Bi2o2co3 / mil-68-nh2 composite material and preparation method and application thereof

Abstract

The application discloses a Bi2O2CO3 / MIL-68-NH2 composite material and a preparation method and application thereof, and belongs to the technical field of photocatalytic materials and the field of water environment treatment. The composite material is formed by loading Bi2O2CO3 on the surface of MIL-68-NH2 to form a heterojunction structure; the MIL-68-NH2 is a regular hexagonal rod-shaped crystal with a length of 10-20 microns; and the Bi2O2CO3 is a sphere with a diameter of 2-3 microns, and the surface is a carnation-shaped hierarchical stacking structure and is dispersed and loaded on the surface of the MIL-68-NH2. The composite material prepared by the application has the advantages of simple preparation method, strong visible light absorption capacity, stable catalytic performance, high degradation efficiency and the like, and has a potential application prospect in the field of water treatment.

Description

Technical Field

[0001] This invention relates to the fields of photocatalytic materials technology, persulfate catalytic oxidation, and water environment treatment, and in particular to a Bi2O2CO3 / MIL-68-NH2 composite material for degrading antibiotics, its preparation method, and its application in degrading antibiotics. Background Technology

[0002] Antibiotics are widely used in livestock and poultry farming as preventative and therapeutic agents for bacterial infections and as growth promoters. Tetracycline (TC) is considered one of the most popular broad-spectrum antibiotics due to its economic benefits and significant efficacy. However, due to the low absorption rate of antibiotics by animals, large amounts of antibiotics enter the environment in the form of maternal cells or active metabolites through livestock urine and feces, causing water pollution. The large amounts of TC residues in the environment not only accumulate in the food chain, inducing serious endocrine and nervous system disorders, but also accelerate the emergence of antibiotic-resistant bacteria (ARBs) and superbugs, posing a serious threat to human health and ecosystem security. Due to the lipophilicity, bioaccumulation, and genotoxicity of antibiotics, traditional wastewater treatment technologies, such as adsorption, flocculation, sedimentation, and membrane filtration, cannot break down the molecular structure of stubborn pollutants and are difficult to effectively remove antibiotics at deep depths. Therefore, it is necessary to explore effective antibiotic elimination strategies.

[0003] Currently, advanced oxidation processes, including peroxymonosulfate (PMS) activation and photocatalysis, are efficient strategies for removing recalcitrant antibiotics from the environment. Based on sulfate radicals (SO42-), these processes... -· Persulfate-activated advanced oxidation technology (AEO) boasts advantages such as rapid reaction rate, stable properties, and easy transportation, showing promising application prospects in the field of advanced antibiotic treatment. However, its practical application is still limited by challenges such as pH dependence, complex byproduct composition, and the potential for secondary pollution from the catalyst. Photocatalysis utilizes light energy to excite semiconductors to generate electron-hole pairs, which are then used to generate reactive oxygen species (ROS) to degrade pollutants. It is a green and sustainable technology, but the rapid recombination of photogenerated charges during photocatalysis remains a challenge limiting its application. Combining persulfate with photocatalysis can promote antibiotic degradation, but research on key factors affecting its degradation efficiency remains limited. Therefore, the removal of antibiotics through the coupling of photocatalysis and persulfate oxidation is a challenging research direction. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides a Bi2O2CO3 / MIL-68-NH2 composite material, its preparation method, and its applications. The composite material prepared by this invention acts as a photocatalyst to activate persulfate under visible light irradiation, thereby degrading antibiotics. The preparation method is simple, and it possesses advantages such as strong visible light absorption capacity, stable catalytic performance, and high degradation efficiency, showing potential application prospects in the field of water treatment.

[0005] The technical solution of the present invention is as follows:

[0006] A Bi2O2CO3 / MIL-68-NH2 composite material, wherein Bi2O2CO3 is loaded onto the surface of MIL-68-NH2 to form a heterojunction structure;

[0007] The MIL-68-NH2 is a regular hexagonal rod-shaped crystal with a length of 10-20 μm; the Bi2O2CO3 is a sphere with a diameter of 2-3 μm and a carnation-shaped layered stacked structure on the surface of the MIL-68-NH2.

