A mil-101 (fe) based fe-confined graphene aerogel composite material, and a preparation method and application thereof

Abstract

The application discloses a kind of Fe confined type graphene aerogel composite material based on MIL-101 (Fe) and its preparation method and application, belong to environmental functional materials and water pollution control technical field.The composite material uses three-dimensional porous graphene aerogel as framework, in situ growth and confine MIL-101 (Fe) metal organic framework nanoparticles in the pore network of framework, and Fe active center is anchored in MIL-101 (Fe) framework with Fe-O coordination structure form.The application utilizes the nanometer confinement effect of graphene aerogel and interface electron synergistic effect, significantly accelerates Fe (III) / Fe (II) cycle, and makes the pollutant degradation path from deep mineralization to oligomerization coupling path, so that the degradation rate of bisphenol A is rapidly improved;The preparation process of the application is simple, and is suitable for efficient low-carbon treatment of high-concentration refractory organic wastewater in chemical, printing and dyeing, pharmaceutical industry.

Description

Technical Field

[0001] This invention relates to the technical field of environmental functional materials and water pollution control, and in particular to a Fe-confined graphene aerogel composite material based on MIL-101(Fe), its preparation method and application. Background Technology

[0002] Wastewater discharged from industries such as chemical, printing and dyeing, and pharmaceutical manufacturing contains a large amount of structurally stable and highly biotoxic organic pollutants, such as antibiotics, dyes, and phenols, posing a serious threat to water environment safety. Heterogeneous Fenton technology has attracted much attention due to its ability to recycle catalysts and adapt to a wide pH range, but its development is still limited by core bottlenecks such as slow Fe(III) / Fe(II) catalyst cycling rate, low oxidant utilization efficiency, and easy loss of active components.

[0003] Metal-organic framework material MIL-101(Fe) exhibits great potential in activating hydrogen peroxide to generate hydroxyl radicals due to its ultra-large specific surface area, abundant mesoporous structure, and accessible Fe-O coordination structure active sites. However, nanoscale MIL-101(Fe) particles are prone to aggregation and partial hydrolysis in water, leading to masking of active sites, decreased catalytic efficiency, and poor cycle stability, which severely restricts its practical application.

[0004] Graphene aerogels, with their three-dimensional interconnected porous networks, excellent conductivity, and structural stability, are ideal catalyst supports. The nanoscale confinement spaces they create not only inhibit the aggregation and loss of active components but also enrich reactants and regulate the reaction microenvironment, potentially solving the stability and activity challenges of MIL-101(Fe) simultaneously. Although existing research has explored the composite of MOFs and carbon materials, the precise preparation process for in-situ, uniformly, and firmly confining MIL-101(Fe) nanoparticles within a graphene aerogel framework to construct a composite material with high activity, high stability, and unique interfacial electronic effects, and then utilizing this confinement effect to fundamentally alter the degradation pathway of pollutants for low-carbon treatment, remains a technological gap. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a Fe-confined graphene aerogel composite material based on MIL-101(Fe), its preparation method, and its applications. The composite material obtained by this invention utilizes the three-dimensional confinement space of the graphene aerogel to achieve high dispersion, anchoring, and enhanced stability of MIL-101(Fe) nanoparticles. Furthermore, by leveraging the resulting synergistic effect, it significantly accelerates the Fe(III) / Fe(II) cycle in the Fenton-like reaction, while simultaneously shifting the pollutant degradation pathway from the energy-intensive "complete mineralization" to a more economical "catalytic oligomerization / coupling" pathway. This achieves efficient, low-carbon, and wide-pH-adaptive treatment of recalcitrant organic wastewater. The composite material obtained by this invention exhibits excellent performance in the Fenton-like catalytic degradation of high-concentration, recalcitrant organic wastewater, particularly under wide pH range and low oxidant consumption conditions.

[0006] The first objective of this invention is to provide a Fe-confined graphene aerogel composite material based on MIL-101(Fe), which uses a three-dimensional porous graphene aerogel as a framework, in which MIL-101(Fe) metal-organic framework nanoparticles are grown and confined in situ, and the Fe active centers are stably anchored in the MIL-101(Fe) framework in the form of Fe-O coordination structure.

