Nitrogen-doped porous biochar, preparation method thereof and application of nitrogen-doped porous biochar as electro-Fenton cathode material
By introducing nitrogen doping and porous structures into biochar, combined with microwave modification and high-temperature roasting technology, an efficient electrofenton cathode material was prepared, which solved the narrow pH range and low H2O2 yield in the traditional electrofenton process. The problem is to achieve wider pH adaptability and higher H2O2 generation efficiency.
Patent Information
- Application Number
- CN202411378703.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-02-21
AI Technical Summary
The traditional electrofenton process has problems with narrow pH range and lower H2O2 yield.
Through hydrothermal reaction, nitrogen doping is applied to the biomass, microwave-assisted modification and high-temperature calcination are used to form layered porous nitrogen-doped biochar, which is used as an electrofenton cathode material.
This method not only broadens the pH range of electrofenton and improves the yield of H2O2, but also promotes Fe2+ cycle and adsorption and degradation of organic pollutants.
Smart Images
Figure CN119490174A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrochemistry, and particularly relates to nitrogen-doped porous biochar and a preparation method thereof and application thereof as an electro-Fenton cathode material. Background Art
[0002] Biochar is an economical, locally available carbonaceous material that can be used as a catalyst support and cathode material. Compared with the conventional electro-Fenton process, the biochar-based electro-Fenton process has the advantages of higher efficiency, reduced iron ion leaching, surface-dominated free radical generation, and the ability to degrade pollutants even under neutral pH conditions. In addition, biochar has the ability to produce large amounts of hydrogen peroxide and rapidly regenerate ferrous ions, and has a high adsorption capacity for many organic pollutants, which ensures that the pollutants are in close proximity to the generated active species. Therefore, there is great potential for the application of biochar as a support, catalyst, or electrode in electro-Fenton and other related processes. Summary of the invention
[0003] The purpose of the present invention is to provide a nitrogen-doped porous biochar and its preparation method and application as an electro-Fenton cathode material. The present invention solves the problems of narrow pH range and low H2O2 production in traditional electro-Fenton. In the biochar preparation process, the internal pore size of the biomass is first widened by hydrothermal reaction, and nitrogen doping is performed by adding nitrogen source and pore-forming agent. The biochar is pyrolyzed in the absence of oxygen to form a layered porous nitrogen-doped biochar. In the electro-Fenton process, the cathode made of biochar can not only efficiently produce H2O2, but also promote Fe 2+ circulates and can adsorb pollutants near the cathode, which is beneficial to the degradation of organic pollutants.
[0004] The technical solution adopted by the present invention is as follows:
[0005] A method for preparing nitrogen-doped porous biochar comprises the following steps:
[0006] 1) The biomass is washed, dried, crushed and sieved, the biomass powder is mixed with deionized water in a mass ratio of 1:5-20, added into a Teflon-lined autoclave, stirred and then put into an oven for hydrothermal carbonization, cooled, dried, ground and sieved to obtain hydrothermal charcoal;
[0007] 2) putting the hydrothermal carbon from step 1) into a dopamine hydrochloride solution, stirring at room temperature to perform a polymerization reaction, and then taking out the hydrothermal carbon and drying it to obtain biochar;
[0008] 3) placing the biochar from step 2) in a quartz tube, placing the quartz tube in a microwave reactor, and starting microwave radiation under the condition of introducing N2 to perform microwave-assisted modification;
[0009] 4) soaking the biochar modified by microwave-assisted method in step 3) in a NaHCO3 or KHCO3 solution with a concentration of 0.05-0.2 mol / L, taking out the biochar after sufficient soaking, drying it, calcining it at high temperature in a tube furnace under N2 atmosphere, and then cooling it to room temperature;
[0010] 5) The biochar obtained in step 4) is washed with HCl solution to remove residual alkali on the surface, and then repeatedly rinsed with deionized water until the eluent is neutral to remove residual impurities, and then dried in a vacuum oven overnight to obtain nitrogen-doped porous biochar.
[0011] Furthermore, the biomass in step 1) is white grapefruit peel, and the mass ratio of biomass powder to deionized water is 1:8-12.
[0012] Furthermore, in step 1), the hydrothermal temperature is 180-220° C., and the hydrothermal time is 10-15 h.
