Method for treating medical wastewater by using iron-nitrogen co-doped biochar activated peroxyacetic acid

Abstract

The application belongs to the technical field of wastewater treatment, and provides a method for treating medical wastewater by using iron-nitrogen co-doped biochar to activate peroxyacetic acid, which comprises the following steps: adding iron-nitrogen co-doped biochar and peroxyacetic acid into medical wastewater, and treating the wastewater under stirring conditions; during the wastewater treatment process, the iron-nitrogen co-doped biochar activates the peroxyacetic acid to generate organic free radicals, superoxide free radicals and singlet oxygen to degrade organic pollutants in the wastewater, and meanwhile, the iron-nitrogen co-doped biochar adsorbs and removes part of the pollutants in the wastewater; the iron-nitrogen co-doped biochar has a porous structure, the iron species in the iron-nitrogen co-doped biochar includes Fe 0 , FeS, Fe3O4, Fe3N and Fe4N, and the intensity ratio I D / I G of the D band and the G band of the Raman spectrum of the iron-nitrogen co-doped biochar is 2-2.6. The application uses biomass-derived iron-nitrogen co-doped biochar as a material for activating peroxyacetic acid, has the characteristics of green efficiency and no secondary pollution, and can improve the degradation efficiency of medical wastewater while reducing the treatment cost.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and relates to a method for treating medical wastewater using iron-nitrogen co-doped biochar to catalyze peracetic acid treatment. Background Technology

[0002] Pharmaceuticals and personal care products (PPCPs) have garnered widespread attention as an emerging class of organic pollutants. Common pharmaceuticals found in the environment include antibiotics, hormones, and nonsteroidal anti-inflammatory drugs (NSAIDs). Even low doses of these drugs can impact environmental organisms; for example, the NSAIDs ibuprofen and naproxen can cause DNA damage and oxidative stress in large water fleas. Pharmaceuticals are closely intertwined with people's lives and production, with high production and consumption volumes. Because pharmaceuticals cannot be completely metabolized by the human body or other organisms, their parent compounds and metabolites are excreted in urine and feces, eventually entering wastewater treatment systems. Hospitals and wastewater treatment plants are the most significant pathways for pharmaceuticals and their metabolites to enter aquatic environments. Medical wastewater has repeatedly drawn public attention, as its discharge poses a significant threat to water resources and has become a major source of harm to public health.

[0003] Advanced oxidation processes (AOPs) can generate active species that degrade and mineralize organic matter in situ, making them an effective means of decomposing organic micropollutants. Common oxidants include hydrogen peroxide (H₂O₂), persulfate (PDS), and permonose sulfate (PMS). In recent years, peracetic acid (PAA), as a highly efficient and economical oxidant, has also found some applications in wastewater purification using AOPs. PAA-based AOPs have the characteristic of high simultaneous elimination capabilities while degrading organic pollutants, making them advantageous for the treatment of medical wastewater. Existing literature reports that PAA activation pathways mainly include activation through external energy input (e.g., thermal activation, UV activation, and photocatalysis) and activation through homogeneous / heterogeneous catalysts. Due to the high cost of activation methods using high-energy inputs such as UV light, catalyst activation of PAA is relatively more economical. Heterogeneous metal-based catalysts, in particular, have attracted widespread attention due to their advantages such as high catalytic activity, easy recycling, and minimal impact from water quality.

[0004] Biochar (BC) generally refers to the carbon-rich product formed by pyrolyzing agricultural and forestry waste and other biomass under anaerobic and certain temperature conditions. Biochar is a low-cost, widely available, and environmentally friendly carbonaceous material that can be produced from widely available waste biomass. It has an adjustable specific surface area and abundant surface functional groups. CN115646525A discloses iron-nitrogen co-doped biochar (Fe-NBC), its preparation method, and its application in wastewater treatment. Fe-NBC is prepared by high-temperature pyrolysis of microalgae, nitrogen source urea, and iron source ferric nitrate nonahydrate. When using Fe-NBC to treat wastewater, Fe-NBC and an oxidant are added to the wastewater containing organic pollutants to carry out a degradation reaction. The oxidant is one or more of hydrogen peroxide, sodium persulfate, ammonium persulfate, and potassium persulfate. The mass ratio of Fe-NBC dosage to organic pollutants in the wastewater is 5:1-10:1; the molar ratio of oxidant dosage to organic pollutants in the wastewater is 10:1-100:1; the degradation reaction time is 30-120 min; the degradation reaction is carried out in a shaker at 100-180 rpm; and the degradation reaction is carried out at room temperature. The principle of Fe-NBC activating persulfate (PDS) is that the introduction of nitrogen and iron into the carbon lattice leads to a redistribution of charge density in graphitic carbon, enhancing the interaction between PDS and the Fe-NBC surface to form a surface complex and promoting charge transfer. On the one hand, experiments have shown that the effectiveness of this method in activating PDS to degrade sulfamethoxazole (SMX) largely depends on the carbon source microalgae used. Furthermore, the method requires a large dosage of PDS and has low SMX degradation efficiency. Additionally, the recycling performance of Fe-NBC is very limited. When using Fe-NBC to activate PDS for SMX degradation, the removal rate was 94% in the first run, but decreased to 68.7% in the second run, and approximately 65.6% in the fourth run. On the other hand, research has found that PAA activation is highly specific to heterogeneous catalysts. Currently, heterogeneous catalysts that can activate H2O2, PDS, and PMS to produce active species for pollutant degradation cannot activate PAA to produce active species. In other words, there is no technical correlation between the ability of Fe-NBC to activate PDS and its ability to effectively activate PAA to produce active species. Therefore, this invention aims to provide a method for treating medical wastewater based on the activation of PAA using iron-nitrogen co-doped biochar, to effectively improve the degradation efficiency of PPCPs pollutants in medical wastewater and improve the recycling performance of iron-nitrogen co-doped biochar. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a method for treating medical wastewater by activating peracetic acid with iron-nitrogen co-doped biochar, so as to improve the degradation efficiency of organic pollutants in medical wastewater.

