Mn-Fe bimetallic magnetic coconut shell charcoal composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of water treatment materials, in particular to a Mn-Fe bimetallic magnetic coconut shell biochar composite material and a preparation method and application thereof. The invention discloses a Mn-Fe bimetallic magnetic coconut shell biochar composite material which is prepared from coconut shell biochar, soluble ferric iron salt and soluble divalent manganese salt, and experiments prove that the composite material provided by the invention is low in cost, wide in pH application range, good in degradation effect on antibiotics, recyclable and easy to prepare. The invention also provides a preparation method of the composite material, and the preparation method provided by the invention is simple to operate and has the potential of industrial production. The invention also provides application of the composite material in catalytic degradation of antibiotics, and experiments prove that the catalytic system has a wide application condition range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment materials, in particular, relates to a Mn-Fe bimetallic magnetic coconut shell biochar composite material and a preparation method and application thereof. BACKGROUND

[0002] Tetracycline antibiotics are a class of drugs that can effectively inhibit or kill a variety of pathogens and harmful microorganisms. With the continuous development of social economy, they are widely used in medical treatment, animal husbandry, aquaculture and agricultural production, and play an important role in the prevention and treatment of infectious diseases. Among them, oxytetracycline (OTC) is widely used due to its broad spectrum and low cost. However, in clinical and breeding industries, most antibiotics cannot be completely metabolized and absorbed by the human body and animals. According to statistics, more than 80% of antibiotics are excreted in the form of original drugs through the feces and urine of animals or humans, and enter the environment through various channels, causing pollution to soil and water, and thus posing a potential threat to the ecological system and human health. Therefore, it is urgent to develop an efficient and feasible method to solve the pollution problem caused by such antibiotics in the water environment.

[0003] Advanced oxidation processes (AOPs) are increasingly used in the degradation of organic pollutants in water, which mainly degrades organic pollutants through the generation of highly active and low selective free radicals. Among them, the photo-Fenton technology as an advanced oxidation process can effectively degrade organic pollutants by generating strong oxidizing hydroxyl radicals (·OH) through the reaction of photocatalyst and H2O2. It has the advantages of simple operation, mild reaction conditions, fast reaction speed, etc., and the generation rate of ·OH is fast and efficient. It has shown great potential in the field of wastewater treatment and is favored by researchers. Therefore, researchers have developed a variety of photo-Fenton catalysts and achieved significant degradation effects. For example, CN113134363A discloses a biochar catalyst for treating organic wastewater containing antibiotics; CN119215925A discloses a biochar-loaded bimetallic MnFeO2 heterogeneous Fenton-like catalyst. However, some materials still face some problems, including complex preparation process, high cost of raw materials, narrow pH range, poor stability of metal ions, and easy overflow of metal ions causing secondary pollution, thus increasing the difficulty of post-treatment. Therefore, it is difficult to apply in actual production, and it is urgent to develop new materials to solve these problems.

[0004] Biochar is a kind of carbon-rich material converted by high-temperature pyrolysis of biomass in an oxygen-free environment. It has low preparation cost, simple process and convenient operation, and the raw materials are cheap and easy to obtain. The material has a rich porous structure and various surface functional groups (such as -OH, C=O and -COOH, etc.). These structures and groups provide adsorption sites and coordination groups for metal ions, thereby significantly enhancing their adsorption capacity for metal ions and effectively inhibiting the overflow of metal ions. In addition, the functional composite material prepared by uniformly loading metal nanoparticles on the surface of biochar not only can reasonably disperse metal particles, optimize the pore structure, but also can significantly increase the number of active sites. Therefore, such materials have broad prospects in practical industrial applications.

[0005] In view of the above background, the applicant has carried out research in this regard in order to obtain a composite material with low cost, wide pH application range, good degradation effect on antibiotics and recyclable. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a Mn-Fe bimetallic magnetic coconut shell biochar composite material and a preparation method and application thereof.

[0007] To solve the above problems, the technical scheme adopted by the present application is: Technical subject one A preparation method of a Mn-Fe bimetallic magnetic coconut shell biochar composite material, comprising the following steps: S1: washing, drying, crushing, calcining at 300-550 DEG C for 3-6 h in a tube furnace, grinding and sieving the coconut shell biomass to obtain coconut shell biochar; S2: dispersing the coconut shell biochar treated above in distilled water, then dissolving soluble ferric salt and soluble manganese salt in the above system, then adding vitamin C, stirring for 25-35 min to make it uniformly dispersed, then adjusting the pH to 8.0-10.0, and stirring at 60-70 DEG C for 25-35 min to obtain a mixture, transferring the obtained mixture to a high-pressure reaction kettle, continuously heating at a temperature of 110-130 DEG C for 5-6 h, cooling, filtering, washing and drying the sample to obtain a composite material intermediate; S3: calcining the composite material intermediate obtained in S2 at 400-550 DEG C under a protective atmosphere for 1-4 h to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC; The mass ratio of the coconut shell biochar to the total mass of iron and manganese in the soluble ferric salt and the soluble manganese salt is 100:6-100:20; The molar ratio of Fe to Mn in the soluble ferric salt and the soluble manganese salt is 3-1:1-2; The molar ratio of the vitamin C to Fe in the soluble ferric salt is 0.8-1.2:1; The pulverizing step aims to process the coconut shell biomass into a size suitable for loading into a tube furnace quartz boat.

