Composite material based on hierarchical structure, preparation method of composite material and application of composite material in degradation of antibiotic pollutants
By using a hierarchical composite material Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene, the problem of efficient adsorption and degradation of antibiotic pollutants in the aquatic environment was solved, achieving high adsorption capacity and high degradation rate, while improving material stability and environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies are difficult to efficiently adsorb and degrade antibiotic pollutants in situ in aquatic environments, and also suffer from problems such as poor material stability, high cost, and environmental unfriendliness.
A hierarchical composite material, Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene, was used. Through gradient pore structure design and functional hierarchy, the material was endowed with magnetic, catalytic activity and hydrophilicity. The adsorption and degradation of antibiotics were achieved by persulfate (PMS) activation.
It achieves efficient adsorption and catalytic degradation of antibiotics, with high adsorption capacity, high degradation rate, good material stability, environmental friendliness and low cost, and is suitable for complex water bodies.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of adsorption degradation materials, and particularly relates to a hierarchical structure composite material and a preparation method thereof and application of the hierarchical structure composite material in degradation of antibiotic pollutants. BACKGROUND
[0002] The residues of antibiotic pollutants in water environment have attracted extensive attention. Existing treatment technologies mainly include adsorption method, catalytic oxidation method and composite material method. However, the adsorption capacity of commonly used adsorption materials such as activated carbon and zeolite for hydrophobic antibiotics (such as tetracycline and norfloxacin) is usually less than 50 mg / g, and only the phase transfer of pollutants can be achieved, and the target substances cannot be degraded in situ. After adsorption saturation, the material needs to be regenerated or disposed frequently, and there is a risk of secondary pollution. The photocatalytic material represented by TiO2 has weak response in the visible light region, and mainly depends on the ultraviolet light source, resulting in slow antibiotic degradation kinetics. In addition, the system has poor selectivity for complex water bodies containing various organic matters, and is easily disturbed by coexisting substances, so that the actual degradation efficiency is limited. Fenton oxidation method needs to add a large amount of H2O2 and other chemical reagents, and solid waste such as iron mud is generated in the reaction process, which needs to be disposed as hazardous waste. This not only increases the operation cost, but also may introduce new pollution sources.
[0003] The MOFs-based composite material developed in recent years has a high specific surface area, but metal ions (such as Zn 2+ and Cu 2+ concentrations exceed the standard) are easily dissolved in the aqueous environment, resulting in a decrease in the structural stability of the material. At the same time, the biocompatibility of the material is insufficient, and the large-scale preparation of the material faces problems such as complex process and high cost, which cannot meet the actual water treatment requirements.
[0004] In summary, in the process of removing antibiotics, the existing technologies are difficult to simultaneously consider high adsorption capacity, in-situ degradation capacity, low-cost operation and environmental safety. Therefore, it is a technical problem to be solved in the field to develop an environmentally friendly material which has efficient adsorption and catalytic degradation functions and is suitable for complex water bodies. SUMMARY
[0005] The application aims to provide a hierarchical structure composite material and a preparation method thereof and application of the hierarchical structure composite material in degradation of antibiotic pollutants.
[0006] The application first provides a hierarchical structure composite material, which comprises, from inside to outside, a Fe3O4 magnetic core, a ZIF-8 layer, a MIL-101 layer and a nitrogen-sulfur co-doped graphene shell.
[0007] The particle size of the Fe3O4 magnetic core is 10-50 nm; preferably 20-30 nm. The thickness of the ZIF-8 layer is about 50-80 nm, and the mesopore size is 1.8-2.5 nm. The thickness of the MIL-101 layer is about 80-120 nm, and the mesopore size is 2-3 nm. The thickness of the nitrogen and sulfur co-doped graphene shell is about 10-20 nm.
[0008] The application further provides a preparation method of the hierarchical structure-based composite material. (1) Preparation of Fe3O4@ZIF-8 core-shell structure: Fe3O4 magnetic nanoparticles with a particle size of 10-50 nm are uniformly dispersed in ethanol, a soluble zinc salt is added, and the mixture is fully dissolved to obtain a mixed solution I; a 2-methylimidazole methanol solution is added dropwise, and the mixture is fully reacted at room temperature under stirring, and then the precipitate is collected by centrifugation, washed and dried to obtain Fe3O4@ZIF-8. The mass ratio of Fe3O4, the soluble zinc salt and 2-methylimidazole is 0.1:1.5:0.8-1.6.
