An activated carbon-loaded manganese and tungsten oxide particle electrode and its preparation method and application

Abstract

The present invention discloses an activated carbon-supported manganese and tungsten oxide particle electrode, its preparation method, and application, belonging to the field of organic wastewater treatment technology. The particle electrode is composed of activated carbon and manganese dioxide and tungsten trioxide supported on the activated carbon, wherein the mass fraction of the activated carbon is 74-80%, the mass fraction of the manganese dioxide is 15-25%, and the mass fraction of the tungsten trioxide is 0.1-1.5%. The preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode comprises: surface treatment of the activated carbon, loading of tungsten trioxide, loading of manganese dioxide, and calcination of the oxides. The particle electrode material produced by the present method has a large specific surface area and strong adsorption capacity, is simple to prepare, and has a simple process. It can efficiently degrade wastewater containing sulfonamide antibiotics, with its degradation efficiency significantly improved compared to activated carbon electrodes.

Description

Technical Field

[0001] The present invention relates to the technical field of organic wastewater treatment, and in particular to an activated carbon-loaded manganese and tungsten oxide particle electrode, a preparation method and application thereof. Background Art

[0002] Aquaculture wastewater contains large amounts of antibiotics, which are difficult to treat and not easily degraded. Improper handling can threaten the biodiversity and function of adjacent ecosystems, as well as human health. Sulfonamides, a class of antimicrobial drugs widely used in aquaculture, have a p-aminobenzenesulfonamide structure and are highly effective and have a broad antimicrobial spectrum. They are often used to prevent and treat bacterial infections. However, sulfonamides are difficult to degrade and are used in large quantities. Therefore, preventing and controlling their pollution is crucial for food safety and the protection of aquatic environments.

[0003] Among existing antibiotic wastewater treatment methods, electrochemical oxidation technology is gaining increasing attention due to its advantages such as high efficiency, cleanliness, ease of operation, and environmental compatibility. Electrochemical oxidation technology effectively degrades most organic pollutants in water by directly or indirectly generating reactive oxygen species through catalytic electrode reactions. Compared to traditional two-dimensional electrodes, three-dimensional electrodes utilize a third electrode filled with granular or other debris-like particles between the anode and cathode. This structure increases the specific surface area for the reaction, improves electrolysis efficiency, and achieves efficient removal of pollutants. The core of the three-dimensional electrode is the particle electrode, which directly affects its effectiveness in degrading organic matter in wastewater.

[0004] Manganese dioxide is considered to be one of the most promising electrode materials due to its abundant, low-cost, safe and environmentally friendly, and high theoretical specific capacitance. However, manganese dioxide has poor conductivity, and is usually enhanced by compounding or doping with other elements. For example, Chen Jixi et al. used the impregnation thermal reduction method to prepare activated carbon particle electrodes loaded with manganese dioxide to treat printing and dyeing wastewater (Chen Jixi, Xiao Xiaoyu, Wang Yongfeng. Preparation of MnO2 / AC particle electrodes and experimental study on treatment of printing and dyeing wastewater. [J] Energy and Environmental Protection. 2022.036(004):65-71). Chinese patent document with publication number CN105481063A discloses a particle electrode for treating difficult-to-degrade organic wastewater. The particle electrode is composed of modified activated carbon and manganese oxide, cobalt oxide and cerium oxide supported on the modified activated carbon. Tests have shown that the addition of cobalt and cerium oxides improves the catalytic degradation performance of the particle electrode in degrading methylene blue. Chinese patent document with publication number CN114249391A discloses a particle electrode with nickel phosphate supported on an activated carbon column. The particle electrode can be used to treat wastewater containing organic pollutants such as humic acid and methyl orange.

[0005] Therefore, preparing a modified manganese dioxide particle electrode that can safely and efficiently remove antibiotics from wastewater is of great significance to improving the removal efficiency of antibiotics. Summary of the Invention

[0006] The present invention provides a method for preparing activated carbon-loaded manganese and tungsten oxide particle electrodes. The process is simple and the raw materials used are from a wide range of sources. The prepared particle electrodes have a porous morphology, a large specific surface area, strong adsorption capacity, and good catalytic performance, and can achieve efficient removal of antibiotics in wastewater.

