A boron-doped biomass charcoal cathode for efficient production of H2O2 and a preparation method and application thereof

Abstract

This invention provides a boron-doped biomass carbon cathode for efficient H2O2 generation, its preparation method, and its application, belonging to the field of advanced electrochemical oxidation technology for water treatment. The invention involves mixing boric acid solution with biomass powder, followed by sequential heating, first cooling, filtration, drying, calcination, second cooling, washing, and drying to obtain boron-doped biomass carbon powder. Carbon black, boron-doped biomass carbon powder, polytetrafluoroethylene dispersion, and anhydrous ethanol are mixed and ultrasonically dispersed, then heated and stirred to obtain a boron-doped biomass carbon slurry. This slurry is then bonded to nickel foam and cured at high temperature to obtain the boron-doped biomass carbon cathode. This invention utilizes the non-metallic element boron doping, where electron-deficient boron replaces carbon to form B-C bonds, generating a positive charge near the boron atom, which is beneficial for H2O2 adsorption and produces no iron sludge. Compared to traditional electro-Fenton cathodes, this invention eliminates the need for external addition of H2O2 and Fe. 2+ It can simultaneously generate activated H2O2 in situ, producing hydroxyl radicals to degrade pollutants.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation technology in water treatment electrochemistry, specifically relating to a boron-doped biomass carbon cathode that efficiently generates H2O2, its preparation method, and its application. Background Technology

[0002] As is well known, antibiotics are effective chemical drugs for preventing and treating diseases in animals and plants, as well as controlling infectious diseases in humans. However, the extensive use of antibiotics has seriously affected public health and caused incalculable damage to the ecological environment. Even more serious is that, due to their highly stable nature, antibiotics easily leave drug residues when released into the environment. When large amounts of antibiotics accumulate in the environment, they eventually enter the human body in various forms through the food chain, thereby depriving humans of resistance to certain diseases and causing significant toxicity. Therefore, the efficient degradation of quinolone antibiotics has significant practical implications.

[0003] Compared to traditional Fenton technology, electro-Fenton (EF) technology can avoid the risks associated with the transportation, storage, and use of high-concentration H2O2. At the same time, it can reduce the use of catalysts and reduce the generation of iron sludge, and is considered a win-win technology that can achieve both economic and environmental benefits.

[0004] Currently, electro-Fenton (EF) technology has made significant progress in the application of antibiotic wastewater, demonstrating excellent degradation effects and attracting considerable research attention. However, while homogeneous EF technology can ensure sufficient H2O2 production, the need for additional iron reagents or solid catalysts leads to the generation of iron sludge and difficulties in particle recovery. Heterogeneous electro-Fenton technology achieves H2O2 and Fe2O3 degradation at a single cathode. 2+ While it is possible to generate H2O2, achieving optimal levels of both Fenton reagents remains challenging, and the amount of hydrogen peroxide is generally low. Although Chinese patent CN110040821A describes a dual-cathode electro-Fenton that can generate H2O2 and Fe... 2+ While the system can regenerate H2O2, the gas diffusion electrode used in this system primarily produces H2O2. However, the raw materials used in this system are mostly non-renewable resources, which are expensive and have complex preparation processes, leading to obstacles in practical applications.

[0005] Biomass, as a renewable organic carbon material derived from plants and animals, is not only green, environmentally friendly, and easy to store, but also has seen significant development in the use of inexpensive biochar to produce H2O2 through oxygen reduction. Summary of the Invention

[0006] In view of this, the present invention aims to provide a boron-doped biomass carbon cathode for efficient H2O2 generation, its preparation method, and its application. The prepared boron-doped biomass carbon cathode improves the utilization rate of H2O2 and eliminates the need for external addition of H2O2 and Fe. 2 + It does not produce iron sludge, is inexpensive, and has a simple preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing a boron-doped biomass carbon cathode that efficiently generates H2O2, comprising the following steps:

[0009] After mixing boric acid solution with biomass powder, the mixture is heated, cooled first, and filtered sequentially to obtain a solid product.

[0010] The solid product was sequentially dried, calcined, cooled, washed, and dried to obtain boron-doped biochar powder.

[0011] The boron-doped biochar powder, binder, carbon black and anhydrous ethanol are mixed and ultrasonically dispersed, and then heated and stirred to obtain boron-doped biochar slurry;

[0012] The boron-doped biomass carbon slurry is bonded to a carrier and cured at high temperature to obtain a boron-doped biomass carbon cathode.

