Preparation method and application of magnetic zirconium-based MOFs-layered double hydroxide composite photocatalyst

Abstract

The invention discloses a preparation method and application of a magnetic zirconium-based MOFs-layered double hydroxide composite photocatalyst, and relates to a preparation method and application of a photocatalyst. The technical problems that an existing MOFs photocatalyst is low in photocatalytic efficiency and difficult to recover are solved. The method comprises the following steps: 1, preparing a Fe3O4 magnetic carrier; 2, a magnetic zirconium-based metal-organic framework UiO-66-NH-Fe3O4 nano composite material is prepared, and the magnetic zirconium-based metal-organic framework UiO-66- And 3, preparing the UN-66 (at) LDH-Fe heterojunction photocatalyst. When being used for treating wastewater containing antibiotics, drug-resistant bacteria and / or resistance genes, the biodegradation rate of the antibiotics within 45 minutes can be greater than 87%, and the biodegradation agent can be used in the field of water treatment.

Description

Technical Field

[0001] This invention relates to the field of environmental remediation technology, specifically to a magnetic metal-organic framework@layered double hydroxide heterojunction photocatalyst and its application in the treatment of antibiotic-related recalcitrant pollutants. Background Technology

[0002] With the continuous exploration and production of antibiotics in disease treatment, antibiotic usage has increased dramatically, placing severe selective pressure on the ecological environment. Simultaneously, the abuse and overuse of antibiotics have led to the rapid proliferation and spread of drug-resistant bacteria and resistance genes, posing a serious threat to the environment and public health. Wastewater treatment plants, as sources of antibiotic resistance, have extremely high bacterial loads and carry various resistance gene pollutants (such as blaTEM-1, sul1, tetA, etc.). Notably, these emerging genetic pollutants are particularly problematic because resistance genes can persist in the environment and be further released into aquatic ecosystems after the death of host microorganisms.

[0003] Traditional biological wastewater treatment technologies and typical disinfection techniques (such as ozonation and chlorination) are ineffective at removing resistant pollutants from wastewater. In some cases, these methods can even increase the abundance and diversity of resistance genes through horizontal gene transfer. To address these challenges, advanced oxidation processes, due to their high efficiency, environmental friendliness, and selective radical targeting, are considered a promising and effective method for removing a range of recalcitrant resistant pollutants. In contrast, photocatalysis has become a highly anticipated treatment technology due to its environmental sustainability, low or non-toxicity, and excellent oxidation and mineralization efficiency. Photocatalysts based on metal-organic frameworks (MOFs) have attracted significant attention due to their unique connections with metal centers.

[0004] Existing single MOF photocatalysts, such as UiO-66-NH2 and MIL-88-Fe nanomonomers, have shortcomings in electrical conductivity and optical performance. They also suffer from low efficiency in treating recalcitrant pollutants such as antibiotics, drug-resistant bacteria, and resistance genes, as well as difficulties in catalyst recovery, which limit their application in light treatment. Summary of the Invention

[0005] The present invention aims to solve the technical problems of low photocatalytic efficiency and difficult catalyst recovery of existing MOF photocatalysts, and provides a method for preparing magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst and its application.

[0006] The preparation method of the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst of the present invention is carried out according to the following steps:

[0007] I. Preparation of Fe3O4 magnetic support;

[0008] II. Preparation of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposites:

[0009] (1) Dissolve zirconium chloride (ZrCl4) and 2-aminoterephthalic acid (BDC-NH2) in dimethylacetamide solvent, then add acetic acid and Fe3O4 magnetic carrier, ultrasonically disperse evenly, and stir for 50~60 min to obtain the precursor solution;

[0010] (2) The precursor liquid was transferred to a polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 120℃, microwave power 500 W, and reaction time 50~60 min.

[0011] (3) The reaction product was washed by centrifugation with dimethylacetamide and methanol, and then dried under vacuum to obtain magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material;

[0012] III. Preparation of UiO@CuFe LDH-Fe3O4 heterojunction photocatalyst:

[0013] (1) According to Cu 2+ / Fe 3+ The molar ratio of Cu(NO3)2·3H2O and Fe(NO3)3·9H2O is 3:1. Cu is dissolved in deionized water to obtain Cu... 2+ / Fe 3+ Ionic solutions;

[0014] (2) Dissolve NaOH and Na2CO3 in deionized water to obtain an alkaline solution;

[0015] (3) Under continuous stirring, the alkaline solution is added dropwise to Cu. 2+ / Fe 3+ In an ionic solution, the mixture was stirred until the pH reached 4.4 ± 0.2 to obtain a mixture; then, the magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material was added to the mixture and stirred thoroughly to obtain the precursor.