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

[0007] A method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid includes the following steps:

[0008] Iron-nitrogen co-doped biochar and peracetic acid were added to medical wastewater, and the wastewater was treated under stirring conditions. The pH value of the wastewater was controlled to be 3-9, the concentration of iron-nitrogen co-doped biochar in the wastewater was controlled to be 0.1-0.3 g / L, and the concentration of peracetic acid in the wastewater was controlled to be 0.1-0.3 mmol / L.

[0009] In wastewater treatment, iron-nitrogen co-doped biochar activates peracetic acid to generate organic free radicals (RO·), superoxide radicals (O2˙ˉ), and singlet oxygen (RO·). 1 O2 degrades organic pollutants in wastewater, while iron-nitrogen co-doped biochar adsorbs and removes some pollutants from the wastewater; after treating one batch of wastewater, the iron-nitrogen co-doped biochar is recycled for the next batch of wastewater treatment.

[0010] The iron-nitrogen co-doped biochar has a porous structure, and the iron species in the iron-nitrogen co-doped biochar include Fe. 0 The intensity ratio of the D band to the G band in the Raman spectra of FeS, Fe3O4, Fe3N, and Fe4N co-doped biochar is I. D / I G It ranges from 2 to 2.6.

[0011] In the above technical solution, the organic free radical (RO·) includes CH3C(O)O· and CH3C(O)OO·.

[0012] In the above technical solution, during the wastewater treatment process, iron-nitrogen co-doped biochar first activates peracetic acid to generate organic free radicals (RO·). These organic free radicals (RO·) then further react, partially transforming into superoxide radicals (O2˙ˉ). The superoxide radicals (O2˙ˉ) then further react, partially transforming into singlet oxygen (…). 1 O2), singlet oxygen ( 1 O2 is a non-free radical reactive species, ultimately mainly existing as singlet oxygen (O2). 1 O2 acts as a reactive species, working in conjunction with organic free radicals (RO·) and superoxide radicals (O2˙ˉ) to degrade organic pollutants in wastewater.

[0013] The preparation method of the iron-nitrogen co-doped biochar in the above technical solution is as follows:

[0014] (1) Dissolve the iron source, nitrogen source and reducing agent in water to obtain a mixture. In this mixture, the molar ratio of reducing agent to iron source is (1-0.7):1, and the molar ratio of nitrogen source to iron source is 1:(0.038-0.38). According to the mass ratio of biomass raw material fragments to nitrogen source of (0.9-1.1):1, mix the biomass raw material fragments with the above mixture thoroughly to obtain the reaction precursor.

[0015] (2) The reaction precursor was transferred to a high-pressure reactor and hydrothermally reacted at 160-180°C for 8-10 hours. The hydrothermal reaction product was dried to obtain the biochar precursor.

[0016] (3) The biochar precursor is heated to 700-900℃ in a non-reactive atmosphere without oxygen and kept at this temperature for 1-2 hours for pyrolysis. The pyrolysis product is then crushed to obtain iron-nitrogen co-doped biochar.

[0017] In the above technical solution, when preparing iron-nitrogen co-doped biochar, the biomass raw material fragments used in step (1) are agricultural and forestry biomass fragments, such as poplar wood fragments.

[0018] In the above technical solution, when preparing iron-nitrogen co-doped biochar, the oxygen-free non-reactive atmosphere mentioned in step (3) refers to an atmosphere that contains neither oxygen nor an atmosphere that would react with the biochar precursor under the conditions in step (3). For example, it can be an argon atmosphere, a nitrogen atmosphere, etc. The specific application can be selected according to the actual situation.

[0019] In the above technical solution, the iron source used in preparing iron-nitrogen co-doped biochar is a water-soluble divalent iron salt.

[0020] In the above technical solution, the nitrogen source used in preparing iron-nitrogen co-doped biochar is at least one of urea and melamine.

[0021] In the above technical solution, ascorbic acid is used as the reducing agent in the preparation of iron-nitrogen co-doped biochar.

[0022] In the above technical solution, when preparing iron-nitrogen co-doped biochar, it is preferable to control the concentration of iron source in the mixed solution in step (1) to be 50-500 mmol / L.

[0023] The iron-nitrogen co-doped biochar prepared by the above technical solution exhibits excellent recycling performance when treating medical wastewater with activated peracetic acid. For example, experiments have demonstrated that when using the iron-nitrogen co-doped biochar in the above technical solution to treat naproxen-containing wastewater with activated peracetic acid, the removal rate of naproxen remained essentially unchanged in the first four cycles. In the fourth cycle, the removal rate remained at 99%. Although the removal rate decreased slightly in the fifth cycle, it still remained at 80%. Therefore, in the above technical solution, the recycling frequency of the iron-nitrogen co-doped biochar is controlled to be at least four times. The specific recycling frequency can be determined based on the removal rate of the target pollutants in the medical wastewater during actual application. For example, the recycling frequency of the iron-nitrogen co-doped biochar can typically be controlled to be four to six times.

[0024] In the above technical solution, the wastewater treatment time is determined according to the water quality of the medical wastewater (e.g., the type and concentration of organic pollutants). Generally, the treatment is carried out until the removal rate of pollutants in the wastewater reaches equilibrium. In general, the wastewater treatment time does not exceed 30 minutes. For example, the wastewater treatment time can be controlled to be 5-25 minutes, 10-25 minutes, 10-20 minutes, 10-15 minutes, etc.

[0025] In the above technical solution, the medical wastewater contains organic pollutants, such as phenolic substances (e.g., phenol (PE), bisphenol A (BPA)), nonsteroidal anti-inflammatory drugs (e.g., naproxen (NAP)), sulfonamide antibiotics (e.g., sulfamethoxazole (SMX)), and nitrobenzene (NB), benzoic acid (BA), etc.