[0008] As a further improvement of the present application, the mass ratio of the coconut shell biochar in S2 to the total mass of iron and manganese elements in the soluble ferric salt and the soluble divalent manganese salt is 100:7.4; the molar ratio of Fe to Mn in the soluble ferric salt and the soluble divalent manganese salt in S2 is 1:1; the molar ratio of the vitamin C to Fe in the soluble ferric salt in S2 is 1:1.

[0009] As a further improvement of the present application, the sieving in S1 is through a 100-mesh sieve; the protective gas in S3 is one of nitrogen, helium, and argon.

[0010] As a further improvement of the present application, the calcination temperature in S1 is 500℃, and the calcination time is 5h; The calcination temperature in S3 is 500℃, and the calcination time is 3h.

[0011] As a further improvement of the present application, the mass-to-volume ratio of the coconut shell biochar to distilled water in S2 is 1g:13-40ml.

[0012] As a further improvement of the present application, the mass-to-volume ratio of the coconut shell biochar to distilled water in S2 is 1g:27ml; after adding the vitamin C, the mixture is stirred for 30 min to make it uniformly dispersed, then the pH is adjusted to 8.0, and the mixture is stirred at 60-70℃ for 30 min to obtain a mixture; the obtained mixture is transferred to a high-pressure reaction kettle, and heated at a temperature of 120℃ for 6h; after cooling, the sample is filtered, washed, and dried to obtain a composite material intermediate.

[0013] Technical subject two A Mn-Fe bimetallic magnetic coconut shell biochar composite material prepared according to the technical subject one.

[0014] Technical subject three The application of the Mn-Fe bimetallic magnetic coconut shell biochar composite material according to the technical subject two in catalytic degradation of antibiotics, specifically, the Mn-Fe bimetallic magnetic coconut shell biochar composite material is mixed with an antibiotic water body, hydrogen peroxide solution is added, and a photo-Fenton reaction is carried out under light and stirring conditions to complete the treatment of the antibiotic in the water body.

[0015] As a further improvement of the application, the antibiotic is oxytetracycline, the pH value of the antibiotic water body is 4, the antibiotic concentration in the water body is 100 mg / L, the dosing amount of the Mn-Fe bimetallic magnetic coconut shell biochar composite material is 0.2 g / L, and the concentration of hydrogen peroxide in the water body after dosing is 20.64 mmol / L.

[0016] As a further improvement of the application, the antibiotic is oxytetracycline, the pH value of the antibiotic water body is 4, the antibiotic concentration in the water body is 100 mg / L, the dosing amount of the Mn-Fe bimetallic magnetic coconut shell biochar composite material is 0.2 g / L, and the concentration of hydrogen peroxide in the water body after dosing is 20.64 mmol / L.

[0017] The beneficial effects produced by the above technical solution are as follows: The application provides a Mn-Fe bimetallic magnetic coconut shell biochar composite material, and experiments prove that the composite material has the advantages of low cost, wide pH application range, good antibiotic degradation effect, recyclability and easy preparation.

[0018] The application further provides a preparation method of the composite material, and the preparation method has the advantages of simple operation and potential for industrial production.

[0019] The application further provides an application of the composite material in catalytic degradation of antibiotics, and the application investigates the pH value of an antibiotic water body, the antibiotic concentration in the water body, the dosing amount of the Mn-Fe bimetallic magnetic coconut shell biochar composite material and the concentration of hydrogen peroxide in a mixed solution after dosing in the experiment of catalytic degradation of antibiotics by the composite material, and determines that the catalytic system has a wide range of applicable conditions. DETAILED DESCRIPTION

[0020] Figure 1 is a synthesis process schematic diagram of the Mn-Fe bimetallic magnetic coconut shell biochar composite material of the application; Figure 2 is a stability and reusability test diagram of the MnFe@CBC prepared in Example 1 of the application, and the columnar diagram and the numbers in the diagram represent OTC removal rates; Figure 3 is an N2 adsorption-desorption isotherm of the CBC and the MnFe@CBC prepared in Example 1 of the application; Figure 4 is a pore size distribution diagram of the CBC and the MnFe@CBC prepared in Example 1 of the application; Figure 5are X-ray diffraction patterns of CBC and MnFe@CBC prepared in Example 1 of the present application and MnFe@CBC recovered in Test Example 1, wherein (a) is CBC, (b) is MnFe@CBC, and (c) is recovered MnFe@CBC; Figure 6 is a magnetization curve of MnFe@CBC prepared in Example 1 of the present application; Figure 7 are infrared spectrograms of CBC and MnFe@CBC prepared in Example 1 of the present application and MnFe@CBC recovered in Test Example 1, wherein (a) is CBC, (b) is MnFe@CBC, and (c) is recovered MnFe@CBC; Figure 8 are XPS analysis diagrams of MnFe@CBC prepared in Example 1 of the present application and MnFe@CBC recovered in Test Example 1, wherein (a) is a total spectrum, (b) is C 1s, (c) is Fe 2p, and (d) is Mn 2p, Before represents MnFe@CBC prepared in Example 1 of the present application, and After represents MnFe@CBC recovered in Test Example 1; Figure 9 are micro-morphology characterization analysis diagrams of CBC and MnFe@CBC prepared in Example 1 of the present application, wherein (a) is a SEM diagram of CBC, (b) is a SEM diagram of MnFe@CBC, (c) is a distribution diagram of Fe element on the surface of MnFe@CBC, (d) is a distribution diagram of Mn element on the surface of MnFe@CBC, (e) is an EDS spectrum of MnFe@CBC, and (f) is an element mass and atomic ratio table of MnFe@CBC; Figure 10 is a purification efficiency diagram of terramycin under different pH conditions in Investigation Example 1; Figure 11 is a purification efficiency diagram of terramycin under different H2O2 concentrations in Investigation Example 2; Figure 12 is a purification efficiency diagram of terramycin under different MnFe@CBC dosages in Investigation Example 3; Figure 13 is a purification efficiency diagram of terramycin under different terramycin concentrations in Investigation Example 4; Figure 14 is a purification efficiency diagram of terramycin under different concentrations of Cl - in Investigation Example 5; Figure 15 is a purification efficiency diagram of terramycin under different molar ratios of iron and manganese in Investigation Example 7. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be described clearly and completely in combination with specific examples.