[0013] Furthermore, the mass concentration of the dopamine hydrochloride solution in step 2) is 5-10%, the pH thereof is adjusted to 8-9, the mass ratio of hydrothermal charcoal to dopamine hydrochloride is 1:0.8-1.5, the polymerization reaction temperature is room temperature, and the reaction time is 5-10 hours.
[0014] Furthermore, in step 3), the microwave power is 400-600 W, and the modification time of microwave radiation is 5-10 min.
[0015] Furthermore, in step 4), the mass ratio of biochar to NaHCO3 or KHCO3 is 1:(1-3), and the impregnation time is 10-15h; the temperature of high-temperature roasting in step 4) is 500-800°C, preferably 700°C, and the roasting time is 1-3h.
[0016] The present invention also discloses the application of the electric-Fenton cathode material of the nitrogen-doped porous biochar. The biochar is mixed with carbon black, polytetrafluoroethylene dispersion and ethanol in a ratio of 100 mg: 40-60 mg: 80-120 mg: (100-200 μL), the concentration of the polytetrafluoroethylene dispersion is 50-70%, and a paste mixture is obtained. The mixture is pressed into a thin sheet by a double-roller machine, and then pressed together with a titanium mesh to form an electrode. The electrode is calcined in a muffle furnace at 300-350° C. for 20-60 min to obtain the electric-Fenton cathode material.
[0017] The application of the electro-Fenton cathode material of the nitrogen-doped porous biochar is used as the cathode in the electro-Fenton system, with a platinum sheet as the anode and a Na2SO4 solution as the electrolyte, and the electrolyte contains a final concentration of 0.005-0.05M Fe 2+Organic pollutants are also added to the electrolyte, and the electro-Fenton reaction is carried out under power-on conditions without aeration to generate H2O2 in situ, which reacts with Fe 2+ Activate to form HO· to degrade organic pollutants.
[0018] Furthermore, the pH of the electrolyte is 1-5, the concentration of Na2SO4 is 0.01-0.1M, and the added Fe 2+ The final concentration is 0.01~0.5M, and the constant voltage of electrolysis is -0.5~-1.2V.
[0019] The present invention aims to provide a biochar material that can efficiently produce H2O2, and H2O2 is directly activated on the cathode surface to produce HO· to degrade pollutants in water. The method comprises: using grapefruit peel biomass as a carbon substrate, hydrothermally widening its internal pores to obtain porous hydrothermal carbon, forming a layer of polymer on the surface of biochar through the polymerization reaction of dopamine hydrochloride, loading it on the carbon material, and then using microwave-assisted modification treatment, and then immersing it in a NaHCO3 solution to make it fully contact with the catalyst, drying it, and calcining it at 500-800°C in a N2 atmosphere for 1-2 hours to form nitrogen-doped porous biochar, cooling it, and washing it with an HCl solution to neutrality to remove impurities to obtain nitrogen-doped modified porous biochar.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] (1) The electro-Fenton cathode is prepared using biochar. The cathode surface has rich pore structures and oxygen-containing functional groups, which is conducive to oxygen mass transfer, has higher H2O2 yield, surface-dominated free radical generation, and can degrade pollutants even under neutral pH conditions;
[0022] (2) The nitrogen element is loaded onto the surface of biochar by polymerization reaction and microwave-assisted modification. The nitrogen element of the nitrogen-doped porous biochar mainly exists in the form of pyridinic nitrogen and pyrrolic nitrogen, and there are abundant oxygen-containing functional groups such as carboxyl and carbonyl on its surface, which has high two-electron selectivity and H2O2 production.
[0023] (3) The low-cost and readily available grapefruit peel biomass is used to prepare the electro-Fenton cathode carbon material for the degradation of persistent organic pollutants. The preparation method is simple, low-cost and high-efficiency, achieving the purpose of "treating waste with waste", which is conducive to industrial use. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The SEM images of the biochar products of Examples 1-4 are compared.
[0025] Figure 2 The results of the change of H2O2 generation over time when different electrode materials are used in Example 8 of the present invention;
[0026] Figure 3 This is a diagram showing the degradation effect of atrazine when the cathode is prepared using biochar prepared at different calcination temperatures in Example 6 of the present invention.
[0027] Figure 4 This is a diagram showing the degradation effect of atrazine under different electrolyte solution pH conditions in Example 10 of the present invention. Specific implementation plan
[0028] The present invention will be further described below with reference to the accompanying drawings and specific implementation examples.