[0007] In some embodiments of the present invention, the particle size of the MIL-101(Fe) metal-organic framework nanoparticles is 40~80 nm.

[0008] The second objective of this invention is to provide a method for preparing a MIL-101(Fe)-based Fe-confined graphene aerogel composite material, comprising the following steps:

[0009] A three-dimensional graphene aerogel substrate was obtained by mixing a graphene oxide dispersion with a reducing agent and then carrying out a hydrothermal reaction followed by freeze-drying.

[0010] The obtained graphene aerogel substrate was immersed in a precursor mixture containing organic solvent, iron source, organic ligand and modulator, and ultrasonically treated until fully wetted;

[0011] The impregnated system was subjected to a solvothermal reaction to allow MIL-101(Fe) nanoparticles to nucleate and grow in situ within the graphene aerogel pore network, thereby obtaining the Fe-confined graphene aerogel composite material based on MIL-101(Fe).

[0012] In some embodiments of the present invention, the reducing agent is ethylenediamine and / or ascorbic acid;

[0013] The mass concentration of the graphene oxide dispersion is 1~5 mg / mL;

[0014] The mass ratio of graphene oxide to reducing agent is 1:(0.5~2).

[0015] In some embodiments of the present invention, the hydrothermal reaction conditions are: the hydrothermal reaction temperature is 160~200°C, and the time is 6~12h;

[0016] Freeze-drying conditions: temperature -50~-30℃, 1~10Pa, time 24~48h.

[0017] In some embodiments of the present invention, all organic solvents are selected from one or more of N,N-dimethylformamide, DMF-anhydrous ethanol mixture and DMAc; further, N,N-dimethylformamide and DMAc are preferred; when ethanol is used as the organic solvent in this experiment, it is easy to cause hydrolysis of the material.

[0018] The iron source is selected from one or more of ferric chloride hexahydrate, ferrous chloride tetrahydrate, ferric nitrate nonahydrate, and ferric sulfate. The present invention found that the use of ferric sulfate is prone to residual sulfate impurities that block the channels; ferric nitrate decomposes at high temperature to produce nitrogen oxides with uneven particle size; if ferrous chloride tetrahydrate is used as a substitute, oxidation is required in the synthesis stage.

[0019] The organic ligands are selected from terephthalic acid, 2-aminoterephthalic acid NH2-BDC, and 2-hydroxyterephthalic acid;

[0020] The modulator is selected from hydrofluoric acid and / or ammonium fluoride.

[0021] The amount of modifier used is based on an iron source molar amount of 1, as shown below:

[0022] (1) When selecting a single component regulator range, the molar ratio of iron source to HF is 1:(0.2~1.0) when only hydrofluoric acid is selected, and the molar ratio of iron source to NH4F is 1:(0.3~1.2) when only ammonium fluoride is selected.

[0023] (2) Hydrofluoric acid + ammonium fluoride compound total regulator: the total molar ratio of iron source to regulator is 1:(0.2~1.2)

[0024] (3) Optimal process range: The molar ratio of iron source to regulator is 1:(0.6~0.9).

[0025] In some embodiments of the present invention, the molar ratio of iron source to organic ligand is 1:(0.8~1.5). If the ratio is less than this, a large amount of amorphous iron oxide impurities are generated, resulting in the absence of complete MOF channels, a significant reduction in catalytic efficiency, and particle agglomeration that prevents aerogel confinement. If the organic ligand is in excess and exceeds this ratio, the excess organic ligand blocks the channels, reduces crystallization stability, increases iron dissolution, and simultaneously increases the cost of raw materials and wastewater treatment. The range of the present invention can yield pure phase, highly crystalline MIL-101(Fe), representing a reasonable feed range that balances product purity, catalytic performance, and cost.

[0026] In some embodiments of the present invention, the conditions for ultrasonic treatment are: ultrasonic degassing at a power of 100-200W for 5-10 minutes;

[0027] The conditions for the solvothermal reaction are: the reaction temperature is 100~130℃ and the reaction time is 18~36h.

[0028] The third objective of this invention is to provide the application of the aforementioned MIL-101(Fe)-based Fe-confined graphene aerogel composite material in the Fenton-like catalytic degradation of high concentrations of recalcitrant organic pollutants in the chemical, printing and dyeing, and pharmaceutical industries.

