Method for preparing metal-doped composite catalyst based on zif-67 and applications thereof

Abstract

This invention discloses a method and application for preparing metal-doped composite catalysts based on ZIF-67, relating to the field of wastewater treatment technology. This invention constructs a multi-component synergistic system through the coordination of functional groups on the surface of biochar with ZIF-67 and the electronic coupling effect between rare earth metals and Co. Compared with traditional pure chemical support synthesis methods, this reduces costs and improves environmental compatibility. The metal-doped composite catalyst prepared by this invention is a novel heterogeneous catalyst. Through the electrostatic interaction between the biochar support and Co ions, and the metal-metal bonds formed between La / Ce and Co, it significantly enhances the stability of Co ions, effectively avoiding secondary pollution. The metal-doped composite catalyst prepared by this invention can efficiently activate persulfate to generate reactive oxygen species and synergistically remove multiple pollutants from complex water bodies containing sulfamethoxazole, tetracycline, levofloxacin, and other antibiotics such as methylene blue.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method and application for preparing metal-doped composite catalysts based on ZIF-67. Background Technology

[0002] With the rapid development of the pharmaceutical industry, the widespread use of antibiotics such as tetracycline (TC), sulfamethoxazole (SMX), and levofloxacin (LEV) in medical treatment and animal husbandry has led to a large amount of incompletely metabolized antibiotics entering natural water bodies through wastewater discharge, resulting in persistent antibiotic pollution of water bodies. These pollutants pose risks of bioaccumulation and antibiotic resistance induction, not only disrupting the balance of aquatic ecosystems but also potentially threatening human health through bioaccumulation in the food chain. Therefore, developing efficient and stable technologies for treating antibiotic-contaminated water bodies has become a key requirement in the field of environmental engineering.

[0003] Persulfate (PMS) activation oxidation technology can generate highly reactive oxygen species (such as •OH, SO4•) with strong oxidizing properties. – O2• – and 1O2 has shown significant advantages in the removal of recalcitrant organic pollutants, and the development of highly efficient activators is the core of its industrial application. Co-based materials have become a research hotspot due to their excellent activation performance for PMS. Among them, Co-based catalysts derived from metal-organic frameworks (MOFs) (such as ZIF-67-derived Co3O4) have further improved PMS activation efficiency due to their high specific surface area, controllable pore structure, and abundant active sites. However, existing ZIF-67-derived Co-based catalysts still have two major problems in practical applications: First, Co ions are not stable enough and are prone to leaching during the reaction, which not only leads to the loss of catalyst active sites and a decline in recycling performance, but also introduces heavy metal ions into the water, causing secondary pollution. Second, single Co-based catalysts have limited universality in the degradation of antibiotics in complex water bodies, and under extreme pH conditions with strong acidity or alkalinity, reactive oxygen species are easily consumed, resulting in a significant reduction in catalytic efficiency, making it difficult to adapt to the complex working conditions of actual water bodies. Furthermore, the preparation of traditional Co-based catalysts often relies on purely chemical supports, which suffers from high costs and poor environmental compatibility. Biomass-based materials (such as sunflower straw-derived biochar, BC) are ideal catalyst supports due to their wide availability, low cost, rich surface functional groups, and good biocompatibility. Combining ZIF-67 with biomass-based materials and introducing other metal elements for doping modification can further improve Co ion stability and PMS activation efficiency by controlling the material's electronic structure and increasing surface defect sites, while simultaneously reducing preparation costs and environmental risks. Based on the shortcomings of existing technologies, this study develops a metal-doped composite catalyst based on in-situ growth of ZIF-67, possessing high stability, high catalytic activity, and environmental compatibility. This catalyst is used for the efficient activation of persulfate degradation of various antibiotics in water, addressing issues such as Co ion leaching and poor catalytic adaptability. This is of great significance for promoting the development of antibiotic-contaminated water treatment technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a method and application for preparing metal-doped composite catalysts based on ZIF-67, and to solve the following technical problems: Existing Co-based catalysts suffer from problems such as secondary pollution, low degradation efficiency, and high preparation costs due to Co ion leaching.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing metal-doped composite catalysts based on ZIF-67 includes the following steps: S1: Mix crop biomass powder, low-carbon alcohol, and cobalt salt, add a low-carbon alcohol solution containing imidazole derivatives, control the temperature at 10℃-50℃, let stand for 12h-48h, dry and grind to obtain ZIF-67 in-situ loaded biomass composite material. S2: ZIF-67 in-situ loaded biomass composite material is mixed and ground with rare earth metal salt to obtain mixed powder; S3: The mixed powder is placed in a tube furnace and pyrolyzed at high temperature under inert gas protection; after cooling to room temperature, it is washed with water until neutral and dried to obtain a metal-doped composite catalyst.