[0029] Embodiment 1:
[0030] A method for preparing nitrogen-doped porous biochar comprises the following steps:
[0031] Step 1: The biomass is the white peel of grapefruit. The biomass is washed, dried and crushed through a 100-200 mesh sieve. The biomass powder and deionized water are added into a Teflon-lined autoclave at a mass ratio of 1:10. After stirring, the autoclave is placed in an oven for hydrothermal carbonization at a hydrothermal temperature of 200°C and a hydrothermal time of 12 hours. The autoclave is cooled, dried, ground and passed through a 200 mesh sieve to obtain hydrothermal carbon.
[0032] Step 2: The pH of an 8% dopamine hydrochloride aqueous solution is adjusted to 8.5, and the hydrothermal carbon prepared in step 1 is put into an 8% dopamine hydrochloride aqueous solution, wherein the mass ratio of the hydrothermal carbon to the dopamine hydrochloride in the solution is 1:1, and the polymerization reaction is carried out by stirring at room temperature for 8 hours, and then the hydrothermal carbon is taken out and dried to obtain biochar;
[0033] Step 3: placing the biochar prepared in step 2 in a quartz tube, placing the quartz tube in a microwave reactor, starting microwave radiation under the condition of N2 flow rate of 150 mL / min, performing microwave-assisted modification, the microwave power is 500 W, and the microwave modification time is 8 min;
[0034] Step 4: The biochar from step 3 was immersed in a KHCO3 solution with a concentration of 0.1 mol / L, the mass ratio of biochar to NaHCO3 in the solution was 1:1, and the immersion time was 12 h; then the biochar was taken out for drying, and heated and roasted in a tubular furnace under a N2 atmosphere, with a N2 introduction rate of 75 mL / min, from room temperature to 700°C at a heating rate of 5°C / min, and then roasted at a constant temperature for 1.5 h, and then cooled to room temperature;
[0035] Step 5: The biochar obtained in step 4 was washed with 1 M HCl solution to remove residual alkali on the surface, and then repeatedly rinsed with deionized water until the eluent was neutral to remove residual impurities, and then dried in a vacuum oven overnight at a temperature of 80 °C to obtain nitrogen-doped porous biochar, which was labeled as NC@KHCO3700.
[0036] Embodiment 2:
[0037] A method for preparing porous biochar comprises the following steps:
[0038] Step 1: The biomass is the white peel of grapefruit. The biomass is washed, dried and crushed through a 100-200 mesh sieve. The biomass powder and deionized water are added into a Teflon-lined autoclave at a mass ratio of 1:10. After stirring, the autoclave is placed in an oven for hydrothermal carbonization at a hydrothermal temperature of 200°C and a hydrothermal time of 12 hours. The autoclave is cooled, dried, ground and passed through a 200 mesh sieve to obtain hydrothermal carbon.
[0039] Step 2: The hydrothermal charcoal in step 1 was heated and roasted in a tubular furnace under a N2 atmosphere, with a N2 introduction rate of 75 mL / min, and the temperature was raised from room temperature to 700°C at a heating rate of 5°C / min, and then constant temperature roasted for 1.5 h, and then cooled to room temperature to obtain biochar;
[0040] Step 3: After washing the biochar obtained in step 2 with 1 M HCl solution, it was repeatedly rinsed with deionized water until the eluent was neutral to remove residual impurities, and then dried in a vacuum oven overnight at a temperature of 80 °C to obtain the original biochar, named BC 700.
[0041] Embodiment 3:
[0042] Step 1: The biomass is the white peel of grapefruit. The biomass is washed, dried and crushed through a 100-200 mesh sieve. The biomass powder and deionized water are added into a Teflon-lined autoclave at a mass ratio of 1:10. After stirring, the autoclave is placed in an oven for hydrothermal carbonization at a hydrothermal temperature of 200°C and a hydrothermal time of 12 hours. The autoclave is cooled, dried, ground and passed through a 200 mesh sieve to obtain hydrothermal carbon.