[0008] The present invention also provides a method for preparing the Bi2O2CO3 / MIL-68-NH2 composite material, comprising the following steps:

[0009] (1) Preparation of MIL-68-NH2:

[0010] In(NO3)3·4H2O and 2-aminoterephthalic acid were dissolved in dimethylformamide (DMF) and ultrasonically stirred until homogeneous. The resulting homogeneous solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and heated at 110-140°C for 4-6 hours. After cooling, the resulting solid was centrifuged, washed, and dried. The resulting solid powder was MIL-68-NH2.

[0011] (2) Preparation of Bi2O2CO3 / MIL-68-NH2 composite material:

[0012] Bi(NO3)3·5H2O, C6H5Na3O7 and MIL-68-NH2 prepared in step (1) were uniformly dispersed in deionized water and ultrasonically stirred until homogeneous. The mixture was then adjusted to pH 9-10 with ammonia and magnetically stirred until homogeneous. The mixture was then transferred to a high-pressure autoclave lined with polytetrafluoroethylene and reacted at 160-200℃ for 22-24 hours. The cooled sample was centrifuged and washed with water and ethanol. After drying, the Bi2O2CO3 / MIL-68-NH2 composite material was obtained.

[0013] Preferably, in step (1), the molar ratio of In(NO3)3·4H2O to 2-aminoterephthalic acid is 3-4:1-2.

[0014] Preferably, in step (1), 6-13 mL of DMF is required as a solvent for each 1-2 mmol of In(NO3)3·4H2O added.

[0015] Preferably, in step (2), the mass ratio is Bi(NO3)3·5H2O:C6H5Na3O7:MIL-68-NH2=1-2:0.5-1:0.1-0.5.

[0016] Preferably, in step (2), the amount of deionized water used is 34-69 mL of deionized water as a solvent for every 1-2 g of Bi(NO3)3·5H2O added.

[0017] Furthermore, the concentration of the ammonia water in step (2) is 25-28 wt%.

[0018] This invention further provides the application of the Bi2O2CO3 / MIL-68-NH2 composite material, namely, the Bi2O2CO3 / MIL-68-NH2 composite material acts as a photocatalyst to activate persulfate under visible light irradiation, causing persulfate to generate sulfate radicals and singlet oxygen, thereby degrading antibiotics.

[0019] Preferably, the wavelength range of the visible light is 400-700nm, and the persulfate is permonosulfate.

[0020] Preferably, the antibiotic is tetracycline.

[0021] Preferably, the antibiotic is dissolved in the mobile phase water.

[0022] The beneficial technical effects of this invention are as follows:

[0023] 1. This invention constructs a heterojunction composite material by loading Bi₂O₂CO₃ nanoparticles onto the surface of MIL-68-NH₂ using a simple hydrothermal method. Bi₂O₂CO₃ semiconductors possess advantages such as simple composition, low toxicity, high chemical stability, and excellent photocatalytic activity, with a band gap typically around 2.7 eV. However, its low visible light response and easy recombination of photogenerated charges limit its application prospects. MIL-68-NH₂ has a band gap of approximately 2.8 eV and exhibits visible light response, but its photocatalytic activity is relatively low. Constructing a heterojunction photocatalyst from MIL-68-NH₂ and Bi₂O₂CO₃ can promote the separation of photogenerated electrons and holes, effectively overcoming the shortcomings of both materials and improving photocatalytic activity, resulting in excellent photocatalytic degradation performance of antibiotics.

[0024] 2. The heterojunction morphology obtained by this invention is a relatively rare "flowering on rods" phenomenon. Unlike conventional heterojunctions, which often have blurred interfaces and thus hinder efficient charge transport, the Bi2O2CO3 / MIL-68-NH2 heterojunction composite material of this invention balances structural stability with a large number of exposed active sites. The Bi2O2CO3 has a clear bonding interface with MIL-68-NH2, which facilitates high-speed electron transport. Simultaneously, the hexahedral rod-shaped MIL-68-NH2(In) exhibits excellent mechanical properties, is not easily bent or broken, and can be used in flowing water, especially turbulent water, greatly expanding its application range. Furthermore, the Bi2O2CO3 nanoparticles are tightly bonded to the rod-shaped MIL-68(In), further adapting to rapid water flow.

[0025] 3. The heterojunction composite material prepared by this invention is rich in oxygen vacancies. The presence of oxygen vacancies can regulate the generation of an electron-rich surface in the catalytic material, promote persulfate activation, and facilitate the induction of... 1 O2 generation enhances the non-radical selective degradation pathway, thereby improving the degradation efficiency of antibiotics.