[0026] This invention demonstrates through experiments that the method described herein can effectively resist the influence of low-concentration water matrix on pollutant degradation. For example, it can overcome the adverse effects of common low-concentration H2PO4-, HCO3-, and humic acid (HA) in wastewater on the degradation process. When the concentration of H2PO4- in the wastewater does not exceed 0.2 mmol / L, the concentration of HCO3- does not exceed 0.1 mmol / L, and the concentration of HA does not exceed 2 mg / L, it essentially does not inhibit the ability of iron-nitrogen co-doped biochar to activate peracetic acid to degrade pollutants. Simultaneously, when the wastewater contains Cl-, it essentially does not adversely affect the ability of iron-nitrogen co-doped biochar to activate peracetic acid to degrade organic pollutants in the wastewater; on the contrary, the Cl- in the wastewater can promote the degradation of organic pollutants to a certain extent. Therefore, in the above technical solution, the medical wastewater may also contain at least one of low-concentration H2PO4-, HCO3-, and humic acid (HA), and the medical wastewater may also contain Cl-.

[0027] In the above technical solutions, it is best to control the stirring conditions during the wastewater treatment process to keep the iron-nitrogen co-doped biochar in a fluidized state.

[0028] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0029] 1. This invention provides a method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid. The method involves adding iron-nitrogen co-doped biochar and peracetic acid to the medical wastewater and treating the wastewater under stirring conditions. During the wastewater treatment process, the iron-nitrogen co-doped biochar activates the peracetic acid to generate organic free radicals (CH3C(O)O· and CH3C(O)OO·), superoxide radicals (O2˙ˉ), and singlet oxygen (…). 1 O2 degrades organic pollutants in wastewater, while iron-nitrogen co-doped biochar adsorbs and removes some pollutants. Compared to existing technologies that use other iron-based catalytic materials to activate peracetic acid for wastewater treatment, this invention uses iron-nitrogen co-doped biochar derived from waste biomass as the material for activating peracetic acid, which is greener, more efficient, and produces no secondary pollution. While achieving efficient activation of peracetic acid to degrade organic pollutants, it can also reduce the material preparation cost and help reduce the treatment cost of medical wastewater.

[0030] 2. This invention will demonstrate through experiments that the method provided by this invention can completely remove naproxen from simulated naproxen wastewater within 10 minutes. The iron-nitrogen co-doped biochar has the ability to efficiently activate peracetic acid to produce active species, and the active species produced by the activated peracetic acid have the ability to efficiently degrade organic pollutants. Simultaneously, the iron-nitrogen co-doped biochar itself is magnetic, easy to separate, and exhibits stable performance in activating peracetic acid to produce active species, allowing for multiple recycling to reduce wastewater treatment costs.

[0031] 3. Experiments have demonstrated that the method of this invention exhibits good degradation effects even under conditions where multiple aquatic substrates coexist, such as common water anions like Cl-, H2PO4-, and HCO3-, as well as humic acid (HA). Furthermore, low concentrations of Cl- and HA are beneficial for pollutant degradation. In other words, the method of this invention can effectively activate peracetic acid to degrade organic pollutants in wastewater even in water bodies with low concentrations of coexisting aquatic substrates. In addition, the method of this invention can effectively degrade various common organic pollutants in water bodies, such as phenolic substances, non-steroidal anti-inflammatory drugs, sulfonamide antibiotics, and benzoic acid. Attached Figure Description

[0032] Figure 1The figures show the characterization results of the iron-nitrogen co-doped biochar prepared in Examples 1 and 2. Figure a is the SEM image of FeN-BC-800, Figure b is the EDS spectrum of FeN-BC-800, Figure c is the XRD test results of FeN-BC-600, FeN-BC-700, FeN-BC-800, FeN-BC-900 and FeN-BC-1000, and Figure d is the Raman spectrum of FeN-BC-600, FeN-BC-700, FeN-BC-800, FeN-BC-900 and FeN-BC-1000.

[0033] Figure 2 The results are the test results of the performance of iron-nitrogen co-doped biochar in Example 4 for activating PAA to degrade NAP.

[0034] Figure 3 These are the results of the recycling performance test of iron-nitrogen co-doped biochar activated PAA.

[0035] Figure 4 This describes the effect of different reaction conditions on the efficiency of iron-nitrogen co-doped biochar in activating PAA to degrade NAP.

[0036] Figure 5 This study examines the effects of different anions on the activation of PAA and NAP degradation by iron-nitrogen co-doped biochar.

[0037] Figure 6 The results show the application potential assessment of iron-nitrogen co-doped biochar activated PAA for pollutant degradation. Figure a shows the degradation of different organic micropollutants, and Figure b shows the test results of actual water treatment.

[0038] Figure 7 This is the result of a study on the mechanism of PAA activation and NAP degradation by iron-nitrogen co-doped biochar. Detailed Implementation

[0039] The following examples further illustrate the method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid, provided by the present invention. It should be noted that the following examples are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0040] In the following examples, the peracetic acid (PAA) used was analytical grade PAA.

[0041] Example 1

[0042] In this embodiment, the iron-nitrogen co-doped biochar is prepared by the following steps:

[0043] (1) Iron source FeSO4·7H2O, nitrogen source urea and ascorbic acid are dissolved in deionized water to obtain a mixture. In the mixture, the molar ratio of ascorbic acid to iron source is 1:1, the molar ratio of nitrogen source to iron source is 1:0.15, and the concentration of iron source is 200 mmol / L.

[0044] Poplar sawdust was added to the above mixture at a mass ratio of 1:1 to nitrogen source, and the mixture was thoroughly mixed to obtain the reaction precursor.

[0045] (2) The reaction precursor obtained in step (1) is transferred to a high-pressure reactor lined with polytetrafluoroethylene and hydrothermally reacted at 160°C for 10 h. The hydrothermal reaction product is then dried in an oven at 80°C for 12 h to obtain the biochar precursor.

[0046] (3) The obtained biochar precursor was transferred into a quartz boat and pyrolyzed in a tube furnace at 5℃ / min under an argon atmosphere to 800℃ and held at that temperature for 2h. The pyrolysis product was ground and passed through a 100-mesh sieve to obtain iron-nitrogen co-doped biochar, denoted as FeN-BC-800.

[0047] Example 2

[0048] In this embodiment, pyrolysis was carried out at four different temperatures to prepare different iron-nitrogen co-doped biochar.

