Iron-doped MOFs-based carbon composite material, preparation method and application thereof

Abstract

The application discloses an iron-doped MOFs-based carbon composite material and a preparation method and application thereof, and relates to the technical field of materials, in particular to the technical field of MOFs-based carbon composite materials. The preparation method comprises the following steps: firstly, preparing a UiO-66-SO3H precursor; then, mixing the UiO-66-SO3H precursor with an iron salt, and performing a solvothermal reaction; and finally, calcining the reaction product to obtain the iron-doped MOFs-based carbon composite material. The preparation method has the advantages of mild reaction conditions, a simple technological process, green environmental protection, low energy consumption, low cost and the like; the iron-doped MOFs-based carbon composite material prepared by the method has the advantages of good catalytic activity, good stability, low metal ion leaching rate and the like, and is suitable for large-scale popularization and application; when the iron-doped MOFs-based carbon composite material is used as an electro-Fenton catalyst to degrade organic pollutants in water or to prepare hydrogen peroxide, not only can the organic pollutants be effectively degraded, but also the yield of hydrogen peroxide can be significantly improved, so that the iron-doped MOFs-based carbon composite material has high use value and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, specifically relating to an iron-doped MOFs-based carbon composite material, its preparation method, and its application. Background Technology

[0002] With the continuous development of industrial technology, the pollution of the environment by organic pollutants has become increasingly serious. Antibiotics, as effective drugs for treating bacterial infections, have been widely used in the treatment of human and animal diseases. However, large amounts of wastewater containing antibiotics are indiscriminately discharged into natural water bodies, leading to serious environmental problems and posing a serious threat to human health. Taking tetracycline as an example, as a broad-spectrum antibiotic, it has inhibitory effects on most Gram-positive and Gram-negative bacteria. High concentrations of tetracycline have bactericidal effects and can inhibit rickettsiae, trachoma virus, etc. Tetracycline antibiotics mainly include chlortetracycline, oxytetracycline, and tetracycline. Chlortetracycline and oxytetracycline are derivatives of tetracycline; the former is chlorotetracycline, and the latter is oxytetracycline. All tetracyclines are amphoteric compounds. In recent decades, the global annual production and consumption of tetracycline have grown rapidly, currently reaching several thousand tons. Surprisingly, many tetracyclines and their metabolites are released into the environment through urine and feces, transferring to the environment along the food chain. Their toxic effects pose a potential threat to ecosystems, public health, and ecosystem security, such as the development of drug-resistant genes or bacteria. However, traditional Fenton technologies, such as membrane filtration, adsorption, oxidation, and biological treatment, are limited in practical application due to high operating costs, complex processes, and the potential generation of many toxic byproducts. Electro-Fenton technology, due to its green nature, ease of operation, short cycle time, and mild reaction conditions, is considered one of the most promising pollutant treatment technologies. The core of electro-Fenton technology is the synthesis of electro-Fenton catalysts. Therefore, to reduce the environmental pollution caused by antibiotics, such as tetracyclines, it is crucial to develop novel and effective electro-Fenton catalysts to remove antibiotics from water and reduce their toxicity.

[0003] In recent years, metal-doped carbonaceous materials have been widely used in redox reactions due to their excellent electrocatalytic activity and stability. Sulfonic acid-based metal-organic frameworks (MOFs) have gradually become a research hotspot due to their good stability, multiple potential oxygen atom coordination sites, and excellent proton conductivity. However, in practical applications, most virgin MOFs exhibit poor conductivity and significant metal ion leaching, severely limiting their application in electro-Fenton processes. Therefore, metal / carbon MOF-derived materials prepared by carbonization of virgin MOFs under an inert atmosphere are rapidly developing. Thus, obtaining a metal / carbon MOF-derived material with high catalytic activity and low metal ion leaching rate as an electro-Fenton catalyst for water purification has become an urgent priority. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an iron-doped MOFs-based carbon composite material with high catalytic activity, good stability and low metal ion leaching rate.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for preparing an iron-doped MOFs-based carbon composite material includes the following steps:

[0007] S1. Zirconium salt and sulfonic acid organic ligand are mixed, and a mixed solvent of N,N-dimethylformamide and acetic acid is added. The mixture is subjected to a solvothermal reaction, filtered, and dried to obtain the UiO-66-SO3H precursor.

[0008] S2. Mix the UiO-66-SO3H precursor obtained in step S1 with iron salt, add organic solvent, carry out solvothermal reaction, filter, and dry to obtain UiO-66-SO3H / Fe precursor.

[0009] S3. The UiO-66-SO3H / Fe precursor obtained in step S2 is calcined at a temperature ≥650℃, washed, and dried to obtain an iron-doped MOFs-based carbon composite material.

[0010] In the above preparation method, preferably, in step S3, the calcination temperature is 700℃~900℃.

[0011] In the above preparation method, preferably, in step S2, the mass ratio of the UiO-66-SO3H precursor to the iron salt is 1:0.38 to 2.28, and the iron salt is at least one of ferric chloride, ferric nitrate, and ferric sulfate.

[0012] In the above preparation method, preferably, in step S1, the molar ratio of the zirconium salt to the sulfonic acid organic ligand is 1:1 to 2, the zirconium salt is at least one of calcium chloride, zirconium oxide, and zirconium oxychloride octahydrate, the sulfonic acid organic ligand is at least one of 2-sulfonic acid terephthalic acid monosodium salt, 2,6-dicarboxy-4,8-dinaphthalenesulfonic acid, and 1,3,5-benzenetrisulfonyl chloride, the volume ratio of N,N-dimethylformamide to acetic acid in the mixed solvent of N,N-dimethylformamide and acetic acid is 8 to 10:1, the temperature of the solvothermal reaction is 80°C to 140°C, the time of the solvothermal reaction is 24 h to 40 h, and the drying temperature is 50°C to 70°C.