[0026] 4. Unlike previous studies that used Na2CO3 and urea as carbon sources for synthesizing Bi2O2CO3, this invention uses trisodium citrate as a carbon source and adjusts the reaction pH to alkaline using ammonia water to hydrothermally synthesize flower-shaped Bi2O2CO3. The carnation-like layered structure has a large specific surface area, which can effectively enhance visible light absorption and pollutant contact, thus improving photocatalytic activity.

[0027] 5. This invention uses a Bi2O2CO3 / MIL-68-NH2 heterojunction composite material as a catalyst to construct an advanced oxidation system based on persulfate for the removal of antibiotics from water under visible light irradiation. The Bi2O2CO3 / MIL-68-NH2 heterojunction composite material exhibits good visible light response and charge separation ability. Photocatalytic activation of persulfate by Bi2O2CO3 / MIL-68-NH2 further enhances the degradation effect on antibiotics in water. The Bi2O2CO3 / MIL-68-NH2 heterojunction-persulfate system provided by this invention can effectively remove antibiotics from water, regardless of the presence of different anions (Cl-, H2PO4). - CO3 2- HCO3 - SO4 2- It maintains good degradation performance under coexisting conditions. The system is recyclable and reusable, and exhibits strong stability.

[0028] 6. In the Bi2O2CO3 / MIL-68-NH2 heterojunction-persulfate system provided by this invention, the heterojunction material generates electron-hole pairs after being irradiated with visible light, subsequently reacting to generate ROS to degrade pollutants; persulfate acts as an electron acceptor, capturing photogenerated electrons to activate and generate active substances for pollutant degradation. Furthermore, compared to single-component materials, the heterojunction material retains a more powerful redox energy level structure, which is beneficial for generating more active substances for antibiotic degradation in water. Therefore, the Bi2O2CO3 / MIL-68-NH2 heterojunction-persulfate system provided by this invention combines heterogeneous photocatalysis with persulfate oxidation, enhancing the removal efficiency of antibiotics in water. Attached Figure Description

[0029] Figure 1 SEM images of flower-shaped Bi2O2CO3 (a), hexahedral MIL-68-NH2 (b), and composite materials Bi2O2CO3 / MIL-68-NH2 (c) and (d) in Example 1;

[0030] Figure 2 The X-ray diffraction patterns of Bi2O2CO3, MIL-68-NH2 and Bi2O2CO3 / MIL-68-NH2 composite materials in Example 2 are shown below.

[0031] Figure 3 This is a comparison of the degradation performance of Bi2O2CO3, MIL-68-NH2, and Bi2O2CO3 / MIL-68-NH2 composite material against 10 mg / L tetracycline under visible light and 0.3 g / L PMS conditions in Test Example 1.

[0032] Figure 4 This is a comparison of the degradation performance of Bi2O2CO3 / MIL-68-NH2 under visible light and 0.3 g / L PMS conditions in Test Example 2, showing the degradation performance of different concentrations of tetracycline.

[0033] Figure 5 This is a comparison of the degradation performance of Bi2O2CO3 / MIL-68-NH2 on tetracycline solutions at different pH values ​​under visible light and 0.3 g / L PMS conditions in Test Example 3.

[0034] Figure 6 To test the effects of Bi2O2CO3 / MIL-68-NH2 on different anions (Cl-, SO42-) under visible light and 0.3 g / L PMS conditions in Example 4. 2- H2PO4 - CO3 2- HCO3 - Comparison of tetracycline degradation performance under coexistence conditions;

[0035] Figure 7 The graph shows the reusability of Bi2O2CO3 / MIL-68-NH2 in Test Example 5 under visible light and 0.3 g / L PMS conditions for the degradation of tetracycline. Detailed Implementation

[0036] Exemplary embodiments of this disclosure will now be described in more detail. While exemplary embodiments of this disclosure are shown, it should be understood that the figures and embodiments presented are only a part of the invention and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of this disclosure to those skilled in the art.

[0037] Example 1:

[0038] (1) Dissolve 1.29 mmol of 2-aminoterephthalic acid and 3.84 mmol of In(NO3)3·4H2O in 24.8 ml of DMF. After ultrasonic stirring for 20 minutes, transfer the resulting homogeneous solution to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and heat it at 125 °C for 5 hours. After naturally cooling to room temperature, collect the sample, centrifuge, wash and dry it. The resulting solid powder is MIL-68-NH2.

