Preparation method of nitrogen-doped carbon material supported transition metal catalyst and application of nitrogen-doped carbon material supported transition metal catalyst in antibiotic degradation

Abstract

The invention belongs to the technical field of preparation and application of catalytic materials, and particularly relates to a preparation method of a nitrogen-doped carbon material loaded transition metal catalyst and application of the nitrogen-doped carbon material loaded transition metal catalyst to antibiotic degradation. The preparation method comprises the following steps: dissolving Fe (NO3) 3.6 H2O, Co (NO3) 2.6 H2O and an organic ligand in deionized water according to a certain proportion, mixing the solution with N, N-dimethylformamide, and uniformly stirring; 2) transferring the stirred mixed solution and carbon cloth into a high-pressure kettle for hydrothermal reaction, and cooling, washing and drying after hydrothermal reaction is finished to obtain a pre-catalyst; and 3) calcining the pre-catalyst in a tubular furnace at high temperature to obtain the catalyst. The catalyst is high in electrocatalytic activity, the antibiotic degradation rate reaches 95% under the condition that the pH value ranges from 2 to 9, meanwhile, the energy consumption is only 0.11 kWh m <-3 > order <-1 >, and the catalyst is suitable for advanced treatment of antibiotic-containing sewage.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation and application of catalytic materials, and particularly relates to a preparation method of a transition metal catalyst supported on a nitrogen-doped carbon material and its application in antibiotic degradation. Background Art

[0002] Antibiotics play an important role in the treatment of human and animal diseases, but their widespread use has also caused environmental pollution. For example, levofloxacin (LEV) is one of the most widely used fluoroquinolone antibiotics for humans and livestock, and is often detected in aquatic environments including surface water, groundwater, and drinking water, with concentrations ranging from ng / L to μg / L. Worse still, LEV has strong antibacterial activity and low metabolic characteristics, which can lead to the accumulation of pollutants even in treated wastewater. For example, the tail water discharged from livestock and poultry farms after biochemical treatment of feces still contains a large amount of antibiotics, with the highest concentration reaching mg / L, and urgent in-depth treatment is needed. Therefore, there is an urgent need to develop an efficient and selective method to remove LEV from wastewater.

[0003] Electro-Fenton is an advanced electrochemical oxidation technology that can effectively remove refractory antibiotics and is considered a technology to solve the increasingly serious environmental pollution. However, limited by the narrow pH range and low efficiency, constructing an efficient electrocatalytic system applicable to a wide pH range is crucial for practical applications. Peroxymonosulfate (PMS) has attracted much attention due to its strong oxidation ability in a wide pH range. PMS decomposes to generate sulfate radicals, and sulfate radicals undergo redox reactions with organic pollutants. However, due to the complex wastewater environment, the selectivity of sulfate radicals is reduced, resulting in a decrease in the degradation rate. Therefore, another degradation pathway that does not rely on SO4 ·– oxidation, namely singlet oxygen oxidation and mediated electron transfer, is selected. The key technology is the effective adsorption of LEV and PMS on the catalyst surface and the efficient directional transfer of electrons. Designing a catalyst that can provide efficient adsorption sites and high directional electron transfer is the key research direction of the present invention.

[0004] Previous research reports have shown that doping nitrogen atoms in carbon materials can cause local charge rearrangement. Regulating the type of nitrogen doping can adjust the adsorption sites of PMS and organic pollutants, and at the same time induce the generation of a local interfacial microelectric field between nitrogen and the catalyst metal center, thereby enabling the directional transfer of electrons. However, the reported degradation efficiencies are all relatively low. Summary of the Invention

[0005] In view of the above problems, the present invention provides a preparation method of a transition metal catalyst supported on a nitrogen-doped carbon material and its application in antibiotic degradation. By adding different organic ligands, the present invention adjusts the proportion of nitrogen species, changes the adsorption sites of PMS and organic pollutants, and simultaneously forms a local interfacial microelectric field, enabling the directional transfer of electrons, promoting the generation of reactive oxygen species (ROS), and improving the degradation efficiency.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of a transition metal catalyst supported on a nitrogen-doped carbon material, comprising the following steps:

