Sulfur-modified defect-containing metal organic framework catalyst, preparation method thereof and application of sulfur-modified defect-containing metal organic framework catalyst in pharmaceutical wastewater treatment

Abstract

The invention discloses a sulfur-modified defect-containing metal organic framework catalyst and a preparation method and application thereof in pharmaceutical wastewater treatment, and the method comprises the following steps: dissolving 2, 6-naphthalic acid, benzothiophene-2-carboxylic acid and ferric nitrate nonahydrate in a solvent under the conditions of normal pressure and air, mixing, heating for condensation reaction, filtering, washing, and drying to obtain the sulfur-modified defect-containing metal organic framework catalyst. A defect structure is introduced through benzothiophene-2-carboxylic acid, and the sulfur modified metal organic framework catalyst containing defects is generated. According to the invention, MOF with iron as a central metal is adopted, defects are introduced into a structure through modification of benzothiophene-2-carboxylic acid to cause vacancy generation, and active sites are provided through construction of a defect structure, so that the adsorption capacity to pollutants is improved, better catalytic performance is shown, and the application prospect is broad. The photocatalyst has a good application prospect in adsorption-photocatalytic degradation of antibiotic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, and relates to a sulfur-modified defective metal-organic framework catalyst, its preparation method, and its application in the treatment of pharmaceutical wastewater. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of compounds composed of metal ions and organic ligands. Due to their diverse structures and high tunability, they have found wide application in catalysis. Therefore, exploring green synthetic methods based on MOF modification and their applications is essential. Some small organic molecules, due to their unique electronic and geometric structures, can be precisely regulated by adjusting their structure and composition, exhibiting excellent catalytic activity. Furthermore, the rapid development of modern society has led to increasingly severe antibiotic pollution in natural aquatic environments, making the development of green, efficient, and economical antibiotic pollution treatment technologies urgent. MOF-based catalysts are a novel type of catalyst with advantages such as strong adsorption performance and low cost, showing great potential in adsorption combined with photo-driven degradation of pollutants. Given the widespread use of antibiotics such as tetracycline (TC) and the resulting environmental pollution and antibiotic resistance problems, developing sustainable, durable, and economical strategies for adsorption combined with photo-driven degradation of pollutants is particularly important, overcoming the disadvantages of traditional treatment strategies such as the need for external oxidants, limited oxidation capacity, and high operating costs.

[0003] Although numerous modification strategies for MOF-based catalytic materials have emerged in recent years, including morphology control, defect introduction, and elemental doping, achieving remarkable results in the field of catalysis, most reported methods still suffer from complex synthesis and difficulty in large-scale preparation. Therefore, developing a simple photocatalyst strategy with higher catalytic efficiency is urgently needed. Summary of the Invention

[0004] The first objective of this invention is to overcome the shortcomings of the aforementioned conventional technologies and provide a method for preparing a sulfur-modified defective metal-organic framework catalyst, achieving a higher catalytic site concentration and thus better catalytic efficiency. Due to the symmetry of 2,6-naphthalenedic acid, the MIL-88C(Fe) obtained from its reaction with ferric nitrate nonahydrate exhibits a repetitive and ordered characteristic. Through defect engineering strategies, organic monomers with asymmetric structures can be inserted into the MIL-88C(Fe) structure. When defects are introduced into MIL-88C(Fe), the active sites and adsorption capacity increase, making it easier for pollutant molecules to be adsorbed by S-MIL-88C(Fe) and decomposed into smaller, less toxic organic molecules. This method offers advantages such as mild reaction conditions, simple operation, low cost, no environmental pollution, high yield, and good enantioselectivity.

[0005] The objective of this invention is achieved through the following technical measures:

[0006] Under normal pressure and air conditions, organic acid molecules and ferric nitrate nonahydrate are dissolved in a solvent and mixed, and heated to carry out a condensation reaction. The organic acid introduces a defect structure to generate the sulfur-modified defective metal-organic framework catalyst, denoted as S-MIL-88C(Fe); wherein the organic acid molecules are 2,6-naphthalenedic acid and benzothiophene-2-carboxylic acid.

[0007] Preferably, the reaction temperature is 100-150 °C and the reaction time is 0.25-2 hours.