[0013] In the above preparation method, preferably, in step S2, the organic solvent is acetonitrile, the temperature of the solvothermal reaction is 80℃~120℃, the time of the solvothermal reaction is 12h~36h, and the drying temperature is 50℃~70℃.

[0014] In step S3, the calcination is carried out under a nitrogen atmosphere, the heating rate during the calcination process is 5℃ / min to 10℃ / min, the calcination time is 1h to 3h, and the drying temperature is 50℃ to 70℃.

[0015] As a general technical concept, the present invention also provides an iron-doped MOFs-based carbon composite material prepared by the above-mentioned method for preparing iron-doped MOFs-based carbon composite materials.

[0016] Preferably, the iron-doped MOFs-based carbon composite material includes a sulfonic acid-based metal-organic framework, on which ferric oxide is loaded, and the iron-doped MOFs-based carbon composite material has a hollow octahedral three-dimensional structure.

[0017] As a general technical concept, the present invention also provides the application of the above-mentioned iron-doped MOFs-based carbon composite material in the treatment of antibiotic wastewater or the preparation of hydrogen peroxide.

[0018] In the above-mentioned application, preferably, when the iron-doped MOFs-based carbon composite material is used to treat antibiotic wastewater, the following steps are included: mixing the iron-doped MOFs-based carbon composite material and antibiotic wastewater, and carrying out an electro-Fenton reaction to complete the degradation of antibiotics in the water.

[0019] When the iron-doped MOFs-based carbon composite material is used to prepare hydrogen peroxide, the following steps are included: mixing the iron-doped MOFs-based carbon composite material with water and performing an electro-Fenton reaction to obtain hydrogen peroxide.

[0020] In the above-described application, preferably, when the iron-doped MOFs-based carbon composite material is used to treat antibiotic wastewater, the electro-Fenton reaction process further includes adding an electrolyte to the reaction system, such that the concentration of the electrolyte in the reaction system is 0.05 mol / L to 0.1 mol / L, and the electrolyte is sodium sulfate; the mass ratio of the iron-doped MOFs-based carbon composite material to the antibiotics in the antibiotic wastewater is 5 to 40:1, the initial concentration of the antibiotics in the antibiotic wastewater is 5 mg / L to 30 mg / L, and the antibiotics in the antibiotic wastewater are at least one of ciprofloxacin, tetracycline, and oxytetracycline. The pH value of the antibiotic wastewater is ≤9; the electro-Fenton reaction process also includes aeration by introducing air into the reaction system, and the aeration rate of the air is 0.1L / min to 1L / min; the two-electrode system constructed in the electro-Fenton reaction process is: a carbon felt electrode as the cathode and a platinum mesh electrode as the anode; the cathode current is controlled at 50mA to 300mA in the electro-Fenton reaction process; the electro-Fenton reaction is carried out under stirring conditions, the stirring speed is 200r / min to 1000r / min, and the electro-Fenton reaction time is 30min to 120min.

[0021] In the above-described application, preferably, when the iron-doped MOFs-based carbon composite material is used to prepare hydrogen peroxide, the electro-Fenton reaction process further includes adding an electrolyte to the reaction system, such that the concentration of the electrolyte in the reaction system is 0.05 mol / L to 0.1 mol / L, and the electrolyte is sodium sulfate; the initial concentration of the iron-doped MOFs-based carbon composite material in the reaction system of the electro-Fenton reaction is 50 mg / L to 300 mg / L; the electro-Fenton reaction process further includes aeration by introducing air into the reaction system, and the aeration rate of the air is 0.1 L / min to 1 L / min; the two-electrode system constructed in the electro-Fenton reaction process is: a carbon felt electrode as the cathode and a platinum mesh electrode as the anode; the cathode current is controlled at 50 mA to 300 mA in the electro-Fenton reaction process; the electro-Fenton reaction is carried out under stirring conditions, the stirring speed is 200 r / min to 1000 r / min, and the electro-Fenton reaction time is 30 min to 120 min.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] (1) This invention provides a method for preparing iron-doped MOFs-based carbon composite materials. First, sulfonic acid-based metal-organic frameworks are prepared using zirconium salt and sulfonic acid-based organic ligands as raw materials. Then, the sulfonic acid-based metal-organic framework and iron salt are mixed and calcined at high temperature (≥650℃) to obtain the iron-doped MOFs-based carbon composite material. In this preparation method, the sulfonic acid-based organic ligands, as organic ligands, contain multiple potential oxygen atom coordination sites. During calcination, a porous carbon structure is easily formed, generating a large number of active sites. Simultaneously, the iron metal centers are transformed into metal nanoparticles embedded in the porous carbon structure, greatly reducing metal agglomeration and facilitating interfacial electron transfer to promote Fe. 2+ The resulting composite material, obtained through regeneration, exhibits a uniform distribution of iron-doped carbon particles and is rich in FeC. x The active sites facilitate the activation of free radicals, thereby promoting the degradation of antibiotics. The preparation method of this invention has advantages such as mild reaction conditions, simple process flow, environmental friendliness, low energy consumption, and low cost.