[0008] (1) Ultrasonically clean the carbon cloth with ethanol and water respectively; dissolve Fe(NO3)3·6H2O, Co(NO3)2·6H2O and an organic ligand in deionized water in a certain proportion and mix them with an N,N-dimethylformamide mixed solution, and stir evenly;

[0009] (2) Transfer the stirred mixed solution and the carbon cloth to a stainless steel autoclave for hydrothermal reaction. The temperature of the hydrothermal reaction is 80 - 180 °C, and the reaction time is 15 - 25 hours; after the hydrothermal reaction, cool to room temperature, wash and dry to obtain a pre-catalyst;

[0010] (3) Calcinate the dried pre-catalyst in a tube furnace at a high temperature to finally obtain a transition metal catalyst supported on a nitrogen-doped carbon material.

[0011] Furthermore, the molar ratio of Fe(NO3)3·6H2O, Co(NO3)2·6H2O and the organic ligand is n(Fe(NO3)3·6H2O):n(Co(NO3)2·6H2O):n(organic ligand) = 2:1:1.5 - 3.

[0012] Furthermore, the organic ligand in step (1) is 2-nitroterephthalic acid, and the transition metal catalyst supported on the nitrogen-doped carbon material is an FC-CN (Po：Pd＝3：1) electrocatalyst.

[0013] Furthermore, the organic ligand in step (1) is 2-aminoterephthalic acid, and the transition metal catalyst supported on the nitrogen-doped carbon material is an FC-CN (Po：Pd＝1：3) electrocatalyst.

[0014] Furthermore, the organic ligand in step (1) is terephthalic acid, and the transition metal catalyst supported on the nitrogen-doped carbon material is an FC-C electrocatalyst.

[0015] Furthermore, in step (3), the heating rate of the tube furnace is 5 °C / min, the calcination temperature is 300 - 500 °C, the calcination time is 3 - 8 hours, and the calcination atmosphere is air.

[0016] The present invention also provides an application of a transition metal catalyst supported on a nitrogen-doped carbon material prepared according to the described preparation method in the degradation of antibiotics.

[0017] Furthermore, the application method is as follows: placing the antibiotic solution in an electrolytic cell, using the transition metal catalyst supported on the nitrogen-doped carbon material as the working electrode, using a platinum sheet as the counter electrode, and adding a PMS solution; adjusting the pH of the reaction solution, stirring for 10 - 30 minutes before the reaction to achieve internal equilibrium of the solution; continuously introducing oxygen during the reaction for electrocatalytic reaction, and regularly sampling to measure the concentration of antibiotics in the solution.

[0018] Furthermore, the antibiotic solution is a levofloxacin solution, and the concentration range of the antibiotic solution is 5 - 40 mg / L.

[0019] Furthermore, the concentration range of the PMS solution is 1 - 3 mM; the pH range is 2 - 9.

[0020] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0021] (1) The transition metal electrocatalyst supported on the nitrogen-doped carbon material prepared by the method of the present invention adjusts the proportion of nitrogen doping types by using different suitable organic ligands, thereby forming an interfacial microelectric field inside the catalyst, promoting the directional transfer of electrons, accelerating the cycle between redox electron pairs, and at the same time facilitating the adsorption of PMS and antibiotics by the catalyst, greatly improving the electrocatalytic activity of FC-CN. (Po：Pd＝3：1) of.

[0022] (2) The present invention regulates the proportion of nitrogen doping types by regulating organic ligands, adjusts the directional transfer of electrons inside the electrocatalyst, induces the activation of peroxymonosulfate (PMS), and the prepared transition metal electrocatalyst supported on the nitrogen-doped carbon material has a high degradation efficiency for antibiotics. Among them, the electrocatalytic degradation efficiency of FC-CN (Po：Pd＝3：1) is the highest, and while achieving a degradation rate of 95% for antibiotics (levofloxacin) at pH = 2 - 9, the energy consumption is only 0.11 kWh m - 3 order -1 . The preparation method of the present invention is simple, the reaction conditions are mild, the energy consumption is low, the operation is simple and easy, the cost is low, and it is easy to industrialize, and has broad application prospects in the treatment of antibiotic degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a field emission scanning electron microscope image of the FC-CN (Po：Pd＝3：1) electrocatalyst prepared according to the method of the present invention.