[0022] The synthesis process of the Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC in the present application is as shown in Figure 1

[0023] Example 1 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined at 500°C for 5h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0024] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonicated to uniformly disperse, then the pH was adjusted to 8.0 with 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, The resulting mixture was transferred to a high-pressure reaction kettle and heated at 120°C for 6h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0025] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3h under nitrogen protection to obtain the Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0026] Example 2 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined at 500°C for 5h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0027] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonicated to uniformly disperse, then the pH was adjusted to 8.0 with 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min,

[0028] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3h under nitrogen protection to obtain the Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.​

[0029] Example 3 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined in a tube furnace at 300°C for 6h, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0030] S2: The above-treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, followed by the addition of vitamin C (0.35 g), stirring for 30 min, and continuous ultrasonication to uniformly disperse the mixture. Then, the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirring was performed at 60-70°C for 30 min. The resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at a temperature of 120°C for 6h. After cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0031] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0032] Example 4 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined in a tube furnace at 550°C for 3h, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0033] S2: The above-treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (1.464 g) and MnSO4·H2O (0.915 g) were dissolved in the above system, followed by the addition of vitamin C (0.95 g), stirring for 30 min, and continuous ultrasonication to uniformly disperse the mixture. Then, the pH was adjusted to 10.0 with a 0.1 mol / L NaHCO3 solution, and stirring was performed at 60-70°C for 30 min. The resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at a temperature of 120°C for 6h. After cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0034] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0035] Example 5 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined in a tube furnace at 500°C for 5h, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0036] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.28 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 25 min, and the obtained mixture was transferred to a high-pressure reaction kettle and continuously heated at 110°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0037] S3: The composite intermediate obtained in S2 was calcined at 400°C for 4 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0038] Example 6 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0039] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.42 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 35 min, and the obtained mixture was transferred to a high-pressure reaction kettle and continuously heated at 130°C for 5 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0040] S3: The composite intermediate obtained in S2 was calcined at 550°C for 1 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0041] Comparative Example 1 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0042] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl2(0.25 g) and MnSO4.H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, and the resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0043] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0044] Comparative Example 2 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined in a tube furnace at 650°C for 5 h, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0045] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, and the resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0046] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0047] Comparative Example 3 S1: Coconut shell biomass was washed with water, dried, crushed, and calcined in a tube furnace at 200°C for 5 h, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0048] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, the obtained mixture was transferred to a high-pressure reaction kettle, and continuously heated at a temperature of 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0049] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0050] Comparative Example 4 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0051] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, the obtained mixture was transferred to a high-pressure reaction kettle, and continuously heated at a temperature of 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0052] S3: The composite intermediate obtained in S2 was calcined at 300°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0053] Comparative Example 5 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0054] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, the obtained mixture was transferred to a high-pressure reaction kettle, and continuously heated at 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0055] S3: The composite intermediate obtained in S2 was calcined at 650°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0056] Comparative Example 6 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0057] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, the obtained mixture was transferred to a high-pressure reaction kettle, and continuously heated at 80°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0058] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC.

[0059] Comparative Example 7 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100 mesh screen to obtain coconut shell biochar (CBC).

[0060] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.35 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, and the resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at 160°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0061] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0062] Comparative Example 8 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0063] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system, then vitamin C (0.18 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform, then the pH was adjusted to 8.0 with a 0.1 mol / L NaHCO3 solution, and stirred at 60-70°C for 30 min, and the resulting mixture was transferred to a high-pressure reaction kettle and continuously heated at 120°C for 6 h; after cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0064] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0065] Comparative Example 9 S1: Coconut shell biomass was washed with water, dried, crushed, calcined at 500°C for 5 h in a tube furnace, ground, and sieved through a 100-mesh screen to obtain coconut shell biochar (CBC).

[0066] S2: The above treated coconut shell biochar (3.0 g) was ultrasonically dispersed in 80 mL of distilled water, and then FeCl3·6H2O (0.54 g) and MnSO4·H2O (0.34 g) were dissolved in the above system. Subsequently, vitamin C (0.70 g) was added, stirred for 30 min, and continuously ultrasonically dispersed until uniform. Then, 0.1 mol / L NaHCO3 solution was used to adjust the pH to 8.0, and stirring was performed at 60-70°C for 30 min. The obtained mixture was transferred to a high-pressure reaction kettle, and continuously heated at a temperature of 120°C for 6 h. After cooling, the sample was filtered, washed, and dried to obtain a composite intermediate.