[0007] The specific technical solutions adopted are as follows:

[0008] A method for preparing an activated carbon-supported manganese and tungsten oxide particle electrode comprises the following steps:

[0009] (1) Pre-treating the activated carbon; the pre-treatment steps include water washing and acid washing;

[0010] (2) Using pretreated activated carbon as raw material, mixing it with ethylene glycol, and obtaining an activated carbon ethylene glycol solution after ultrasonic dispersion;

[0011] (3) Mix the sodium tungstate solution and the activated carbon ethylene glycol solution, add hydrochloric acid dropwise while stirring under heating conditions, separate the solid and liquid, wash the solid phase, dry it and set aside;

[0012] (4) soaking the solid phase dried in step (3) in a manganese nitrate solution for at least 12 hours, taking it out and drying it, and further calcining it to obtain a particle electrode precursor;

[0013] (5) Using the particle electrode precursor in step (4) as a raw material, repeat steps (2), (3) and (4) at least twice, and further calcining the obtained product to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0014] The present invention uses activated carbon as a carrier and adopts a specific method to load manganese dioxide and tungsten trioxide onto the surface of the activated carbon. The liquid phase method can be used to load nano-scale tungsten trioxide with fine particles and large specific surface area on the activated carbon. The impregnation method is used to load metal oxides, which is simple to operate and has obvious effects. In addition, a particle electrode with a porous morphology, a large specific surface area, strong adsorption capacity and good catalytic performance is prepared.

[0015] Preferably, in step (1), the particle size of the activated carbon is 0.4 to 0.8 mm, the activated carbon is soaked in hydrochloric acid for 24 to 26 hours to complete the pickling step, and then dried after pickling; the molar concentration of the hydrochloric acid is 0.1 to 0.3 mol / L.

[0016] In step (2), ethylene glycol acts as a surfactant, allowing the activated carbon to be fully dispersed in the ethylene glycol solution, thereby facilitating the loading of the metal oxide; in the activated carbon ethylene glycol solution, the mass concentration of the activated carbon is 4 to 8 wt%.

[0017] In step (3), the molar concentration of the sodium tungstate solution is 0.0016-0.078 mol / L, and the volume ratio of the sodium tungstate solution to the activated carbon ethylene glycol solution is 0.8-1:1; under the condition of 110-130° C., hydrochloric acid is added dropwise while stirring, and stirring is continued until the reaction is complete, and then the solid phase is separated by suction filtration.

[0018] In step (4), the concentration of the manganese nitrate solution is 1-2 mol / L.

[0019] In step (4), the calcination conditions are 200-300° C. and calcination time is 2-3 hours.

[0020] In step (5), the calcination conditions are: in a nitrogen atmosphere, the temperature is increased to 650-750° C. at a heating rate of 5-10° C. / min, and calcined for 2-3 hours.

[0021] In step (5), steps (2), (3) and (4) are repeated three times. Repeating the steps three times can ensure the loading amount of the metal oxide and the preparation efficiency of the product particle electrode.

[0022] The present invention also provides an activated carbon-loaded manganese and tungsten oxide particle electrode prepared by the preparation method of the activated carbon-loaded manganese and tungsten oxide particle electrode. The activated carbon-loaded manganese and tungsten oxide particle electrode comprises activated carbon and manganese dioxide and tungsten trioxide loaded on the activated carbon, wherein the mass fraction of the activated carbon is 74-80%, the mass fraction of the manganese dioxide is 15-25%, and the mass fraction of the tungsten trioxide is 0.1-1.5%.

[0023] The present invention also provides application of the activated carbon-loaded manganese and tungsten oxide particle electrode in treating wastewater containing antibiotics.

[0024] The antibiotic is a sulfonamide, more preferably sulfamethoxazole. Experiments have shown that the activated carbon-supported manganese and tungsten oxide particle electrodes of the present invention can efficiently degrade sulfamethoxazole in wastewater.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention uses activated carbon with a large specific surface area and strong adsorption capacity as a carrier, and adopts a specific method to load manganese dioxide and tungsten trioxide onto the surface of the activated carbon. The advantages of manganese dioxide and tungsten trioxide in conductivity and electrocatalysis are utilized to enhance the electrochemical performance and chemical stability of the product particle electrode, thereby providing an activated carbon-loaded manganese and tungsten oxide particle electrode with good degradation effect on wastewater containing antibiotics.