[0029] In some embodiments of the present invention, the Fenton-like catalytic degradation is carried out at pH 3.0 to 10.0;

[0030] The organic pollutants include phenols, antibiotics, and aromatic organic pollutants;

[0031] Furthermore, the organic pollutants include one or more of bisphenol A, levofloxacin, phenol, methyl orange, rhodamine B, tetracycline, and carbamazepine;

[0032] The concentration of the Fe-confined graphene aerogel composite material based on MIL-101(Fe) is 0.2~1.0 g / L;

[0033] The concentration of the organic pollutant is 15~20 mg / L;

[0034] The Fenton-like catalytic degradation also includes hydrogen peroxide, the concentration of which is 30 wt%, and the amount of hydrogen peroxide used is based on the molar amount of organic pollutants, with a molar ratio range of 5 to 30 times the substrate; the optimal low-consumption range is 8 to 15 times the substrate.

[0035] Furthermore, in the Fenton-like catalytic degradation system, the concentration of hydrogen peroxide is 0.5~2.0 mmol / L or 0.5~1.4 mmol / L. For example, it can be 0.5, 1.0, 1.4, 2.0 mmol / L, or any range between any two values.

[0036] The technical solution of the present invention has the following advantages over the prior art:

[0037] (1) Synergistic enhancement of catalytic activity and stability: The physical confinement effect of graphene aerogel effectively prevents the aggregation and detachment of MIL-101(Fe) nanoparticles, exposing more active sites. The interfacial electronic interaction between its conductive network and MIL-101(Fe) significantly accelerates the rate-determining step of Fe(III) reduction in the catalytic cycle. The apparent rate constant for the degradation of bisphenol A by this composite material can reach 0.22 min. -1 It is more than 180 times that of unconfined MIL-101(Fe) under the same conditions, and the activity retention rate exceeds 92% after running 50 cycles in a continuous flow reaction.

[0038] (2) Constructing a low-carbon degradation pathway to achieve energy conservation and emission reduction from the source: The nano-confined microenvironment constructed by the composite material of this invention can regulate the transformation pathway of pollutant degradation intermediates, transforming the reaction pathway of deep mineralization by a large amount of oxidant in traditional processes into an intermediate oligomerization coupling pathway mediated by the material surface. This material uses three-dimensional graphene aerogel as a framework to confine MIL-101(Fe) iron-based active clusters in multi-level channels, and the graphene defect sites anchor the active iron sites to form efficient electron transport channels; after a low dose of hydrogen peroxide enters the confined space, it preferentially generates surface-bound hydroxyl radicals. The confined space can enrich reactants and intermediates, and macromolecular products can be generated through intermolecular oligomerization without a large amount of oxidant, which can be removed by solid-liquid separation. Multiple comparative experiments with hydrogen peroxide dosage gradients have verified that, under the same pollutant removal efficiency, the dosage of traditional homogeneous Fenton hydrogen peroxide is 12 mmol / L, while this invention requires only 1.4 mmol / L, reducing the oxidant consumption per unit pollutant by more than 88%. The significant reduction in oxidant dosage can reduce energy consumption in reagent production, transportation, and waste liquid disposal, thereby reducing direct carbon emissions from the process by approximately 65%, which meets the requirements of green chemical development.

[0039] (3) Broadening the pH application window and strong process adaptability: This composite material exhibits high and stable catalytic performance in a wide pH range of 3.0-10.0, overcoming the dependence of homogeneous Fenton technology on strong acidic conditions, simplifying the wastewater pretreatment process, and reducing operating costs. The three-dimensional graphene porous network balances the pH of the microenvironment through the protonation and deprotonation of oxygen-containing functional groups on its surface, resisting external acid and alkali interference; the MIL-101(Fe) ligand forms a stable coordination structure with iron ions, inhibiting iron ion dissolution and the formation of the iron hydroxide passivation layer; the heterogeneous interface between iron-based MOF and graphene can stably activate hydrogen peroxide in various acid and alkali environments without the need for strong acid to maintain Fe. 2+ / Fe 3+It can be circulated and adapted to various complex wastewaters.