[0016] (4) The precursor was transferred to a polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 130℃, microwave power 500 W, reaction time 40~50 min. The product was washed and dried with deionized water and ethanol to obtain magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst.

[0017] Furthermore, the magnetic carrier Fe3O4 described in step one is synthesized using a microwave hydrothermal method. Specifically, the method is as follows: First, 10 mmol of FeCl3·H2O and 4 mmol of sodium citrate are dissolved in 70 mL of ethylene glycol to obtain a mixed solution. Then, 40 mmol of sodium acetate is added to the mixed solution and magnetically stirred for 60 minutes to obtain a precursor. The precursor is then subjected to a microwave hydrothermal reaction with the following parameters: temperature 200℃, microwave power 500 W, and reaction time 45 minutes. The microwave hydrothermal reaction product is washed clean with deionized water and anhydrous ethanol by centrifugation and then vacuum dried to obtain the magnetic carrier Fe3O4, which is a blackish-brown nanoparticle powder.

[0018] Furthermore, in step two, the molar ratio of ZrCl4 to 2-aminoterephthalic acid (BDC-NH2) is 1:(0.9~1.1).

[0019] Furthermore, in step two, the ratio of the amount of ZrCl4 to the volume of dimethylacetamide is 1 mmol: (40~60) mL.

[0020] Furthermore, in step two, the ratio of the amount of ZrCl4 to the volume of acetic acid is 1 mmol: (10~40) mL.

[0021] Furthermore, in step two, the ratio of the amount of ZrCl4 to the mass of the Fe3O4 magnetic carrier is 1 mmol: (180~220) mg.

[0022] Furthermore, in step three (3), Cu 2+ / Fe 3+ Cu in ionic solution 2+ The ratio of the amount of substance to the mass of the magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material is 1 mmol:(130~160) mg.

[0023] The application of the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared by the above method is to use the composite photocatalyst to treat wastewater containing antibiotics, drug-resistant bacteria and / or resistance genes.

[0024] The method for treating wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes using a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst shall be carried out according to the following steps:

[0025] A magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst was added to wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes at a dosage of 0.1–0.4 g / L. The mixture was stirred in the dark for 30–40 minutes to ensure sufficient contact and adsorption between the catalyst and the wastewater. Then, a visible light source was turned on for photoreaction at an intensity of 7.2–12 mW / cm², maintaining the reaction temperature at 36.5–37.5℃ and the initial pH at 3–11. After 20–30 minutes of illumination, the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst was separated from the wastewater using a magnet, thus completing the treatment of wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes.

[0026] The magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared in this invention successfully constructs an internal electric field between MOFs@layered double hydroxides. The MOFs@layered double hydroxide heterojunction structure effectively improves electron-hole separation capability and photogenerated charge transfer efficiency, thereby optimizing the photocatalyst's photoelectric performance: reducing resistance and increasing conductivity. The system simultaneously enhances the redox efficiency during pollutant degradation, effectively promoting the generation of reactive oxygen species (ROS), including •OH and •O2, during photocatalysis. - This invention enables the efficient catalytic degradation of antibiotics, drug-resistant bacteria, and / or resistance genes in polluted water by targeting specific pollutant sites. Furthermore, the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared in this invention possesses the excellent physicochemical characteristics of its MOF-based material, such as specific surface area, ensuring high adsorption efficiency during water purification. In addition, the introduction of the magnetic support Fe3O4 gives the catalyst good magnetic recovery performance, facilitating the separation and reuse of the catalyst after reaction, thus reducing wastewater treatment costs.

[0027] The magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared by this invention can be used in the field of water treatment. Attached Figure Description

[0028] Figure 1 Here are SEM comparison images of zirconium-based metal-organic frameworks prepared in Example 1 before and after modification: (a) UiO, (b) UiO@CuFe LDH-Fe3O4;

[0029] Figure 2 SEM comparison of (a) UiO, (b) Fe3O4, and (c) CuFe LDH monomers prepared in Example 1;

[0030] Figure 3 This is the EDX-mapping image of the zirconium-based metal-organic framework UiO@CuFe LDH-Fe3O4 prepared in Example 1;

[0031] Figure 4The graph shows the optimal ratio of UiO@CuFe LDH-Fe3O4 composites prepared in Examples 1-6.