[0006] As a further aspect of the present invention: the grinding in S2 specifically involves grinding in a mortar or planetary ball mill for 10 minutes to 1 hour at a grinding rate of 200 rpm to 500 rpm.

[0007] As a further aspect of the present invention: the inert gas protection in S3 specifically involves introducing inert gas into the tubular furnace at a rate of 50 mL / min to 200 mL / min.

[0008] As a further aspect of the present invention: the drying in S3 is carried out at 50℃-100℃ for 10h-24h.

[0009] As a further aspect of the present invention, the method for preparing crop biomass powder includes the following steps: washing the crop biomass, drying it at 105℃-120℃ for 4h-6h, pulverizing it, and passing it through an 80-120 mesh sieve to obtain biomass powder.

[0010] As a further aspect of the present invention: waste agricultural biomass includes any one of corn stalks, sunflower stalks, grapefruit peels, or ginkgo leaves.

[0011] As a further aspect of the present invention: the lower alcohol is any one of methanol, ethanol or isopropanol; The cobalt salt is any one of Co(NO3)2・6H2O, CoSO4・7H2O or CoCl2・6H2O; The imidazole derivative is any one of 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole or 2-ethylimidazole.

[0012] As a further aspect of the present invention: the addition ratio of crop biomass powder, cobalt salt, and imidazole derivative in S1 is 1-10g: 1-10mmol: 1-5mmol; The ratio of cobalt salt to lower alcohol in S1 is 1-10 mmol: 10-200 mL; In S1, the ratio of imidazole derivatives to low-carbon alcohols in the solution is 1-5 mmol: 10-200 mL.

[0013] As a further embodiment of the present invention: the rare earth metal salt is La(NO3)3·6H2O or Ce(NO3)3·6H2O; The mass ratio of ZIF-67 in-situ loaded biomass composite material to rare earth metal salt is 1:1-5.

[0014] As a further aspect of the present invention: the inert gas is one or more of nitrogen, helium, and argon mixed in any ratio; the specific steps of the high-temperature pyrolysis are: heating to 500℃-900℃ at a heating rate of 2℃ / min-20℃ / min, and pyrolyzing at a constant temperature for 1h-5h.

[0015] The metal-doped composite catalyst prepared by the above method is used in the field of wastewater treatment, specifically in the degradation of antibiotic-containing wastewater. Antibiotics can be obtained by mixing one or more of sulfamethoxazole, tetracycline, and levofloxacin in any proportion.

[0016] As a further aspect of the present invention, the specific steps of the application are as follows: adding a metal-doped composite catalyst and persulfate to the wastewater containing antibiotics for degradation treatment; the content ratio of antibiotics, persulfate and metal-doped composite catalyst in each liter of wastewater is 3mg-50mg: 50mg-1000mg: 3mg-50mg.

[0017] As a further aspect of the present invention, the specific steps for the degradation treatment of antibiotics are as follows: react under stirring conditions for 30 min to 120 min.

[0018] As a further embodiment of the present invention: the stirring is magnetic stirring with a rotation speed of 200rpm-800rpm.

[0019] The metal-doped composite catalyst prepared by the above method is used in the field of wastewater treatment, and is applied to the degradation of dye-containing wastewater.

[0020] As a further aspect of the present invention, the specific steps of the application are as follows: the metal-doped composite catalyst and persulfate are added to the dye wastewater for degradation treatment; the content ratio of dye, persulfate and metal-doped composite catalyst in each liter of wastewater is 10mg-50mg: 100mg-500mg: 3mg-20mg.