[0024] Figure 2 FC-CN prepared according to the method of the present invention (Po：Pd＝1：3) Field emission scanning electron microscope image of the electrocatalyst

[0025] Figure 3 FC-CN prepared according to the method of the present invention (Po：Pd＝3：1) and FC-CN (Po：Pd＝1：3) X-ray diffraction pattern of the electrocatalyst

[0026] Figure 4 Degradation-time graph of electrocatalytic degradation of levofloxacin by the transition metal catalyst supported on nitrogen-doped carbon material prepared according to the method of the present invention

[0027] Figure 5 Reaction kinetics graph of the degradation of levofloxacin by the transition metal catalyst supported on nitrogen-doped carbon material prepared according to the method of the present invention

[0028] Figure 6 FC-CN prepared according to the method of the present invention (Po：Pd＝3：1) Degradation-time graph of electrocatalytic degradation of levofloxacin by the electrocatalyst under different pH conditions

[0029] Figure 7 FC-CN prepared according to the method of the present invention (Po：Pd＝3：1) Degradation-time graph of electrocatalytic degradation of levofloxacin by the electrocatalyst at different concentrations

[0030] Figure 8 FC-CN prepared according to the method of the present invention (Po：Pd＝3：1) Degradation-time graph of electrocatalytic degradation of levofloxacin by the electrocatalyst under different PMS concentration conditions

[0031] Figure 9 FC-CN prepared according to the method of the present invention (Po：Pd＝3：1) Energy consumption graph of the electrocatalyst during the electrocatalytic degradation of levofloxacin Detailed implementation mode

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Example 1

[0034] FC-CN (Po：Pd＝3：1) Preparation of the electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0035] (1) Preparation of FC-CN (Po：Pd＝3：1) Preparation of electrocatalyst: The carbon cloth was ultrasonically cleaned with ethanol and water for 20 min respectively; Fe(NO3)3·6H2O, Co(NO3)2·6H2O and 2-nitroterephthalic acid (molar ratio 2:1:1.5) were dissolved in a mixed solution of deionized water and N,N-dimethylformamide and stirred. The solution and the carbon cloth were transferred to a stainless-steel autoclave and hydrothermally treated at 100 °C for 20 hours. After the hydrothermal treatment, it was cooled to room temperature, washed with deionized water and dried at 80 °C for 5 hours. The dried catalyst was calcined in a tubular furnace at 400 °C for 3 hours (the heating rate of the tubular furnace was 5 °C / min) to obtain FC-CN (Po：Pd＝3：1) Electrocatalyst. Detect the prepared FC-CN (Po：Pd＝3：1) Field emission scanning electron microscope image, as shown in Figure 1 shown; The X-ray diffraction pattern of the obtained FC-CN (Po：Pd＝3：1) was tested, as shown in Figure 3 shown.

[0036] (2) Degradation of levofloxacin using FC-CN (Po：Pd＝3：1) electrocatalyst: 70 mL of the solution of livestock and poultry manure tail water (levofloxacin concentration 10 mg / L) after biochemical treatment was placed in an electrolytic cell. The working electrode used the FC-CN (Po：Pd＝3：1) electrocatalyst, the counter electrode was a platinum sheet, and 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to 3. It was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken regularly to measure the concentration of levofloxacin in the solution.