[0027] (2) The present invention adopts multiple impregnation and heat treatment methods to prepare activated carbon-loaded manganese and tungsten oxide particle electrodes. Multiple impregnation helps to increase the metal oxide loading. The prepared particle electrode has a porous morphology, a large specific surface area, strong adsorption capacity, and good catalytic performance. It increases the specific surface area of ​​the reaction and improves the reaction rate of the electrode. It can efficiently degrade wastewater containing antibiotics. The degradation efficiency is significantly improved compared with that of the activated carbon electrode, and the degradation rate of sulfamethoxazole reaches 4.60mmol / h·kg.

[0028] (3) The preparation method of the carbon-loaded manganese and tungsten oxide particle electrode provided by the present invention is simple and easy, with a simple process and technology, and the raw materials used are widely available. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD pattern of the activated carbon-supported manganese and tungsten oxide particle electrode prepared in Example 2.

[0030] Figure 2 This is the SEM image of the activated carbon-supported manganese and tungsten oxide particle electrode prepared in Example 2. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0032] In the examples and comparative examples, the particle size of the activated carbon used was 0.4 to 0.8 mm.

[0033] Example 1

[0034] In this embodiment, the preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode includes the following steps:

[0035] (1) Pretreatment of activated carbon: After washing the activated carbon with water, soak it in 0.1 mol / L hydrochloric acid for 24 hours, separate it, and dry it at 110°C for 12 hours before use;

[0036] (2) using the activated carbon pretreated in step (1) as a raw material, adding it to ethylene glycol to form a mixed solution, placing the mixed solution in an ultrasonic cleaner for ultrasonic dispersion to obtain an activated carbon ethylene glycol solution with an activated carbon mass concentration of 4 wt%;

[0037] (3) Add 80 mL of 0.0016 mol / L sodium tungstate solution to 100 mL of activated carbon ethylene glycol solution. Add 4 mL of 2 mol / L hydrochloric acid dropwise while stirring at 120°C. Continue stirring for 4 hours and then filter to separate the solid phase. Wash the solid phase several times with distilled water and ethanol, respectively, and dry it for later use.

[0038] (4) Soaking the solid phase dried in step (3) in a 1.5 mol / L manganese nitrate solution for 12 hours, taking it out, drying it at 110° C. for 4 hours, and then heating it to 200° C. at a heating rate of 5° C. / min for 2 hours to obtain a particle electrode precursor;

[0039] (5) The particle electrode precursor in step (4) is used as a raw material, added to ethylene glycol to form a mixed solution, and steps (2), (3) and (4) are repeated three times. The mixture is then calcined from room temperature to 700°C at a heating rate of 10°C / min under a nitrogen atmosphere for 2 hours to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0040] In the activated carbon-supported manganese and tungsten oxide particle electrode prepared in this embodiment, the mass fraction of activated carbon is 79.9%, the mass fraction of manganese dioxide is 20%, and the mass fraction of tungsten trioxide is 0.1%.

[0041] The prepared activated carbon-loaded manganese and tungsten oxide particle electrodes were applied in a three-dimensional electrode reactor. The anode and cathode were titanium mesh electrodes and manganese dioxide electrodes, respectively. The molar concentration of the electrolyte sodium sulfate was 0.05 mol / L, the concentration of sulfamethoxazole was 10-100 mg / L, and the current density was 5-10 mA / cm 2 The plate spacing is 4.5 cm, the degradation rate of sulfamethoxazole is 2.50-3.00 mmol / h·kg, and the degradation rate of sulfamethoxazole can reach 52.5% within 3 hours.