[0013] Preferably, the mass concentration of the boric acid solution is 1.5-85 g / L.

[0014] Preferably, the ratio of biomass powder to boric acid solution is 2-8g:100mL.

[0015] Preferably, the biomass powder is walnut shell powder, tea seed shell powder, or coconut shell powder.

[0016] Preferably, the calcination temperature is 700-900℃ and the calcination time is 0.8-1.5h.

[0017] Preferably, the ratio of boron-doped biochar, carbon black, binder, and anhydrous ethanol is 40-160 mg: 5 mg-20 mg: 0.05-0.2 mL: 1-4 mL; the binder is a polytetrafluoroethylene dispersion or a perfluorosulfonic acid polymer solution.

[0018] Preferably, the loading of boron-doped biochar slurry on the carrier is 18-72 mg / cm³. 2 The carrier is nickel foam, iron foam, or stainless steel mesh.

[0019] Preferably, the high-temperature curing temperature is 300-400℃, and the high-temperature curing time is 0.5-1.5h.

[0020] The present invention also provides a boron-doped biomass carbon cathode prepared by the above preparation method.

[0021] The present invention also provides the application of the above-mentioned boron-doped biomass carbon cathode in a dual-cathode electric Fenton system, wherein the dual-cathode electric Fenton system is used to treat antibiotic wastewater.

[0022] Beneficial Technical Effects: This invention involves mixing boric acid solution with biomass powder, followed by sequential heating, first cooling, filtration, drying, calcination, second cooling, washing, and drying to obtain boron-doped biomass char powder. The carbon black, boron-doped biomass char powder, polytetrafluoroethylene dispersion, and anhydrous ethanol are mixed and ultrasonically dispersed, then heated and stirred to obtain boron-doped biomass char slurry. This boron-doped biomass char slurry is then bonded to nickel foam and cured at high temperature to obtain a boron-doped biomass char cathode. Firstly, this invention utilizes the non-metallic element boron doping, where electron-deficient boron replaces carbon to form BC bonds, generating a positive charge near the boron atom, which is beneficial for H2O2 adsorption. Due to the absence of metal, the H2O2 hydrolysis reaction can be suppressed, improving the utilization rate of H2O2. Furthermore, this invention utilizes the prepared boron-doped biomass char cathode material connected in parallel with a commercially available iron sheet cathode, using a platinum sheet as the anode to form a dual-cathode EF system. The boron-doped biomass char cathode is used to generate H2O2, while the iron sheet cathode supplies Fe. 2+ It exhibits good treatment effect on doxycycline and produces no iron sludge. Compared with traditional electro-Fenton systems, this invention uses a dual-cathode electro-Fenton system that eliminates the need for external addition of H2O2 and Fe. 2+ This process can simultaneously generate activated H2O2 in situ, producing hydroxyl radicals to degrade pollutants. Finally, the boron-doped biochar cathode material prepared by this invention solves the problem of resource utilization of waste agricultural biochar and avoids the environmental problems caused by the large-scale accumulation of agricultural waste such as walnut shells. The preparation process disclosed in this invention is simple, easy to operate, highly efficient, green, environmentally friendly, clean, and pollution-free. It is a widely applicable method for efficiently removing pollutants and has significant application and commercial value. Attached Figure Description

[0023] Figure 1 Here is a scanning electron microscope image of the boron-doped biochar material prepared in Example 1;

[0024] Figure 2 This is a scanning electron microscope image of the original biochar in Comparative Example 2;

[0025] Figure 3 These are H2O2 production effect diagrams of the original biochar and boron-doped biochar prepared in Example 1 and Comparative Example 2;

[0026] Figure 4 This is a schematic diagram of a dual-cathode electro-Fenton device;

[0027] Figure 5 This is a comparison chart of the degradation effects of raw biochar and boron-doped biochar on doxycycline in dual-cathode electro-Fenton reactors in Example 1 and Comparative Example 2. Detailed Implementation

[0028] This invention provides a method for preparing a boron-doped biomass carbon cathode that efficiently generates H2O2, comprising the following steps:

[0029] After mixing boric acid solution with biomass powder, the mixture is heated, cooled first, and filtered sequentially to obtain a solid product.

[0030] The solid product was sequentially dried, calcined, cooled, washed, and dried to obtain boron-doped biochar powder.

[0031] The boron-doped biochar powder, binder, carbon black and anhydrous ethanol are mixed and ultrasonically dispersed, and then heated and stirred to obtain boron-doped biochar slurry;

[0032] The boron-doped biomass carbon slurry is bonded to a carrier and cured at high temperature to obtain a boron-doped biomass carbon cathode.