[0067] S3: The composite intermediate obtained in S2 was calcined at 500°C for 3 h under nitrogen protection to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite material MnFe@CBC.

[0068] Test Example 1 This test example is used to verify the recovery rate and reusability of the catalyst.

[0069] An electromagnet was installed around the simulated wastewater pool, and the specific verification implementation process was as follows: Under continuous stirring, 0.10 g of the MnFe@CBC catalyst material prepared in Example 1 was added to 500 mL of a 100 mg·L -1 OTC solution, and the pH of the solution was adjusted to 4 using 0.1 mol·L -1 NaOH or HCl solution. Then, 2 mL of H2O2 solution with a concentration of 5.16 mol·L -1 was added, and the solution was irradiated under a 500 W xenon light system for 80 min. The degradation rate was detected using HPLC. After the degradation was completed, the electromagnet was turned off, and the magnetic material was adsorbed on the inner wall of the degradation pool, completing the recycling process of the MnFe@CBC composite material. Continuous 5-time cycle photodegradation experiments were performed. There was no significant loss in the mass of the catalyst during the entire recycling process (recovery rate > 98%). The experimental results proved that the MnFe@CBC composite material exhibited good stability in the continuous 5-time cycle photodegradation experiments, and the removal rate of OTC was always more than 96%. The MnFe@CBC recovered after the fifth degradation was denoted as recycled MnFe@CBC. Figure 2

[0070] Test Example 2 The specific surface area and pore structure of the CBC and MnFe@CBC prepared in Example 1 were evaluated by N2 adsorption-desorption method.

[0071] The structural data of the obtained materials are shown in Table 1: ​ N2 adsorption isotherm ( Figure 3 ) and aperture distribution ( Figure 4 The figure shows that both samples possess microporous and mesoporous structures, and the N2 adsorption-desorption isotherm exhibits a typical type II isotherm mode. This result is consistent with... d BJH The data are consistent (Table 1). As can be seen from Table 1, the total specific surface area ( S BET ) and total pore volume ( V total A significant portion of the biochar's surface area can be attributed to the specific surface area and pore volume of micropores / mesopores, indicating that the CBC and MnFe@CBC prepared in this application possess abundant microporous / mesoporous properties. On the other hand, the BET specific surface area of ​​MnFe@CBC (337.1 m²·g⁻¹) is significantly increased compared to that of biochar CBC (228.5 m²·g⁻¹). Iron and manganese modification can effectively improve the specific surface area of ​​biochar.

[0072] Test Example 3 The CBC prepared in Example 1 was analyzed by X-ray diffraction (XRD). Figure 5 (a) and MnFe@CBC ( Figure 5 (b) Analysis was performed on MnFe@CBC at 2 θ Obvious diffraction peaks were observed at 18.07°, 30.62°, 36.05°, 43.72°, 54.12°, 57.72°, and 63.32°, corresponding to the (111), (220), (311), (400), (422), (511), and (440) crystal planes of the material, respectively. These peak positions showed good matching with spinel-type manganese ferrite crystals (MnFe2O4, JCPDS 10-0319) and iron(III) oxide crystals (Fe3O4, JCPDS19-0629). Therefore, based on the material preparation conditions, it can be inferred that the crystal structure of manganese and iron in the MnFe@CBC material is a mixed crystal structure composed of MnFe2O4 and Fe3O4. XRD characterization of the recovered MnFe@CBC in Test Example 1 ( Figure 5 (c) Compared to the original material, the diffraction pattern of the recovered MnFe@CBC catalyst material has a better peak position matching, indicating that the crystal structure of the material remained stable during the experiment and did not undergo significant changes, thus exhibiting good stability.

[0073] Test Example 4 The MnFe@CBC material prepared in Example 1 was subjected to VSM analysis at room temperature, and the results are as follows: Figure 6The hysteresis loop exhibits a symmetric "S" shape with two overlapping loops. It can be seen that the curve passes through the origin, the coercivity is zero, and there is no remanence phenomenon. As can be seen from the figure, the saturation magnetization (Ms) is about 21.5 emu·g⁻¹, which indicates that MnFe@CBC exhibits obvious paramagnetic properties at room temperature.

[0074] Test Example 5 The surface functional group structure of CBC and MnFe@CBC prepared in Example 1 was analyzed and identified by FTIR spectrum, and the results are shown in Figure 7 As can be seen from the figure, the spectrum has significant characteristic peaks at 3438, 3135, 2920, 1619, 1417, 1260 and 1127 cm⁻¹, which are respectively attributed to -OH, =C-H, C-H, C=O, C-O-C and C-O groups. By comparing the spectra of MnFe@CBC and CBC, it is found that the absorption peak at 3135 cm⁻¹ of MnFe@CBC indicates the existence of unsaturated bond C-H stretching vibration. At the same time, the increase of absorption peak intensity between 1576 cm⁻¹ and 1642 cm⁻¹ can be attributed to the stretching vibration of benzene ring, quinone group and cyclic structure. In addition, the absorption peak at 1260 cm⁻¹ is significantly enhanced, which further proves that the cyclic structure containing C-O-C in the material has increased. Therefore, considering the above factors, it can be speculated that a series of chemical isomerization reactions may occur in the preparation process of MnFe@CBC, including intramolecular or intermolecular dehydration of hydroxyl group, esterification of carboxyl group and cyclization and other complex reactions. In addition, the absorption peaks at 620 cm⁻¹ and 570 cm⁻¹ are significantly enhanced, indicating that Fe-O and Mn-O bonds are successfully formed in the process of double metal doping. The recovered MnFe@CBC in Test Example 1 was detected by FTIR spectrum, and the results showed that the FTIR spectrum of the recovered MnFe@CBC had high consistency with that of the original MnFe@CBC. This observation is consistent with the XRD analysis results, further proving that the functional group structure of the material did not change significantly during the experiment.