[0049] Experiment 1: The operation is the same as in Example 1, except that in step (3), the temperature is raised to 600°C and held at that temperature for 2 hours to carry out pyrolysis, and iron-nitrogen co-doped biochar is obtained, denoted as FeN-BC-600.

[0050] Experiment 2: The operation is the same as in Example 1, except that in step (3), the temperature is raised to 700°C and held at that temperature for 2 hours to carry out pyrolysis, and iron-nitrogen co-doped biochar is obtained, denoted as FeN-BC-700.

[0051] Experiment 3: The operation is the same as in Example 1, except that in step (3), the temperature is raised to 900°C and held at that temperature for 2 hours to carry out pyrolysis, and iron-nitrogen co-doped biochar is obtained, denoted as FeN-BC-900.

[0052] Experiment 4: The operation is the same as in Example 1, except that in step (3), the temperature is raised to 1000℃ and held at that temperature for 2 hours to carry out pyrolysis, and iron-nitrogen co-doped biochar is obtained, denoted as FeN-BC-1000.

[0053] Comparative Example 1

[0054] In this comparative example, different biochars were prepared by changing the type of elemental doping.

[0055] Experiment 1: The operation is the same as in Example 1, except that no iron source and nitrogen source are added in step (1), and undoped biochar is obtained, denoted as BC.

[0056] Experiment 2: The operation is the same as in Example 1, except that no iron source is added in step (1), and nitrogen-doped biochar is obtained, denoted as N-BC.

[0057] Experiment 3: The operation is the same as in Example 1, except that no nitrogen source is added in step (1), and iron-doped biochar is obtained, denoted as Fe-BC.

[0058] Example 3

[0059] In this embodiment, the iron-nitrogen co-doped biochar prepared in Examples 1 and 2 was characterized.

[0060] The iron-nitrogen co-doped biochar was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR).

[0061] Figure 1 Figures a through d show the results of SEM, EDS, XRD, and Raman tests, respectively. Figure 1 As shown in Figure a, the SEM image of FeN-BC-800 reveals that the iron-nitrogen co-doped biochar exhibits irregular blocky shapes with pronounced wrinkles and a rich porous structure, with iron and nitrogen particles distributed on its surface. Figure 1 As shown in Figure b, the EDS spectrum of FeN-BC-800 indicates that the nitrogen element is uniformly distributed on the surface of the iron-nitrogen co-doped biochar, while the iron element is distributed in a granular manner, indicating that the method of the present invention successfully doped Fe and N into the biochar. Figure 1 The XRD results of FeN-BC-600, FeN-BC-700, FeN-BC-800, FeN-BC-900, and FeN-BC-1000 shown in Figure c indicate that the surface of the iron-nitrogen co-doped biochar is mainly composed of iron and iron oxides. Specifically, the iron species in FeN-BC-700, FeN-BC-800, and FeN-BC-900 include Fe... 0 FeS, Fe3O4, Fe x N (Fe3N and Fe4N); the iron species in FeN-BC-600 do not include Fe. 0 It only includes FeS, Fe3O4, and Fe. x N (Fe3N and Fe4N); while the iron species in FeN-BC-1000 do not include Fe. x N (Fe3N and Fe4N), including only Fe 0FeS and Fe3O4. This indicates that different calcination (pyrolysis) temperatures produce different iron species. With increasing calcination temperature, the Fe on the surface of iron-nitrogen co-doped biochar increases. 0 The diffraction intensity of the species changed. The Raman spectra of FeN-BC-600, FeN-BC-700, FeN-BC-800, FeN-BC-900, and FeN-BC-1000 are as follows: Figure 1 As shown in the d-plot, the D band of the Raman spectrum (1350 cm⁻¹) -1 ) and G-band (1584cm) -1 The strength ratio of (I) D / I G It is commonly used to assess the structural defects and graphitization degree of carbon materials, by Figure 1 As shown in the d-plot, the highest degree of defect was observed in FeN-BC-800 (I D / I G =2.56), which may be beneficial for activating PAA to produce active species.

[0062] Example 4

[0063] In this embodiment, the iron-nitrogen co-doped biochar prepared in Examples 1 and 2 is used to activate PAA to degrade naproxen (NAP).

[0064] Iron-nitrogen co-doped biochar and PAA were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L. The concentration of iron-nitrogen co-doped biochar in the wastewater was controlled at 0.20 g / L and the concentration of PAA in the wastewater was controlled at 0.1 mmol / L. The mixture was treated for 10 min at 25 °C and a rotation speed of 300 r / min.

[0065] During the wastewater treatment process, samples were taken at regular intervals, filtered through a 0.22 μm filter membrane, and sodium thiosulfate was added to terminate the reaction. The NAP concentration was determined by liquid chromatography (HPLC), and the pollutant (NAP) removal rate (the ratio of the final NAP concentration [C] to its initial concentration [C]0 [C] / [C]0) × 100% and the reaction rate constant k were calculated. obs .

[0066] As a comparison, the reaction rate constant k was also tested in this embodiment without the addition of PAA. obs The testing method is the same as the basic operation described above, the only difference being that PAA is not added. The results are as follows: Figure 2 As shown in the Adsorption group data in Figure a, it can be seen that the adsorption capacity of FeN-BC-1000 is stronger than that of FeN-BC-600, FeN-BC-700, FeN-BC-800 and FeN-BC-900.

[0067] As a control, this embodiment also tested the NAP removal rate when only PAA was added. The testing method was basically the same as the aforementioned operation, except that iron-nitrogen co-doped biochar was not added. As a control, this embodiment also tested the NAP removal rate when only BC, only N-BC, only Fe-BC, and only FeN-BC-800 were added. The testing method was basically the same as the aforementioned operation, except that PAA was not added, and the iron-nitrogen co-doped biochar was replaced with equal amounts of BC, N-BC, Fe-BC, and FeN-BC-800. The results are as follows... Figure 2 The data in the inset (Adsorption) of Figure b, showing the groups of PAA alone, BC alone, N-BC alone, Fe-BC alone, and FeN-BC alone, actually represent the removal rates of NAP by adding only PAA, as well as the removal rates of NAP by BC, N-BC, Fe-BC, and FeN-BC-800 through adsorption. The figure shows that adding only PAA or N-BC cannot remove NAP, and adding only FeN-BC-800 also results in very weak NAP removal, indicating that FeN-BC-800 has a weak adsorption capacity for NAP, while BC and Fe-BC have strong adsorption capacities for NAP. This suggests that iron-nitrogen co-doping reduces the specific surface area of ​​BC, weakening its adsorption capacity for pollutants.