[0021] As a further aspect of the present invention, the dye can be any one or more of basic dyes, acid dyes, direct dyes, disperse dyes, reactive dyes, vat dyes, sulfur dyes, mordant dyes, and oxidative dyes in any proportion.

[0022] As a further aspect of the present invention, the specific steps for the degradation treatment of the dye are as follows: react under stirring conditions for 30 min to 120 min.

[0023] As a further aspect of the present invention, the stirring is performed using magnetic stirring at a speed of 200 rpm to 800 rpm. Magnetic stirring allows for better contact between the metal-doped composite catalyst and the PMS.

[0024] As a further aspect of the present invention: the metal-doped composite catalyst uses biochar as a support, with Co3O4 crystal phase and rare earth metal oxide / carbonate crystal phase (La2CO5, La2O2CO3 or CeO2, Ce2O3) loaded on its surface, and has a specific surface area of ​​150 m². 2 / g-300m 2 / g, Co ion leaching amount <0.5mg / L, good stability in pH range of 3-11.

[0025] The beneficial effects of this invention are: (1) The preparation process of metal-doped composite catalysts is simple and low in cost. This invention utilizes in-situ loading of ZIF-67 onto waste crop biomass to obtain a ZIF-67 in-situ loaded biomass composite material. The ZIF-67 in-situ loaded biomass composite material is then mixed and ground with a metal salt, followed by one-step high-temperature pyrolysis under an inert atmosphere to prepare a metal-doped composite catalyst. This process requires no sophisticated instruments or complex multi-step reactions; preparation can be completed through simple operations such as settling, grinding, and pyrolysis, simplifying the process and making it easy to control. Furthermore, the raw materials used are waste crop biomass such as corn stalks and sunflower stalks, which are widely available and inexpensive. Compared to traditional pure chemical carriers (such as alumina and carbon nanotubes), the material preparation cost is significantly reduced, thereby lowering the economic barrier to industrial production.

[0026] (2) High activation efficiency of metal-doped composite catalysts The metal-doped composite catalyst prepared in this application significantly enhances the activation capacity of persulfate (PMS) through the synergistic effect of metal doping (such as La and Ce) and biochar, and can achieve a degradation rate of 98.67% for sulfamethoxazole in water, thus rapidly and efficiently removing antibiotic pollutants. (3) Metal-doped composite catalysts have strong stability and no secondary pollution. This application utilizes the dual effects of metal doping modification and biochar support to firmly immobilize Co ions. During catalyst use, the Co ion leaching amount is <0.5mg / L, which is more than 60% lower than that of pure Co3O4 catalyst, completely avoiding secondary pollution of water bodies caused by the release of heavy metal ions. Moreover, after 5 cycles of use, the degradation rate of sulfamethoxazole still remains at 81.2%, and the material structure and active sites are not easily lost, demonstrating excellent recycling performance.

[0027] (4) The preparation process can be directly adapted to large-scale production. The catalyst can be mass-produced in batches of more than 10g using a tubular furnace, and the production process produces no toxic or harmful byproducts, meeting the requirements of green industry. In addition to its core application in the degradation of sulfamethoxazole, it can also be extended to the removal of other antibiotics such as tetracycline and levofloxacin. It also has the ability to adsorb and degrade dye pollutants (MB), which can meet the needs of synergistic treatment of multiple types of water pollutants, providing an efficient, economical and environmentally friendly integrated solution for the field of environmental engineering. Attached Figure Description