[0033] This invention involves mixing boric acid solution with biomass powder, followed by heating, first cooling, and filtration to obtain a solid product.

[0034] In this invention, the mass concentration of the boric acid solution is preferably 1.5-85 g / L, more preferably 50 g / L.

[0035] In this invention, the preferred material-to-liquid ratio of the biomass powder to the boric acid solution is 2-8 g:100 mL, more preferably 5 g:100 mL.

[0036] In this invention, the biomass powder is preferably walnut shell powder, tea seed shell powder, or coconut shell powder, more preferably walnut shell powder; the mesh size of the biomass powder is preferably 80-120 mesh, more preferably 100 mesh.

[0037] In this invention, the heating temperature is preferably 160-200℃, and more preferably 180℃.

[0038] In this invention, the first cooling is preferably natural cooling to 23-26°C.

[0039] In this invention, the pore size of the filter membrane is preferably 0.22 μm or 0.45 μm, more preferably 0.22 μm; the filtration method is preferably vacuum pump filtration.

[0040] After obtaining the solid product, the solid product is successively dried, calcined, cooled a second time, washed and dried to obtain boron-doped biochar powder.

[0041] This invention utilizes the doping of non-metallic element boron to replace carbon and form BC bonds, generating a positive charge near the boron atom, which is beneficial for the adsorption of H2O2, can inhibit the occurrence of H2O2 hydrolysis reaction, and improve the utilization rate of H2O2.

[0042] In this invention, the calcination temperature is preferably 700-900℃, more preferably 800℃, and the calcination time is preferably 0.8-1.5h, more preferably 1h; the high-temperature curing is carried out under a protective gas, which is preferably nitrogen, argon or hydrogen, more preferably nitrogen.

[0043] In this invention, the second cooling is preferably natural cooling to 23-26°C.

[0044] In this invention, the detergent used for washing is preferably water and / or anhydrous ethanol, more preferably water and anhydrous ethanol; the number of washing cycles is preferably 2-4 times, more preferably 3 times.

[0045] After obtaining boron-doped biochar powder, the present invention mixes the boron-doped biochar powder, carbon black, binder and anhydrous ethanol, disperses them ultrasonically, and then heats and stirs to obtain boron-doped biochar slurry.

[0046] In this invention, the preferred ratio of boron-doped biochar, carbon black, binder, and anhydrous ethanol is 40-160 mg: 5 mg-20 mg: 0.05-0.2 mL: 1-4 mL; more preferably, it is 110-130 mg: 15-20 mg: 0.1-0.6 mL: 2.5-3.5 mL; even more preferably, it is 128 mg: 16 mg: 0.144 mL: 2.8 mL.

[0047] In this invention, the adhesive is preferably a polytetrafluoroethylene or perfluorosulfonic acid polymer solution; more preferably a polytetrafluoroethylene solution.

[0048] In this invention, the heating and stirring temperature is preferably 70-90°C, more preferably 80°C. Preferably, the material is heated and stirred until it becomes a paste or dough-like consistency.

[0049] After obtaining boron-doped biomass carbon slurry, the boron-doped biomass carbon slurry is bonded to a carrier and cured at high temperature to obtain a boron-doped biomass carbon cathode.

[0050] In this invention, the loading of the boron-doped biochar slurry on the nickel foam is preferably 18-72 mg / cm³. 2 More preferably 36-54 mg / cm³ 2 The curing temperature is preferably 300-400℃, more preferably 350℃, and the curing time is preferably 0.5-1.5h, more preferably 1h.

[0051] In this invention, the carrier is preferably nickel foam, iron foam, or stainless steel mesh, more preferably nickel foam; the specific shape is preferably rectangular, circular, or triangular, more preferably rectangular.

[0052] The present invention also provides a boron-doped biomass carbon cathode prepared by the above preparation method.

[0053] This invention also provides the application of the aforementioned boron-doped biochar cathode in a dual-cathode Fenton system for treating antibiotic wastewater. The specific steps for treating antibiotic wastewater using the boron-doped biochar cathode in the dual-cathode Fenton system are as follows: the boron-doped biochar cathode and a commercially available iron sheet are used as cathodes, connected to a platinum anode sheet in an electrolytic cell to form a dual-cathode Fenton system. Under DC power, the wastewater containing antibiotics is degraded, and air is introduced through an aeration head to carry out the reaction, thus completing the wastewater treatment. The concentration of antibiotics in the antibiotic wastewater is ≤30 mg / L; the pH value of the antibiotic wastewater is 2–11.