[0068] As a control, this embodiment also tested the removal rate of NAP when BC, N-BC, Fe-BC, FeN-BC, and FeN-BC-800 activated PAA to degrade NAP. The test method was basically the same as the aforementioned operation, except that equal amounts of BC, N-BC, Fe-BC, FeN-BC, and FeN-BC-800 were used to replace the iron-nitrogen co-doped biochar. The results are as follows: Figure 2 The data for the BC / PAA, N-BC / PAA, Fe-BC / PAA, FeN-BC / PAA, and FeN-BC / PAA groups are shown in the larger plot of Figure b. As a control, this embodiment also tested the removal rate of NAP by FeN-BC-800 activated hydrogen peroxide (H2O2). During the test, PAA was replaced with an equal concentration of H2O2, and other test conditions were the same as described above. Figure 2As shown in Figure b, N-BC cannot activate PAA to produce active species for NAP degradation, while FeN-BC-800 cannot activate H2O2 to produce active species for NAP degradation. Furthermore, for BC, the NAP removal rate after adding PAA is essentially the same as the removal rate without PAA (removing NAP solely through adsorption), indicating that BC cannot activate PAA to produce active species for PAA degradation. For Fe-BC, the NAP removal rate only slightly increases after adding PAA, indicating that the ability of iron-doped Fe-BC to activate PAA to produce active species for NAP degradation is very weak, and it still primarily removes NAP through adsorption.

[0069] Further integration Figure 2 The reaction rate constant k obs Data on NAP removal rates show that FeN-BC-700, FeN-BC-800, and FeN-BC-900 can all efficiently activate PAA to generate active species that degrade NAP, removing over 97.9% of NAP with a treatment time of 10 minutes. Among these, the FeN-BC-800 / PAA system exhibits the best NAP degradation effect and the fastest reaction rate. While FeN-BC-1000 can also activate PAA to generate active species that degrade NAP, considering that FeN-BC-1000 contributes more to NAP removal through adsorption, its ability to degrade NAP through PAA activation is less than that of FeN-BC-700, FeN-BC-800, and FeN-BC-900. FeN-BC-600, on the other hand, has virtually no ability to activate PAA to generate active species that degrade NAP. Figure 2 This also illustrates that, in this invention, the removal of organic pollutants (such as NAP in this embodiment) by iron-nitrogen co-doped biochar (e.g., FeN-BC-700, FeN-BC-800, and FeN-BC-900) is mainly achieved through oxidative degradation by activating PAA to generate active species, rather than solely through adsorption and migration. Furthermore, iron-nitrogen co-doping exhibits a synergistic effect; despite a reduced adsorption capacity for organic pollutants, the iron-nitrogen co-doped biochar achieves a more efficient ability to activate PAA to generate active species and degrade organic pollutants.

[0070] Example 5

[0071] In this embodiment, the recycling performance of FeN-BC-800 was examined.

[0072] (1) The FeN-BC-800 and PAA prepared in Example 1 were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L. The concentration of FeN-BC-800 in the wastewater was controlled to be 0.20 g / L and the concentration of PAA in the wastewater was controlled to be 0.1 mmol / L. The mixture was treated for 30 min at 25 °C and 300 r / min.

[0073] During wastewater treatment, the concentration of NAP in the wastewater is measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final concentration of NAP [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0074] (2) After each reaction for 30 minutes, replace the wastewater with the same wastewater as in step (1) and repeat the operation of step (1) to treat the wastewater. The FeN-BC-800 in step (1) is recycled and reused for a total of 5 times.

[0075] Figure 3 These are the cycle performance test results for FeN-BC-800, from... Figure 3 It can be seen that the removal rate of NAP did not decrease significantly in the first four cycles. In the fourth cycle, the removal rate of NAP remained at 99% within 30 minutes. Although the removal rate of NAP decreased in the fifth cycle, it was still as high as 80%. This indicates that when the iron-nitrogen co-doped biochar (e.g., FeN-BC-800) is used to activate PAA to degrade organic pollutants, the iron-nitrogen co-doped biochar has excellent reusability, which is very beneficial for the promotion and application of the method of this invention in engineering practice.

[0076] Example 6

[0077] In this embodiment, a total of 3 sets of experiments were conducted to prepare iron-nitrogen co-doped biochar with different iron doping amounts.

[0078] Experiment 1: The operation is basically the same as in Example 1, except that no iron source is added in step (1).

[0079] Experiment 2: The operation was basically the same as in Example 1, except that in step (1), the molar ratio of nitrogen source to iron source was controlled to be 1:0.038 and the concentration of iron source was 50 mmol / L.

[0080] Experiment 3: The operation was the same as in Example 1, that is, the molar ratio of nitrogen source to iron source was 1:0.15, and the concentration of iron source was 200 mmol / L.

[0081] Experiment 4: The operation was basically the same as in Example 1, except that in step (1), the molar ratio of nitrogen source to iron source was controlled to be 1:0.38 and the concentration of iron source was 500 mmol / L.

[0082] The iron-nitrogen co-doped biochar prepared in Experiments 1, 2, 3, and 4 were used in... Figure 4 In Figure a, these values ​​are represented as 0.000 mmol, 0.625 mmol, 2.500 mmol, and 6.250 mmol, respectively.

[0083] Example 7

[0084] In this embodiment, the effects of iron-nitrogen co-doped biochar with different iron doping amounts, the dosage of iron-nitrogen co-doped biochar and PAA, and the pH value of wastewater on the activation of PAA by iron-nitrogen co-doped biochar to degrade pollutants were investigated.