[0037] Example 2

[0038] Preparation of FC-CN (Po：Pd＝1：3) electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0039] (1) Preparation of FC-CN (Po：Pd＝1：3) Preparation of electrocatalyst: The carbon cloth was ultrasonically cleaned with ethanol and water for 20 min respectively; Fe(NO3)3·6H2O, Co(NO3)2·6H2O and 2-aminoterephthalic acid (molar ratio 2:1:1.5) were dissolved in a mixed solution of deionized water and N,N-dimethylformamide and stirred. The solution and the carbon cloth were transferred to a stainless-steel autoclave and hydrothermally treated at 100 °C for 20 hours. After the hydrothermal treatment, it was cooled to room temperature, washed with deionized water and dried at 80 °C for 5 hours. The dried catalyst was calcined in a tubular furnace at 400 °C for 3 hours (the heating rate of the tubular furnace was 5 °C / min) to obtain FC-CN (Po：Pd＝1：3) Electrocatalyst. Detect the prepared FC-CN(Po：Pd＝1：3) Field emission scanning electron microscope images, such as Figure 2 shown; the X-ray diffraction pattern of the detected FC-CN (Po：Pd＝1：3) , such as Figure 3 shown.

[0040] (2) The steps for the electrocatalyst to degrade levofloxacin are the same as those in Example 1.

[0041] Example 3

[0042] Preparation of the FC-C electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0043] (1) Preparation of the FC-C electrocatalyst: The carbon cloth was ultrasonically cleaned with ethanol and water for 20 min respectively; Fe(NO3)3·6H2O, Co(NO3)2·6H2O and terephthalic acid (molar ratio 2:1:1.5) were dissolved in a mixed solution of deionized water and N,N-dimethylformamide and stirred. The solution and the carbon cloth were transferred to a stainless steel autoclave and hydrothermally treated at 100 °C for 20 hours. After the hydrothermal treatment, it was cooled to room temperature, washed with deionized water and dried at 80 °C for 5 hours. The dried catalyst was calcined in a tubular furnace at 400 °C for 3 hours (the heating rate of the tubular furnace was 5 °C / min) to obtain the FC-C electrocatalyst.

[0044] (2) The steps for the electrocatalyst to degrade levofloxacin are the same as those in Example 1.

[0045] The degradation efficiency of the three electrocatalysts for the electrocatalytic degradation of levofloxacin obtained in the above Examples 1-3 was tested, and the degradation-time diagrams of the three electrocatalysts for the electrocatalytic degradation of levofloxacin were obtained as Figure 4 shown. The reaction kinetics of the three electrocatalysts for the electrocatalytic degradation of levofloxacin are as Figure 5 shown, where k is the reaction rate constant and R 2 is the coefficient of determination in the linear fitting. It can be seen that among the three catalysts, the FC-CN (Po：Pd＝3：1) electrocatalyst has a higher degradation rate and a faster degradation rate within 90 minutes. The results show that the FC-CN (Po：Pd＝3：1) has a higher removal rate of LEV.

[0046] Example 4

[0047] FC-CN (Po：Pd＝3：1) electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0048] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0049] (2) Using FC-CN (Po：Pd＝3：1)Electrocatalytic degradation of levofloxacin by an electrocatalyst: 70 mL of the solution of the livestock and poultry manure tail water after biochemical treatment (levofloxacin concentration 10 mg / L) was placed in an electrolytic cell, and the working electrode used FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode was a platinum sheet. 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to pH = 2, and it was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken at regular intervals and the concentration of levofloxacin in the solution was measured.

[0050] Example 5

[0051] FC-CN (Po：Pd＝3：1) Preparation of the electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0052] (1) The preparation steps of the electrocatalyst were the same as those in Example 1.

[0053] (2) Electro-catalytic degradation of levofloxacin using FC-CN (Po：Pd＝3：1) as the electrocatalyst: 70 mL of the solution of the livestock and poultry manure tail water after biochemical treatment (levofloxacin concentration 10 mg / L) was placed in an electrolytic cell, and the working electrode used FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode was a platinum sheet. 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to pH = 5, and it was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken at regular intervals and the concentration of levofloxacin in the solution was measured. The degradation-time graph of levofloxacin by this method is as Figure 4 shown.

[0054] Example 6

[0055] FC-CN (Po：Pd＝3：1) Preparation of the electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0056] (1) The preparation steps of the electrocatalyst were the same as those in Example 1.