[0054] In this invention, the dual-cathode Fenton system uses boron-doped biomass carbon cathode material connected in parallel with a commercial iron sheet cathode, and uses a platinum sheet as the anode.

[0055] This invention utilizes a prepared boron-doped biomass carbon cathode material connected in parallel with a commercially available iron sheet cathode, forming a dual-cathode EF system with a platinum sheet as the anode. The boron-doped biomass carbon cathode is used to generate H2O2, while the iron sheet cathode supplies Fe. 2+ It exhibits good treatment effect on doxycycline and produces no iron sludge. Compared with traditional electro-Fenton systems, this invention uses a dual-cathode electro-Fenton system that eliminates the need for external addition of H2O2 and Fe. 2+ It can simultaneously generate activated H2O2 in situ, producing hydroxyl radicals to degrade pollutants.

[0056] In this invention, the current density on the boron-doped biochar in the dual-cathode electro-Fenton system is 10–45 mA / cm². 2 The current density on the iron cathode is 0–2.5 mA / cm². 2 .

[0057] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0058] Example 1

[0059] 3g of boric acid was poured into a reaction vessel containing 60mL of deionized water and stirred until the boric acid dissolved to form a clear solution. Then, 3.0g of 100-mesh walnut shell powder was poured into the reaction vessel and stirred for 30 minutes at room temperature to mix evenly. The mixture was then hydrothermally heated at 180℃ in an oven for 12 hours, allowed to cool naturally to room temperature, filtered, and dried. The dried material was placed in a quartz boat and placed in the center of a tube furnace. Nitrogen gas was introduced and the material was calcined at 800℃ for 1 hour. After cooling to room temperature, the biochar was washed three times with water and anhydrous ethanol and dried to obtain boron-doped biochar powder.

[0060] After obtaining boron-doped biochar powder, carbon black, boron-doped biochar powder, polytetrafluoroethylene dispersion and anhydrous ethanol were mixed in a ratio of 16mg:128mg:0.144mL:2.8mL and ultrasonically dispersed. Then, the mixture was heated and stirred in a water bath at 80℃ until it reached a dough-like consistency to obtain boron-doped biochar slurry.

[0061] After obtaining the boron-doped biochar slurry, the dough-like boron-doped biochar slurry was spread onto sheet-like nickel foam, with a loading of 144 mg on each side and an area of ​​2 cm² for each carrier. 2 Finally, it was placed in a muffle furnace and cured at 350°C for 1 hour to obtain a boron-doped biomass carbon cathode.

[0062] Figure 1 The image shown is a scanning electron microscope (SEM) image of the boron-doped biochar material in Example 1 of this invention. It can be seen that the surface of the boron-doped biochar has a porous structure and an increased specific surface area, which is conducive to the reduction of oxygen by two electrons to produce H2O2 and provides electrocatalytic efficiency.

[0063] Example 2

[0064] 1g of boric acid was poured into a reaction vessel containing 60mL of deionized water and stirred until the boric acid dissolved to form a clear solution. Then, 3.0g of 80-mesh walnut shell powder was poured into the reaction vessel and stirred for 30 minutes at room temperature to mix evenly. The mixture was then hydrothermally heated at 180℃ in an oven for 12 hours, allowed to cool naturally to room temperature, filtered through a mesh screen, and dried. The dried material was then placed in a quartz boat and placed in the center of a tube furnace. Nitrogen gas was introduced and the material was calcined at 700℃ for 1 hour. After cooling to room temperature, the biochar was washed three times with water and anhydrous ethanol and dried to obtain boron-doped biochar powder.

[0065] After obtaining boron-doped biochar powder, carbon black, boron-doped biochar powder, polytetrafluoroethylene dispersion and anhydrous ethanol were mixed in a ratio of 40 mg: 5 mg: 0.05 mL: 1 mL and ultrasonically dispersed. Then, the mixture was heated and stirred in a water bath at 80°C until it reached a dough-like consistency to obtain boron-doped biochar slurry.

[0066] After obtaining the boron-doped biochar slurry, the dough-like boron-doped biochar slurry was spread onto sheet-like nickel foam, with a loading of 144 mg on each side and an area of ​​2 cm² for each carrier. 2 Finally, it was placed in a muffle furnace and cured at 300°C for 1 hour to obtain a boron-doped biomass carbon cathode.

