0031] Step S1, Preparation of MIL-53(Fe) Powder: 1.66 g of terephthalic acid and 2.70 g of ferric chloride hexahydrate were separately added to 50 mL of N,N-dimethylformamide. The mixture was stirred for 30 minutes and then placed in an autoclave and incubated at 150°C for 24 hours. The mixture was then washed several times with deionized water and anhydrous ethanol and activated overnight in a 50% ethanol solution. The mixture was then dried at 60°C for 12 hours to obtain MIL-53(Fe) powder.

[0032] Step S2, Preparation of MIL-88B(Fe) Powder: 2.70 g of ferric chloride hexahydrate and 1.16 g of terephthalic acid were added to a mixed solution containing 50 mL of N,N-dimethylformamide and 4 mL of sodium hydroxide (4 mol / L). The mixture was then sonicated for 30 minutes and magnetically stirred for 30 minutes. The resulting mixture was placed in a reactor and maintained at 100°C for 12 hours. The orange solid was collected by centrifugation at 8000 rpm for 5 minutes, then stirred overnight in deionized water, centrifuged, and washed. Finally, it was dried at 60°C for 12 hours to obtain MIL-88B(Fe) powder.

[0033] Step S3, Preparation of MIL-101(Fe) Powder: 0.824 g of terephthalic acid and 1.350 g of ferric chloride hexahydrate were added to 30 mL of N,N-dimethylformamide and stirred continuously for 1 hour to obtain a homogeneous solution. This solution was then placed in an autoclave and crystallized at 90°C for 24 hours. Centrifugation yielded a reddish-brown powder precipitate, which was subsequently washed with DMF and 60°C anhydrous ethanol. The solution was then dried under vacuum at 70°C for 12 hours to obtain MIL-101(Fe) powder.

[0034] Step S4, Preparation of an Open-Porous and Mixed-Valence Fe-MIL Photocatalyst: 1.00 g of MIL-53(Fe) powder obtained in Step S1 was dispersed in 60 mL of ethylene glycol and sonicated for 30 minutes. After stirring at room temperature for 5 hours, the mixture was transferred to an autoclave, set to 150°C, and incubated for 12 hours. Finally, the powder was centrifuged and washed to obtain a powder, which was labeled EG-M53-150 or EG-M53.

[0035] Example 2: The difference from Example 1 is that the oven temperature in step S4 is adjusted to 90° C. Other experimental conditions remain unchanged, and the obtained powder is recorded as EG-M53-90.

[0036] Example 3: The difference from Example 1 is that the oven temperature in step S4 is adjusted to 120° C. The other experimental conditions remain unchanged, and the obtained powder is recorded as EG-M53-120.

[0037] Example 4: The difference from Example 1 is that the oven temperature in step S4 is adjusted to 180° C. The other experimental conditions remain unchanged, and the obtained powder is recorded as EG-M53-180.

[0038] Example 5: The difference from Example 1 is that the MIL-53(Fe) powder in step S4 is replaced with MIL-88B(Fe) powder. The other experimental conditions remain unchanged, and the resulting powder is recorded as EG-M88.

[0039] Example 6: The difference from Example 1 is that the MIL-53(Fe) powder in step S4 is replaced by MIL-101(Fe) powder, and the other experimental conditions remain unchanged. The obtained powder is recorded as EG-M101.

[0040] In this invention, the photocatalytic activity of the modified MIL-53(Fe) was evaluated using tetracycline as a simulated pollutant. Treatment of MIL-88B(Fe) and MIL-101(Fe) under optimal experimental conditions also demonstrated significant improvements in tetracycline photodegradation performance, with removal rates exceeding 90%. This treatment process enables the application of porous, environmentally friendly, and highly active Fe-MIL photocatalytic materials for pollutant degradation in real-world environments.

[0041] Table 1 shows some specific surface area data of the photocatalysts in step S1 and step S4 in Example 1.

[0042] Table 1

[0043]

[0044] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0045] The above descriptions are only preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a Fe-MIL photocatalytic material with open pores and mixed valence, characterized by: The preparation method specifically includes the following steps: first, adding 0.5 to 2 g of Fe-MIL original powder to a beaker with a volume of 40 to 80 mL of organic alcohol, ultrasonically stirring at room temperature for 3 to 9 hours, wherein the organic alcohol is one or more of ethylene glycol and propylene glycol, and the purity is analytically pure; transferring the solution to a high-pressure reactor, and then placing it in an oven for insulation for 6 to 18 hours, and the oven temperature is 120 to 180°C; finally, centrifugally washing to obtain a Fe-MIL photocatalytic material with open pores and mixed valence, wherein the Fe-MIL original powder is any one of MIL-53 powder, MIL-88B (Fe) powder and MIL-101 (Fe) powder.

2. Application of an open-pore and mixed-valence Fe-MIL photocatalytic material, characterized by: The Fe-MIL photocatalytic material with open pores and mixed valence prepared by the preparation method of the Fe-MIL photocatalytic material with open pores and mixed valence according to claim 1 is used in the field of photocatalytic degradation of antibiotics.

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