[0039] The surface morphology of the prepared MIL-68-NH2 is as follows Figure 1 As shown in (b), the figure shows a rod-shaped MIL-68-NH2(In) with a length of 10-20 μm and a regular and thick overall structure. Therefore, it has excellent mechanical properties, is not easy to bend or break, and can be used in mobile phase water, with a wide range of applications.

[0040] (2) 200 mg of MIL-68-NH2 was dispersed in 25 mL of deionized water to obtain a uniformly dispersed MIL-68-NH2 suspension. Then, 1.5 mmol of Bi(NO3)3·5H2O (0.73 g) and 2.25 mmol of C6H5Na3O7 (0.58 g) were added to the suspension. After stirring evenly, the mixture was adjusted to pH 9 with 25 wt% ammonia water. After stirring evenly with magnetic force, the mixture was transferred to a polytetrafluoroethylene-lined autoclave and reacted at 180 °C for 24 hours. The cooled sample was centrifuged and washed with ethanol and water. The dried sample was recorded as Bi2O2CO3 / MIL-68-NH2-200.

[0041] The surface morphology of the prepared Bi2O2CO3 / MIL-68-NH2 composite material is as follows: Figure 1 As shown in (c) and (d), the flower-like Bi2O2CO3 is as follows Figure 1 As shown in (a), Bi2O2CO3 is composed of stacked nanosheets with a size of 200-300 nm, forming a carnation-like hierarchical structure with spheres 2-3 μm in diameter. This structure has more exposed active sites, and its tortuous surface is conducive to light reflection, thereby improving light absorption. The Bi2O2CO3 spheres are firmly loaded on the surface of the MIL-68-NH2 rods, forming a "flowering on a rod" morphology.

[0042] Example 2:

[0043] Same as Example 1, except that the dosage of MIL-68-NH2 was 250 mg, and the final sample was recorded as Bi2O2CO3 / MIL-68-NH2-250, the XRD pattern of which is attached. Figure 2 As shown, the diffraction intensity of Bi2O2CO3 / MIL-68-NH2-250 at 33.6° corresponding to the (110) crystal plane is significantly higher than that of Bi2O2CO3 / MIL-68-NH2-200, indicating that the exposure of the high-energy crystal plane is beneficial to improving the efficiency of photocatalytic activation of persulfate.

[0044] Example 3:

[0045] Same as Example 1, except that the dosage of MIL-68-NH2 was 300 mg, and the final sample was recorded as Bi2O2CO3 / MIL-68-NH2-300.

[0046] Test Example 1:

[0047] The Bi2O2CO3 / MIL-68-NH2 composite material prepared in this invention was used for photocatalytic degradation of the target pollutant tetracycline, and a single carnation-shaped Bi2O2CO3 and a single hexagonal rod-shaped MIL-68-NH2 material were used as comparative experiments.

[0048] The specific operating method is as follows: The Bi2O2CO3 / MIL-68-NH2 composite material prepared in Example 2 and two comparative materials were added to 100 ml of tetracycline hydrochloride solution with an initial concentration of 10 mg / L, with an addition amount of 0.2 g / L. After reacting for 30 min under light-free conditions to reach adsorption equilibrium, the solution was irradiated with a 300 W xenon lamp with λ>420 nm to simulate visible light, and 30 mg of PMS solid powder was added simultaneously to conduct a degradation experiment on the pollutants. The concentration of the remaining tetracycline was determined by high-performance liquid chromatography, and the degradation rate was calculated.

[0049] The measurement results are as follows Figure 3 As shown, the horizontal axis represents degradation time (Time), and the vertical axis represents tetracycline degradation rate (C). t / C0), where C0 is the initial concentration of tetracycline, C t This is the real-time concentration. (From...) Figure 3 It was found that after 60 min of reaction under visible light irradiation and 30 mg persulfate, the total degradation rates of the single materials Bi2O2CO3 and MIL-68-NH2 were only 75.6% and 70.0%, respectively. Under the same conditions, the photocatalytic efficiency of the composite material Bi2O2CO3 / MIL-68-NH2 was significantly improved, with the degradation rate increasing to 100%. This indicates that the material exhibits higher photocatalytic activity after constructing a heterojunction. The construction of the heterojunction inhibited the recombination of photogenerated carriers, improved the photocatalytic activity, and promoted the migration of photogenerated carriers, which is beneficial for the persulfate to capture electrons and generate oxidative active substances, thereby effectively degrading tetracycline.