[0042] Example 2

[0043] In this embodiment, the preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode includes the following steps:

[0044] (1) Pretreatment of activated carbon: After washing the activated carbon with water, soak it in 0.1 mol / L hydrochloric acid for 24 hours, separate it, and dry it at 110°C for 12 hours before use;

[0045] (2) using the activated carbon pretreated in step (1) as a raw material, adding it to ethylene glycol to form a mixed solution, placing the mixed solution in an ultrasonic cleaner for ultrasonic dispersion to obtain an activated carbon ethylene glycol solution with an activated carbon mass concentration of 5 wt%;

[0046] (3) Add 100 mL of 0.0016 mol / L sodium tungstate solution to 100 mL of activated carbon ethylene glycol solution. Add 4 mL of 2 mol / L hydrochloric acid dropwise while stirring at 120°C. Continue stirring for 4 hours and then filter to separate the solid phase. Wash the solid phase several times with distilled water and ethanol, respectively, and dry it for later use.

[0047] (4) Soaking the solid phase dried in step (3) in a 1.5 mol / L manganese nitrate solution for 12 hours, taking it out, drying it at 110° C. for 4 hours, and then heating it to 200° C. at a heating rate of 5° C. / min for 2 hours to obtain a particle electrode precursor;

[0048] (5) The particle electrode precursor in step (4) is used as a raw material, added to ethylene glycol to form a mixed solution, and steps (2), (3) and (4) are repeated three times. The mixture is then calcined from room temperature to 700°C at a heating rate of 10°C / min under a nitrogen atmosphere for 2 hours to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0049] In the activated carbon-supported manganese and tungsten oxide particle electrode prepared in this embodiment, the mass fraction of activated carbon is 78.2%, the mass fraction of manganese dioxide is 21%, and the mass fraction of tungsten trioxide is 0.8%. The XRD test results of the particle electrode are as follows: Figure 1 As shown, it proves that manganese dioxide and tungsten trioxide are successfully loaded on activated carbon. The SEM surface morphology is as follows Figure 2 As shown, it can be seen that the particle electrode has a porous morphology and the oxide is evenly loaded on the activated carbon.

[0050] The prepared activated carbon-loaded manganese and tungsten oxide particle electrodes were applied in a three-dimensional electrode reactor. The anode and cathode were titanium mesh electrodes and manganese dioxide electrodes, respectively. The molar concentration of the electrolyte sodium sulfate was 0.05 mol / L, the concentration of sulfamethoxazole was 10-100 mg / L, and the current density was 5-10 mA / cm 2 The plate spacing is 4.5 cm, the degradation rate of sulfamethoxazole is 4.00-4.60 mmol / h·kg, and the degradation rate of sulfamethoxazole can reach 88.9% within 3 hours.

[0051] Example 3

[0052] In this embodiment, the preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode includes the following steps:

[0053] (1) Pretreatment of activated carbon: After washing the activated carbon with water, soak it in 0.1 mol / L hydrochloric acid for 24 hours, separate it, and dry it at 110°C for 12 hours before use;

[0054] (2) using the activated carbon pretreated in step (1) as a raw material, adding it to ethylene glycol to form a mixed solution, placing the mixed solution in an ultrasonic cleaner for ultrasonic dispersion to obtain an activated carbon ethylene glycol solution with an activated carbon mass concentration of 8 wt%;

[0055] (3) Add 90 mL of 0.047 mol / L sodium tungstate solution to 100 mL of activated carbon ethylene glycol solution. Add 4 mL of 2 mol / L hydrochloric acid dropwise while stirring at 120°C. Continue stirring for 4 hours and then filter to separate the solid phase. Wash the solid phase several times with distilled water and ethanol, respectively, and dry it for later use.

[0056] (4) Soaking the solid phase dried in step (3) in a 1.5 mol / L manganese nitrate solution for 12 hours, taking it out, drying it at 110° C. for 4 hours, and then heating it to 200° C. at a heating rate of 5° C. / min for 2 hours to obtain a particle electrode precursor;

[0057] (5) The particle electrode precursor in step (4) is used as a raw material, added to ethylene glycol to form a mixed solution, and steps (2), (3) and (4) are repeated three times. The mixture is then calcined from room temperature to 700°C at a heating rate of 10°C / min under a nitrogen atmosphere for 3 hours to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0058] In the activated carbon-supported manganese and tungsten oxide particle electrode prepared in this embodiment, the mass fraction of activated carbon is 80%, the mass fraction of manganese dioxide is 19%, and the mass fraction of tungsten trioxide is 1%.