[0043] Step 2: The pH of an 8% dopamine hydrochloride aqueous solution is adjusted to 8.5, and the hydrothermal carbon prepared in step 1 is put into an 8% dopamine hydrochloride aqueous solution, wherein the mass ratio of the hydrothermal carbon to the dopamine hydrochloride in the solution is 1:1, and the polymerization reaction is carried out by stirring at room temperature for 8 hours, and then the hydrothermal carbon is taken out and dried to obtain biochar;
[0044] Then, the biochar was calcined in a tubular furnace under a N2 atmosphere, with a N2 introduction rate of 75 mL / min, and the temperature was increased from room temperature to 700°C at a heating rate of 5°C / min, and then calcined at a constant temperature for 1.5 h, and then cooled to room temperature to obtain biochar;
[0045] Step 3: placing the biochar prepared in step 2 in a quartz tube, placing the quartz tube in a microwave reactor, starting microwave radiation under the condition of N2 flow rate of 150 mL / min, performing microwave-assisted modification, the microwave power is 500 W, and the microwave modification time is 8 min;
[0046] Step 4: After washing the biochar obtained in step 3 with 1 M HCl solution, it was repeatedly rinsed with deionized water until the eluent was neutral to remove residual impurities, and then dried in a vacuum oven overnight at a temperature of 80 °C to finally obtain nitrogen-doped biochar, named NC 700.
[0047] Embodiment 4:
[0048] A method for preparing porous biochar, wherein the preparation steps are repeated in Example 1, the only difference being that "the operation of step 2 in Example 1 is omitted", and other conditions remain unchanged, and the porous biochar finally obtained is named BC@KHCO3700.
[0049] Embodiment 5:
[0050] A method for preparing microwave-assisted modified biochar is disclosed. The preparation steps of the method are repeated in Example 1, except that "the operation of step 4 of Example 1 is omitted" and other conditions remain unchanged. The porous biochar finally obtained is named MWS-BC.
[0051] Embodiment 6:
[0052] A method for preparing nitrogen-doped porous biochar, wherein the preparation steps are repeated in Example 1, with the only difference being that "the constant temperature calcination in step 4 is 500°C, 600°C, 700°C, and 800°C, respectively", and the other conditions remain unchanged. The nitrogen-doped porous biochars finally obtained are named NC@KHCO3500, NC@KHCO3600, NC@KHCO3700, and NC@KHCO3800, respectively.
[0053] Example 7: Morphology Characterization and EDS Spectrum Analysis
[0054] The SEM images of the biochar products of Examples 1-4 are compared in Figure 1, it can be seen from the morphology of the biochars of Examples 1 to 4 that the original biochar BC 700 has a smooth surface without layered or porous structures; the porous biochar BC@KHCO3700 has a rich porous structure, and the surface of the biochar is rougher; the nitrogen-doped biochar NC 700 does not show a porous structure, and the surface is rougher than BC700; the nitrogen-doped porous biochar NC@KHCO3700 also shows a rich porous structure, and the pores are more uniform. EDS energy spectrum analysis shows that the N content of the original BC 700 is very low, and the addition of nitrogen source to NC 700 significantly increases the N content, but no porous structure appears. The nitrogen content of BC@KHCO3700 is no different from that of the original BC, but a porous structure appears due to the addition of pore-forming agent.
[0055] Comparative Example 1:
[0056] The biomass is the white peel of grapefruit. The biomass is washed, dried and crushed through a 100-200 mesh sieve. The biomass powder and deionized water are added into a Teflon-lined autoclave at a mass ratio of 1:10, stirred and put into an oven for hydrothermal carbonization at a hydrothermal temperature of 200°C. The biomass is cooled, dried and ground through a 200 mesh sieve to obtain hydrothermal charcoal.
[0057] Example 8: Comparison of the difference in H2O2 generation in cathodes prepared by biochar with or without nitrogen doping or pore formation and microwave modification
[0058] The biochar prepared in the embodiment or comparative example of the present invention is used to prepare a cathode, comprising the following steps: the biochar is mixed with carbon black, polytetrafluoroethylene dispersion, and ethanol in a feed ratio of 100 mg: 50 mg: 100 mg: 150 μL to obtain a paste mixture, the polytetrafluoroethylene dispersion is used as a dispersant and a binder to firmly and evenly attach catalyst particles to an electrode, and the concentration of the polytetrafluoroethylene dispersion is 60 wt %. The paste mixture is pressed into a sheet by a roller machine, and the sheet is pressed with a titanium mesh (the thickness of the titanium mesh is about 0.8 mm and the size is a circle with a diameter of 10 mm) by a tablet press at 5 MPa for 10 min to obtain an electrode, and calcined at 340° C. in a muffle furnace for 30 min to obtain a cathode, and the cathode sheet is 2 mm thick and the size is a circle with a diameter of 10 mm.