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Figure 1 SEM image of the metal-doped composite catalyst (i.e., Co-La2@BC) prepared in Example 1; Figure 2 The XRD patterns of the metal-doped composite catalysts prepared in Examples 1-3 and the Co@BC prepared in Comparative Example 1 are shown. Figure 3 The graphs show the degradation performance of sulfamethoxazole in Examples 7-9 and Comparative Example 2. Figure 4 The graphs show the degradation performance of sulfamethoxazole in Example 7 and Comparative Examples 3-4. Figure 5 The graphs show the degradation performance of sulfamethoxazole in Examples 7 and 10-13. Figure 6 The graphs show the degradation performance of sulfamethoxazole in Examples 7 and 14-16. Figure 7 The graphs show the degradation performance of sulfamethoxazole in Examples 15, 17, 18, and Comparative Example 5. Figure 8 The graphs show the degradation performance of sulfamethoxazole in Examples 15 and 19-22. Figure 9 Repeatability testing of the metal-doped composite oxidant / PMS system used in Example 15; Figure 10 The degradation rates of pollutants in wastewater in Examples 15 and 23-25 ​​are shown. Figure 11 This is a visual representation of the degradation of methylene blue in Example 25; Figure 12 The images are XRD patterns before and after 5 cycles in Example 25. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: A method for preparing metal-doped composite catalysts based on ZIF-67, comprising the following steps: S1: After washing the sunflower stalks, dry them at 120℃ for 4 hours, crush them, and pass them through a 120-mesh sieve to obtain sunflower stalk biomass powder; 8g of sunflower straw biomass powder was soaked in methanol, 1mmol of cobalt nitrate hexahydrate (Co(NO3)2・6H2O) was added to dissolve it, and then a methanol solution containing 4mmol of 2-methylimidazole was added dropwise. After reacting at a stirring rate of 500rpm for 5min, the mixture was allowed to stand and age at 50℃ for 24h, dried at 60℃ for 12h and ground to obtain ZIF-67 in-situ supported biomass composite material. S2: Mix ZIF-67 in-situ supported biomass composite material with lanthanum nitrate hexahydrate (La(NO3)3・6H2O) at a mass ratio of 1:2, grind in a mortar for 20 min to obtain mixed powder; S3: Place the mixed powder in a tube furnace and heat it to 700℃ at a heating rate of 5℃ / min under a nitrogen atmosphere. Pyrolyze it at a constant temperature for 2 hours. After the tube furnace cools naturally to room temperature, wash it with distilled water until the filtrate is neutral and dry it to obtain the metal-doped composite catalyst (i.e., Co-La2@BC).

[0032] Example 2: A method for preparing a metal-doped composite catalyst based on ZIF-67. Compared with Example 1, the difference is that the mass ratio of ZIF-67 in situ supported biomass composite material to lanthanum nitrate hexahydrate (La(NO3)3・6H2O) is 1:1. All other preparation steps are the same, and a metal-doped composite catalyst (i.e., Co-La@BC) is obtained.

[0033] Example 3: A method for preparing a metal-doped composite catalyst based on ZIF-67. Compared with Example 1, the difference is that the mass ratio of ZIF-67 in situ supported biomass composite material to lanthanum nitrate hexahydrate (La(NO3)3・6H2O) is 1:3. All other preparation steps are the same, and a metal-doped composite catalyst (i.e., Co-La3@BC) is obtained.

[0034] Example 4: A method for preparing metal-doped composite catalysts based on ZIF-67, comprising the following steps: S1: After washing the sunflower stalks, dry them at 120℃ for 4 hours, crush them, and pass them through a 120-mesh sieve to obtain sunflower stalk biomass powder; 4g of sunflower straw biomass powder was soaked in methanol, 1mmol of cobalt nitrate hexahydrate (Co(NO3)2・6H2O) was added to dissolve it, and then a methanol solution containing 4mmol of 2-methylimidazole was added dropwise. After reacting at a stirring rate of 500rpm for 5min, the mixture was allowed to stand at 50℃ for 24h, dried at 60℃ for 12h and ground to obtain ZIF-67 in-situ supported biomass composite material. S2: Mix ZIF-67 in-situ supported biomass composite material with lanthanum nitrate hexahydrate (La(NO3)3・6H2O) at a mass ratio of 1:2, grind in a mortar for 20 min to obtain mixed powder; S3: The mixed powder is placed in a tube furnace and heated to 700°C at a heating rate of 5°C / min under a nitrogen atmosphere. It is then kept at a constant temperature for 2 hours. After the tube furnace cools naturally to room temperature, it is washed with distilled water until the filtrate is neutral and dried to obtain the metal-doped composite catalyst.