[0024] (2) This invention also provides an iron-doped MOFs-based carbon composite material with high catalytic activity, good stability, and exhibits a low metal ion leaching rate (iron ion concentration in solution <1.000 ug·L after 90 min of reaction). -1 ) and low energy consumption (4.39 kWh·kg -1 TOC -1 It is green and environmentally friendly, suitable for large-scale preparation, and of great significance for industrial promotion.

[0025] (3) This invention also provides an application of iron-doped MOFs-based carbon composite material in the treatment of antibiotic wastewater or the preparation of hydrogen peroxide. It can not only effectively degrade organic pollutants, but also significantly increase the yield of hydrogen peroxide. It has high use value and good application prospects. When iron-doped MOFs-based carbon composite material is used to treat antibiotic wastewater, it has good dispersibility and can be uniformly dispersed in the wastewater to be treated. This facilitates full contact with the antibiotics to be treated, thereby improving the degradation efficiency. For example, the degradation efficiency of tetracycline is as high as 90.10%. At the same time, the iron-doped MOFs-based carbon composite material of this invention has good stability and can be recycled and reused through simple filtration (it can still achieve a tetracycline degradation rate of 84.66% after eight cycles). It has the advantages of simple operation, low material consumption, and short cycle. It can react at room temperature and has good anti-interference ability. It can be applied to different actual water environments and has high use value and application prospects in antibiotic wastewater treatment. The iron-doped MOFs-based carbon composite material of the present invention can undergo a two-electron redox reaction to produce H2O2 without any additives, and then generate hydroxyl radicals, as shown in formulas (1), (2), and (3). It can also accelerate the reaction of Fe. 2+ The regeneration of iron source is maintained, as shown in formula (4); moreover, as the reaction proceeds, highly active singlet oxygen can be generated, as shown in formulas (5) and (6). These free radicals participate in the oxidative degradation of tetracycline, effectively enhancing the electro-Fenton catalytic activity of the composite electro-Fenton material, as shown in formulas (7) and (8).

[0026] O2 + 2H + +2e - →H2O2 (1)

[0027] Fe 2+ +H₂O₂→Fe 3+ +·OH+OH - (2)

[0028] Fe 2+ +H₂O₂ + H + →Fe 3+ +·OH+H2O (3)

[0029] Fe 3+ +2e - →Fe 2+ (4)

[0030] 2·OH + 2·OH → 2H₂O + 1 O2 (5)

[0031] ·OH+·O2H→H2O+ 1 O2 (6)

[0032] ·OH+TC→Deincubation product(7)

[0033] 1 O2 + TC → Degradation products (8) Attached Figure Description

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0035] Figure 1 This is a SEM image of UiO-66-SO3H / Fe(1∶0.76)-800 in Example 2 of the present invention.

[0036] Figure 2 This is a TEM image of UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 of the present invention.

[0037] Figure 3 This is the XPS diagram of Fe 2p in UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 of the present invention.

[0038] Figure 4 The images show the FTIR spectra of UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 and UiO-66-SO3H-800 in Comparative Example 1.

[0039] Figure 5 The graph shows the degradation effect of UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 on tetracycline in Example 5 of this invention.

[0040] Figure 6 This is a comparison chart of the degradation rates of tetracycline by UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 in Example 5 of the present invention.

[0041] Figure 7The degradation effect of UiO-66-SO3H / Fe(1:0.76)-700, UiO-66-SO3H / Fe(1:0.76)-800, and UiO-66-SO3H / Fe(1:0.76)-900 on tetracycline in Example 5 of this invention.

[0042] Figure 8 The graph shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different applied current intensities in Example 6 of this invention.

[0043] Figure 9 The graph shows the yield of hydrogen peroxide synthesized by UiO-66-SO3H / Fe(1:0.76)-800 under different applied current intensities in Example 7 of this invention.

[0044] Figure 10 The image shows the degradation effect of different concentrations of tetracycline treated with UiO-66-SO3H / Fe(1:0.76)-800 in Example 8 of this invention.

[0045] Figure 11 The graph shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different pH conditions in Example 9 of this invention.

[0046] Figure 12 The graph shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different water conditions in Example 10 of this invention.

[0047] Figure 13 The graph shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different interfering conditions in Example 11 of this invention. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0049] Example 1:

[0050] A method for preparing an iron-doped MOFs-based carbon composite material according to the present invention includes the following steps:

[0051] S1. Weigh 1 mmol of zirconium chloride (ZrCl4) and 1 mmol of monosodium 2-sulfonic terephthalate (H2BDC-SO3Na) and place them in a polytetrafluoroethylene liner. Add a mixed solvent of N,N-dimethylformamide and acetic acid, which is prepared by mixing 40 mL of N,N-dimethylformamide and 4.43 mL of acetic acid. Stir at 450 r / min for 30 min to obtain a homogeneous mixed solution. Solvothermically react the mixed solution at 120 °C for 40 h. After cooling to room temperature, filter and dry the filtered product at 60 °C to obtain the UiO-66-SO3H precursor.

[0052] In this step, the organic solvent used is a mixture of N,N-dimethylformamide and acetic acid. The acetic acid removes the Na+ ligand from the 2-sulfonic acid terephthalic acid monosodium salt ligand. + With the H provided by acetic acid + Complete exchange leads to the formation of sulfonic acid functional groups (-SO3H).