[0085] (1) Add iron-nitrogen co-doped biochar and PAA to NAP aqueous solution (simulated wastewater) with NAP concentration of 10 μmol / L, control the concentration of iron-nitrogen co-doped biochar in wastewater to 0.20 g / L, and the concentration of PAA in wastewater to 0.1 mmol / L, and treat for 10 min at 25℃ and 300 r / min.

[0086] During the wastewater treatment process, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0087] This step involved four sets of experiments. The iron-nitrogen co-doped biochar used in each set of experiments was the iron-nitrogen co-doped biochar prepared in Experiments 1-4 of Example 6. The test results are as follows: Figure 4 The larger image in Figure a is shown.

[0088] As a control, this step also tested the NAP removal rate when only the iron-nitrogen co-doped biochar prepared in Experiments 1-4 of Example 6 was added. The test method was basically the same as the aforementioned operation, except that PAA was not added. The results are as follows: Figure 4 The small plot (Adsorption) in Figure a is shown.

[0089] Depend on Figure 4 As shown in Figure a, when biochar is not doped with iron, it can only remove a small amount of organic pollutants through adsorption. When iron is doped into the biochar, the degradation effect of iron-nitrogen co-doped biochar activated PAA on organic pollutants is significantly improved. Among them, the iron-nitrogen co-doped biochar activated PAA prepared in Experiment 3 has the best effect on degrading organic pollutants and can produce a higher organic pollutant removal rate in a shorter time.

[0090] (2) The iron-nitrogen co-doped biochar and PAA prepared in Experiment 3 of Example 6 were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L, and the concentration of PAA in the wastewater was controlled to be 0.1 mmol / L. The mixture was treated for 15 min at 25 °C and a rotation speed of 300 r / min.

[0091] During the wastewater treatment process, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0092] This step involved five sets of experiments. The concentrations of the iron-nitrogen co-doped biochar (prepared from Experiment 3 of Example 6) in the wastewater were 0.05 g / L, 0.10 g / L, 0.20 g / L, 0.30 g / L, and 0.50 g / L, respectively. The test results are as follows: Figure 4 The larger image in Figure b is shown.

[0093] As a control, this step also tested the NAP removal rate when only the iron-nitrogen co-doped biochar prepared in Experiment 3 of Example 6 was added. The testing method was basically the same as the aforementioned operation, except that PAA was not added. That is, a total of 5 control experiments were conducted. In the 5 control experiments, the concentrations of the iron-nitrogen co-doped biochar (prepared in Experiment 3) in the wastewater were 0.05 g / L, 0.10 g / L, 0.20 g / L, 0.30 g / L, and 0.50 g / L, respectively, and PAA was not added in the control experiments. The results are as follows... Figure 4 The small plot (Adsorption) in Figure b is shown.

[0094] Depend on Figure 4 As shown in Figure b, with the increase of the dosage of iron-nitrogen co-doped biochar prepared in Experiment 3 of Example 6, the removal rate of organic pollutants in the wastewater gradually increases. However, when the dosage of the iron-nitrogen co-doped biochar increases to a certain extent, the removal rate of organic pollutants in the wastewater no longer increases. Therefore, in practical applications, the appropriate dosage of iron-nitrogen co-doped biochar can be selected through experiments based on the actual wastewater quality. For example, for the simulated wastewater in this step, the highest organic pollutant removal rate can be achieved when the concentration of iron-nitrogen co-doped biochar in the wastewater is 0.20 g / L.

[0095] (3) The iron-nitrogen co-doped biochar and PAA prepared in Experiment 3 of Example 6 were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L. The concentration of iron-nitrogen co-doped biochar in the wastewater was controlled to be 0.20 g / L. The mixture was treated for 15 min at 25 °C and a rotation speed of 300 r / min.

[0096] During the wastewater treatment process, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0097] This step involved five sets of experiments, with the concentration of PAA in the wastewater controlled at 0, 0.1, 0.2, 0.3, and 0.5 mmol / L in each set.

[0098] The test results for this step are as follows: Figure 4 As shown in Figure c, without the addition of PAA, iron-nitrogen co-doped biochar removes pollutants solely through adsorption, resulting in a very low removal rate. However, the addition of PAA significantly increases the removal efficiency. In practical applications, the dosage of PAA should be determined by comprehensively considering its relationship with pollutant removal efficiency and cost. For example, for the simulated wastewater in this step, a PAA concentration of 0.1 mmol / L is appropriate after considering both pollutant removal efficiency and operating costs.

[0099] (4) The iron-nitrogen co-doped biochar and PAA prepared in Experiment 3 of Example 6 were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L. The concentration of iron-nitrogen co-doped biochar in the wastewater was controlled to be 0.20 g / L. The mixture was treated for 10 min at 25 °C and 300 r / min.

[0100] During the wastewater treatment process, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0101] This step involved five sets of experiments, in which the pH of the simulated wastewater was adjusted to 3.0, 5.0, 7.0, 9.0, and 11.0, respectively. The test results are as follows: Figure 4 The larger image in d is shown.

[0102] As a control, this step also tested the NAP removal rate when only the iron-nitrogen co-doped biochar prepared in Experiment 3 of Example 6 was added. The test method was basically the same as the aforementioned operation, except that PAA was not added. The results are as follows: Figure 4 The small plot (Adsorption) in the d-plot is shown.

[0103] As shown in Figure 4d, when the pH of the wastewater is between 3 and 9, the method of this invention achieves a removal rate of over 95% for organic pollutants. Furthermore, when the pH of the wastewater is 3, the iron-nitrogen co-doped biochar exhibits better adsorption capacity for organic pollutants. When the pH of the wastewater is 11, the removal rate of organic pollutants by the method of this invention is severely inhibited. Therefore, in practical applications, the method of this invention can treat wastewater with a pH of 3 to 9.

[0104] Example 8

[0105] In this experimental example, the effects of common anions and humic acids in water on the pollutant degradation capacity of the method described in this invention are evaluated.