[0032] Figure 5 This is a comprehensive comparison chart of the photocatalytic effects of UiO@CuFe LDH-Fe3O4 prepared in Example 1 on oxytetracycline treatment;

[0033] Figure 6 The image shows the photocatalytic effect of UiO@CuFe LDH-Fe3O4 prepared in Example 1 on the treatment of various antibiotics.

[0034] Figure 7 This is a graph showing the reproducibility of the UiO@CuFe LDH-Fe3O4 photocatalytic system prepared in Example 1. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] Example 1: The preparation method of the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst of this example is carried out according to the following steps:

[0037] I. Preparation of Fe3O4 magnetic support: First, 10 mmol of FeCl3·H2O and 4 mmol of sodium citrate were dissolved in 70 mL of ethylene glycol to obtain a mixed solution. Then, 40 mmol of sodium acetate was added to the mixed solution and the mixture was magnetically stirred for 60 minutes to obtain a precursor. The precursor was subjected to a microwave hydrothermal reaction with the following parameters: temperature 200℃, microwave power 500 W, and reaction time 45 minutes. The microwave hydrothermal reaction product was washed with deionized water and anhydrous ethanol by centrifugation and then vacuum dried to obtain the magnetic support Fe3O4, which is a black-brown nanoparticle powder.

[0038] II. Preparation of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposites using a microwave hydrothermal method:

[0039] (1) Dissolve 1 mmol of zirconium chloride (ZrCl4) and 1 mmol of 2-aminoterephthalic acid (BDC-NH2) in 50 mL of dimethylacetamide solvent, then add 10 mL of acetic acid and 200 mg of Fe3O4 magnetic carrier, disperse evenly by ultrasonication, and stir for 60 min to obtain the precursor solution.

[0040] (2) The precursor solution was transferred to a 100 mL polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 120℃, microwave power 500 W, and reaction time 60 minutes.

[0041] (3) The reaction product was washed by centrifugation with dimethylacetamide and methanol, and then dried under vacuum at 80°C to obtain a magnetic zirconium-based metal-organic framework nanocomposite material, denoted as UiO-Fe3O4;

[0042] III. Preparation of UiO@CuFe LDH-Fe3O4 heterojunction photocatalyst using a co-precipitation method combined with a microwave hydrothermal method:

[0043] (1) Dissolve 3 mmol Cu(NO3)2·3H2O and 1 mmol Fe(NO3)3·9H2O in 50 mL of deionized water to obtain Cu 2+ / Fe 3+ Ionic solutions;

[0044] (2) Dissolve 4 mmol NaOH and 1 mmol Na2CO3 in 50 mL of deionized water to obtain an alkaline solution;

[0045] (3) Under continuous stirring, the alkaline solution is added dropwise to Cu. 2+ / Fe 3+ In an ionic solution, the mixture was stirred until the pH reached 4.4 to obtain a mixture. Then, 150 mg of magnetic zirconium-based metal-organic framework nanocomposite material was added to the mixture and stirred thoroughly to obtain the precursor. In this step, the molar ratio of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH was 3:1.

[0046] (4) The precursor was transferred to a polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 130℃, microwave power 500 W, reaction time 45 min. The reaction product was washed three times with deionized water and three times with ethanol, and then dried to obtain magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst, denoted as UiO@CuFeLDH-Fe3O4.

[0047] Figure 1 These are SEM comparison images of UiO-Fe3O4 obtained in step two of Example 1 and UiO@CuFe LDH-Fe3O4 obtained in step three: where (a) is UiO-Fe3O4 and (b) is UiO@CuFe LDH-Fe3O4. Figure 1 It can be seen that the surface of the photocatalyst becomes significantly rougher, and sheet-like nanoparticles are loaded on it.

[0048] Figure 2These are SEM comparison images of Fe3O4 obtained in step one, UiO obtained in step two, and CuFe LDH obtained in step three of Example 1, where (a) is the UiO monomer, (b) is the Fe3O4 monomer, and (c) is the CuFe LDH monomer. Figure 2 It can be seen that the morphology of its corresponding monomer nanomaterials is similar to... Figure 1 The changes in the morphology of the composite particles are shown.