[0057] (2) Electro-catalytic degradation of levofloxacin using FC-CN (Po：Pd＝3：1) as the electrocatalyst: 70 mL of the solution of the livestock and poultry manure tail water after biochemical treatment (levofloxacin concentration 10 mg / L) was placed in an electrolytic cell, and the working electrode used FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode was a platinum sheet. 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to pH = 6, and it was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken at regular intervals to measure the concentration of levofloxacin in the solution.

[0058] Example 7

[0059] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0060] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0061] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin with the FC-CN electrocatalyst: Place 70 mL of the solution of the livestock and poultry manure tail water after biochemical treatment (levofloxacin concentration 10 mg / L) in an electrolytic cell. The working electrode uses the FC-CN (Po：Pd＝3：1) electrocatalyst, and the counter electrode is a platinum sheet. Add 2 mM of PMS solution. Use sodium hydroxide and sulfuric acid to adjust the pH of the reaction solution to pH = 7. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Continuously introduce oxygen during the reaction for electrocatalytic reaction, and take samples regularly to measure the concentration of levofloxacin in the solution.

[0062] Example 8

[0063] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0064] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0065] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin with the FC-CN electrocatalyst: Place 70 mL of the solution of the livestock and poultry manure tail water after biochemical treatment (levofloxacin concentration 10 mg / L) in an electrolytic cell. The working electrode uses the FC-CN (Po：Pd＝3：1) electrocatalyst, and the counter electrode is a platinum sheet. Add 2 mM of PMS solution. Use sodium hydroxide and sulfuric acid to adjust the pH of the reaction solution to pH = 9. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Continuously introduce oxygen during the reaction for electrocatalytic reaction, and take samples regularly to measure the concentration of levofloxacin in the solution.

[0066] Analysis of the degradation efficiency of the FC-CN (Po：Pd＝3：1) electrocatalyst for electrocatalytic degradation of levofloxacin under different pH conditions, as Figure 6 shown, the degradation rate is the highest at pH = 3, and as the pH value increases, the degradation rate gradually decreases, which is mainly due to the decrease in the generation rate of H2O2 with the increase in the pH value. However, with the increase in the reaction time, a degradation rate of nearly 100% can still be achieved under different pH conditions, indicating that the catalyst is suitable not only for acidic conditions but also for neutral and weakly alkaline conditions.

[0067] Example 9

[0068] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0069] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0070] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin with the electrocatalyst: Place 70 mL of the solution of the livestock and poultry manure tail water (levofloxacin concentration 5 mg / L) after biochemical treatment in an electrolytic cell. Use FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode is a platinum sheet. Add 2 mM of PMS solution. Use sodium hydroxide and sulfuric acid to adjust the pH of the reaction solution to 3. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Continuously introduce oxygen during the reaction for electrocatalytic reaction, take samples regularly and measure the concentration of levofloxacin in the solution. The degradation-time graph of levofloxacin by this method is as Figure 7 shown.

[0071] Example 10

[0072] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0073] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0074] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin with the electrocatalyst: Place 70 mL of the solution of the livestock and poultry manure tail water (levofloxacin concentration 20 mg / L) after biochemical treatment in an electrolytic cell. Use FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode is a platinum sheet. Add 2 mM of PMS solution. Use sodium hydroxide and sulfuric acid to adjust the pH of the reaction solution to 3. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Continuously introduce oxygen during the reaction for electrocatalytic reaction, take samples regularly and measure the concentration of levofloxacin in the solution. The degradation-time graph of levofloxacin by this method is as Figure 7 shown.

[0075] Example 11

[0076] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0077] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0078] (2) Using FC-CN (Po：Pd＝3：1)Electrocatalytic degradation of levofloxacin by electrocatalyst: 70 mL of the tail water of livestock and poultry manure after biochemical treatment (levofloxacin concentration 30 mg / L) was placed in an electrolytic cell, and the working electrode used was FC-CN (Po：Pd＝3：1) electrocatalyst, and the counter electrode was a platinum sheet. And 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to 3. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken regularly and the concentration of levofloxacin in the solution was measured. The degradation-time graph of levofloxacin by this method is as Figure 7 shown.