[0106] FeN-BC-800 and PAA prepared in Example 1 were added to a NAP aqueous solution (simulated wastewater) with a NAP concentration of 10 μmol / L. The concentration of FeN-BC-800 in the wastewater was controlled to be 0.20 g / L and the concentration of PAA in the wastewater was controlled to be 0.1 mmol / L. The mixture was treated for 10 min at 25 °C and a rotation speed of 300 r / min.

[0107] During the wastewater treatment process, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [NAP] to its initial concentration [NAP]0: [NAP] / [NAP]0.

[0108] In this embodiment, four sets of experiments were conducted. The wastewater in each set contained different types of anions or humic acid (HA). The anions specifically included H₂PO₄ˉ, HCO₃ˉ, and Cl⁻. The concentrations of H₂PO₄ˉ and HCO₃ˉ were 0.10, 0.20, 0.50, and 1.00 mmol / L, respectively; the concentrations of Cl⁻ were 1.0 and 5.0 mmol / L, respectively; and the concentrations of HA were 1.0, 2.0, 5.0, and 10.0 mg / L, respectively. A NAP aqueous solution without added anions or HA was used as the control group. The results are as follows: Figure 5 As shown.

[0109] Depend on Figure 5It is known that anions such as Cl-, H2PO4-, and HCO3-, as well as HA in wastewater, affect the ability of the FeN-BC-800 / PAA system to degrade organic pollutants. Cl- has a certain promoting effect on the pollutant degradation performance of the FeN-BC-800 / PAA system. H2PO4-, HCO3-, and HA have varying degrees of inhibitory effects on the pollutant degradation performance of the FeN-BC-800 / PAA system. However, when the concentration of H2PO4- in the wastewater does not exceed 0.20 mmol / L, the concentration of HCO3- does not exceed 0.10 mmol / L, and the concentration of HA does not exceed 2.0 mg / L, they have virtually no inhibitory effect on the pollutant degradation performance of the FeN-BC-800 / PAA system. These experimental results indicate that when actual water bodies contain Cl-... - When the concentrations of H2PO4-, HCO3-, and HA in the actual water body are not high, the ability of the method described in this invention to remove pollutants will not be significantly affected.

[0110] Example 9

[0111] In this embodiment, FeN-BC-800 prepared in Example 1 was used to activate PAA to degrade various organic micropollutants.

[0112] FeN-BC-800 and PAA were added to the wastewater, with the concentration of FeN-BC-800 in the wastewater controlled at 0.20 g / L and the concentration of PAA in the wastewater controlled at 0.1 mmol / L. The mixture was treated for 10 min at 25 °C and a rotation speed of 300 r / min.

[0113] In the wastewater treatment process, samples were taken at regular intervals, filtered through a 0.22 μm filter membrane, and sodium thiosulfate was added to terminate the reaction. The pollutant concentration was determined by high-performance liquid chromatography (HPLC), and the pollutant removal rate was calculated as the ratio of the final pollutant concentration [C] to its initial concentration [C]0 ([C] / [C]0) × 100%, along with the reaction rate constant k. obs .

[0114] In this embodiment, a total of 6 sets of experiments were conducted. The pollutants in the wastewater used in each set of experiments were naproxen (NAP), phenol (Ph), bisphenol A (BPA), nitrobenzene (NB), benzoic acid (BA), and sulfamethoxazole (SMX), respectively. The concentration of the pollutants in the wastewater was 10 μmol / L.

[0115] As a control, this embodiment also tested the removal rate of the above pollutants when only FeN-BC-800 was added. The test method was basically the same as the aforementioned operation, except that PAA was not added. The results are as follows: Figure 6 The Adsorption group data is shown in Figure a.

[0116] Depend on Figure 6 As shown in Figure a, the FeN-BC-800 / PAA system exhibits good removal effects on all the different organic pollutants used above. When the treatment time is 10 min, the removal rate for each pollutant reaches over 78.5%, with the best removal effect on NAP. Previous experiments have confirmed that the method of this invention can achieve a NAP removal rate of 99.0% or higher. The reaction rate constants of the FeN-BC-800 / PAA system for NAP, phenol, BPA, NB, and BA are all close to 0.5 min. -1 The reaction rate is relatively fast, indicating that the FeN-BC-800 / PAA system can be used to remove a variety of organic pollutants.

[0117] Example 10

[0118] In this embodiment, the degradation ability of FeN-BC-800-activated PAA on NAP in actual water bodies was investigated.

[0119] FeN-BC-800 and PAA prepared in Example 1 were added to NAP wastewater with a NAP concentration of 10 μmol / L. The concentration of FeN-BC-800 in the wastewater was controlled at 0.20 g / L and the concentration of PAA in the wastewater was controlled at 0.1 mmol / L. The mixture was treated for 10 min at 25 °C and a rotation speed of 300 r / min.

[0120] During wastewater treatment, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [C] to its initial concentration [C]0 ([C] / [C]0) × 100%, as well as the reaction rate constant k. obs .

[0121] In this embodiment, three sets of experiments were conducted. Each set of experiments used tap water, surface water sample 1, and surface water sample 2 as solvents to prepare NAP wastewater. Surface water sample 1 was lake water, and surface water sample 2 was river water. The results are as follows: Figure 6 As shown in Figure b.

[0122] As a control, this embodiment also tested the removal rate of NAP when only FeN-BC-800 was added. The test method was basically the same as the aforementioned operation, except that PAA was not added. The results are as follows: Figure 6 The Adsorption group data are shown in Figure b.

[0123] Depend on Figure 6As shown in Figure b, the method of this invention has virtually no impact on the degradation of NAP in NAP wastewater prepared using tap water and surface water sample 1 as solvents, with a removal rate of 100% in both cases. However, it does show some inhibition on the degradation of NAP in wastewater prepared using surface water sample 2 as solvent, but the removal rate of NAP in that wastewater still reaches 75%. This indicates that the iron-nitrogen co-doped biochar of this invention has relatively stable performance and strong anti-interference ability as an activator for PAA.

[0124] Example 11

[0125] In this embodiment, the mechanism by which FeN-BC-800 activates PAA to degrade NAP in water was investigated.