[0035] Example 5: A method for preparing metal-doped composite catalysts based on ZIF-67, comprising the following steps: S1: After washing the sunflower stalks, dry them at 120℃ for 4 hours, crush them, and pass them through a 120-mesh sieve to obtain sunflower stalk biomass powder; 8g of biomass powder prepared from sunflower straw was soaked in methanol, 2mmol of cobalt nitrate hexahydrate (Co(NO3)2・6H2O) was added to dissolve it, and then a methanol solution containing 4mmol of 2-methylimidazole was added dropwise. After reacting at a stirring rate of 500rpm for 5min, it was aged at 50℃ for 24h, dried at 60℃ for 12h and ground to obtain ZIF-67 in-situ supported biomass composite material. S2: Mix ZIF-67 in-situ supported biomass composite material with lanthanum nitrate hexahydrate (La(NO3)3・6H2O) at a mass ratio of 1:2, grind in a mortar for 20 min to obtain mixed powder; S3: The mixed powder is placed in a tube furnace and heated to 700°C at a heating rate of 5°C / min under a nitrogen atmosphere. It is then kept at a constant temperature for 2 hours. After the tube furnace cools naturally to room temperature, it is washed with distilled water until the filtrate is neutral and dried to obtain the metal-doped composite catalyst.

[0036] Example 6: A method for preparing metal-doped composite catalysts based on ZIF-67, comprising the following steps: S1: After washing the sunflower stalks, dry them at 120℃ for 4 hours, crush them, and pass them through a 120-mesh sieve to obtain sunflower stalk biomass powder; 8g of biomass powder prepared from sunflower straw was soaked in methanol, 1mmol of cobalt nitrate hexahydrate (Co(NO3)2・6H2O) was added to dissolve it, and then a methanol solution containing 4mmol of 2-methylimidazole was added dropwise. After reacting at a stirring rate of 500rpm for 5min, it was aged at 50℃ for 24h, dried at 60℃ for 12h and ground to obtain ZIF-67 in-situ supported biomass composite material. S2: Mix ZIF-67 in-situ supported biomass composite material with cerium nitrate hexahydrate (Ce(NO3)3・6H2O) at a mass ratio of 1:2, grind in a mortar for 20 min to obtain mixed powder; S3: The mixed powder is placed in a tube furnace and heated to 700°C at a heating rate of 5°C / min under a nitrogen atmosphere. It is then kept at a constant temperature for 2 hours. After the tube furnace cools naturally to room temperature, it is washed with distilled water until the filtrate is neutral and dried to obtain the metal-doped composite catalyst.

[0037] Example 7: The application of metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0038] Example 8: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La1@BC) prepared in Example 2 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0039] Example 9: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La3@BC) prepared in Example 3 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0040] Example 10: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 100 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0041] Example 11: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 200 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0042] Example 12: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 300 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0043] Example 13: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 20 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 500 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0044] Example 14: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 5 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0045] Example 15: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0046] Example 16: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 7, add 30 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0047] Example 17: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 15 mg of sulfamethoxazole per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0048] Example 18: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: prepare wastewater containing 20 mg of sulfamethoxazole per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0049] Example 19: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 3, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0050] Example 20: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 5, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0051] Example 21: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 9, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0052] Example 22: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: Prepare wastewater containing 10 mg of sulfamethoxazole per liter, adjust the pH to 11, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0053] Example 23: The application of metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: prepare wastewater containing 10 mg tetracycline per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0054] Example 24: Application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps are as follows: Prepare wastewater containing 10 mg of levofloxacin per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg of PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min. Example 25: The application of a metal-doped composite catalyst in the degradation of antibiotic-containing wastewater. The specific steps of the application are as follows: prepare wastewater containing 10 mg methylene blue per liter, adjust the pH to 7, add 10 mg of the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 + 400 mg PMS to each liter of wastewater, and stir magnetically at 800 rpm for 120 min.

[0055] Comparative Example 1: The method for preparing metal-doped composite catalysts based on ZIF-67 differs from Example 1 in that S2 was not performed in this comparative example, while all other preparation steps were the same, resulting in Co@BC.