[0009] The volume ratio of the mixed solution I to the 2-methylimidazole methanol solution is 1:1.
[0010] The soluble zinc salt is a zinc sulfate, a nitrate, a chloride or the like, and a hydrate thereof, and preferably Zn(NO3)3·6H2O.
[0011] (2) Outer layer coating of Fe3O4@ZIF-8@MIL-101
[0012] Fe3O4@ZIF-8 is dispersed in N,N-dimethylformamide (DMF), a soluble chromium salt is added, and the mixture is fully dissolved to obtain a mixed solution II; a 2-amino terephthalic acid DMF solution is added dropwise, and the mixture is reacted at 120°C for 24 hours; after cooling, the mixture is centrifuged, washed and dried to obtain Fe3O4@ZIF-8@MIL-101.
[0013] The mass ratio of Fe3O4@ZIF-8, the soluble chromium salt and 2-amino terephthalic acid is 1.6:1.2:0.9-1.8.
[0014] The volume ratio of the mixed solution II to the 2-amino terephthalic acid DMF solution is 1:1.
[0015] The soluble chromium salt is a chromium sulfate, a nitrate, a chloride or the like, and a hydrate thereof, and preferably Cr(NO3)3·9H2O.
[0016] (3) Nitrogen and sulfur co-doped graphene shell modification: Graphene oxide, urea, and thiourea were mixed uniformly and annealed at 600°C for 2 hours under an inert atmosphere to obtain nitrogen-sulfur co-doped graphene. The mass ratio of graphene oxide, urea, and thiourea was 1:0.5:0.2-0.5.
[0017] Nitrogen-sulfur co-doped graphene was dispersed in water, and Fe3O4@ZIF-8@MIL-101 composite material was added. After sonication for 1 hour, the mixture was stirred for 12 hours. After centrifugation, washing, and drying, Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material was obtained.
[0018] The mass ratio of the nitrogen-sulfur co-doped graphene to Fe3O4@ZIF-8@MIL-101 is 1:4.
[0019] Further, the synthesis method of the Fe3O4 magnetic nanoparticles is as follows: FeCl2·4H2O aqueous solution and FeCl3·6H2O aqueous solution are mixed and stirred until homogeneous. NaOH solution is then added dropwise until the pH reaches 10, and the mixture is stirred continuously for 30 minutes. The precipitate is separated by centrifugation, washed three times successively with deionized water and ethanol, and dried under vacuum at 60°C for 12 hours to obtain Fe3O4 magnetic nanoparticles. The molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:2.
[0020] The present invention further provides the application of the above-mentioned hierarchical structure-based composite material in the degradation of antibiotic pollutants. Specifically, in the degradation system of antibiotic pollutants containing PMS, the hierarchical structure-based composite material does not require the addition of H2O2, and the utilization rate of PMS is significantly improved.
[0021] The technical principles and beneficial effects of this invention are as follows: This invention is based on a hierarchical and gradient pore structure design. The Fe3O4 core imparts magnetism to the material and provides catalytic active sites; the inner ZIF-8 mesoporous structure enables selective capture of small-molecule antibiotics; and the outer MIL-101 macroporous framework significantly improves mass transfer efficiency. A bilayer MOF structure enables confined activation of persulfate (PMS), while the graphene shell enhances electron mobility. Nitrogen-sulfur co-doping optimizes the hydrophilic properties of the material surface, and carboxyl, hydroxyl, and thiol functional groups synergistically enhance the adsorption performance for antibiotics. Antibiotic molecules achieve adsorption of antibiotic pollutants through multiple mechanisms, including π-π stacking, hydrogen bonding, and electrostatic adsorption; PMS activation generates SO4· - · - Free radicals, Fe 3+ / Fe 2+ The cycle accelerates electron transfer, achieving a Fenton-like reaction, which causes antibiotics to undergo ring opening and mineralization into CO2 / H2O, thereby degrading the antibiotics. Detailed Implementation
[0022] The present invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of the present invention.