[0059] The prepared activated carbon-loaded manganese and tungsten oxide particle electrodes were applied in a three-dimensional electrode reactor. The anode and cathode were titanium mesh electrodes and manganese dioxide electrodes, respectively. The molar concentration of the electrolyte sodium sulfate was 0.05 mol / L, the concentration of sulfamethoxazole was 10-100 mg / L, and the current density was 5-10 mA / cm 2 The plate spacing is 4.5 cm, the degradation rate of sulfamethoxazole is 2.80-3.00 mmol / h·kg, and the degradation rate of sulfamethoxazole can reach 57.7% within 3 hours.

[0060] Example 4

[0061] In this embodiment, the preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode includes the following steps:

[0062] (1) Pretreatment of activated carbon: After washing the activated carbon with water, soak it in 0.1 mol / L hydrochloric acid for 24 hours, separate it, and dry it at 110°C for 12 hours before use;

[0063] (2) using the activated carbon pretreated in step (1) as a raw material, adding it to ethylene glycol to form a mixed solution, placing the mixed solution in an ultrasonic cleaner for ultrasonic dispersion to obtain an activated carbon ethylene glycol solution with an activated carbon mass concentration of 5 wt%;

[0064] (3) Add 100 mL of 0.078 mol / L sodium tungstate solution to 100 mL of activated carbon ethylene glycol solution. Add 4 mL of 2 mol / L hydrochloric acid dropwise while stirring at 120°C. Stir for 4 hours and filter to separate the solid phase. Wash the solid phase several times with distilled water and ethanol, respectively, and dry it for later use.

[0065] (4) Soaking the solid phase dried in step (3) in a 1.5 mol / L manganese nitrate solution for 12 hours, taking it out, drying it at 110° C. for 4 hours, and then heating it to 200° C. at a heating rate of 5° C. / min for 3 hours to obtain a particle electrode precursor;

[0066] (5) The particle electrode precursor in step (4) is used as a raw material, added to ethylene glycol to form a mixed solution, and steps (2), (3) and (4) are repeated three times. The mixture is then calcined from room temperature to 700°C at a heating rate of 10°C / min under a nitrogen atmosphere for 3 hours to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0067] In the activated carbon-supported manganese and tungsten oxide particle electrode prepared in this embodiment, the mass fraction of activated carbon is 78.5%, the mass fraction of manganese dioxide is 20%, and the mass fraction of tungsten trioxide is 1.5%.

[0068] The prepared activated carbon-loaded manganese and tungsten oxide particle electrodes were applied in a three-dimensional electrode reactor. The anode and cathode were titanium mesh electrodes and manganese dioxide electrodes, respectively. The molar concentration of the electrolyte sodium sulfate was 0.05 mol / L, the concentration of sulfamethoxazole was 10-100 mg / L, and the current density was 5-10 mA / cm 2 The plate spacing is 4.5 cm, the degradation rate of sulfamethoxazole is 3.00-3.30 mmol / h·kg, and the degradation rate of sulfamethoxazole can reach 63.2% within 3 hours.

[0069] Comparative Example 1

[0070] In this comparative example, the preparation method of the activated carbon-supported manganese and tungsten oxide particle electrode comprises the following steps:

[0071] (1) Pretreatment of activated carbon: After washing the activated carbon with water, soak it in 0.1 mol / L hydrochloric acid for 24 hours, separate it, and dry it at 110°C for 12 hours before use;

[0072] (2) using the activated carbon pretreated in step (1) as a raw material, adding it to ethylene glycol to form a mixed solution, placing the mixed solution in an ultrasonic cleaner for ultrasonic dispersion to obtain an activated carbon ethylene glycol solution with an activated carbon mass concentration of 5 wt%;

[0073] (3) Add 100 mL of 0.0016 mol / L sodium tungstate solution to 100 mL of activated carbon ethylene glycol solution. Add 4 mL of 2 mol / L hydrochloric acid dropwise while stirring at 120°C. Stir for 4 hours and filter to separate the solid phase. Wash the solid phase several times with distilled water and ethanol, respectively, and dry it for later use.