[0050] Test Example 2:

[0051] The Bi₂O₂CO₃ / MIL-68-NH₂ composite catalyst prepared in Example 2 was added to 100 ml of tetracycline hydrochloride solutions with initial concentrations of 5, 10, and 20 mg / L, respectively, at a dosage of 0.2 g / L. After reaching adsorption equilibrium under dark conditions for 30 min, the solution was irradiated with a 300 W xenon lamp (λ > 420 nm) to simulate visible light, and 30 mg of persulfate was added simultaneously to conduct a degradation experiment on the pollutant. The remaining tetracycline concentration was determined by high-performance liquid chromatography (HPLC), and the degradation rate was calculated.

[0052] The measurement results are as follows Figure 4 As shown, the horizontal axis represents degradation time (Time), and the vertical axis represents tetracycline degradation rate (C). t / C0), where C0 is the initial concentration of tetracycline, C t This is the real-time concentration. (From...) Figure 4 It can be seen that when the tetracycline concentration increases from 5 mg / L to 20 mg / L, the degradation efficiency of Bi2O2CO3 / MIL-68-NH2 decreases from 100% to 96%. This is because with the increase of tetracycline concentration, more tetracycline molecules consume the free radicals and holes of the catalyst, thereby reducing the removal efficiency of tetracycline.

[0053] Test Example 3:

[0054] The pH of the TC solution was adjusted to 3, 5, 7, 9, and 11 using H2SO4 and NaOH, respectively. The Bi2O2CO3 / MIL-68-NH2 composite catalyst prepared in Example 2 was added to 100 ml of tetracycline hydrochloride solution with an initial concentration of 10 mg / L, at a dosage of 0.2 g / L. After reaching adsorption equilibrium under dark conditions for 30 min, the solution was irradiated with a 300W xenon lamp (λ>420 nm) to simulate visible light, while 30 mg of persulfate was added. The degradation of the pollutant was then investigated, and the remaining tetracycline concentration was determined using high-performance liquid chromatography (HPLC), and the degradation rate was calculated.

[0055] The measurement results are as follows Figure 5 As shown, the horizontal axis represents degradation time (Time), and the vertical axis represents tetracycline degradation rate (C). t / C0), where C0 is the initial concentration of tetracycline, C t This is the real-time concentration. (From...) Figure 5 It can be seen that the optimal degradation pH for Bi2O2CO3 / MIL-68-NH2 is between 5 and 9. When the degradation solution is acidic, especially at pH=3, the degradation rate drops to 85.2%. This is due to the free radical O2 excited by the photocatalyst under acidic conditions. - Easily H + Consumption leads to a decrease in the concentration of reactive oxygen species and a reduction in photocatalytic degradation efficiency.

[0056] Test Example 4:

[0057] The Bi2O2CO3 / MIL-68-NH2 composite catalyst prepared in Example 2 was added to a solution containing 10 mM Cl. - SO4 2- H2PO4 - CO3 2- HCO3 - In a 10 mg / L tetracycline hydrochloride solution containing anions, the dosage was 0.2 g / L. After reacting for 30 min under dark conditions to reach adsorption equilibrium, the solution was irradiated with a 300W xenon lamp (λ>420 nm) to simulate visible light, while 30 mg of persulfate was added. The degradation experiment was then conducted on the pollutant. The concentration of the remaining tetracycline was determined by high-performance liquid chromatography (HPLC), and the degradation rate was calculated.

[0058] The measurement results are as follows Figure 6 As shown, the horizontal axis represents degradation time (Time), and the vertical axis represents tetracycline degradation rate (C). t / C0), where C0 is the initial concentration of tetracycline, C t This is the real-time concentration. (From...) Figure 6 It can be seen that C1 - SO4 2- H2PO4 -The degradation efficiency of Bi2O2CO3 / MIL-68-NH2 inhibited by tetracycline decreased from 100% to 95.6%, 93.7%, and 87.3%, respectively. 2- HCO3 - The degradation efficiency of tetracycline was improved, which may be due to the increased reaction rate caused by the increase in the pH of the reaction solution.