[0079] Example 12

[0080] FC-CN (Po：Pd＝3：1) Preparation of electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0081] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0082] (2) Using FC-CN (Po：Pd＝3：1) electrocatalyst for electrocatalytic degradation of levofloxacin: 70 mL of the tail water of livestock and poultry manure after biochemical treatment (levofloxacin concentration 40 mg / L) was placed in an electrolytic cell, and the working electrode used was FC-CN (Po：Pd＝3：1) electrocatalyst, and the counter electrode was a platinum sheet. And 2 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to 3. Stir for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken regularly and the concentration of levofloxacin in the solution was measured. The degradation-time graph of levofloxacin by this method is as Figure 7 shown.

[0083] As Figure 7 shown, the LEV degradation experiment was carried out when the initial concentration of LEV was 5 - 40 mg L -1 to observe the influence of the initial concentration of LEV. As the initial concentration increases, the intermediate products will also increase, and there will be more competitive adsorption between the LEV antibiotic molecules and the intermediate products. Therefore, the LEV concentration was selected as 10 mg L -1 as the optimal condition for the degradation experiment.

[0084] Example 13

[0085] FC-CN (Po：Pd＝3：1) Preparation of electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0086] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0087] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin by an electrocatalyst: 70 mL of the solution of the livestock and poultry manure tail water (levofloxacin concentration 10 mg / L) after biochemical treatment was placed in an electrolytic cell, and the working electrode used FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode was a platinum sheet. 1 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to 3. The solution was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken at regular intervals and the concentration of levofloxacin in the solution was measured. The degradation-time graph of levofloxacin by this method is as Figure 8 shown.

[0088] Example 14

[0089] FC-CN (Po：Pd＝3：1) Preparation of an electrocatalyst and its electrocatalytic degradation of levofloxacin, including the following steps:

[0090] (1) The preparation steps of the electrocatalyst are the same as those in Example 1.

[0091] (2) Using FC-CN (Po：Pd＝3：1) Electrocatalytic degradation of levofloxacin by an electrocatalyst: 70 mL of the solution of the livestock and poultry manure tail water (levofloxacin concentration 10 mg / L) after biochemical treatment was placed in an electrolytic cell, and the working electrode used FC-CN (Po：Pd＝3：1) as the electrocatalyst, and the counter electrode was a platinum sheet. 3 mM of PMS solution was added. Sodium hydroxide and sulfuric acid were used to adjust the pH of the reaction solution to 3. The solution was stirred for 30 minutes before the reaction to achieve internal equilibrium of the solution. Oxygen was continuously introduced during the reaction for electrocatalytic reaction, and samples were taken at regular intervals and the concentration of levofloxacin in the solution was measured. The degradation-time graph of levofloxacin by this method is as Figure 8 shown.

[0092] As Figure 8 shown, when the dosage of PMS increased from 1 mM to 2 mM (k = 0.0737 min -1 ), a significant increase in the degradation rate of LEV was observed within 90 minutes (from 93.96% to 99.8%). However, when the amount of PMS continued to increase to 3.0 mM, the percentage within 90 minutes dropped to 94.53%. It indicates that when the dosage of PMS is 2 mM, the degradation rate is the highest. Therefore, 2 mM of PMS dosage was selected as the optimal condition for the LEV degradation experiment.

[0093] In summary, the method of the present invention for degrading levofloxacin has a wide application range, is simple and easy to operate, has high efficiency, achieves a high degradation rate of levofloxacin while consuming low energy, and the method of the present invention has broad application prospects in the treatment of antibiotic-containing wastewater.

[0094] In addition, the applicant also analyzed the energy consumption generated during the degradation of antibiotics by the FC-CN (Po：Pd＝3：1) electrocatalyst (as shown in Figure 9 ), and compared it with existing catalysts. The comparison data is shown in Table 1.