[0056] Comparative Example 2: The metal-doped composite catalyst was applied to the degradation of antibiotic-containing wastewater. The specific steps of the application were as follows: wastewater containing 10 mg sulfamethoxazole per liter was prepared, the pH was adjusted to 7, 20 mg Co@BC prepared in Comparative Example 1 and 400 mg PMS were added to each liter of wastewater, and the mixture was stirred magnetically at 800 rpm for 120 min.

[0057] Comparative Example 3: The metal-doped composite catalyst was applied to the degradation of antibiotic-containing wastewater. The specific steps of the application were as follows: wastewater containing 10 mg sulfamethoxazole per liter was prepared, the pH was adjusted to 7, 400 mg PMS was added to each liter of wastewater, and the mixture was stirred magnetically at 800 rpm for 120 min.

[0058] Comparative Example 4: The metal-doped composite catalyst was applied to the degradation of antibiotic-containing wastewater. The specific steps of the application were as follows: wastewater containing 10 mg of sulfamethoxazole per liter was prepared, the pH was adjusted to 7, 20 mg of the metal-doped composite catalyst (Co3O4-LaO2@BC) prepared in Example 1 was added to each liter of wastewater, and the mixture was stirred magnetically at 800 rpm for 120 min.

[0059] Comparative Example 5: The metal-doped composite catalyst was applied to the degradation of antibiotic-containing wastewater. The specific steps of the application were as follows: wastewater containing 5 mg of sulfamethoxazole per liter was prepared, the pH was adjusted to 7, and 10 mg of the metal-doped composite catalyst (Co3O4-LaO2@BC) prepared in Example 1 and 400 mg of PMS were added to each liter of wastewater. The mixture was stirred magnetically at 800 rpm for 120 min.

[0060] Performance testing (1) Product characterization results Please see Figure 1 The image shows a SEM image of the metal-doped composite catalyst (i.e., Co-La2@BC) prepared in Example 1. SEM images from Example 1 demonstrate that, after the introduction of metallic La, the synthesized Co-La2@BC composite nanoparticles are uniformly dispersed on the surface of biochar. The introduction of La may have altered the pyrolysis behavior of the precursor or the surface energy of the metal particles, thereby inhibiting the aggregation of Co particles at high temperatures. The abundant oxygen-containing functional groups (such as -COOH, -OH) on the surface of biochar may bind with La and Co ions through coordination or electrostatic adsorption, forming dispersed nucleation sites.

[0061] Please see Figure 2 The XRD patterns of the metal-doped composite catalysts prepared in Examples 1, 2, and 3, and the pure Co@BC prepared in Comparative Example 1 are shown. The four catalysts prepared in Examples 1-3 and Comparative Example 1 all exhibited the diffraction peak characteristics of Co. The diffraction peaks of Co were located at 44.216°, 51.522° and 75.853°, respectively, corresponding to the (111), (200) and (220) crystal planes under JCPDS:15-0806.

[0062] Strong diffraction peaks of La2CO5 and La2O2CO3 were also detected in Co3O4-LaOx@BC (x=1,2,3). La2CO5 exhibited sharp diffraction peaks at 22.902°, 29.554°, 31.126°, and 44.599°, corresponding to the (101), (103), (110), and (200) crystal planes under JCPDS:23-0320, respectively. The characteristic peaks of La2O2CO3 were located at 25.779°, 30.346°, 33.875°, and 44.396°, belonging to the (101), (103), (104), and (110) crystal planes under JCPDS:37-0804, respectively. Therefore, this sample simultaneously possesses the crystal structures of La2CO5 and La2O2CO3.

[0063] (2) PMS synergistic metal-doped composite catalyst for antibiotic degradation Please see Figure 3 In Comparative Example 2, the pure Co@BC-ZIF prepared in Comparative Example 1 did not show very good results in the advanced oxidation degradation of SMX. In Examples 7-9, the metal-doped composite oxidants prepared in Examples 1-3 were doped with metallic La, which greatly improved the SMX degradation efficiency. In Example 7, the metal-doped composite oxidant prepared in Example 1, combined with persulfate, achieved a removal rate of 98.67% for sulfamethoxazole.