[0126] FeN-BC-800 and PAA prepared in Example 1 were added to NAP wastewater with a NAP concentration of 10 μmol / L. The concentration of FeN-BC-800 in the wastewater was controlled to be 0.20 g / L and the concentration of PAA in the wastewater was controlled to be 0.1 mmol / L. The corresponding active species quenchers were added, and the mixture was treated for 10 min at 25 °C and 300 r / min.

[0127] During wastewater treatment, the concentration of NAP in the wastewater is sampled and measured at regular intervals, and the NAP removal rate is calculated, which is the ratio of the final NAP concentration [C] to its initial concentration [C]0 ([C] / [C]0) × 100%), as well as the reaction rate constant k. obs .

[0128] In this embodiment, a total of 7 groups of experiments were conducted. Different types of quenchers were added to the wastewater in each group, as follows: Group 1: methanol was added to a concentration of 300 mmol / L (300 mM MeOH); Group 2: tert-butanol was added to a concentration of 300 mmol / L (300 mM TBA); Group 3: 2,4-hexadiene was added to a concentration of 20 mmol / L (20 mM 2,4-HD); Group 4: superoxide dismutase was added to a concentration of 2400 U / mL (2400 U / mL SOD); Group 5: furfuryl alcohol was added to a concentration of 20 mmol / L (20 mM FFA); Group 6: no quencher was added, only FeN-BC-800 and PAA (FeN-BC / PAA); Group 7: no quencher and PAA were added, only FeN-BC-800 (FeN-BC). The results are as follows: Figure 7 As shown in Figure a.

[0129] Depend on Figure 7As shown in Figure a, the addition of 2,4-HD, SOD, and FFA significantly inhibited the degradation of NAP, indicating that organic free radicals (RO·), superoxide radicals (O2˙ˉ), and singlet oxygen (O2˙ˉ) were generated in the FeN-BC-800 / PAA system. 1 O2). Electron paramagnetic resonance spectroscopy (EPR) further confirmed that O2 was generated in the FeN-BC-800 / PAA system. 1 O2, and 1 O2 is the dominant active species in NAP degradation, as shown in the results. Figure 7 As shown in Figure b.

[0130] Phase analysis of FeN-BC-600, FeN-BC-700, FeN-BC-800, FeN-BC-900, and FeN-BC-1000 prepared in Examples 1 and 2 was performed using X-ray diffraction. Among them, Fe... 0 The diffraction intensity of FeS is as follows Figure 7 As shown in Figure c, Fe 0 The changes in species content were significantly correlated with the ability of iron-nitrogen co-doped biochar to activate PAA and degrade pollutants. 0 The higher the diffraction intensity of the species, the better the performance of iron-nitrogen co-doped biochar in activating PAA. The Fe... 0 The peak areas of the diffraction peaks of the species were integrated, and correlation analysis was performed with the corresponding reaction rate constants. The results are as follows: Figure 7 As shown in the d-plot, the relevant absorption R 2 The value is 0.879, indicating that in the iron-nitrogen co-doped biochar of this invention, Fe... 0 It is the main active site for activating PAA.

Claims

1. A method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid, characterized in that, Includes the following steps: Iron-nitrogen co-doped biochar and peracetic acid were added to medical wastewater, and the wastewater was treated under stirring conditions. The pH value of the wastewater was controlled at 3-9, the concentration of iron-nitrogen co-doped biochar in the wastewater was controlled at 0.1-0.3 g / L, and the concentration of peracetic acid in the wastewater was controlled at 0.1-0.3 mmol / L. During the wastewater treatment process, iron-nitrogen co-doped biochar activates peracetic acid to generate organic free radicals, superoxide free radicals, and singlet oxygen to degrade organic pollutants in the wastewater. At the same time, iron-nitrogen co-doped biochar adsorbs and removes some pollutants from the wastewater. After treating one batch of wastewater, the iron-nitrogen co-doped biochar is recycled for the treatment of the next batch of wastewater. The iron-nitrogen co-doped biochar has a porous structure, and the iron species in the iron-nitrogen co-doped biochar include Fe. 0 The intensity ratio of the D band to the G band in the Raman spectra of FeS, Fe3O4, Fe3N, and Fe4N co-doped biochar is I. D / I G It is 2~2.6; The iron-nitrogen co-doped biochar was prepared by the following method: (1) Dissolve the iron source, nitrogen source and reducing agent in water to obtain a mixture. In this mixture, the molar ratio of reducing agent to iron source is (1 ~ 0.7): 1, and the molar ratio of nitrogen source to iron source is 1: (0.038 ~ 0.38). According to the mass ratio of biomass raw material fragments to nitrogen source of (0.9 ~ 1.1): 1, mix the biomass raw material fragments with the above mixture thoroughly to obtain the reaction precursor. The iron source is a water-soluble ferrous salt, the nitrogen source is at least one of urea and melamine, and the reducing agent is ascorbic acid; (2) The reaction precursor was transferred to a high-pressure reactor and hydrothermally reacted at 160-180 °C for 8-10 h. The hydrothermal reaction product was dried to obtain the biochar precursor. (3) The biochar precursor is heated to 700 ~ 900 °C in a non-reactive atmosphere without oxygen and kept at this temperature for 1 ~ 2 h for pyrolysis. The pyrolysis product is crushed to obtain iron-nitrogen co-doped biochar.

2. The method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid according to claim 1, characterized in that, When preparing iron-nitrogen co-doped biochar, the concentration of the iron source in the mixture in step (1) is controlled to be 50~500 mmol / L.

3. The method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid according to claim 1 or 2, characterized in that, The recycling frequency of iron-nitrogen co-doped biochar should be controlled to at least 4 times.

4. The method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid according to claim 1 or 2, characterized in that, The wastewater treatment time is determined based on the water quality of the medical wastewater.

5. The method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid according to claim 4, characterized in that, The wastewater treatment time should be controlled between 5 and 25 minutes.

6. The method for treating medical wastewater using iron-nitrogen co-doped biochar activated peracetic acid according to claim 1 or 2, characterized in that, The medical wastewater contains polluting organic matter.

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