[0053] S2. Weigh 0.21g of UiO-66-SO3H and 0.08g of FeCl3·6H2O obtained in step S1 and place them in a polytetrafluoroethylene liner. Measure 16mL of acetonitrile and pour it into the liner. Stir at 450r / min for 30min to obtain a homogeneous mixed solution. Solvothermal react the mixed solution at 100℃ for 24h. After cooling to room temperature, filter and dry the filtered product at 60℃ to obtain the UiO-66-SO3H / Fe precursor.

[0054] S3. Place the UiO-66-SO3H / Fe precursor obtained in step S2 in a quartz boat, and calcine it at 800℃ for 2 hours under nitrogen conditions at a rate of 5℃ / min. After washing, dry it overnight under vacuum at 60℃ to obtain an iron-doped MOFs-based carbon composite material, denoted as UiO-66-SO3H / Fe(1:0.38)-800.

[0055] The iron-doped MOFs-based carbon composite material prepared in this embodiment includes a sulfonic acid-based metal-organic framework, on which ferric oxide is loaded.

[0056] The iron-doped MOFs-based carbon composite material prepared in this embodiment has a hollow octahedral three-dimensional structure.

[0057] Example 2:

[0058] The preparation method of the iron-doped MOFs-based carbon composite material of the present invention is basically the same as the preparation method of the iron-doped MOFs-based carbon composite material in Example 1, except that: in step S2, the amount of FeCl3·6H2O is 0.16g; the iron-doped MOFs-based carbon composite material obtained therefrom is denoted as UiO-66-SO3H / Fe(1:0.76)-800.

[0059] Figure 1 This is a SEM image of UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 of the present invention. From... Figure 1 As can be seen from the above, the iron-doped MOFs-based carbon composite material prepared by this invention exhibits a porous, hollow octahedral three-dimensional structure with a particle size of 200 nm and a rough surface.

[0060] Figure 2 This is a TEM image of UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 of the present invention. From... Figure 2 It can be seen that UiO-66-SO3H / Fe(1:0.76)-800 exhibits relatively clear lattice fringes with fringe spacing of 0.265 nm and 0.184 nm, corresponding to the (116) plane of Fe2O3 and the (220) plane of ZrO2, respectively. Such a compact structure is beneficial to reducing the leaching of metal ions. At the same time, it also shows that Fe2O3 and UiO-66-SO3H are tightly doped together, which proves the successful composite of the two materials.

[0061] Figure 3 This is the XPS plot of Fe 2p in UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 of this invention. From... Figure 3 It can be seen that the two peaks at 712.22 eV and 725.72 eV correspond to Fe 2p, respectively. 3 / 2 and Fe 2p 1 / 2 Fe 2p 3 / 2 711.68 eV and Fe 2p 1 / 2 The 724.97 eV peak is attributed to Fe. 2+ Fe 2p 3 / 2 713.80 eV and Fe 2p 1 / 2 The 727.35 eV peak is attributed to Fe. 3+ Satellite peaks appear at 719.86 eV and 733.68 eV, which may be due to Fe. 3+ Fingerprints.

[0062] In this embodiment, iron-doped MOFs-based carbon composite materials with different calcination temperatures were also prepared. The preparation method was basically the same as that of the iron-doped MOFs-based carbon composite material (UiO-66-SO3H / Fe(1:0.76)-800) in Example 2, except that in step S3, the calcination temperatures were 700℃ and 900℃, respectively; the iron-doped MOFs-based carbon composite materials obtained were denoted as UiO-66-SO3H / Fe(1:0.76)-700 and UiO-66-SO3H / Fe(1:0.76)-900, respectively.

[0063] Example 3:

[0064] The preparation method of the iron-doped MOFs-based carbon composite material of the present invention is basically the same as the preparation method of the iron-doped MOFs-based carbon composite material in Example 1, except that: in step S2, the amount of FeCl3·6H2O is 0.32g; the iron-doped MOFs-based carbon composite material obtained therefrom is denoted as UiO-66-SO3H / Fe(1:1.52)-800.

[0065] Example 4:

[0066] The preparation method of the iron-doped MOFs-based carbon composite material of the present invention is basically the same as the preparation method of the iron-doped MOFs-based carbon composite material in Example 1, except that: in step S2, the amount of FeCl3·6H2O is 0.48g; the iron-doped MOFs-based carbon composite material obtained therefrom is denoted as UiO-66-SO3H / Fe(1:2.28)-800.

[0067] Comparative Example 1:

[0068] A method for preparing a sulfonic acid-based metal-organic framework-derived electro-Fenton catalytic material includes the following steps:

[0069] Weigh out 1 mmol ZrCl4 and 1 mmol H2BDC-SO3Na and mix them. Add a mixed solvent of N,N-dimethylformamide and acetic acid, which is composed of 40 mL N,N-dimethylformamide and 4.43 mL acetic acid. Solvothermal reaction at 120 °C for 40 h, filter and dry to obtain white UiO-66-SO3H. Place UiO-66-SO3H in a quartz boat and calcine at 800 °C for 2 h under nitrogen at a rate of 5 °C / min. Wash and dry overnight under vacuum at 60 °C to obtain an Fe-free sulfonic acid-based metal-organic framework derivative electro-Fenton catalytic material, denoted as UiO-66-SO3H-800.