[0040] (4) The preparation method is simple and has good repeatability: the composite is achieved in one step by using a mild solvothermal method, the process parameters are easy to control, the raw materials are cheap and readily available, and it has the potential for large-scale production. Attached Figure Description

[0041] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0042] Figure 1 This is a scanning electron microscope (SEM) image of the unconfined MIL-101(Fe) material prepared in Comparative Example 1 of the present invention.

[0043] Figure 2 This is a scanning electron microscope (SEM) image of the GA-confined MIL-101(Fe) / GA composite material prepared in Example 1 of the present invention.

[0044] Figure 3 The X-ray diffraction (XRD) spectra of the MIL-101(Fe) / GA prepared in Example 1 of this invention are compared with those of the material in Comparative Example 1 (unconfined MIL-101(Fe)).

[0045] Figure 4 This is a comparison chart showing the performance of the MIL-101(Fe) / GA prepared in Example 1 of this invention and the unconfined MIL-101(Fe) material prepared in Comparative Example 1 in the bisphenol A degradation reaction.

[0046] Figure 5 This is a comparison chart of bisphenol A removal rates under different H2O2 dosages in Application Example 1.

[0047] Figure 6 A comparison of the degradation efficiency of phenol by MIL-101(Fe) / GA prepared in Example 1 of this invention and the traditional homogeneous Fenton system under different interference conditions.

[0048] Figure 7 The graph shows the degradation efficiency of levofloxacin by MIL-101(Fe) / GA prepared in Example 1 of this invention under different pH conditions. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0050] Example 1

[0051] This embodiment provides a method for preparing Fe-confined graphene aerogel composite material based on MIL-101(Fe), as detailed below.

[0052] I. Preparation of three-dimensional graphene aerogel (GA):

[0053] Take 40 mL of a 2.5 mg / mL graphene oxide aqueous dispersion, add 60 mg of ascorbic acid, and ultrasonically disperse until homogeneous. Transfer the mixture to a 100 mL polytetrafluoroethylene-lined high-pressure reactor and react at 180 °C for 8 h. After natural cooling, remove the obtained hydrogel, thoroughly soak and wash it with deionized water, and then freeze-dry it at -50 °C and 5 Pa for 48 h to obtain a lightweight three-dimensional porous GA substrate.

[0054] II. In-situ confined synthesis of MIL-101(Fe) / GA composite materials

[0055] Weigh 0.675 g (2.5 mmol) of ferric chloride hexahydrate and 0.415 g (2.5 mmol) of terephthalic acid, dissolve them in 30 mL of N,N-dimethylformamide (DMF), and stir until clear. Add 0.15 mL of 40 wt% hydrofluoric acid as a modifier, and continue stirring for 10 min to obtain the precursor solution. Immerse a piece of GA (approximately 30 mg) obtained in step one into this precursor solution, let it stand at room temperature for 1 h, and then sonicate it at 150 W for 15 min to ensure complete wetting. Then transfer the entire system to a 50 mL polytetrafluoroethylene-lined high-pressure reactor and solvothermal react at 120 °C for 24 h. After the reaction, wash the product three times alternately with hot DMF and anhydrous ethanol, centrifuge, and finally dry it in a vacuum oven at 80 °C for 12 h to obtain the final product MIL-101(Fe) / GA, the microstructure of which is shown in the attached figure. Figure 2 As shown in the figure, MIL-101(Fe) nanoparticles were successfully confined within the three-dimensional pores of GA.

[0056] Application Example 1

[0057] Hydrogen peroxide usage optimization and carbon emission assessment

[0058] Using bisphenol A (BPA) as the target pollutant, the degradation performance of the MIL-101(Fe) / GA composite material prepared in Example 1 of this invention under different hydrogen peroxide dosages was investigated and compared with the traditional homogeneous Fenton system.

[0059] 50 mL of 20 mg / L bisphenol A solution was added to several 250 mL Erlenmeyer flasks, and the pH was adjusted to 6.5 with dilute NaOH. 10 mg of the MIL-101(Fe) / GA catalyst prepared in Example 1 was added to each solution, followed by different volumes of 30% H2O2 solution, resulting in initial H2O2 concentrations of 0.5, 1.0, 1.4, 2.0, 5.0, 10.0, and 12.0 mmol / L, respectively. A conventional homogeneous Fenton control group (Fe...) was also included. 2+ (0.1 mmol / L, H2O2 concentration gradient as above). All reactions were carried out at 25 ℃ under light-protected shaking conditions. Samples were taken periodically, filtered through a 0.22 μm filter membrane, and the bisphenol A concentration was determined by high performance liquid chromatography.