[0008] Preferably, the solvent for the reaction is selected from all nonpolar and polar solvents that can be used in the reaction; further, the solvent is selected from one or more of benzene, toluene, xylene, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, chloroform, carbon tetrachloride, ethylene glycol dimethyl ether, dimethyl sulfoxide, 1,2-dichloroethane, dimethylformamide, diethylformamide, acetone, acetonitrile, methanol, ethanol, isopropanol, n-propanol, butanol, or ethyl acetate.

[0009] Preferably, the molar ratio of ferric nitrate nonahydrate to organic acid molecules is 1:(0.5-1.5), more preferably 1:0.82. Among the organic acid molecules, the molar ratio of 2,6-naphthalenedicarboxylic acid and benzothiophene-2-carboxylic acid is 1:(0.1-1), more preferably 1:0.4, which is the optimal ratio obtained after continuous experimentation.

[0010] The second objective of this invention is to provide a sulfur-modified defective metal-organic framework (S-MIL-88C(Fe)) catalyst, which is prepared by the above method.

[0011] A third objective of this invention is to provide the application of the aforementioned S-MIL-88C(Fe) in the treatment of pharmaceutical wastewater.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. This invention uses an iron-centered MOF and introduces defects into the structure through modification with benzothiophene-2-carboxylic acid, resulting in vacancies. The resulting S-MIL-88C(Fe) exhibits significantly better catalytic activity than MIL-88C(Fe). By constructing a defective structure, active sites are provided, thereby improving the adsorption capacity for pollutants and demonstrating better catalytic performance. It has good application prospects in the adsorption-photocatalytic degradation of antibiotic pollutants.

[0014] 2. The preparation method of the present invention has a wide range of applicability, simple synthesis steps, short reaction time, mild conditions, simple operation, and low cost;

[0015] 3. The preparation method of this invention is environmentally friendly and has good application prospects. Attached Figure Description

[0016] Figure 1 The X-ray diffraction (XRD) patterns of MIL-88C(Fe) and S-MIL-88C(Fe) in Examples 1 and 2 are shown.

[0017] Figure 2 Infrared images of MIL-88C(Fe) and S-MIL-88C(Fe) in Examples 1 and 2.

[0018] Figure 3 This is a structural diagram of MIL-88C(Fe).

[0019] Figure 4 This is a structural diagram of S-MIL-88C(Fe).

[0020] Figure 5 The diagram shows the tetracycline degradation activity of MIL-88C(Fe) and S-MIL-88C(Fe) in Test Example 1. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0022] As mentioned above, this invention provides a method for preparing a sulfur-modified defective metal-organic framework (S-MIL-88C(Fe)) catalyst, specifically including the following steps:

[0023] Organic acid molecules are mixed with ferric nitrate nonahydrate in a molar ratio of 1:(0.5-1.5), wherein the organic acid molecules include 2,6-naphthalenedicarboxylic acid and benzothiophene-2-carboxylic acid in a molar ratio of 1:(0.1-1), and reacted in a solvent at 100-150 °C for 0.25-2 hours to generate the defective metal-organic framework; wherein the solvent is selected from one or more of benzene, toluene, xylene, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, chloroform, carbon tetrachloride, ethylene glycol dimethyl ether, dimethyl sulfoxide, 1,2-dichloroethane, dimethylformamide, diethylformamide, acetone, acetonitrile, methanol, ethanol, isopropanol, n-propanol, butanol, or ethyl acetate; in the embodiments of the present invention, dimethylformamide is used as an example of solvent, but those skilled in the art can also choose according to actual needs, which will not be elaborated here.

[0024] The technical solution of the present invention will be further explained and described below with reference to several preferred embodiments, but the experimental conditions and setting parameters therein should not be regarded as limitations on the basic technical solution of the present invention. Furthermore, the scope of protection of the present invention is not limited to the following embodiments.

[0025] Example 1

[0026] The preparation of MIL-88C(Fe) includes the following steps:

[0027] 2,6-Naphthalic acid (78 mg, 0.36 mmol) and ferric nitrate nonahydrate (178 mg, 0.44 mmol) were added to a 50 mL round-bottom flask, followed by 16 mL of dimethylformamide (DMF) and mixed thoroughly. The mixture was heated at 120 °C for 0.5 h while stirring. After filtration and washing with methanol, the mixture was dried in a 150 °C oven for 3 h to obtain an orange-yellow solid. The stirring speed was 420 rpm throughout. The XRD pattern of the prepared MIL-88C(Fe) is shown in the figure below. Figure 1 Infrared image Figure 2 See the structural diagram. Figure 3 .