[0095] Table 1 Energy consumption related to different catalysts

[0096]

[0097]

[0098] Note: CIP: ciprofloxacin; LOM: lomefloxacin

[0099] From Figure 9 it can be seen that when the current increases from 20 mA to 100 mA, the electrical energy consumption power value (EEC) increases from 0.11 kWh m -3 to 2.4931 kWh m -3 and the electrical energy consumption power value per order (EEO) increases from 0.298 kWh m -3 order -1 to 12.8399 kWh m -3 order -1 . According to Table 1, compared with other catalyst electrodes, the EEC and EEO of FC-CN (Po:Pd＝3:1) are at a relatively low level (Table 1), and the removal rate of LEV by FC-CN (Po:Pd＝3:1) is also relatively high. This indicates that FC-CN (Po:Pd＝3:1) can achieve a relatively high removal rate of LEV with relatively low energy consumption (Table 1).

[0100] The above description is a detailed description of the preferred and feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.

Claims

1. A preparation method of a transition metal catalyst supported on a nitrogen-doped carbon material, characterized in that, It includes the following steps: (1) Clean the carbon cloth; dissolve Fe(NO3)3·6H2O, Co(NO3)2·6H2O and the organic ligand in deionized water in a certain proportion and mix it with the N,N-dimethylformamide mixed solution, and stir evenly; (2) Transfer the stirred mixed solution and the carbon cloth to a stainless steel autoclave for hydrothermal reaction. The temperature of the hydrothermal reaction is 80-180 °C, and the reaction time is 15-25 hours; after the hydrothermal reaction, cool it to room temperature, wash and dry to obtain the pre-catalyst; (3) Calcinate the dried pre-catalyst at high temperature in a tubular furnace to finally obtain the transition metal catalyst supported on nitrogen-doped carbon material.

2. The preparation method of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 1, wherein The molar ratio of the Fe(NO3)3·6H2O, Co(NO3)2·6H2O and the organic ligand is n(Fe(NO3)3·6H2O):n(Co(NO3)2·6H2O):n(organic ligand)=2:1:1.5-3.

3. The preparation method of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 1, characterized in that, The organic ligand described in step (1) is 2-nitroterephthalic acid, and the transition metal catalyst supported on the nitrogen-doped carbon material is FC-CN (Po：Pd＝3：1) electrocatalyst.

4. The preparation method of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 1, wherein, The organic ligand described in step (1) is 2-aminoterephthalic acid, and the nitrogen-doped carbon material supported transition metal catalyst is FC-CN (Po：Pd＝1：3) electrocatalyst 5. The preparation method of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 1, wherein The organic ligand in step (1) is terephthalic acid, and the transition metal catalyst supported on nitrogen-doped carbon material is the FC-C electrocatalyst.

6. The preparation method of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 1, wherein, In step (3), the heating rate of the tubular furnace is 5 °C / min, the calcination temperature is 300-500 °C, the calcination time is 3-8 hours, and the calcination atmosphere is air.

7. Application of the transition metal catalyst supported on nitrogen-doped carbon material prepared by the preparation method according to any one of claims 1-6 in antibiotic degradation.

8. Use of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 7 in antibiotic degradation, characterized in that, The method of the application is: place the antibiotic solution in an electrolytic cell, use the transition metal catalyst supported on nitrogen-doped carbon material as the working electrode, the counter electrode is a platinum sheet, and add the PMS solution; adjust the pH of the reaction solution, stir for 10-30 minutes before the reaction to achieve internal equilibrium of the solution; continuously introduce oxygen during the reaction for electrocatalytic reaction, and regularly take samples to measure the concentration of antibiotics in the solution.

9. Use of the transition metal catalyst supported on nitrogen-doped carbon material according to claim 8 in antibiotic degradation, characterized in that, The antibiotic solution is levofloxacin solution, and the concentration range of the antibiotic solution is 5-40 mg / L.

10. Use of the transition metal catalyst supported on the nitrogen-doped carbon material according to claim 8 in antibiotic degradation, characterized in that The concentration range of the PMS solution is 1-3 mM; the pH range is 2-9.

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