[0070] Figure 4These are the FTIR spectra of UiO-66-SO3H / Fe(1:0.76)-800 in Example 2 and UiO-66-SO3H-800 in Comparative Example 1. From... Figure 4 It can be seen that the corresponding FTIR spectrum shows Zr-O stretching vibration (738 cm⁻¹). -1 C=O vibration (1632cm) -1 ), OH stretching (3446cm) -1 Two different catalysts were used at 1026 and 1116 cm⁻¹, respectively. -1 The peak value appears at [value], which is due to the -SO3H group of H2BDC-SO3Na. This result indicates that Na in the H2BDC-SO3Na ligand [values ​​are missing]. + With H + In-situ exchange was performed while maintaining its molecular structure. Furthermore, UiO-66-SO3H / Fe(1:0.76)-800 exhibits the aforementioned peaks, and also shows a peak at 562 cm⁻¹. -1 A new peak was added nearby, which can be attributed to the Fe-O vibration, further confirming that Fe2O3 successfully bound to the oxygen-containing functional group on UiO-66-SO3H.

[0071] Example 5:

[0072] The application of the iron-doped MOFs-based carbon composite material of the present invention in the treatment of antibiotic wastewater includes the following steps:

[0073] According to the mass ratio of iron-doped MOFs-based carbon composite material to tetracycline in tetracycline solution of 10:1, the following solutions were used: UiO-66-SO3H / Fe(1:0.38)-800 prepared in Example 1, UiO-66-SO3H / Fe(1:0.76)-700, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:0.76)-900 prepared in Example 2, UiO-66-SO3H / Fe(1:1.52)-800 prepared in Example 3, and UiO-66-SO3H / Fe(1:0.76)-900 prepared in Example 4. 2.28)-800 and UiO-66-SO3H-800 prepared in Comparative Example 1 were added to tetracycline solutions with an initial concentration of 10 mg / L and a pH of 5.56, respectively. Sodium sulfate was also added to each solution to bring the sodium sulfate concentration in the reaction system to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode current was controlled at 200 mA during the electro-Fenton catalytic reaction. The electro-Fenton catalytic reaction was carried out at 450 r / min for 90 min to complete the degradation of tetracycline in the water. After the reaction was completed, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0074] Blank group: No catalyst added, all other conditions are the same.

[0075] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of different catalytic materials for tetracycline in water was calculated, and the results are as follows: Figure 5 , 6 As shown.

[0076] Figure 5 This image shows the degradation effect of UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 on tetracycline in Example 5 of this invention. (From...) Figure 5It can be seen that after 90 min of electro-Fenton reaction, the removal rates of tetracycline by UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 were 87.63%, 90.10%, 88.03%, 85.92%, and 71.19%, respectively, while the removal rate of the blank group was 13.54%. It is evident that, compared to the blank group and the Fe-free sulfonic acid-based metal-organic framework derivative electro-Fenton catalytic material, the iron-doped MOFs-based carbon composite material of this invention significantly improves the degradation efficiency of tetracycline, and UiO-66-SO3H / Fe(1:0.76)-800 exhibits the best degradation effect on tetracycline.

[0077] Figure 6 This is a comparison chart of the degradation rates of tetracycline by UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 in Example 5 of the present invention. From... Figure 6 It can be seen that the degradation of tetracycline by UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, UiO-66-SO3H / Fe(1:2.28)-800, and UiO-66-SO3H-800 follows pseudo-first-order kinetics, and the corresponding kinetic constant k values ​​are in the following order: UiO-66-SO3H / Fe(1:0.76)-800 (0.0305 min... -1 )>UiO-66-SO3H / Fe(1:1.52)-800(0.0272 min -1 )>UiO-66-SO3H / Fe(1:0.38)-800(0.0264 min -1 )>UiO-66-SO3H / Fe(1:2.28)-800(0.0251 min -1 )>UiO-66-SO3H-800(0.0160min -1 > Blank (without catalyst) > (0.0018 min) -1Within the content range defined in this invention, UiO-66-SO3H / Fe(1:0.38)-800, UiO-66-SO3H / Fe(1:0.76)-800, UiO-66-SO3H / Fe(1:1.52)-800, and UiO-66-SO3H / Fe(1:2.28)-800 can all achieve good degradation effects on tetracycline.

[0078] Figure 7 The degradation effect of UiO-66-SO3H / Fe(1:0.76)-700, UiO-66-SO3H / Fe(1:0.76)-800, and UiO-66-SO3H / Fe(1:0.76)-900 on tetracycline in Example 5 of this invention is shown in the graph. Figure 7 It can be seen that the iron-doped MOFs-based carbon composite materials calcined under different temperature conditions exhibited different tetracycline degradation efficiencies, indicating that temperature has a certain impact on material properties. At excessively low temperatures, the reaction between FeCl3·6H2O and the carbon layer in the sulfonic acid-based metal-organic framework is localized or incomplete; at excessively high temperatures, FeCl3·6H2O is decomposed before it can effectively react with the carbon layer in the sulfonic acid-based metal-organic framework. Therefore, the iron-doped MOFs-based carbon composite material exhibits the best performance under high-temperature calcination at 800℃, with the FeCl3·6H2O content being optimal. x The increase in active sites is beneficial for promoting the generation of hydrogen peroxide near the cathode in the electro-Fenton reaction system and the generation of hydroxyl radicals during the Fenton reaction.