[0028] Example 2

[0029] The preparation of S-MIL-88C(Fe) includes the following steps:

[0030] Benzothiophene-2-carboxylic acid (24 mg, 0.13 mmol), 2,6-naphthalenedicarboxylic acid (49 mg, 0.23 mmol), and ferric nitrate nonahydrate (178 mg, 0.44 mmol) were added to a 50 mL round-bottom flask, followed by the addition of 16 mL of dimethylformamide (DMF). The mixture was heated at 120 °C for 0.5 h with stirring. After filtration and washing with methanol, the mixture was dried in a 150 °C oven for 3 h to obtain an orange-yellow solid. The stirring speed was 420 rpm throughout. The XRD pattern of S-MIL-88C(Fe) was obtained. Figure 1 Infrared image Figure 2 See the structural diagram. Figure 4 .

[0031] Test Example 1

[0032] The specific steps for pollutant degradation using MIL-88C(Fe) and S-MIL-88C(Fe) are as follows:

[0033] 1) 20 mg of catalyst was dispersed in 100 mL of 20 mg / L tetracycline solution and sonicated for 5 min.

[0034] 2) Under dark conditions, stir for 30 min to reach adsorption-desorption equilibrium, and obtain an adsorption polygon diagram, as shown below. Figure 5 As shown.

[0035] 3) The photocatalytic reaction was started under a simulated visible light source.

[0036] 4) During the reaction, take 3 mL of the reaction solution every 10 min (total time 30 min) and filter it with a 0.45 μm microporous filter.

[0037] 5) Use a UV-Vis spectrophotometer to detect the concentration of pollutants.

[0038] Its catalytic activity results are as follows Figure 5 As shown.

[0039] Among them, the adsorption efficiency of MIL-88C(Fe) prepared in Example 1 for tetracycline is 15%, and the tetracycline degradation rate can reach 34%; the adsorption efficiency of S-MIL-88C(Fe) prepared in Example 2 for tetracycline is 19%, and the tetracycline degradation rate can reach 93%.

[0040] The above results demonstrate that the defective metal-organic framework S-MIL-88C(Fe) catalyst prepared by the method of this invention exhibits good catalytic activity.

[0041] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a sulfur-modified defective metal-organic framework catalyst, characterized in that, The preparation method is specifically: Under the condition of normal pressure and air, the organic acid molecules and the iron nitrate nonahydrate are dissolved in a solvent and mixed, and a condensation reaction is carried out by heating, so that the defect structure is introduced by the organic acid to generate the sulfur-modified metal-organic framework catalyst with defects; wherein the organic acid molecules are 2,6-naphthalene dicarboxylic acid and benzothiophene-2-carboxylic acid.

2. The production method according to claim 1, characterized by, The reaction temperature of the reaction is 100-150 DEG C.

3. The production method according to claim 2, characterized by, The reaction time is 0.25-2 hours.

4. The production method according to claim 1, characterized by, The solvent of the reaction is selected from a non-polar solvent or a polar solvent.

5. The production method according to claim 4, characterized by, The solvent is selected from one or more of benzene, toluene, xylene, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, chloroform, carbon tetrachloride, ethylene glycol dimethyl ether, dimethyl sulfoxide, 1,2-dichloroethane, dimethylformamide, diethylformamide, acetone, acetonitrile, methanol, ethanol, isopropanol, n-propanol, butanol or ethyl acetate.

6. The method of claim 1, wherein, The molar ratio of the iron nitrate nonahydrate to the organic acid molecules is 1:(0.5-1.5).

7. The preparation method according to claim 1, characterized in that, The molar ratio of 2,6-naphthalene dicarboxylic acid to benzothiophene-2-carboxylic acid is 1:(0.1-1).

8. A sulfur-modified defective metal-organic framework catalyst, characterized in that, The method is prepared by using any one of claims 1-7.

9. The sulfur-modified metal-organic framework catalyst with defects for treating medical wastewater according to claim 8.

Images