[0059] Platinum sheet is used as anode counter electrode, cathode and anode are assembled in an electrolytic cell, the electrode spacing is 2cm, and electrolyte solution is added to the electrolytic cell. The electrolyte solution is 200mL of 0.05M Na2SO4 solution, the pH is adjusted to 3, and the electrolysis reaction is carried out by power, and the constant voltage of electrolysis is -0.7V.
[0060] According to the above experimental process, when different electrode materials are used, the results of the change of H2O2 generation over time can be found in Figure 2 In. Figure 2 As shown, after 120 min of electrolysis, the nitrogen-doped porous biochar (i.e., NC@KHCO3 in Example 1) was loaded.
[0061] 700) The cathode produces about 2337.5 μmol L H2O2 -1 , the current efficiency can reach 73.79%, which is significantly higher than that of biochar cathode without pore-forming agent or nitrogen source. This is because nitrogen doping increases the defect sites on the surface of the material, where a large amount of pyrrolic nitrogen and abundant defects act as additional active sites, making a great contribution to the removal of target pollutants.
[0062] The biochar yield after microwave modification without high-temperature calcination was 1434.2 μmol L -1 , which is significantly lower than the H2O2 yield of carbon materials calcined at high temperature. This is because pyrolysis produces a rich porous structure, which significantly increases the specific surface area, thereby increasing the number of active centers of the catalyst and improving the catalytic efficiency.
[0063] Example 9: Degradation efficiency of the electro-Fenton system at different calcination temperatures
[0064] A single variable experiment of nitrogen-doped porous biochar with four temperature gradients of calcination temperature of 500-800°C was set up. The nitrogen-doped porous biochar used was NC@KHCO3500, NC@KHCO3600, NC@KHCO3700, and NC@KHCO3800 in Example 6. The electro-Fenton system degradation reaction was constructed. The experimental conditions were as follows:
[0065] The biochar prepared at different calcination temperatures in Example 6 of the present invention was used to prepare the cathode, and the preparation conditions were repeated in Example 8.
[0066] Platinum sheet was used as anode counter electrode, cathode and anode were assembled in an electrolytic cell, the electrode spacing was 2 cm, electrolyte was added to the electrolytic cell. 0.05M Na2SO4 solution was used as electrolyte, the organic pollutant in the electrolyte was atrazine with a final concentration of 10ppm, FeCl2 with a final concentration of 0.01M was added to the electrolyte, the pH of the electrolyte was adjusted to 3, and the electrolysis reaction was carried out by power, and the constant voltage of electrolysis was -0.7V.
[0067] When the biochar prepared at different calcination temperatures in Example 6 of the present invention is used as the cathode, the degradation effect of atrazine is shown in the figure below: Figure 3As shown. The results show that with the increase of pyrolysis temperature, the degradation effect of cathode catalysis on atrazine gradually increases. This is because as the pyrolysis temperature increases, the graphitization degree of biochar increases, the conductivity increases, the current efficiency increases, and its adsorption increases. When the pyrolysis temperature is 700℃, the degradation effect is the best, reaching 99.26%. When the pyrolysis temperature is 800℃, the oxygen-containing functional groups in the biochar are basically removed, the H2O2 production decreases, and the atrazine degradation rate decreases.
[0068] Example 10: Degradation efficiency of the electro-Fenton system under different pH conditions
[0069] The NC@KHCO3700 prepared in Example 1 was used to prepare a cathode for constructing an electro-Fenton system degradation reaction. The experimental conditions were repeated in Example 9, except that the pH of the electrolyte was adjusted to 1.0, 2.0, 3.0, 4.0 or 5.0, and the other conditions remained unchanged.
[0070] Example 10 set up a single variable experiment with five electrolyte solution pH gradients of 1.0, 2.0, 3.0, 4.0, and 5.0. The atrazine degradation effect diagram is as follows: Figure 4 The results show that the degradation rate is the highest at pH 3, and the degradation rate of atrazine can reach 94.11%. The degradation rate of atrazine is not much different in the pH range of 1 to 5, indicating that the system has indeed broadened the pH range of electro-Fenton and can be more widely used in industrialization.