[0049] Figure 3 This is the EDX-mapping image of UiO@CuFe LDH-Fe3O4 prepared in Example 1. Figure 3 It can be seen that the proportions of different elements in the UiO@CuFe LDH-Fe3O4 composite photocatalyst are consistent with the composite ratio of 3:1. The elemental composition is shown in Table 1.

[0050] Table 1. Elemental composition of UiO@CuFe LDH-Fe3O4 prepared in Example 1

[0051] element Weight percentage (%) Atomic percentage (%) Zr 46.78 14.81 OK 30.63 55.17 N 12.16 25.01 Fe 5.18 2.67 Cu 5.16 2.34

[0052] Example 2: The difference between this example and Example 1 is that in step 3 (3), the molar ratio of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH is 1:1. Other steps and parameters are the same as in Example 1.

[0053] Example 3: The difference between this example and Example 1 is that in step three (3), the molar ratio of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH is 1:2. Other steps and parameters are the same as in Example 1.

[0054] Example 4: The difference between this example and Example 1 is that in step 3 (3), the molar ratio of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH is 1:3. Other steps and parameters are the same as in Example 1.

[0055] Example 5: The difference between this example and Example 1 is that the ratio of the amount of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH in step three (3) is 4:1. The other steps and parameters are the same as in Example 1.

[0056] Example 5: The difference between this example and Example 1 is that the ratio of the amount of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanoparticles to CuFe LDH in step 3 (3) is 2:1. The other steps and parameters are the same as in Example 1.

[0057] The UiO@CuFe LDH-Fe3O4 prepared in Examples 1-6 were used to treat wastewater containing resistant pollutants. The specific steps are as follows: 1. 100 mL of a 1 mg / L solution of resistant pollutants was added to a quartz reactor. The resistant pollutants were oxytetracycline and a resistance gene, respectively. Then, 0.2 g / L of the UiO@CuFe LDH-Fe3O4 photocatalyst prepared in Examples 1-6 was added, and the mixture was stirred at 400 rpm in the dark for 20 min. The concentration of the target pollutant was measured to evaluate the adsorption performance of the novel composite photocatalyst. 2. A 300 W xenon lamp was turned on at a distance of 10 cm from the reactor, with a light intensity of 9.6 mW / cm². The reaction temperature was maintained at 37°C using a condenser circulation device, and the initial pH was adjusted to 7.54 for the photocatalytic reaction. 5 mL samples were taken at regular intervals, and Na2S2O3 was added to quench the reaction. The concentration of the target pollutant was measured using liquid chromatography to calculate the degradation effect of the novel composite photocatalyst on resistant pollutants. Figure 4 The results are from experiments using UiO@CuFe LDH-Fe3O4 prepared in Examples 1-6 to treat resistant contaminants. From... Figure 4 It can be seen that when the composite ratio of UiO@CuFe LDH-Fe3O4 is 3:1, it is much higher than that of other nanomaterials.

[0058] The UiO@CuFe LDH-Fe3O4 prepared in Example 1 was used to treat wastewater containing antibiotics. The specific steps are as follows:

[0059] 1. Take 100 mL of 1 mg / L oxytetracycline solution into a quartz reactor, and add 0.2 g / L of Fe3O4, UiO-Fe3O4, UiO@CuFe LDH-Fe3O4, UiO, and CuFe LDH prepared in Example 1, respectively. Stir at 400 rpm in the dark for 20 min. Take samples to determine the concentration of the target pollutant to evaluate the adsorption performance of the novel composite photocatalyst.

[0060] 2. At a distance of 10 cm from the reactor, turn on a 300 W xenon lamp with a light intensity of 9.6 mW / cm². Maintain the reaction temperature at 37℃ through a condensation circulation device and adjust the initial pH value to 7.54 for photocatalytic reaction. Take 5 mL samples at regular intervals and add Na2S2O3 to quench the reaction. Use liquid chromatography to determine the concentration of the target pollutant and calculate the effect of the novel composite photocatalyst on antibiotic degradation. Figure 5 The chart shows a comprehensive comparison of the photocatalytic effects on oxytetracycline. The experimental results indicate that the UiO@CuFeLDH-Fe3O4 photocatalyst prepared in Example 1 can adsorb 33.51% of oxytetracycline within 45 minutes, exhibiting excellent adsorption performance.