[0023] Example 1
[0024] A method for preparing a Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material includes the following steps: (1) Synthesis of Fe3O4 magnetic core: A 0.5 mol / L FeCl2·4H2O aqueous solution and a FeCl3·6H2O aqueous solution were mixed at a volume ratio of 1:2 and stirred until homogeneous. Then, 1 mol / L NaOH solution was added dropwise until the pH reached 10, and the mixture was stirred continuously for 30 minutes. The precipitate was separated by centrifugation, washed three times successively with deionized water and ethanol, and dried under vacuum at 60°C for 12 hours to obtain Fe3O4 magnetic nanoparticles with a particle size of 20-30 nm.
[0025] (2) Preparation of Fe3O4@ZIF-8 core-shell structure: 0.1 g of Fe3O4 was dispersed in 100 mL of ethanol and sonicated for 30 minutes. Then, Zn(NO3)3·6H2O (1.5 g, 5 mmol) was added and stirred for 30 minutes. 100 mL of a methanol solution containing 0.8 g, 10 mmol of 2-methylimidazole was added dropwise, and the mixture was stirred at room temperature for 2 hours. The precipitate was collected by centrifugation, washed three times with methanol, and dried to obtain Fe3O4@ZIF-8. The ZIF-8 layer was approximately 50 nm thick, and the average mesopore diameter was approximately 2.1 nm.
[0026] (3) Fe3O4@ZIF-8@MIL-101 outer coating
[0027] 1.6 g of Fe3O4@ZIF-8 was dispersed in 100 mL of DMF, and 1.2 g of 3 mmol Cr(NO3)3·9H2O was added. The mixture was sonicated for 30 minutes. Then, 100 mL of DMF solution containing 0.9 g of 5 mmol 2-aminoterephthalic acid was added dropwise, and the mixture was reacted at 120 °C for 24 hours. After cooling, the mixture was centrifuged, washed three times with DMF, and dried to obtain Fe3O4@ZIF-8@MIL-101. The MIL-101 layer had an average pore size of approximately 2.5 nm and an outer layer thickness of approximately 80 nm.
[0028] (4) Nitrogen-sulfur co-doped graphene shell modification: Graphene oxide was prepared by the Hummers method and mixed with urea (mass ratio 1:0.5) and thiourea (mass ratio 1:0.2). The mixture was annealed at 600℃ for 2 hours under an Ar atmosphere to obtain nitrogen-sulfur co-doped graphene. 0.3 g of the nitrogen-sulfur co-doped graphene was dispersed in 50 ml of water, and 1.2 g of the Fe3O4@ZIF-8@MIL-101 composite material was added. The mixture was sonicated for 1 hour and then stirred for 12 hours. After centrifugation, washing, and drying, the Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material was obtained. The surface contained -COOH, -OH, and -SH functional groups, and its BET specific surface area was measured to be 520 m² / g.
[0029] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8) and stirred at room temperature for 2 hours. The concentration of tetracycline was determined using a UV spectrophotometer, and the adsorption rate was calculated to be 95.2%, with a maximum adsorption capacity of 92 mg / g.
[0030] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm UV light for 30 minutes. The tetracycline degradation rate was 96.7%, the TOC removal rate was 89%, and LC-MS analysis showed no intermediate residues. The mineralization product was C. and O.
[0031] The composite material was washed with deionized water, dried, and reused. The results showed that the degradation rate of the composite material prepared in this example remained above 88% after 10 adsorption-catalysis cycles.
[0032] Example 2
[0033] A method for preparing a Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material includes the following steps: (1) Synthesis of Fe3O4 magnetic core: Same as in Example 1.
[0034] (2) Preparation of Fe3O4@ZIF-8 core-shell structure
[0035] 0.1 g Fe3O4 was dispersed in 100 mL of ethanol and sonicated for 30 minutes. 1.5 g Zn(NO3)3·6H2O was added and stirred for 30 minutes. 100 mL of a methanol solution containing 1.6 g 2-methylimidazole was added dropwise, and the mixture was stirred at room temperature for 4 hours. After centrifugation, washing, and drying, a Fe3O4@ZIF-8 layer with a ZIF-8 layer thickness of approximately 80 nm was obtained.
[0036] (3) Fe3O4@ZIF-8@MIL-101 outer coating: same as in Example 1.
[0037] (4) Nitrogen-sulfur co-doped graphene shell modification: Same as Example 1.