[0060] Experimental results are as follows Figure 5 As shown, the MIL-101(Fe) / GA system of this invention achieved a bisphenol A removal rate of 97.5% after 12 minutes of reaction with an H2O2 dosage of only 1.4 mmol / L. Further increasing the H2O2 dosage did not significantly improve the removal rate, exhibiting a clear "plateau effect." In contrast, the traditional homogeneous Fenton system requires an H2O2 dosage of 12.0 mmol / L to achieve a similar removal rate (approximately 97%).

[0061] Based on the above experimental results, the oxidant consumption per unit pollutant in this invention is reduced by more than 88% compared to the traditional homogeneous Fenton reactor. Further calculations based on the carbon emission coefficient of hydrogen peroxide industrial production (approximately 1.2 kg CO2 / kg H2O2) show that the consumption per unit volume of wastewater treated (1 m³) is significantly lower. 3 When BPA is 20 mg / L, the direct carbon emissions of the process of this invention are approximately 0.057 kg CO2, which is about 88.4% lower than that of the traditional homogeneous Fenton process (approximately 0.490 kg CO2). Taking into account the energy consumption reduction in oxidant production, transportation and waste liquid disposal, the overall direct carbon emissions of the process of this invention are reduced by approximately 65%.

[0062] This application example demonstrates that the composite material of the present invention, through the synergistic effect of nano-confinence and interfacial electrons, can significantly reduce the demand for hydrogen peroxide while maintaining efficient degradation, thereby significantly saving reagent costs and reducing process carbon emissions, which meets the requirements of green chemical industry.

[0063] Performance Testing: Continuous Flow Cyclic Stability Test

[0064] Verify the long-term operational stability of the MIL-101(Fe) / GA composite material prepared in Example 1 of this invention under continuous flow reaction conditions.

[0065] A laboratory-scale continuous flow fixed-bed reactor was used. 50 mg of the MIL-101(Fe) / GA composite material prepared in Example 1 was uniformly packed into a 10 mm inner diameter glass chromatography column, with both ends secured with silica wool to prevent material loss. Simulated wastewater was prepared with a bisphenol A (BPA) concentration of 20 mg / L and an H2O2 concentration of 0.5 mmol / L (equivalent to adding approximately 17 μL of 30% H2O2 solution per liter of simulated wastewater), and the pH was adjusted to 6.5 with dilute NaOH solution. The simulated wastewater was fed into the reaction column from top to bottom using a peristaltic pump at a flow rate of 0.5 mL / min, with an empty bed contact time of approximately 5 minutes. The reaction was carried out at 25 °C under dark conditions. Each cycle consisted of treating one column volume (approximately 50 mL) of simulated wastewater, and the effluent BPA concentration was measured. A total of 50 cycles were performed, treating approximately 2.5 L of simulated wastewater. Each sample was filtered through a 0.22 μm filter membrane, and the residual concentration of bisphenol A was determined by high performance liquid chromatography (HPLC).

[0066] In the first cycle, the bisphenol A removal rate reached 97.8%. With increasing cycle number, the removal rate decreased slightly, but by the end of the 50th cycle, the bisphenol A removal rate remained above 92.5%, and the activity retention rate (calculated based on the removal rate of the first cycle) exceeded 92%. These results demonstrate that the MIL-101(Fe) / GA composite material prepared in this invention exhibits excellent long-term catalytic stability in continuous flow operation, with minimal loss of active components and intact catalyst structure, making it suitable for industrial continuous processing requirements.

[0067] Comparative Example 1: Material Characterization Comparison

[0068] This comparative example provides a method for preparing an unconfined MIL-101(Fe) material, as detailed below:

[0069] The preparation method is similar to that in Example 1, except that a lightweight three-dimensional porous GA substrate is not added to the precursor solution, resulting in the control sample MIL-101(Fe), the morphology of which is shown in the attached figure. Figure 1 As shown in the figure, the material has undergone severe aggregation.