Claims
1. A method for preparing nitrogen-doped porous biochar, characterized in that: The steps include: 1) The biomass is washed, dried, crushed and sieved, and the biomass powder is mixed with deionized water in a mass ratio of 1:5-20, added into a Teflon-lined autoclave, stirred and then placed in an oven for hydrothermal carbonization, cooled, dried, ground and sieved to obtain hydrothermal charcoal; 2) putting the hydrothermal carbon in step 1) into a dopamine hydrochloride solution, stirring at room temperature to perform a polymerization reaction, and then taking out the hydrothermal carbon and drying it to obtain biochar; 3) placing the biochar from step 2) in a quartz tube, placing the quartz tube in a microwave reactor, and starting microwave radiation under the condition of introducing N2 to perform microwave-assisted modification; 4) The biochar modified by microwave-assisted treatment in step 3) is immersed in a NaHCO3 or KHCO3 solution with a concentration of 0.05-0.2 mol / L. After being fully immersed, the biochar is taken out for drying, calcined at high temperature in a tube furnace under a N2 atmosphere, and then cooled to room temperature; 5) The biochar obtained in step 4) is washed with HCl solution to remove residual alkali on the surface, and then repeatedly rinsed with deionized water until the eluent is neutral to remove residual impurities, and then dried in a vacuum oven overnight to obtain nitrogen-doped porous biochar.
2. The method for preparing nitrogen-doped porous biochar according to claim 1, characterized in that: The biomass in step 1) is white grapefruit peel, and the mass ratio of biomass powder to deionized water is 1:8-12.
3. The method for preparing nitrogen-doped porous biochar according to claim 1, characterized in that: In step 1), the hydrothermal temperature is 180-220°C and the hydrothermal time is 10-15h.
4. The method for preparing nitrogen-doped porous biochar according to claim 1, characterized in that: The mass concentration of the dopamine hydrochloride solution in step 2) is 5-10%, the pH thereof is adjusted to 8-9, the mass ratio of the hydrothermal carbon to the dopamine hydrochloride is 1:0.8-1.5, the polymerization reaction temperature is room temperature, and the reaction time is 5-10 hours.
5. The method for preparing nitrogen-doped porous biochar according to claim 1, characterized in that: In step 3), the microwave power is 400-600 W, and the modification time by microwave radiation is 5-10 min.
6. The method for preparing nitrogen-doped porous biochar according to claim 1, characterized in that: In step 4), the mass ratio of biochar to NaHCO3 or KHCO3 is 1:(1-3), and the impregnation time is 10-15h; the temperature of high-temperature roasting in step 4) is 500-800°C, preferably 700°C, and the roasting time is 1-3h.
7. A nitrogen-doped porous biochar prepared by the method according to any one of claims 1 to 6.
8. The use of a nitrogen-doped porous biochar electro-Fenton cathode material as claimed in claim 7, characterized in that The biochar is mixed with carbon black, polytetrafluoroethylene dispersion and ethanol in a ratio of 100 mg: 40-60 mg: 80-120 mg: (100-200 μL), the concentration of the polytetrafluoroethylene dispersion is 50-70%, and a paste mixture is obtained. The mixture is pressed into a thin sheet by a double-roller machine, and then pressed together with a titanium mesh to form an electrode. The electrode is calcined in a muffle furnace at 300-350° C. for 20-60 min to obtain an electro-Fenton cathode material.
9. The use of a nitrogen-doped porous biochar electro-Fenton cathode material as claimed in claim 8, characterized in that The electro-Fenton cathode material is used as the cathode in the electro-Fenton system, with a platinum sheet as the anode and a Na2SO4 solution as the electrolyte, wherein the electrolyte contains a final concentration of 0.005-0.05M Fe 2+ Organic pollutants are also added to the electrolyte, and the electro-Fenton reaction is carried out under power-on conditions without aeration to generate H2O2 in situ, which reacts with Fe 2+ Activate to form HO· to degrade organic pollutants.
10. The use of a nitrogen-doped porous biochar electro-Fenton cathode material as claimed in claim 9, characterized in that The pH of the electrolyte is 1-5, the concentration of Na2SO4 is 0.01-0.1M, and the added Fe 2+ The final concentration is 0.01~0.5M, and the constant voltage of electrolysis is -0.5~ -1.2v.