[0064] Please see Figure 4 PMS can effectively activate metal-doped composite oxidants, playing a good auxiliary role in the degradation of antibiotic pollutants. In Comparative Example 3, PMS alone hardly degraded SMX. In Comparative Example 4, the metal-doped composite catalyst (Co-La2@BC) prepared in Example 1 also could not effectively remove SMX through adsorption.

[0065] (3) Detection of antibiotic degradation performance at different PMS addition levels The amount of PMS added directly affects the SO4· in the reaction system. - The content of these substances affects the efficiency of advanced oxidation reactions. Please refer to [link / reference]. Figure 5 The system achieved the best degradation efficiency of 98.67% in the presence of 400 mg / L PMS. When the PMS concentration increased from 100 mg / L to 500 mg / L, the SMX degradation rate increased by approximately 31%. This can be attributed to the reaction of the added PMS with the catalyst to generate active species, leading to rapid SMX degradation. However, when the PMS dosage was further increased, the SMX degradation efficiency could not be further improved. This can be attributed to the excessive generation of ROS by excess PMS, leading to self-consumption.

[0066] (4) Detection of antibiotic degradation performance by adding different amounts of composite oxidants with different metal doping Please see Figure 6 When the dosage of the metal-doped composite oxidant was 5 mg (Example 14), 10 mg (Example 15), 20 mg (Example 7), and 30 mg (Example 16), the removal rates were 89.20%, 99.34%, 99.95%, and 99.95%, respectively. Since increasing the dosage of the metal-doped composite oxidant provides more active sites for pollutant removal and generates more free radicals to attack and destroy the SMX molecular structure, the pollutant removal rate increases with the increase of the catalyst dosage. However, excessive addition of catalyst material can lead to secondary environmental pollution. Considering both the performance and environmental friendliness of the catalyst, a catalyst dosage of 10 mg was used as the initial catalyst material dosage for subsequent experiments.

[0067] (4) Test on the performance of metal-doped composite oxidant in degrading antibiotics under different initial pollutant concentrations Please see Figure 7 As the SMX concentration in the solution increases, the removal rate gradually decreases. This is attributed to the fact that a fixed dosage of catalyst and oxidant cannot provide enough active sites and active groups. Furthermore, higher SMX concentrations result in intermediates that compete with SMX molecules for ROS consumption due to their smaller steric hindrance. Therefore, higher SMX dosages exacerbate the decrease in degradation rate.

[0068] (5) Degradation of antibiotics by metal-doped composite oxidants under different pH conditions in the reaction environment Please see Figure 8 When the initial pH of SMX was within the acidic range (pH=3 and pH=5), the degradation rate of SMX decreased to 87.38% and 91.02%, respectively. This is because H... + It has an inhibitory effect on the generated free radicals. However, when the pH of the initial SMX solution is further increased to 9 and 11, the degradation of SMX is extremely inhibited, due to the reaction of PMS and SO4• under alkaline conditions. – Will be OH − Consumption, (6) Cyclic stability Please see Figure 9 The reproducibility of the metal-doped composite oxidant / PMS system used in Example 15 was investigated. The removal rates of SMX within 120 min after five cycles were 98.9%, 93.6%, 90.1%, 86.7%, and 81.2%, respectively. Even after five cycles, the degradation rate of SMX remained high, indicating that the metal-doped composite oxidant retains good potential activity after repeated use. The decrease in removal efficiency can be attributed to the fact that SMX and intermediates covered the active sites on the surface of the metal-doped composite oxidant during the entire reaction process, causing slight structural damage to the material, as well as the loss of metal ions.

[0069] (7) Degradation performance of metal-doped composite oxidants for different pollutants Please see Figure 10 The degradation of tetracycline, levofloxacin, and methylene blue, such as Figure 10 As shown, metal-doped composite oxidants exhibit good degradation performance for other antibiotics and dyes.

[0070] Please see Figure 11 A visual representation of the degradation of methylene blue in Example 25.

[0071] Please see Figure 12 XRD characterization of the material after use in Example 25 showed that there was no significant difference in the characteristic peaks before and after catalyst use, confirming the cyclic stability of the catalyst.