[0067] Example 3

[0068] 5g of boric acid was poured into a reactor containing 60mL of deionized water and stirred until the boric acid dissolved to form a clear solution. Then, 3.0g of 120-mesh walnut shell powder was poured into the reactor and stirred for 30 minutes at room temperature to mix evenly. The mixture was then hydrothermally heated at 180℃ in an oven for 12 hours, allowed to cool naturally to room temperature, filtered, and dried. The dried material was placed in a quartz boat and placed in the center of a tube furnace. Nitrogen gas was introduced and the material was calcined at 900℃ for 1 hour. After cooling to room temperature, the biochar was washed three times with water and anhydrous ethanol and dried to obtain boron-doped biochar powder.

[0069] After obtaining boron-doped biochar powder, carbon black, boron-doped biochar powder, polytetrafluoroethylene dispersion and anhydrous ethanol were mixed in a ratio of 128 mg: 16 mg: 0.144 mL: 2.88 mL and ultrasonically dispersed. Then, the mixture was heated and stirred in a water bath at 90°C until it reached a dough-like consistency to obtain boron-doped biochar slurry.

[0070] After obtaining the boron-doped biochar slurry, the dough-like boron-doped biochar slurry was spread onto sheet-like nickel foam, with a loading of 144 mg on each side and an area of ​​2 cm² for each carrier. 2 Finally, it was placed in a muffle furnace and cured at 400℃ for 1.5h to obtain a boron-doped biomass carbon cathode.

[0071] Example 4

[0072] The only difference from Example 1 is that the loading of boron-doped biochar slurry on each side of the nickel foam is 72 mg.

[0073] Example 5

[0074] The only difference from Example 1 is that the loading of boron-doped biochar slurry on each side of the nickel foam is 108 mg.

[0075] Example 6

[0076] The only difference from Example 1 is that the adhesive is a perfluorosulfonic acid polymer solution.

[0077] Example 7

[0078] The only difference from Example 1 is that the biomass powder is coconut shell powder.

[0079] Example 8

[0080] The only difference from Example 1 is that the carrier is foamed iron.

[0081] Example 9

[0082] The only difference from Example 1 is that the carrier is a stainless steel mesh.

[0083] Example 10

[0084] The only difference from Example 1 is that the nickel foam carrier is circular in shape, while the surface area remains the same.

[0085] Example 11

[0086] The only difference from Example 1 is that the nickel foam carrier is triangular in shape, while the surface area remains the same.

[0087] Comparative Example 1

[0088] The only difference from Example 1 is that the loading of boron-doped biochar slurry on each side of the nickel foam is 180 mg.

[0089] Comparative Example 2

[0090] The only difference from Example 1 is that no boric acid was added, and only biochar was used.

[0091] After drying the walnut shell powder, the dried material was placed in a quartz boat and placed in the center of a tube furnace. Nitrogen gas was introduced and the material was calcined at 800°C for 1 hour. After cooling to room temperature, the biochar was washed three times with water and anhydrous ethanol and then dried to obtain biochar powder.

[0092] After obtaining biochar powder, carbon black, boron-doped biochar powder, polytetrafluoroethylene dispersion and anhydrous ethanol are mixed in a ratio of 16mg:128mg:0.144mL:2.8mL and then ultrasonically dispersed. The mixture is then heated and stirred in a water bath at 80℃ until it reaches a dough-like consistency to obtain biochar slurry.

[0093] After obtaining the biomass slurry, the dough-like biomass slurry was laid on nickel foam with a loading of 144 mg on each side. Finally, it was placed in a muffle furnace and cured at 350°C for 1 hour to obtain a boron-doped biomass slurry cathode.

[0094] Figure 2 The image shown is a scanning electron microscope image of the original biochar material in Comparative Example 2 of this invention. It can be seen that the undoped biochar has a blocky structure with fewer pores and a smaller specific surface area, which is not conducive to the generation of H2O2.

[0095] Figure 3 This is a comparison diagram of H2O2 production from the biomass char cathodes prepared in Example 1 and Comparative Example 2. From... Figure 3As can be seen, the H2O2 yield of the boron-modified biomass carbon cathode is much higher than that of the undoped biomass carbon, indicating that the boron-doped cathode material can effectively increase the H2O2 yield.

[0096] Experimental Example 1

[0097] The amount of H2O2 produced by electro-Fenton cathode materials prepared in Examples 1-5 and Comparative Example 1 after 3 hours of electrolysis was tested. The results are shown in Table 1.