[0075] Test Example 6 The elements of MnFe@CBC prepared in Example 1 were analyzed by XPS spectrum, and the results are shown in Figure 8 (Before part) XPS spectrum shows the existence of C (284.5 eV), O (532.6 eV), Fe (711.9 eV) and Mn (643.8 eV) elements. As shown in Figure 8 b, four different C1s binding energy peaks were observed, located at 284.2, 284.9, 285.9 and 288.4 eV, corresponding to C-C, C=O, C-O and O=C-O groups, which is consistent with the FTIR spectrum Figure 1 . AsFigure 8 As shown in c, the Fe2p spectrum displays two distinct peaks, namely Fe2p 3 / 2 (711.9 eV) and Fe2p 1 / 2 (725.4 eV). Specifically, the binding energy of Fe(II) is at Fe2p. 3 / 2 The peak observed was 711.2 eV (50.8%), while the binding energy of Fe(III) appeared at 715.2 eV (49.2%). High-resolution XPS spectra of Mn2p in MnFe@CBC also showed Mn2p... 3 / 2 (642.9 eV) and Mn2p 1 / 2 (654.7eV) characteristic double peaks ( Figure 8 d). The three distinct peaks observed at binding energies of 642.4 eV (52.1%), 645.2 eV (38.5%), and 647.3 eV (9.4%) were attributed to different oxidation states of manganese: Mn(II), Mn(III), and Mn(IV). The MnFe@CBC recovered in Test Example 1 was characterized using XPS. Figure 8 (After section). The results show that the crystal structures of the two metals remained essentially unchanged, while the valence state of manganese underwent slight changes. Specifically, the proportion of Mn(II) decreased slightly, while the proportions of Mn(III) and Mn(IV) increased slightly, indicating that manganese plays a crucial role in the efficient degradation of OTC. Furthermore, the total amount of oxidized carbon species (such as C=O and CO) in the material increased significantly, while the fitted area ratio of -COOH decreased slightly.

[0076] Test Example 7 The morphology and surface elemental composition of the CBCs and MnFe@CBCs prepared in Example 1 were analyzed and characterized using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Figure 9 As shown in the scanning electron microscope image, some solid particles can be clearly seen attached to the surface of MnFe@CBC, exhibiting a crystalline flower-like structure. Figure 9 b), which makes its surface texture relatively rough, while the original CBC ( Figure 9 a) The surface is smooth and the pore structure is uniform. Furthermore, the elemental mapping image ( Figure 9 c and 9d) indicate that iron / manganese elements were successfully loaded onto the CBC surface and uniformly distributed. (Comparison) Figure 9 Based on c and 9d, it can be inferred that the distribution of iron and manganese elements is relatively consistent, indicating that they exist in combined form, which is consistent with the conclusions drawn from XRD analysis. Additionally, the energy spectrum of MnFe@CBC ( Figure 9 e) and the elemental proportion distribution table ( Figure 9f) The weight ratio and molar ratio of iron / manganese loaded to the surface of CBC are both close to 1:1, which is consistent with the amount of iron and manganese added during the preparation of the material.

[0077] Investigation Example 1 This investigation example is related to the comparison of purification efficiency under different pH values under dark conditions and under irradiation of a spotlight system during the implementation of the experiment, and the specific implementation process is as follows: Under continuous stirring, 0.10 g of MnFe@CBC prepared in Example 1 was added to 500 mL of a terramycin solution with a concentration of 100 mg·L -1 , and a 0.1 mol·L -1 NaOH or HCl solution was used to adjust the pH of the solution to 2, 4, 6, 7, and 9. The solution was stirred for 30 min (300 r / min) in the dark, and then 2 mL of a H2O2 solution with a concentration of 5.16 mol·L -1 was added. The solution was irradiated for 80 min under a 500 W xenon light system under the same stirring speed, and the implementation result data are shown in Table 2: The data in Table 2 show that (1) under different pH conditions, the degradation efficiency with the participation of the spotlight system is significantly higher than the purification efficiency without the participation of the spotlight system. (2) The comparison of the total purification efficiency under different pH values shows that the purification efficiency is best when the pH is 4.

[0078] Investigation Example 2 This investigation example is related to the comparison of purification efficiency under different H2O2 dosages under dark conditions and under irradiation of a spotlight system during the implementation of the experiment, and the specific implementation process is as follows: Under continuous stirring, 0.10 g of MnFe@CBC prepared in Example 1 was added to 500 mL of a terramycin solution with a concentration of 100 mg·L -1 , and a 0.1 mol·L -1 NaOH or HCl solution was used to adjust the pH of the solution to 4. The solution was stirred for 30 min (300 r / min) in the dark, and then 2 mL of a H2O2 solution with different concentrations of 1.29, 2.58, 5.16, and 10.32 mol·L -1 was added. At this time, the H2O2 concentration in the water body was 5.16, 10.32, 20.64, and 41.28 mmol·L -1 , respectively. The solution was irradiated for 80 min under a 500 W xenon light system under the same stirring speed, and the implementation result data are shown in Table 3: From the data in Table 3, it is shown that (1) under different H2O2 dosing conditions, the degradation efficiency with the light collection system is significantly higher than that without the light collection system. (2) The total purification efficiency of different H2O2 dosing amounts is compared, and it is found that although the concentration of H2O2 solution is 10.32 mol·L -1 , the purification efficiency is the best, however, compared with the dosing amount of 5.16 mol·L -1 , there is no significant increase. From the calculation of the cost of raw materials, the concentration of 5.16 mol·L -1 is relatively good.