[0038] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8) and stirred at room temperature for 2 hours. The concentration of tetracycline was determined using a UV spectrophotometer, and the adsorption rate was calculated to be 98.2%, with a maximum adsorption capacity of 98 mg / g (fitted by the Langmuir model).
[0039] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm UV light for 30 minutes. The tetracycline degradation rate was 97.2%.
[0040] The composite material was washed with deionized water, dried, and reused. The results showed that the composite material prepared in this example still maintained a degradation rate of over 90% after 10 adsorption-catalysis cycles.
[0041] Example 3
[0042] A method for preparing a Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material includes the following steps: (1) Synthesis of Fe3O4 magnetic core: Same as in Example 1.
[0043] (2) Preparation of Fe3O4@ZIF-8 core-shell structure: Same as in Example 2.
[0044] (3) Fe3O4@ZIF-8@MIL-101 outer coating
[0045] 1.6 g of Fe3O4@ZIF-8 was dispersed in 100 mL of DMF, and 1.2 g of Cr(NO3)3·9H2O was added. The mixture was sonicated for 30 minutes. Then, 100 mL of DMF solution containing 1.8 g of 2-aminoterephthalic acid was added dropwise, and the mixture was reacted at 140 °C for 36 hours. After cooling, the mixture was centrifuged, washed, and dried to obtain a MIL-101 layer with a thickness of approximately 120 nm, consisting of Fe3O4@ZIF-8@MIL-101.
[0046] (4) Nitrogen-sulfur co-doped graphene shell modification: Same as Example 1.
[0047] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8), stirred at room temperature for 2 hours, and the concentration of tetracycline was determined by ultraviolet spectrophotometer. The adsorption rate was calculated to be 98.5%, and the maximum adsorption capacity was 98 mg / g.
[0048] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm UV light for 30 minutes. The tetracycline degradation rate was 96.8%.
[0049] The composite material was washed with deionized water, dried, and reused. The results showed that the composite material prepared in this example still maintained a degradation rate of over 90% after 10 adsorption-catalysis cycles.
[0050] Example 4
[0051] A method for preparing a Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material includes the following steps: (1) Prepare Fe3O4@ZIF-8@MIL-101 core-shell structure in the same steps (1)-(3) as in Example 1.
[0052] (2) Graphene oxide was prepared by the Hummers method and mixed with urea (mass ratio 1:0.5) and thiourea (mass ratio 1:0.5), and annealed at 600°C for 2 hours under an Ar atmosphere. The remaining steps were the same as in Example 1.
[0053] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8), stirred at room temperature for 2 hours, and the concentration of tetracycline was determined by ultraviolet spectrophotometer. The adsorption rate was calculated to be 95.3%, and the maximum adsorption capacity was 91 mg / g.
[0054] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm UV light for 30 minutes. The tetracycline degradation rate was 96.5%.
[0055] Comparative Example 1
[0056] A method for preparing a Fe3O4@ZIF-8@MIL-101@graphene oxide composite material includes the following steps: (1) Prepare Fe3O4@ZIF-8@MIL-101 core-shell structure in the same steps (1)-(3) as in Example 1.
[0057] (2) Graphene oxide coated with Fe3O4@ZIF-8@MIL-101 prepared using only the Hummers method.
[0058] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8), stirred at room temperature for 2 hours, and the concentration of tetracycline was determined by ultraviolet spectrophotometer. The adsorption rate was calculated to be 79.4%.
[0059] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm ultraviolet light for 30 minutes, resulting in a tetracycline degradation rate of 78%.
[0060] Comparative Example 2
[0061] A method for preparing a Fe3O4@MIL-101@nitrogen-sulfur co-doped graphene composite material includes the following steps: (1) Synthesis of Fe3O4 magnetic core: Same as in Example 1.
[0062] (2) Preparation of Fe3O4@MIL-101 core-shell structure: 1.6 g of Fe3O4 was dispersed in 100 mL of DMF, and 1.2 g of Cr(NO3)3·9H2O was added. The mixture was sonicated for 30 minutes. Then, 100 mL of DMF solution containing 0.9 g of 2-aminoterephthalic acid was added dropwise, and the mixture was reacted at 120 °C for 24 hours. After centrifugation, washing, and drying, Fe3O4@MIL-101 was obtained.