[0074] (4) soaking the solid phase dried in step (3) in a 1.5 mol / L manganese nitrate solution for 12 hours, taking it out, drying it at 110° C. for 4 hours, and then heating it to 200° C. at a heating rate of 5° C. / min for 2 hours to obtain a particle electrode precursor;

[0075] (5) Using the particle electrode precursor in step (4) as a raw material, the mixture was calcined from room temperature to 700°C at a heating rate of 10°C / min under a nitrogen atmosphere for 2 hours to obtain the activated carbon-supported manganese and tungsten oxide particle electrode.

[0076] In the activated carbon-supported manganese and tungsten oxide particle electrode prepared in this comparative example, the mass fraction of activated carbon is 91.9%, the mass fraction of manganese dioxide is 8%, and the mass fraction of tungsten trioxide is 0.1%.

[0077] The prepared activated carbon-loaded manganese and tungsten oxide particle electrodes were applied in a three-dimensional electrode reactor. The anode and cathode were titanium mesh electrodes and manganese dioxide electrodes, respectively. The molar concentration of the electrolyte sodium sulfate was 0.05 mol / L, the concentration of sulfamethoxazole was 10-100 mg / L, and the current density was 5-10 mA / cm 2 The plate spacing is 4.5 cm, the degradation rate of sulfamethoxazole is 1.00-1.80 mmol / h·kg, and the degradation rate of sulfamethoxazole can reach 37.1% within 3 hours.

[0078] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Application of activated carbon-supported manganese and tungsten oxide particle electrodes in treating antibiotic-containing wastewater, characterized in that: The antibiotic is sulfamethoxazole, and the activated carbon-loaded manganese and tungsten oxide particle electrode comprises activated carbon and manganese dioxide and tungsten trioxide loaded on the activated carbon, wherein the mass fraction of the activated carbon is 74-80%, the mass fraction of the manganese dioxide is 19-25%, and the mass fraction of the tungsten trioxide is 0.1-1.5%; The method for preparing the activated carbon-supported manganese and tungsten oxide particle electrode comprises the following steps: (1) Pretreatment of activated carbon; the pretreatment steps include water washing and acid washing; (2) Using pretreated activated carbon as raw material, mixing it with ethylene glycol and ultrasonically dispersing it to obtain an activated carbon ethylene glycol solution; the mass concentration of activated carbon in the activated carbon ethylene glycol solution is 4~8 wt%; (3) Mix the sodium tungstate solution and the activated carbon ethylene glycol solution, add hydrochloric acid dropwise while stirring under heating conditions, separate the solid and liquid, wash the solid phase, dry it and set it aside; wherein, the molar concentration of the sodium tungstate solution is 0.0016~0.078 mol / L, and the volume ratio of the sodium tungstate solution to the activated carbon ethylene glycol solution is 0.8~1:1; under the condition of 110~130℃, add hydrochloric acid dropwise while stirring, continue stirring until the reaction is complete, and separate the solid phase by suction filtration; (4) Soaking the solid phase dried in step (3) in a manganese nitrate solution for at least 12 hours, removing it and drying it, and further calcining it to obtain a particle electrode precursor; the concentration of the manganese nitrate solution is 1-2 mol / L; the calcination conditions are 200-300°C and calcination for 2-3 hours; (5) Using the particle electrode precursor in step (4) as a raw material, repeat steps (2), (3) and (4) at least twice, and further calcining the obtained product to obtain the activated carbon-supported manganese and tungsten oxide particle electrode; the calcination conditions are: in a nitrogen atmosphere, heating at a rate of 5-10°C / min to 650-750°C, and calcining for 2-3 hours.

2. The use according to claim 1, characterized in that In step (1), the particle size of the activated carbon is 0.4-0.8 mm, and the activated carbon is soaked in hydrochloric acid to complete the pickling step.

3. The use according to claim 1, characterized in that In step (5), steps (2), (3) and (4) are repeated three times.

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