[0079] Example 6:

[0080] The degradation efficiency of tetracycline by the iron-doped MOFs-based carbon composite material of the present invention under different applied current intensities was investigated. Specifically, the tetracycline solution was treated with UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2, including the following steps:

[0081] Five portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were added to tetracycline solutions with an initial concentration of 10 mg / L and a pH of 5.56, according to a mass ratio of 10:1 for iron-doped MOFs-based carbon composite material and tetracycline in the solution. Sodium sulfate was added to each solution to bring the sodium sulfate concentration in the reaction system to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode currents were controlled at 50 mA, 100 mA, 150 mA, 200 mA, and 300 mA during the electro-Fenton catalytic reaction in the five experimental groups. The electro-Fenton catalytic reaction was carried out at 450 r / min for 90 min to complete the degradation of tetracycline in the water. After the reaction, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0082] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of the catalytic material for tetracycline in water under different applied current intensities was calculated. The results are as follows: Figure 8 As shown.

[0083] Figure 8 This image shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different applied current intensities in Example 6 of this invention. From... Figure 8 It can be seen that when the cathode current is 50mA, 100mA, 150mA, 200mA, and 300mA, the removal rates of tetracycline by UiO-66-SO3H / Fe(1:0.76)-800 are 70.53%, 77.61%, 83.76%, 90.10%, and 91.56%, respectively.

[0084] Example 7:

[0085] The hydrogen peroxide yield of the iron-doped MOFs-based carbon composite material of the present invention was investigated under different applied current intensities. Specifically, the hydrogen peroxide yield was measured using UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2, including the following steps:

[0086] Five portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were taken with an initial catalyst concentration of 100 mg / L and added to pure water, along with sodium sulfate, to achieve a sodium sulfate concentration of 0.05 mol / L in the reaction system. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system to conduct an electro-Fenton catalytic reaction. During the electro-Fenton catalytic reaction, the cathode control currents for the five experimental groups were 50 mA, 100 mA, 150 mA, 200 mA, and 300 mA, respectively, and the air aeration rate was 0.5 L / min. The electro-Fenton catalytic reaction was carried out at a rotation speed of 450 r / min for 90 min to obtain hydrogen peroxide. The concentration of hydrogen peroxide was measured by sampling, and the effect of different current intensities on the hydrogen peroxide yield was calculated. The results are as follows: Figure 9 As shown.

[0087] Figure 9 This is a graph showing the yield of hydrogen peroxide synthesized from UiO-66-SO3H / Fe(1:0.76)-800 under different applied current intensities in Example 7 of this invention. From... Figure 9 It can be seen that when the current density increases to 200 mA, UiO-66-SO3H / Fe(1:0.76)-800 exhibits a large amount of H2O2 generation, that is, the amount of H2O2 generated within 90 min reaches 147.0 × 10⁻⁶. -4 M; and at current densities of 50mA, 100mA, 150mA, and 300mA, the amount of H2O2 generated in the four electro-Fenton systems within 90 minutes was 29.2 × 10⁻⁶. -4 M, 61.9×10 -4 M, 100.4×10 -4 M, 147.4×10 -4 M, where the increase in H2O2 production is negligible when the current increases to 300mA. The iron-doped MOFs-based carbon composite material of this invention contains FeC... x The active sites of the species can effectively promote electron transfer in the reaction system, thereby promoting the generation of hydrogen peroxide in the system.

[0088] Example 8:

[0089] The degradation efficiency of the iron-doped MOFs-based carbon composite material of the present invention in treating tetracycline solutions of different concentrations was investigated, including the following steps:

[0090] Four portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were added to tetracycline solutions with initial concentrations of 5 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L, respectively, according to a mass ratio of 10:1. The pH of each tetracycline solution was 5.56. Sodium sulfate was added to each solution to bring the concentration of sodium sulfate in the reaction system to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode current was controlled at 200 mA during the electro-Fenton catalytic reaction. The electro-Fenton catalytic reaction was carried out at 450 r / min for 90 min to complete the degradation of tetracycline in the water. After the reaction, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0091] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of the catalytic material for tetracycline in water was calculated, and the results are as follows: Figure 10 As shown.

[0092] Figure 10 This image shows the degradation effect of different concentrations of tetracycline treated with UiO-66-SO3H / Fe(1:0.76)-800 in Example 8 of this invention. (From...) Figure 10 It can be seen that when the tetracycline concentration is 5 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L, the removal rates of tetracycline by UiO-66-SO3H / Fe(1:0.76)-800 are 92.40%, 90.10%, 83.29%, and 78.83%, respectively. This is because as the tetracycline concentration increases, more tetracycline competes for the active sites of the catalyst, and the catalytic sites reach saturation. At the same time, some intermediates are generated during the degradation of tetracycline, and the generated intermediates also compete with tetracycline for the active sites of the catalyst, thereby causing a decrease in catalytic efficiency.

[0093] Example 9:

[0094] The effect of the iron-doped MOFs-based carbon composite material of the present invention on the degradation efficiency of tetracycline under different pH conditions was investigated, including the following steps:

[0095] Five portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were added to tetracycline solutions with an initial concentration of 10 mg / L, based on a mass ratio of 10:1. The pH values ​​of these solutions were 3, 5, 5.56 (equivalent to natural conditions), 7, and 9, respectively. Sodium sulfate was added to each solution to bring the concentration to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode current was controlled at 200 mA during the electro-Fenton catalytic reaction. The electro-Fenton catalytic reaction was carried out at 450 r / min for 90 min to complete the degradation of tetracycline in the water. After the reaction, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0096] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of the catalytic material for tetracycline in water under different pH conditions was calculated. The results are as follows: Figure 11 As shown.