[0079] Investigation Example 3 This investigation example is related to the purification efficiency comparison of different dosing amounts of MnFe@CBC catalytic materials under dark conditions and light collection system irradiation in the experimental implementation process, and the specific experimental process is as follows: Under continuous stirring, 0.02 g, 0.06 g, 0.10 g, 0.14 g and 0.20 g of MnFe@CBC catalyst material prepared in Example 1 were added to 500 mL, 100 mg·L -1 of terramycin solution, 0.1 mol·L -1 of NaOH or HCl solution was used to adjust the pH of the solution to 4, stirred in the dark for 30 min (300 r / min), then 2 mL of H2O2 solution with a concentration of 5.16 mol·L -1 was added, and under the same stirring speed, the light-Fenton reaction was carried out under 500 W xenon light system for 80 min, and the implementation result data is shown in Table 4: From the data in Table 4, it is shown that (1) under different MnFe@CBC catalyst material dosing conditions, the degradation efficiency with the light collection system is significantly higher than that without the light collection system. (2) The total purification efficiency of different MnFe@CBC catalyst material dosing amounts is compared, and it is found that the purification efficiency of 0.10 g MnFe@CBC catalyst material dosing is the best.

[0080] Investigation Example 4 This investigation example is related to the purification efficiency comparison of different concentrations of terramycin under dark conditions and light collection system irradiation in the experimental implementation process, and the specific implementation process is as follows: Under continuous stirring, 0.10 g of MnFe@CBC prepared in Example 1 was added to different concentrations of 25 mg·L -1 , 75 mg·L -1 , 100 mg·L -1 , 125 mg·L -1 , 150 mg·L -1, 500 mL terramycin solution, using 0.1 mol·L -1 NaOH or HCl solution to adjust the pH of the solution to 4, stirring in the dark for 30 min (300 r / min), then adding 2 mL of H2O2 solution with a concentration of 5.16 mol·L -1 , under the same stirring speed, under 500 W xenon light system for 80 min for photo-Fenton reaction, and the implementation result data are shown in Table 5: From the data in Table 5, (1) under the condition of different terramycin concentrations, the degradation efficiency with the participation of the light collection system is significantly higher than that without the light collection system. (2) When the terramycin concentration is different, it is found that the total purification efficiency is best when the terramycin concentration is 100 mg·L -1 .

[0081] Investigation Example 5 In the actual wastewater of agriculture or medicine, some common anions often coexist, which may affect the efficiency of photocatalytic reaction. In this embodiment, Cl - is taken as an example. In the experimental implementation process, the influence of terramycin purification efficiency under the conditions of no interfering ions and different concentrations of chloride ions under dark conditions and under light collection system irradiation is compared, and the specific implementation process is as follows: Under continuous stirring, 0.10 g of MnFe@CBC prepared in Example 1 was added to 500 mL of 100 mg·L -1 terramycin solution with different chloride ion concentrations of 0 mmol·L -1 , 1 mmol·L -1 , 5 mmol·L -1 , 10 mmol·L -1 , using 0.1 mol·L -1 NaOH or HCl solution to adjust the pH of the solution to 4, stirring in the dark for 30 min (300 r / min), then adding 2 mL of H2O2 solution with a concentration of 5.16 mol·L -1 , under the same stirring speed, under 500 W xenon light system for 80 min for photo-Fenton reaction, and the implementation result data are shown in Table 6: From the data in Table 6, when the concentration of chloride ions is low (<1 mmol·L -1 ), the degradation efficiency is slightly lower than that of the purification reaction without the participation of chloride ions, but the influence is not too great.

[0082] Investigation Example 6 With the method and conditions described in Example 1, the molar amounts of iron and manganese elements are kept constant, and the soluble ferric salt and soluble manganese salt are replaced and screened, the soluble ferric salt is selected from FeCl3, Fe2(SO4)3, and the soluble manganese salt is selected from MnCl2, MnSO4, MnAc2, to prepare MnFe@CBC materials, and compare the purification efficiency of these materials on terramycin.

[0083] After combination, MnFe@CBC-CC, MnFe@CBC-SC, MnFe@CBC-AC, MnFe@CBC-SS, and MnFe@CBC-AS are obtained.

[0084] Note: In MnFe@CBC-AB, A is the first letter of the anion of the manganese salt, and B is the first letter of the anion of the iron salt. Specifically, C represents Cl, S represents SO4, and A represents Ac.