[0059] Test Example 5:

[0060] The Bi₂O₂CO₃ / MIL-68-NH₂ composite catalyst prepared in Example 2 was added to 100 ml of tetracycline hydrochloride solution with an initial concentration of 10 mg / L, at a dosage of 0.2 g / L. After reaching adsorption equilibrium under dark conditions for 30 min, the solution was irradiated with a 300 W xenon lamp (λ > 420 nm) to simulate visible light, while 30 mg of PMS was added simultaneously. The pollutant degradation experiment was then conducted, with each cycle consisting of 90 min of dark adsorption followed by light reaction. After one cycle, the reaction solution was centrifuged and dried to collect the catalyst for the next cycle. The remaining tetracycline concentration was determined using high-performance liquid chromatography (HPLC), and the degradation rate was calculated.

[0061] The measurement results are as follows Figure 7 As shown, the horizontal axis represents degradation time (Time), and the vertical axis represents tetracycline degradation rate (C). t / C0), where C0 is the initial concentration of tetracycline, C t This is the real-time concentration. (From...) Figure 7 It can be seen that after four degradation cycles, the Bi2O2CO3 / MIL-68-NH2-persulfate system can still maintain a tetracycline degradation efficiency of 97.4%, demonstrating excellent reusability.

[0062] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, and for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. A Bi2O2CO3 / MIL-68-NH2 composite material, characterized in that, The composite material is formed by loading Bi2O2CO3 onto the surface of MIL-68-NH2 to form a heterojunction structure. The MIL-68-NH2 is a regular hexagonal rod-shaped crystal with a length of 10-20 μm; the Bi2O2CO3 is a sphere with a diameter of 2-3 μm and a carnation-shaped layered stacked structure on the surface, dispersed and loaded on the surface of the MIL-68-NH2, and the MIL-68-NH2 is MIL-68-NH2(In).

2. The method for preparing the Bi2O2CO3 / MIL-68-NH2 composite material according to claim 1, characterized in that, Includes the following steps: (1) Preparation of MIL-68-NH2: In(NO3)3·4H2O and 2-aminoterephthalic acid were dissolved in dimethylformamide (DMF) and ultrasonically stirred until homogeneous. The resulting homogeneous solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and heated at 110-140°C for 4-6 hours. After cooling, the resulting solid was centrifuged, washed, and dried. The resulting solid powder was MIL-68-NH2. (2) Preparation of Bi2O2CO3 / MIL-68-NH2 composite material: Bi(NO3)3·5H2O, C6H5Na3O7 and MIL-68-NH2 prepared in step (1) were uniformly dispersed in deionized water and ultrasonically stirred until homogeneous. The mixture was then adjusted to pH 9-10 with ammonia and magnetically stirred until homogeneous. The mixture was then transferred to a high-pressure autoclave lined with polytetrafluoroethylene and reacted at 160-200℃ for 22-24 hours. The cooled sample was centrifuged and washed with water and ethanol. After drying, the Bi2O2CO3 / MIL-68-NH2 composite material was obtained.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of In(NO3)3·4H2O to 2-aminoterephthalic acid is 3-4:1-2.

4. The preparation method according to claim 2, characterized in that, In step (1), 6-13 mL of DMF is required as a solvent for every 1-2 mmol of In(NO3)3·4H2O added.

5. The preparation method according to claim 2, characterized in that, In step (2), the mass ratio is Bi(NO3)3·5H2O:C6H5Na3O7:MIL-68-NH2=1-2:0.5-1:0.1-0.

5.

6. The preparation method according to claim 2, characterized in that, In step (2), the amount of deionized water used is 34-69 mL of deionized water as a solvent for every 1-2 g of Bi(NO3)3·5H2O added.

7. The application of the Bi2O2CO3 / MIL-68-NH2 composite material according to claim 1, characterized in that, The Bi2O2CO3 / MIL-68-NH2 composite material acts as a photocatalyst, activating persulfate under visible light irradiation, causing persulfate to generate sulfate radicals and singlet oxygen, thereby degrading antibiotics.

8. The application according to claim 7, characterized in that, The wavelength range of the visible light is 400-700nm, and the persulfate is permonosulfate.

9. The application according to claim 7, characterized in that, The antibiotic in question is tetracycline.

10. The application according to claim 9, characterized in that, The antibiotic is dissolved in the mobile phase water.

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