[0097] Figure 11 This is a graph showing the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different pH conditions in Example 9 of this invention. From... Figure 11 It can be seen that at pH values ​​of 3, 5, 5.56, 7, and 9, the removal rates of tetracycline by UiO-66-SO3H / Fe(1:0.76)-800 were 76.34%, 88.81%, 90.10%, 90.30%, and 89.07%, respectively. This indicates that the UiO-66-SO3H / Fe(1:0.76)-800 / HEF system exhibits excellent catalytic performance and stability over a wide pH range. This is because the system can promote the two-electron reduction reaction to degrade tetracycline under all pH conditions, thus ensuring excellent catalytic performance.

[0098] Example 10:

[0099] The effect of the iron-doped MOFs-based carbon composite material of the present invention on the degradation efficiency of tetracycline under different water conditions was investigated, including the following steps:

[0100] Four portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were added to tetracycline solutions with an initial concentration of 10 mg / L and a pH of 5.56. These solutions were prepared by dissolving tetracycline in distilled water, tap water, river water, and lake water, respectively. Sodium sulfate was added to each solution to bring the concentration of sodium sulfate in the reaction system to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode current was controlled at 200 mA during the electro-Fenton catalytic reaction. The electro-Fenton catalytic reaction was carried out at 450 r / min for 90 min to complete the degradation of tetracycline in the water. After the reaction, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0101] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of the catalytic material for tetracycline in water under different water conditions was calculated. The results are as follows: Figure 12 As shown.

[0102] Figure 12 This image shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different water conditions in Example 10 of this invention. Figure 12 It can be seen that when the water body is distilled water, tap water, river water, and lake water, the removal rates of tetracycline by UiO-66-SO3H / Fe(1:0.76)-800 are 90.10%, 83.67%, 81.82%, and 81.37%, respectively. This indicates that the iron-doped MOFs-based carbon composite material of the present invention exhibits high degradation performance for tetracycline in different water environments. However, the degradation performance of the iron-doped MOFs-based carbon composite material for tetracycline in the three actual water bodies is lower than that in distilled water. This may be because there are some interfering substances such as inorganic ions and organic matter in the actual water bodies. During the reaction, these interfering substances adhere to the catalyst material, causing some catalysts to fail to effectively contact tetracycline, thereby reducing the degradation effect of tetracycline. In summary, the iron-doped MOFs-based carbon composite material of the present invention can achieve satisfactory results in treating various real water matrices and can be widely used to treat tetracycline in different water environments, showing good practical application prospects in the field of electro-Fenton chromatography.

[0103] Example 11:

[0104] The effect of the iron-doped MOFs-based carbon composite material of the present invention on the degradation efficiency of tetracycline under different interfering conditions was investigated, including the following steps:

[0105] Five portions of UiO-66-SO3H / Fe(1:0.76)-800 prepared in Example 2 were taken according to a mass ratio of 10:1 between the iron-doped MOFs-based carbon composite material and tetracycline in the tetracycline solution. These were then added to a solution containing 10 mM Cl. - 10mM H2PO4 - 10mMNO3 - In a tetracycline solution containing 10 mM HA (initial concentration 10 mg / L, pH 5.56), sodium sulfate was added to bring the sodium sulfate concentration in the reaction system to 0.05 mol / L. A two-electrode system was constructed using a carbon felt electrode as the cathode and a platinum mesh electrode as the anode. Air was then introduced into the reaction system at an aeration rate of 0.5 L / min. The cathode current was controlled at 200 mA during the electro-Fenton catalytic reaction. The electro-Fenton catalytic reaction was carried out at 450 rpm for 90 min to complete the degradation of tetracycline in the water. After the reaction, solid-liquid separation was performed, and the catalytic material from the above reaction process was recovered.

[0106] During the electro-Fenton catalytic reaction, samples were taken at 0 min, 10 min, 20 min, 30 min, 50 min, 70 min, and 90 min to measure the concentration of tetracycline. The degradation efficiency of the catalytic material for tetracycline in water under different interference conditions was calculated. The results are as follows: Figure 13 As shown.

[0107] Figure 13 This image shows the degradation effect of UiO-66-SO3H / Fe(1:0.76)-800 on tetracycline under different interfering conditions in Example 11 of this invention. (From...) Figure 13 It can be seen that when tetracycline solution contains Cl - H2PO4 - NO3 - When combined with HA, UiO-66-SO3H / Fe(1:0.76)-800 achieved tetracycline removal rates of 99.8%, 75.2%, 87.6%, and 88.6%, respectively, all exhibiting highly efficient electro-Fenton catalytic performance. This indicates that the iron-doped MOFs-based carbon composite material of the present invention has strong anti-interference ability, further demonstrating that the iron-doped MOFs-based carbon composite material of the present invention has good practical application prospects.

[0108] In summary, the application of the iron-doped MOFs-based carbon composite material of the present invention in the electro-Fenton degradation of antibiotic wastewater has the advantages of simple operation steps, economic and environmental protection, high degradation efficiency and strong practical wastewater application capability, and has good practical application prospects.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing an iron-doped MOF-based carbon composite material, characterized in that, Includes the following steps: S1. Zirconium salt and sulfonic acid organic ligand are mixed, and a mixed solvent of N,N-dimethylformamide and acetic acid is added. The mixture is subjected to a solvothermal reaction, filtered, and dried to obtain the UiO-66-SO3H precursor. S2. Mix the UiO-66-SO3H precursor obtained in step S1 with iron salt, add organic solvent, carry out solvothermal reaction, filter, and dry to obtain UiO-66-SO3H / Fe precursor. S3. The UiO-66-SO3H / Fe precursor obtained in step S2 is calcined at a temperature ≥650℃, washed, and dried to obtain an iron-doped MOFs-based carbon composite material. The iron-doped MOFs-based carbon composite material includes a sulfonic acid-based metal-organic framework, on which ferric oxide is loaded, and the iron-doped MOFs-based carbon composite material has a hollow octahedral three-dimensional structure.