[0061] The UiO@CuFe LDH-Fe3O4 prepared in Example 1 was used to treat wastewater containing antibiotics. The specific steps are as follows:

[0062] 1. Take 100 mL of an antibiotic solution with a concentration of 1 mg / L into a quartz reactor. The antibiotics are oxytetracycline solution, sulfadiazine solution, norfloxacin solution, and amoxicillin solution, respectively. Add 0.2 g / L of the UiO@CuFe LDH-Fe3O4 photocatalyst prepared in Example 1, and stir at 400 rpm in the dark for 20 min. Take samples to determine the concentration of the target pollutant to evaluate the adsorption performance of the novel composite photocatalyst.

[0063] 2. A 300 W xenon lamp was turned on 10 cm away from the reactor, with a light intensity of 9.6 mW / cm². The reaction temperature was maintained at 37°C using a condenser circulation device, and the initial pH was adjusted to 7.54 for photocatalytic reaction. 5 mL samples were taken at regular intervals, and Na₂S₂O₃ was added to quench the reaction. The concentration of the target pollutant was determined using liquid chromatography, and the antibiotic degradation efficiency of the novel composite photocatalyst was calculated. The photodegradation efficiency of the UiO@CuFe LDH-Fe₃O₄ photocatalyst prepared in Example 1 on different types of antibiotics (including oxytetracycline, sulfadiazine, norfloxacin, and amoxicillin) is shown in the figure below. Figure 6 As shown, Figure 6 This indicates that over 87% of antibiotics can decompose within 45 minutes, with a degradation rate greater than 87%. The UiO@CuFe LDH-Fe3O4 heterojunction provides a wide range of applications.

[0064] The UiO@CuFe LDH-Fe3O4 prepared in Example 1 was used to inhibit contamination by antibiotic-resistant bacteria with resistance genes. The specific steps are as follows:

[0065] I. Screening for target drug-resistant strains from the secondary effluent of urban wastewater treatment plants, determining their resistance to antibiotics (tet A and Ampr) by measuring the minimum inhibitory concentration (MIC), and then culturing them to a concentration of 3 × 10⁻⁶. 8 CFU / mL was used to obtain a suspension of drug-resistant bacteria;

[0066] 2. Take 100 mL of drug-resistant bacterial suspension, add 0.2 g / L of UiO@CuFe LDH-Fe3O4 photocatalyst, and stir at 400 rpm in the dark for 30 min;

[0067] 3. At a distance of 10 cm from the reactor, turn on a 300 W xenon lamp with a light intensity of 9.6 mW / cm². Maintain the reaction temperature at 37°C using a condenser circulation device and adjust the initial pH value to 7.54 for the light-induced reaction. Take a 5 mL sample at regular intervals, add Na2S2O3 to quench the reaction, and use a McFarland turbidimeter to determine the concentration of drug-resistant bacteria. Use real-time quantitative polymerase chain reaction (PCR) technology to determine the concentration of resistance genes.

[0068] The results of photocatalytic treatment of drug-resistant bacteria with resistance genes using UiO@CuFe LDH-Fe3O4 prepared in Example 1 showed that the concentration of drug-resistant bacteria decreased by 5.63 log after 6 hours, and the degradation rates of tetA and Ampr genes were 3.66 log and 3.57 log, respectively, demonstrating excellent treatment effect.

[0069] The stability of the UiO@CuFe LDH-Fe3O4 photocatalyst prepared in Example 1 was evaluated. In the stability evaluation, after each photocatalytic reaction, the UiO@CuFe LDH-Fe3O4 photocatalyst was separated and recovered using an external magnet, washed multiple times with deionized water, and dried at 60°C. The recovered catalyst was reused in the treatment experiment of resistant pollutants for a total of 6 cycles. Figure 7 The stability evaluation results of the UiO@CuFe LDH-Fe3O4 photocatalyst prepared in Example 1 are shown in the figure. Figure 7 It can be seen that the photodegradation efficiency of the resistance gene remained between 2.89 log and 3.66 log after 6 cycles, indicating that the catalyst has good reusability and stability. The redox cycle of the UiO@CuFe LDH-Fe3O4 photocatalysis can ensure the long-term operation of the photocatalytic technology. The characteristic peaks obtained from the physicochemical characterization of the novel nanomaterial did not change significantly before and after repeated use, verifying that its crystal structure and chemical state are quite stable.

[0070] The magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared by this invention improves the treatment efficiency by successfully constructing an internal heterojunction, and on this basis, it is magnetized to facilitate recycling and reuse in water treatment and save technical costs.