[0072] (8) Leaching rate of Co ions The Co ion leaching amount of the metal-doped composite oxidant prepared in Example 1 in the metal-doped composite oxidant / PMS system was 0.318 mg / L; the Co ion leaching amount of the pure ZIF-67@BC prepared in Comparative Example 1 in the Co@BC / PMS system was 7.541 mg / L. This indicates that the strong solid-solid interaction in the composite material enhances stability and reduces the risk of ion leaching.

[0073] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing metal-doped composite catalysts based on ZIF-67, characterized in that, Includes the following steps: S1: Mix crop biomass powder, low-carbon alcohol, and cobalt salt, add a low-carbon alcohol solution containing imidazole derivatives, control the temperature at 10℃-50℃, let stand for 12h-48h, dry and grind to obtain ZIF-67 in-situ loaded biomass composite material. S2: ZIF-67 in-situ loaded biomass composite material is mixed and ground with rare earth metal salt to obtain mixed powder; S3: The mixed powder is placed in a tube furnace and pyrolyzed at high temperature under inert gas protection; after cooling to room temperature, it is washed with water until neutral and then dried to obtain the metal-doped composite catalyst.

2. The method for preparing metal-doped composite catalysts based on ZIF-67 according to claim 1, characterized in that, The preparation method of crop biomass powder includes the following steps: after washing the crop biomass, it is dried at 105℃-120℃ for 4h-6h, pulverized and passed through an 80-120 mesh sieve to obtain biomass powder.

3. The method for preparing metal-doped composite catalysts based on ZIF-67 according to claim 1, characterized in that, The lower alcohol is any one of methanol, ethanol or isopropanol; The cobalt salt is any one of Co(NO3)2·6H2O, CoSO4·7H2O or CoCl2·6H2O; The imidazole-containing derivative is any one of 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, or 2-ethylimidazole.

4. The method for preparing metal-doped composite catalysts based on ZIF-67 according to claim 1, characterized in that, The addition ratio of crop biomass powder, cobalt salt, and imidazole derivatives in S1 is 1-10g: 1-10mmol: 1-5mmol; The ratio of cobalt salt to lower alcohol in S1 is 1-10 mmol: 10-200 mL; In S1, the ratio of imidazole derivatives to low-carbon alcohols in the solution is 1-5 mmol: 10-200 mL.

5. The method for preparing metal-doped composite catalysts based on ZIF-67 according to claim 1, characterized in that, The rare earth metal salts are La(NO3)3·6H2O or Ce(NO3)3·6H2O; The mass ratio of the ZIF-67 in-situ supported biomass composite material to the rare earth metal salt is 1:1-5.

6. The method for preparing metal-doped composite catalysts based on ZIF-67 according to claim 1, characterized in that, The inert gas is one or more of nitrogen, helium, and argon mixed in any ratio; the specific steps of the high-temperature pyrolysis are as follows: heating to 500℃-900℃ at a heating rate of 2℃ / min-20℃ / min, and pyrolyzing at a constant temperature for 1h-5h.

7. The metal-doped composite catalyst prepared by the method according to any one of claims 1-6 is applied in the field of wastewater treatment, characterized in that, The metal-doped composite catalyst is used to degrade antibiotic-containing wastewater.

8. The application according to claim 7, characterized in that, The specific steps of the application are as follows: the metal-doped composite catalyst and persulfate are added to the wastewater containing antibiotics for degradation treatment; the content ratio of antibiotics, persulfate and metal-doped composite catalyst in each liter of wastewater is 3mg-50mg: 50mg-1000mg: 3mg-50mg.

9. The metal-doped composite catalyst prepared by the method according to any one of claims 1-6 is applied in the field of wastewater treatment, characterized in that, The metal-doped composite catalyst is used to degrade dye-containing wastewater.

10. The application according to claim 9, characterized in that, The specific steps of the application are as follows: the metal-doped composite catalyst and persulfate are added to the dye wastewater for degradation treatment; the content ratio of dye, persulfate and metal-doped composite catalyst in each liter of wastewater is 10mg-50mg: 100mg-500mg: 3mg-20mg.

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