[0063] (3) Nitrogen-sulfur co-doped graphene shell modification: Same as Example 1.
[0064] 10 mg of the composite material prepared in this example was mixed with 100 mL of 10 mg / L tetracycline solution (pH 6.8), stirred at room temperature for 2 hours, and the concentration of tetracycline was determined by ultraviolet spectrophotometer. The adsorption rate was calculated to be 51.5%.
[0065] After adsorption equilibrium was reached, 0.1 g / L PMS was added, and the mixture was irradiated with 365 nm UV light for 30 minutes. The tetracycline degradation rate was 65.8%.
[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A composite material based on a hierarchical structure, characterized in that, From the inside out, the structure consists of: a Fe3O4 magnetic core, a ZIF-8 layer, a MIL-101 layer, and a nitrogen-sulfur co-doped graphene shell; wherein the Fe3O4 magnetic core has a particle size range of 10–50 nm.
2. The method for preparing the composite material based on the hierarchical structure according to claim 1, characterized in that, Includes the following steps: (1) Preparation of Fe3O4@ZIF-8 core-shell structure: Fe3O4 magnetic nanoparticles with a particle size of 10-50 nm were uniformly dispersed in ethanol, and soluble zinc salt was added and fully dissolved to obtain mixed solution I; 2-methylimidazole methanol solution was added dropwise, and the mixture was stirred at room temperature to react fully. The precipitate was collected by centrifugation, washed, and dried to obtain Fe3O4@ZIF-8. (2) Fe3O4@ZIF-8@MIL-101 outer coating Fe3O4@ZIF-8 was dispersed in DMF, and a soluble chromium salt was added and dissolved completely to obtain mixed solution II; 2-aminoterephthalic acid DMF solution was added dropwise, and the reaction was carried out at 120℃ for 24 hours; after cooling, centrifugation, washing, and drying were performed to obtain Fe3O4@ZIF-8@MIL-101; (3) Nitrogen-sulfur co-doped graphene shell modification: Nitrogen-sulfur co-doped graphene was dispersed in water, and Fe3O4@ZIF-8@MIL-101 composite material was added. The mixture was ultrasonically stirred, centrifuged, washed, and dried to obtain Fe3O4@ZIF-8@MIL-101@nitrogen-sulfur co-doped graphene composite material.
3. The method for preparing composite materials based on hierarchical structures according to claim 2, characterized in that, The synthesis method of the Fe3O4 magnetic nanoparticles is as follows: FeCl2·4H2O aqueous solution and FeCl3·6H2O aqueous solution are mixed and stirred evenly. Then, NaOH solution is added dropwise until pH=10, and stirring is continued for 30 minutes. The precipitate is separated by centrifugation, washed three times with deionized water and ethanol, and dried under vacuum at 60℃ for 12 hours to obtain Fe3O4 magnetic nanoparticles; wherein, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:
2.
4. The method for preparing composite materials based on hierarchical structures according to claim 2, characterized in that, In step (1), the mass ratio of Fe3O4, soluble zinc salt, and 2-methylimidazole is 0.1:1.5:0.8-1.
6.
5. The method for preparing composite materials based on hierarchical structures according to claim 2, characterized in that, In step (2), the mass ratio of Fe3O4@ZIF-8, soluble chromium salt, and 2-aminoterephthalic acid is 1.6:1.2:0.9-1.
8.
6. The method for preparing composite materials based on hierarchical structures according to claim 2, characterized in that, The method for preparing nitrogen-sulfur co-doped graphene is as follows: graphene oxide, urea, and thiourea are mixed evenly and annealed at 600°C for 2 hours under an inert atmosphere to obtain nitrogen-sulfur co-doped graphene. The mass ratio of graphene oxide, urea, and thiourea is 1:0.5:0.2-0.
5.
7. The method for preparing composite materials based on hierarchical structures according to claim 2, characterized in that, In step (3), the mass ratio of nitrogen-sulfur co-doped graphene to Fe3O4@ZIF-8@MIL-101 is 1:
4.
8. The application of the hierarchical composite material according to claim 1 in the degradation of antibiotic pollutants.
9. The application according to claim 8, characterized in that, The composite material based on the hierarchical structure is added to antibiotic pollutants to adsorb antibiotics, and then PMS is added to degrade the antibiotics under light conditions.