Claims

1. A method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst, characterized in that, This method is performed in the following steps: I. Preparation of Fe3O4 magnetic support; II. Preparation of magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposites: (1) Dissolve zirconium chloride and 2-aminoterephthalic acid in dimethylacetamide solvent, then add acetic acid and Fe3O4 magnetic carrier, ultrasonically disperse evenly, and stir for 50~60 min to obtain the precursor solution; (2) The precursor liquid was transferred to a polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 120℃, microwave power 500 W, and reaction time 50~60 min. (3) The reaction product was washed by centrifugation with dimethylacetamide and methanol, and then dried under vacuum to obtain magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material; III. Preparation of UiO@CuFe LDH-Fe3O4 heterojunction photocatalyst: (1) According to Cu 2+ / Fe 3+ The molar ratio of Cu(NO3)2·3H2O and Fe(NO3)3·9H2O is 3:

1. Cu is dissolved in deionized water to obtain Cu... 2+ / Fe 3+ Ionic solutions; (2) Dissolve NaOH and Na2CO3 in deionized water to obtain an alkaline solution; (3) Under continuous stirring, the alkaline solution is added dropwise to Cu. 2+ / Fe 3+ In an ionic solution, the mixture was stirred until the pH reached 4.4 ± 0.2 to obtain a mixture; then, the magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material was added to the mixture and stirred thoroughly to obtain the precursor. (4) The precursor was transferred to a polytetrafluoroethylene container for microwave hydrothermal reaction. The specific hydrothermal reaction parameters were set as follows: temperature 130℃, microwave power 500 W, reaction time 40~50 min. The product was washed and dried with deionized water and ethanol to obtain magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst.

2. The preparation method of a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1, characterized in that, The magnetic support Fe3O4 mentioned in step one is synthesized by a microwave hydrothermal method. The specific method is as follows: First, 10 mmol of FeCl3·H2O and 4 mmol of sodium citrate are dissolved in 70 mL of ethylene glycol to obtain a mixed solution; then, 40 mmol of sodium acetate is added to the mixed solution and magnetically stirred for 60 minutes to obtain a precursor; the precursor is subjected to a microwave hydrothermal reaction, and the specific hydrothermal reaction parameters are set as follows: temperature 200℃, microwave power 500 W, and reaction time 45 minutes; the microwave hydrothermal reaction product is washed clean by centrifugation with deionized water and anhydrous ethanol, and then vacuum dried to obtain the magnetic support Fe3O4.

3. The method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1 or 2, characterized in that, In step two, the molar ratio of ZrCl4 to 2-aminoterephthalic acid is 1:(0.9~1.1).

4. The method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1 or 2, characterized in that, In step two, the ratio of the amount of ZrCl4 to the volume of dimethylacetamide is 1 mmol: (40~60) mL.

5. The method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1 or 2, characterized in that, In step two, the ratio of the amount of ZrCl4 to the volume of acetic acid is 1 mmol: (10~40) mL.

6. The method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1 or 2, characterized in that, In step two, the ratio of the amount of ZrCl4 to the mass of the Fe3O4 magnetic carrier is 1 mmol: (180~220) mg.

7. The method for preparing a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 1 or 2, characterized in that, In step three (3), Cu 2+ / Fe 3+ Cu in ionic solution 2+ The ratio of the amount of substance to the mass of the magnetic zirconium-based metal-organic framework UiO-Fe3O4 nanocomposite material is 1 mmol:(130~160) mg.

8. The application of the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst prepared by the method of claim 1, characterized in that, This application involves using magnetic zirconium-based MOFs@layered double hydroxide composite photocatalysts to treat wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes.

9. The application of the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst according to claim 8, characterized in that, The method for treating wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes using a magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst shall be carried out according to the following steps: A magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst was added to wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes at a dosage of 0.1–0.4 g / L. The mixture was stirred in the dark for 30–40 minutes to ensure sufficient contact and adsorption between the catalyst and the wastewater. Then, a visible light source was turned on for photoreaction at an intensity of 7.2–12 mW / cm², with the reaction temperature maintained at 37°C and the initial pH value at 3–11. After 20–30 minutes of irradiation, the magnetic zirconium-based MOFs@layered double hydroxide composite photocatalyst was separated from the wastewater using a magnet, thus completing the treatment of wastewater containing antibiotics, drug-resistant bacteria, and / or resistance genes.

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