[0070] 1. Scanning electron microscopy (SEM) characterization: as shown in the attached document. Figure 1 As shown, MIL-101(Fe) exhibits as micron-sized, heavily aggregated, polyhedral particles; as shown in the attached figure. Figure 2 As shown, the three-dimensional porous framework of GA can be clearly observed in MIL-101(Fe) / GA. MIL-101(Fe) particles with a size of about 40-80 nm are uniformly attached and embedded in the pores of the framework without obvious aggregation, indicating that the confinement effect of GA effectively regulates the growth of MIL-101(Fe) and inhibits particle aggregation.

[0071] 2. X-ray diffraction (XRD) characterization: as shown in the attached document. Figure 3 As shown, the composite material MIL-101(Fe) / GA exhibits high consistency with the pure phase MIL-101(Fe) in the position of characteristic diffraction peaks, with all major diffraction peaks completely corresponding to the spectrum of standard MIL-101(Fe). The shapes of the two spectra almost completely overlap, and no additional diffraction peaks belonging to impurities or new crystalline phases were observed. This result demonstrates that during the in-situ growth of MIL-101(Fe) in a graphene aerogel (GA) three-dimensional network, the characteristic crystal structure of MIL-101(Fe) is completely preserved, and the introduction of GA does not alter its crystal phase composition, proving that the prepared composite material possesses a pure and complete crystal morphology.

[0072] Anti-interference performance test

[0073] To objectively evaluate the performance advantages of the composite material of this invention, this comparative example uses the traditional homogeneous Fenton technology, most commonly used in industrial wastewater treatment, as a benchmark. Comparative tests were conducted under identical conditions for key parameters such as total iron content, H₂O₂ dosage, pollutant concentration, solution volume, pH, and temperature. The iron content in the MIL-101(Fe) / GA composite material prepared in Example 1, as determined by ICP-OES, was approximately 12 wt%, meaning approximately 1.2 mg of Fe (approximately 0.0215 mmol) per 10 mg catalyst. To ensure consistency of variables, the Fe content in the traditional homogeneous Fenton system was... 2+ The dosage was also set at 0.0215 mmol (i.e., about 6.0 mg of FeSO4·7H2O was added).

[0074] Add 50 mL of 20 mg / L phenol solution to a 250 mL Erlenmeyer flask, adjust the pH to 6.5 with dilute NaOH, and add 6.0 mg FeSO4·7H2O and 20 μL 30% H2O2 to initiate the reaction. The reaction was then carried out under undisturbed conditions and with the addition of NaCl (Cl... - (Concentration 50 mmol / L), add NaHCO3 (HCO3) - Concentration 10 mmol / L), add NaNO3 (NO3) - (Concentration 10 mmol / L), add Na2SO4 (SO4) 2- (Concentration 10 mmol / L), add Na3PO4 (PO4) 3- Degradation experiments were conducted under seven conditions: phenol concentration (5 mmol / L) and the addition of humic acid (HA concentration 10 mg / L). The reaction was carried out at 25 °C under light-protected shaking conditions. Samples were taken after 30 minutes, filtered through a 0.22 μm filter membrane, and the phenol concentration was determined by high-performance liquid chromatography.

[0075] Experimental results are as follows Figure 6As shown, the traditional homogeneous Fenton system achieved a removal rate of 86.2% under undisturbed conditions; however, the removal rate plummeted to 30.5% after the addition of Cl⁻, and further reductions occurred after the addition of HCO₃. - It then decreased to 26.8%, and after adding HA it decreased to 43.1%, and after adding NO3... - It was later reduced to 78.5% by adding SO4. 2- It later dropped to 81.3%, after adding PO4. 3- It later dropped to 55.6%. Among them, Cl - HCO 3- PO4 3- The inhibitory effect of HA on the traditional homogeneous Fenton system is the most significant, with a reduction of 40% to 69%. In contrast, under the same total iron content and interference conditions, the phenol removal rate in Example 1 of this invention remained above 89% for 30 minutes, with a reduction of no more than 8%.