2. The method for preparing iron-doped MOFs-based carbon composite materials according to claim 1, characterized in that, In step S3, the calcination temperature is 700℃~900℃.

3. The method for preparing iron-doped MOFs-based carbon composite materials according to claim 1, characterized in that, In step S2, the mass ratio of the UiO-66-SO3H precursor to the iron salt is 1:0.38 to 2.28, and the iron salt is at least one of ferric chloride, ferric nitrate, and ferric sulfate.

4. The method for preparing the iron-doped MOFs-based carbon composite material according to any one of claims 1 to 3, characterized in that, In step S1, the molar ratio of the zirconium salt to the sulfonic acid organic ligand is 1:1 to 2. The zirconium salt is at least one of calcium chloride, zirconium oxide, and zirconium oxychloride octahydrate. The sulfonic acid organic ligand is at least one of monosodium 2-sulfonic acid terephthalate, 2,6-dicarboxy-4,8-dinaphthalenesulfonic acid, and 1,3,5-benzenetrisulfonyl chloride. The volume ratio of N,N-dimethylformamide to acetic acid in the mixed solvent of N,N-dimethylformamide and acetic acid is 8 to 10:

1. The temperature of the solvothermal reaction is 80°C to 140°C. The time of the solvothermal reaction is 24 h to 40 h. The drying temperature is 50°C to 70°C.

5. The method for preparing iron-doped MOFs-based carbon composite materials according to any one of claims 1 to 3, characterized in that, In step S2, the organic solvent is acetonitrile, the temperature of the solvothermal reaction is 80℃~120℃, the time of the solvothermal reaction is 12h~36h, and the drying temperature is 50℃~70℃. In step S3, the calcination is carried out under a nitrogen atmosphere, the heating rate during the calcination process is 5℃ / min to 10℃ / min, the calcination time is 1h to 3h, and the drying temperature is 50℃ to 70℃.

6. An iron-doped MOFs-based carbon composite material prepared by the method described in any one of claims 1 to 5.

7. The application of the iron-doped MOFs-based carbon composite material as described in claim 6 in the treatment of antibiotic wastewater or the preparation of hydrogen peroxide.

8. The application according to claim 7, characterized in that, When the iron-doped MOFs-based carbon composite material is used to treat antibiotic wastewater... The process includes the following steps: mixing iron-doped MOFs-based carbon composite materials with antibiotic wastewater and performing an electro-Fenton reaction to degrade the antibiotics in the water. When the iron-doped MOFs-based carbon composite material is used to prepare hydrogen peroxide... The process includes the following steps: mixing iron-doped MOFs-based carbon composite materials with water and performing an electro-Fenton reaction to obtain hydrogen peroxide.

9. The application according to claim 8, characterized in that, When the iron-doped MOFs-based carbon composite material is used to treat antibiotic wastewater, the electro-Fenton reaction process further includes adding an electrolyte to the reaction system, making the electrolyte concentration in the reaction system 0.05 mol / L to 0.1 mol / L, wherein the electrolyte is sodium sulfate; the mass ratio of the iron-doped MOFs-based carbon composite material to the antibiotics in the antibiotic wastewater is 5 to 40:1, the initial concentration of the antibiotics in the antibiotic wastewater is 5 mg / L to 30 mg / L, the antibiotics in the antibiotic wastewater are at least one of ciprofloxacin, tetracycline, and oxytetracycline, and the pH value of the antibiotic wastewater is ≤9; the electro-Fenton reaction process further includes aeration by introducing air into the reaction system, wherein the air aeration rate is 0.1 L / min to 1 L / min. L / min; the two-electrode system constructed during the electro-Fenton reaction is: a carbon felt electrode as the cathode and a platinum mesh electrode as the anode; the cathode current is controlled at 50mA to 300mA during the electro-Fenton reaction; the electro-Fenton reaction is carried out under stirring conditions, the stirring speed is 200r / min to 1000r / min, and the electro-Fenton reaction time is 30min to 120min; When the iron-doped MOFs-based carbon composite material is used to prepare hydrogen peroxide, the electro-Fenton reaction process further includes adding an electrolyte to the reaction system, such that the concentration of the electrolyte in the reaction system is 0.05 mol / L to 0.1 mol / L, and the electrolyte is sodium sulfate; the initial concentration of the iron-doped MOFs-based carbon composite material in the reaction system of the electro-Fenton reaction is 50 mg / L to 300 mg / L; the electro-Fenton reaction process further includes aeration by introducing air into the reaction system, and the aeration rate of the air is 0.1 L / min to 1 L / min; the two-electrode system constructed in the electro-Fenton reaction process is: a carbon felt electrode as the cathode and a platinum mesh electrode as the anode; the cathode current is controlled at 50 mA to 300 mA in the electro-Fenton reaction process; the electro-Fenton reaction is carried out under stirring conditions, the stirring speed is 200 r / min to 1000 r / min, and the electro-Fenton reaction time is 30 min to 120 min.

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