[0085] Under continuous stirring, 0.10 g of the five different modified biochar materials prepared above was added into 100 mg·L -1 of terramycin solution, 500 mL, and 0.1 mol·L -1 of NaOH or HCl solution was used to adjust the pH of the solution to 4, and the solution was stirred in the dark for 30 min (300 r / min), then 2 mL of 5.16 mol·L -1 of H2O2 solution was added, and the same stirring speed was used for the light-Fenton reaction under 500 W xenon light for 80 min. The implementation result data are shown in Table 7: As shown in Table 7, the light-Fenton purification effect of different FeMn acid modified biochar on terramycin showed no significant difference. During the preparation of the materials, most of the anions were washed away during the washing process, which had little effect on the later light-Fenton degradation.

[0086] Investigation Example 7 With the method and conditions described in Example 1, the molar ratio of vitamin C to iron element was kept at 1:1, and the mass ratio of coconut shell biochar to iron and manganese elements was kept constant, and the amount of FeCl3·6H2O and MnSO4·H2O was adjusted to investigate and screen the molar ratio of iron element to manganese element, to prepare MnFe@CBC materials, and compare the purification efficiency of these materials on terramycin.

[0087] The ratio is 1:1, 1:2, 1:3, 3:1, 2:1, to obtain biochar materials with different molar ratios of iron and manganese salts, which are denoted as Fe:Mn = 1:1, 1:2, 1:3, 3:1, and 2:1.

[0088] Under continuous stirring, 0.10 g of the five different metal ratio modified biochar materials prepared above were added into 500 mL oxytetracycline solution with a concentration of 100 mg / L, and the pH of the solution was adjusted to 4 using 0.1 mol / L NaOH or HCl solution, and stirred in the dark for 30 min (300 r / min), then 2 mL of H2O2 solution with a concentration of 5.16 mol / L was added, and the light-Fenton reaction was carried out under 500 W xenon light system for 80 min under the same stirring speed, and the implementation result data are shown in Table 8: The data in Table 8 show that different Fe / Mn ratios have certain effects on the modified biochar and its crystal structure, resulting in certain differences in the light-Fenton purification effect of oxytetracycline, and the optimal ratio is Fe:Mn = 1:1.

[0089] Investigation Example 8 MnFe@CBC prepared in Examples 1-6 was taken to investigate the application range of the preparation conditions of MnFe@CBC.

[0090] Under continuous stirring, 0.10 g of the five different metal ratio modified biochar materials prepared above were added into 500 mL oxytetracycline solution with a concentration of 100 mg / L, and the pH of the solution was adjusted to 4 using 0.1 mol / L NaOH or HCl solution, and stirred in the dark for 30 min (300 r / min), then 2 mL of H2O2 solution with a concentration of 5.16 mol / L was added, and the light-Fenton reaction was carried out under 500 W xenon light system for 80 min under the same stirring speed, and the implementation result data are shown in Table 8: As can be seen from the data in Table 9, the MnFe@CBC material prepared according to the method of Example 1 shows the best purification effect on oxytetracycline. In comparison, slight changes in other example conditions, such as the calcination temperature and time in S1 / S3, the iron and manganese content and the vitamin C dosage, the hydrothermal reaction temperature and time, and other process parameters, do not significantly change the purification performance of the MnFe@CBC material on oxytetracycline.

[0091] Investigation Example 9 The biomass material was screened according to the method and conditions described in Example 1, the only difference being that walnut skin, peanut shell, and oak wood chips were used instead of coconut shell to prepare the carbon material, and the purification efficiency of these materials on oxytetracycline was compared.

[0092] The carbon materials prepared under the above conditions are designated as MnFe@WBC (walnut shell), MnFe@PBC (peanut shell), and MnFe@OBC (oak chips), respectively, and are compared with MnFe@CBC prepared in Example 1.

[0093] Under continuous stirring, 0.10 g of the four different modified biochar materials prepared above were added to a solution with a concentration of 100 mg·L⁻¹. -1 In 500 mL of oxytetracycline solution, using 0.1 mol·L⁻¹ -1 Adjust the pH of the solution to 4 with NaOH or HCl solution, stir in the dark for 30 min (300 r / min), and then add a solution with a concentration of 5.16 mol·L⁻¹. -1 Two mL of H₂O₂ solution was used, and under the same stirring speed, a photo-Fenton reaction was carried out under a 500 W xenon light system for 80 min of illumination. The results are shown in Table 10. The data in Table 10 show that the photo-Fenton purification effect of MnFe on biochar made from different biomass materials varies significantly, with MnFe@CBC showing the best effect (98.5%).

[0094] Examining Example 10 Using the method and conditions described in Example 1, the selection of vitamin C was screened, and vitamin C was replaced with other reducing agents such as glucose (0.36 g), oxalic acid (0.18 g), and lactic acid (0.18 g) in equal molar amounts to prepare MnFe@CBC materials. The purification efficiency of these materials for oxytetracycline was compared.

[0095] Under continuous stirring, 0.10 g of the four different modified biochar materials prepared above were added to a solution with a concentration of 100 mg·L⁻¹. -1 In 500 mL of oxytetracycline solution, using 0.1 mol·L⁻¹ -1 Adjust the pH of the solution to 4 with NaOH or HCl solution, stir in the dark for 30 min (300 r / min), and then add a solution with a concentration of 5.16 mol·L⁻¹. -1 Two mL of H₂O₂ solution was used, and under the same stirring speed, a photo-Fenton reaction was carried out under a 500 W xenon light system for 80 min of illumination. The results are shown in Table 11. The data in Table 11 show that different reducing agents may affect the structure of FeMn modified biochar. Comparing the photo-Fenton purification effect of oxytetracycline, the total purification efficiency shows a significant difference.