[0076] This anti-interference experiment demonstrates that, under conditions of identical total iron content, the traditional homogeneous Fenton system heavily relies on ·OH radicals, Cl... - HCO3 - PO4 3- Common water components such as HA have a significant inhibitory effect on its catalytic activity; the composite material of this invention activates the non-radical degradation pathway through the nano-confining effect and the synergistic effect of interfacial electrons, effectively avoiding the risk of ·OH being quenched, and has excellent anti-interference ability under complex water quality conditions.

[0077] Application Example 2: Catalytic Performance Test of Bisphenol A Degradation Reaction

[0078] The Fenton-like catalytic performance of the catalyst was evaluated using bisphenol A (BPA) as a typical recalcitrant organic pollutant. The test conditions simulated routine industrial wastewater treatment: 50 mL of a 20 mg / L BPA solution was added to a 250 mL Erlenmeyer flask, and the pH was adjusted to 6.5 with dilute acid or alkali. 10 mg of catalyst (MIL-101(Fe) / GA from Example 1 of this invention or MIL-101(Fe) from Comparative Example 1) was added to the solution, followed by 20 μL of 30% H2O2 solution to initiate the Fenton-like reaction. The Erlenmeyer flask was placed at 25°C under light-protected, vibrating conditions. Samples were taken periodically, filtered through a 0.22 μm filter membrane, and the BPA concentration was determined by high-performance liquid chromatography (HPLC).

[0079] The results showed that using the material MIL-101(Fe) obtained in Comparative Example 1, the bisphenol A removal rate was only 11.8% after 60 minutes of reaction, indicating extremely low catalytic activity. However, using the MIL-101(Fe) / GA catalyst prepared in Example 1 of this invention, the bisphenol A removal rate reached 97.5% after only 12 minutes of reaction, demonstrating extremely excellent catalytic oxidation activity. Degradation performance comparisons are attached. Figure 4 As shown, kinetic fitting calculations yielded an apparent reaction rate constant (k) of 0.22 min for MIL-101(Fe) / GA. -1 , is MIL-101(Fe) (k=0.0012min -1 The effect is more than 180 times that of the nano-confined composite material prepared in this invention, which fully demonstrates the great advantage of improving Fenton-like reaction kinetics.

[0080] Application Example 3: Wide pH Adaptability Validation (Levofloxacin Degradation)

[0081] Using levofloxacin (LEV) as the target pollutant, the wide pH adaptability of the composite material was verified: 50 mL of a 15 mg / L levofloxacin solution was added to several 250 mL Erlenmeyer flasks. The initial pH of the reaction system was precisely adjusted to 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, and 12.0 respectively using dilute nitric acid or sodium hydroxide solution. 15 mg of the MIL-101(Fe) / GA catalyst prepared in Example 1 of this invention was added to each solution, and 30 μL of 30% H2O2 was added to initiate the reaction. All reactions were carried out at 25 °C under light-protected and isothermal shaking conditions. Samples were taken at set time points, filtered through a 0.22 μm filter membrane, and the residual concentration of levofloxacin was immediately determined by high-performance liquid chromatography (HPLC).

[0082] Experimental results are as follows Figure 7 As shown, the MIL-101(Fe) / GA composite material exhibits significant catalytic activity over a very wide pH range from 2.0 to 12.0. Its performance is particularly outstanding within the pH range of 3.0 to 10.0, with a removal rate of over 94% for levofloxacin after 30 minutes of reaction, reaching an optimal value of 98.2% near pH 6.0, effectively overcoming the dependence of traditional Fenton technology on strongly acidic conditions. Even under strong acid conditions (pH 2.0) or strong alkaline conditions (pH 11.0 and 12.0), the removal rates after 30 minutes still reach over 85% and 80%, respectively, demonstrating excellent acid and alkali tolerance. These results fully demonstrate that the composite material of this invention possesses efficient and stable catalytic ability within the pH range of 3.0–10.0 and exhibits good adaptability to extreme pH environments, greatly broadening its application prospects in practical complex wastewater treatment.