[0098] Table 1: Comparison of H2O2 Production Amount

[0099] serial number Loading capacity (mg) Boric acid: Biomass ratio <![CDATA[H2O2 production (mg / L)]]> Example 1 144 3:3 303.186 Example 2 144 1:3 153.345 Example 3 144 5:3 180.703 Example 4 72 3:3 156.214 Example 5 108 3:3 164.353 Comparative Example 1 180 3:3 177.848 Comparative Example 2 144 0:3 144.745

[0100] As can be seen from the table above, different loading amounts result in different amounts of H2O2 produced by the electrode. The reason for this may be that excessive loading will hinder mass transfer and oxygen reduction reaction activity, thus reducing the yield of H2O2, while insufficient loading will result in insufficient active sites, thus causing the yield of H2O2 to be lower than that of the biochar electrode with a loading of 144 mg.

[0101] The H2O2 yields of Examples 6-7 are not significantly different from those of Example 1; the H2O2 yields of Examples 8-9 are between 200-300 mg / L, which is less than that of Example 1. Therefore, the change in the carrier material affects the H2O2 yield to some extent; the H2O2 yields of Examples 10-11 are consistent with those of Example 1, indicating that when the surface area of ​​the carrier is the same, the change in shape has little effect on its H2O2 yield. This invention can use carriers of various shapes to suit different environments.

[0102] Experimental Example 2

[0103] Experimental study on the removal of antibiotic wastewater using dual-cathode electro-Fenton.

[0104] Experiments were conducted to remove antibiotic wastewater using a dual-cathode Fenton system with boron-doped biomass carbon cathodes from Example 1 and a dual-cathode Fenton system with biomass carbon cathodes from Comparative Example 2.

[0105] Figure 4 The apparatus described in Example 1 and Comparative Example 2 for degrading antibiotic wastewater in a dual-cathode electro-Fenton system has a distance of 1 cm between the biochar cathode and the iron and platinum sheet cathodes. 1 represents the platinum electrode; 2 represents the iron sheet electrode; 3 represents the self-made electrode; and 4 represents the aeration head.

[0106] Figure 5 This is a comparison of the electro-Fenton degradation effect of boron-doped biochar prepared in Example 1 and Comparative Example 2 on the antibiotic doxycycline, between the two methods. Figure 5It can be seen that the boron-modified biochar cathode has a significant effect in the experiment simulating the degradation of doxycycline in wastewater, directly confirming the effectiveness of boron-doped biochar as an electro-Fenton cathode material for degrading doxycycline in wastewater.

[0107] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a boron-doped biomass carbon cathode that efficiently generates H2O2, characterized in that, Includes the following steps: After mixing boric acid solution with biomass powder, the mixture is heated, cooled first, and filtered sequentially to obtain a solid product. The solid product was sequentially dried, calcined, cooled, washed, and dried to obtain boron-doped biochar powder. The boron-doped biochar powder, binder, carbon black and anhydrous ethanol are mixed and ultrasonically dispersed, and then heated and stirred to obtain boron-doped biochar slurry; The boron-doped biomass carbon slurry is bonded onto a carrier and cured at high temperature to obtain a boron-doped biomass carbon cathode. The boric acid solution has a mass concentration of 1.5-85 g / L; the ratio of biomass powder to boric acid solution is 2-8 g: 100 mL; the biomass powder is walnut shell powder, tea seed shell powder, or coconut shell powder.

2. The preparation method according to claim 1, characterized in that, The calcination temperature is 700-900℃, and the calcination time is 0.8-1.5h.

3. The preparation method according to claim 1, characterized in that, The ratio of boron-doped biochar, carbon black, binder, and anhydrous ethanol is 40-160 mg: 5 mg-20 mg: 0.05-0.2 mL: 1-4 mL; The binder is a polytetrafluoroethylene dispersion or a perfluorosulfonic acid polymer solution.

4. The preparation method according to claim 1, characterized in that, The loading of boron-doped biochar slurry on the carrier is 18-72 mg / cm³. 2 The carrier is nickel foam, iron foam, or stainless steel mesh.

5. The preparation method according to claim 1, characterized in that, The high-temperature curing temperature is 300-400℃, and the high-temperature curing time is 0.5-1.5h.

6. The boron-doped biomass carbon cathode prepared by the preparation method according to any one of claims 1-5.

7. The application of the boron-doped biomass carbon cathode according to claim 6 in a dual-cathode Fenton system, characterized in that, The dual-cathode electro-Fenton system is used to treat antibiotic wastewater.

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