[0096] Investigation Example 11 The MnFe@CBC prepared in Example 1 and Comparative Examples 1-9 was used to investigate the scope of application of the preparation conditions of MnFe@CBC.

[0097] Under continuous stirring, 0.10 g of the MnFe@CBC composite material prepared in Example 1 and Comparative Examples 1-9 was added into a 500 mL oxytetracycline solution with a concentration of 100 mg / L, and a 0.1 mol / L NaOH or HCl solution was used to adjust the pH of the solution to 4. The solution was stirred in the dark for 30 min (300 r / min), and then 2 mL of a H2O2 solution with a concentration of 5.16 mol / L was added. The solution was irradiated for 80 min under a 500 W xenon light system under the same stirring speed, to perform a photo-Fenton reaction. The implementation results are shown in Table 12: As can be seen from the data in Table 12, the MnFe@CBC material prepared by the method of Example 1 exhibits the best purification effect on oxytetracycline. In contrast, in each of the comparative examples, the experimental conditions were greatly changed, such as the use of divalent iron salt, the adjustment of calcination or calcination temperature, the hydrothermal reaction temperature, and the dosage of vitamin C, which all had a significant impact on the texture characteristics of CBC and the surface crystal structure of MnFe@CBC, and thus affected the purification performance of the material to varying degrees.

[0098] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a Mn-Fe bimetallic magnetic coconut shell biochar composite material, characterized in that, The method comprises the following steps: S1: washing, drying, crushing, roasting at 300-550 ℃ for 3-6 h in a tube furnace, grinding, and sieving the coconut shell biomass to obtain coconut shell biochar; S2: dispersing the coconut shell biochar obtained in step S1 in distilled water, dissolving soluble ferric salt and soluble manganese salt in the system, then adding vitamin C, stirring for 25-35 min to disperse uniformly, adjusting the pH to 8.0-10.0, and stirring at 60-70 ℃ for 25-35 min to obtain a mixture, transferring the mixture into a high-pressure reaction kettle, and continuously heating at 110-130 ℃ for 5-6 h, then cooling, filtering, washing, and drying the sample to obtain a composite intermediate; S3: roasting the composite intermediate obtained in step S2 at 400-550 ℃ for 1-4 h under a protective gas to obtain a Mn-Fe bimetallic magnetic coconut shell biochar composite MnFe@CBC; The mass ratio of the coconut shell biochar to the total mass of iron and manganese in the soluble ferric salt and the soluble manganese salt is 100:6-100:20; The molar ratio of Fe to Mn in the soluble ferric salt and the soluble manganese salt is 3-1:1-2; The molar ratio of vitamin C to Fe in the soluble ferric salt is 0.8-1.2:

1.

2. The production method according to claim 1, characterized by, In step S2, the mass ratio of the coconut shell biochar to the total mass of iron and manganese in the soluble ferric salt and the soluble manganese salt is 100:7.4; the molar ratio of Fe to Mn in the soluble ferric salt and the soluble manganese salt is 1:1; and the molar ratio of vitamin C to Fe in the soluble ferric salt is 1:

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the sieving is performed through a 100-mesh sieve; and in step S3, the protective gas is one of nitrogen, helium, and argon.

4. The production method according to claim 1, characterized by, In step S1, the roasting temperature is 500 ℃, and the roasting time is 5 h; and in step S3, the roasting temperature is 500 ℃, and the roasting time is 3 h.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass-to-volume ratio of the coconut shell biochar to distilled water is 1 g:13-40 ml.

6. The method of claim 1, wherein, In step S2, the mass-to-volume ratio of the coconut shell biochar to distilled water is 1 g:27 ml; after adding vitamin C, the mixture is stirred for 30 min to disperse uniformly, then the pH is adjusted to 8.0, and the mixture is stirred at 60-70 ℃ for 30 min to obtain a mixture; the mixture is transferred into a high-pressure reaction kettle, and continuously heated at 120 ℃ for 6 h; after cooling, the sample is filtered, washed, and dried to obtain a composite intermediate.

7. A Mn-Fe bimetallic magnetic coconut shell biochar composite prepared by the method of any one of claims 1-6.

8. Use of the Mn-Fe bimetallic magnetic coconut shell biochar composite material according to claim 7 for catalytic degradation of antibiotics, characterized in that, The Mn-Fe bimetallic magnetic coconut shell biochar composite is mixed with an antibiotic water body, hydrogen peroxide solution is added, and a photo-Fenton reaction is performed under light and stirring to complete the treatment of antibiotics in the water body.

9. Use according to claim 8, characterized in that, The antibiotic is a tetracycline antibiotic, the pH value of the antibiotic water body is 2-6, the antibiotic concentration in the water body is 25-150 mg / L, the dosing amount of the Mn-Fe bimetallic magnetic coconut biochar composite material is 0.12-0.40 g / L, and the hydrogen peroxide concentration in the water body after dosing is 10.32-41.28 mmol / L.

10. Use according to claim 8, characterized in that, The antibiotic is oxytetracycline, the pH value of the antibiotic water body is 4, the antibiotic concentration in the water body is 100 mg / L, the dosing amount of the Mn-Fe bimetallic magnetic coconut biochar composite material is 0.2 g / L, and the hydrogen peroxide concentration in the water body after dosing is 20.64 mmol / L.

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