[0083] In summary, this invention successfully prepared a MIL-101(Fe) / graphene aerogel (GA) composite material with a well-defined nano-confined structure through an optimized two-step solvothermal and freeze-drying process. (See attached diagram.) Figure 2 and attached Figure 3As shown, the composite material has a well-defined structure, with MIL-101(Fe) nanoparticles uniformly confined within the three-dimensional porous framework of GA, and exhibiting a complete crystal structure. (See attached image.) Figure 4 and attached Figure 6 As shown, this material exhibits extremely high catalytic degradation efficiency and cycle stability for typical organic pollutants (such as bisphenol A and levofloxacin) across a wide pH range of 3.0-10.0, demonstrating significantly superior overall performance compared to traditional unconfined materials. The composite material preparation method provided by this invention is simple and reproducible, showing significant practical application value and broad prospects for the efficient and low-carbon treatment of high-concentration, recalcitrant organic wastewater.

[0084] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A Fe-confined graphene aerogel composite material based on MIL-101(Fe), characterized in that, Using a three-dimensional porous graphene aerogel as a framework, MIL-101(Fe) metal-organic framework nanoparticles are grown and confined in situ within the pore network of the framework, and the Fe active centers are stably anchored in the MIL-101(Fe) framework in the form of Fe-O coordination structure.

2. The Fe-confined graphene aerogel composite material based on MIL-101(Fe) according to claim 1, characterized in that, The particle size of the MIL-101(Fe) metal-organic framework nanoparticles is 40~80nm.

3. The method for preparing a Fe-confined graphene aerogel composite material based on MIL-101(Fe) as described in claim 1 or 2, characterized in that, Includes the following steps: A three-dimensional graphene aerogel substrate was obtained by mixing a graphene oxide dispersion with a reducing agent and then carrying out a hydrothermal reaction followed by freeze-drying. The obtained graphene aerogel substrate was immersed in a precursor mixture containing organic solvent, iron source, organic ligand and modulator, and ultrasonically treated until fully wetted; The impregnated system was subjected to a solvothermal reaction to allow MIL-101(Fe) nanoparticles to nucleate and grow in situ within the graphene aerogel pore network, thereby obtaining the Fe-confined graphene aerogel composite material based on MIL-101(Fe).

4. The preparation method according to claim 3, characterized in that, The reducing agent is ethylenediamine and / or ascorbic acid; The mass concentration of the graphene oxide dispersion is 1~5 mg / mL; The mass ratio of graphene oxide to reducing agent is 1:(0.5~2).

5. The preparation method according to claim 3, characterized in that, Hydrothermal reaction conditions: The hydrothermal reaction temperature is 160~200℃, and the time is 6~12h; Freeze-drying conditions: temperature -50~-30℃, 1~10Pa, time 24~48h.

6. The preparation method according to claim 3, characterized in that, All organic solvents are selected from one or more of N,N-dimethylformamide, DMF-anhydrous ethanol mixture and DMAc; The iron source is selected from one or more of ferric chloride hexahydrate, ferric nitrate nonahydrate, and ferric sulfate. The organic ligand is selected from one or more of terephthalic acid, 2-aminoterephthalic acid NH2-BDC and 2-hydroxyterephthalic acid; The modulator is selected from hydrofluoric acid and / or ammonium fluoride.

7. The preparation method according to claim 3, characterized in that, The molar ratio of iron source to organic ligand is 1:(0.8~1.5).

8. The preparation method according to claim 3, characterized in that, Ultrasonic treatment conditions: ultrasonic degassing at 100~200W power for 5~10 minutes; The conditions for the solvothermal reaction are: the reaction temperature is 100~130℃ and the reaction time is 18~36h.

9. The application of the Fe-confined graphene aerogel composite material based on MIL-101(Fe) as described in claim 1 or 2 in the Fenton-like catalytic degradation of high concentrations of recalcitrant organic pollutants in the chemical / printing and dyeing / pharmaceutical industries.

10. The application according to claim 9, characterized in that, The degradation under Fenton-like catalytic conditions was carried out at pH 3.0–10.

0. The organic pollutants include phenols, antibiotics, and aromatic organic pollutants; The concentration of the Fe-confined graphene aerogel composite material based on MIL-101(Fe) is 0.2~1.0 g / L; The concentration of the organic pollutant is 15~20 mg / L; The Fenton-like catalytic degradation also includes hydrogen peroxide, the concentration of which is 30 wt%, and the amount of hydrogen peroxide used is based on the molar amount of organic pollutants, with a molar ratio ranging from 5 to 30 times that of the substrate.

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