Preparation method and application of penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar

Abstract

This invention provides a method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar. The method involves: freezing penicillin bacterial residue, followed by vacuum freeze-drying to obtain dried penicillin bacterial residue; pulverizing and sieving the dried residue to obtain penicillin bacterial residue powder; mixing anhydrous ferric chloride, potassium oxalate, and the penicillin bacterial residue powder to obtain a mixture; heating the mixture to 400-800℃ under a nitrogen atmosphere and isothermal pyrolysis; naturally cooling to room temperature; and then grinding and sieving to obtain penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar. An application is also provided: this penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. This invention uses penicillin bacterial residue as a precursor and employs anhydrous ferric chloride and potassium oxalate dual activation to prepare nitrogen-oxygen co-doped biochar, and applies it to the treatment of antibiotic wastewater, realizing the resource utilization of bacterial residue.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization of solid waste and wastewater treatment technology, specifically relating to a method for preparing and applying penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biocarbon. Background Technology

[0002] Antibiotic fermentation residues (AFRs) refer to the solid waste generated during antibiotic production after the effective components of the fermentation broth are extracted using a pressure filtration process. Their increasing threat to environmental safety has drawn significant public attention. AFRs contain a certain amount of antibiotic residues and antibiotic resistance genes (ARGs). Residual antibiotics in AFRs can enter wastewater treatment plants and surface water environments, directly threatening biological health with their toxicity. The accumulation and spread of residual antibiotics in the environment can induce the expression of intrinsic ARGs or gene mutations in bacteria, leading to resistance. ARGs spread in the environment through horizontal gene transfer, causing a series of biosafety issues. Due to their environmental risks, AFRs have been included in the "National Hazardous Waste List" and require strict supervision and proper disposal in accordance with the requirements for hazardous waste environmental management.

[0003] Currently, developed technologies for the harmless treatment of AFRs include incineration, anaerobic digestion, hydrothermal treatment, and pyrolysis. AFRs have a high water content, making direct incineration costly and prone to causing secondary pollution due to the multi-media transmission of toxic substances such as dioxins. Chinese patent application CN 119680703 A discloses a method for degrading residual antibiotics in macrolide antibiotic fermentation waste, using stainless steel beads as the grinding medium to ball mill the antibiotic residue in a ball mill jar. This technology can effectively remove residual antibiotics. However, this method mainly focuses on the removal of residual antibiotics, and does not address further volume reduction and resource utilization of the residue after ball milling. Pyrolysis, due to its ability to convert antibiotic residue into high-value products such as biochar, is gradually becoming a promising treatment technology. Chinese patent CN 117025247 B simultaneously removes residual antibiotics and prepares biochar products through pyrolysis of antibiotic residue, achieving harmless treatment and high-value recovery of antibiotic residue, but lacks application evaluation of the biochar products. Biochar materials, due to their excellent physicochemical properties, are widely used as adsorbents in wastewater treatment. However, biochar obtained through direct carbonization often has limited adsorption capacity, necessitating modification or activation to improve its adsorption performance. Therefore, rationally designing preparation strategies to effectively control the structure of biochar materials is of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing and applying penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar, which addresses the shortcomings of the prior art. The method uses penicillin bacterial residue as a precursor and prepares nitrogen-oxygen co-doped biochar by stepwise dual activation with anhydrous ferric chloride and potassium oxalate, and applies it to the treatment of antibiotic wastewater, thereby realizing the high-value utilization of bacterial residue.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar, the method being as follows: S1. Freeze the penicillin bacterial residue and then freeze-dry it under vacuum to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, sieve it to obtain penicillin residue powder. S3. Anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 are mixed to obtain a mixture; S4. Under a nitrogen atmosphere, the mixture obtained in S3 is pyrolyzed at a temperature of 400~800℃, then naturally cooled to room temperature, and after grinding and sieving, penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is obtained.

[0006] Preferably, the freezing temperature of the penicillin bacterial residue in S1 is -20±5℃, and the freezing time is 24~48h; the vacuum freeze-drying temperature is -55±5℃, and the time is 12~48h.

[0007] Preferably, the sieving in S2 is through a 100-mesh sieve.

[0008] Preferably, the mass ratio of anhydrous ferric chloride, potassium oxalate, and penicillin bacterial residue powder in S3 is 1:1:1.

[0009] Preferably, the flow rate of nitrogen gas in S4 is 20–50 mL / min.

[0010] Preferably, the pyrolysis conditions in S4 are: heating to 400~800℃ at a heating rate of 5~10℃ / min, and pyrolyzing at a constant temperature for 2h.

[0011] Preferably, the sieving in S4 is through a 100-mesh sieve.

[0012] The present invention also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method, wherein the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater.

[0013] Preferably, the antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention transforms waste bacterial residue into functional biochar material, while providing a green and economical solution for the deep treatment of antibiotic wastewater, combining environmental and economic benefits, and offering a new approach for the harmless disposal of bacterial residue and the synergistic treatment of antibiotic wastewater.

[0015] 2. This invention employs a stepwise dual activation strategy using ferric chloride and potassium oxalate to construct a hierarchical porous structure of "micropores + mesopores" in biochar. During pyrolysis, ferric chloride etches the carbon framework, generating abundant micropores and mesopores, providing a high specific surface area. The K₂CO₃ produced by the high-temperature decomposition of potassium oxalate further reacts with carbon, generating a pore-expanding effect and widening some micropores into mesopores. This structure retains the high specific surface area advantage of micropores while providing rapid material transport channels through mesopores, significantly facilitating the diffusion and adsorption of antibiotic molecules into the pore interior.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a SEM image of commercial activated carbon AC used in Comparative Example 2 of this invention.

[0018] Figure 2 This is a SEM image of the penicillin bacterial residue-based single activated nitrogen-oxygen co-doped bio-carbon IBC prepared in Comparative Example 1 of this invention.

[0019] Figure 3 This is a SEM image of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biocarbon PIBC800-1 prepared in Example 1 of this invention.

[0020] Figure 4 This is the EDS spectrum of commercial activated carbon AC used in Comparative Example 2 of this invention.

[0021] Figure 5 This is the EDS spectrum of the penicillin bacterial residue-based single activated nitrogen-oxygen co-doped bio-carbon IBC prepared in Comparative Example 1 of this invention.

[0022] Figure 6 This is the EDS spectrum of the penicillin bacterial residue-based double-activated nitrogen-oxygen co-doped biocarbon PIBC800-1 prepared in Example 1 of this invention.

[0023] Figure 7 These are the N2 adsorption-desorption isotherms of the biochar samples in Examples 1 and 1-2 of this invention.

[0024] Figure 8 These are FTIR images of biochar samples from Examples 1 and 1-2 of this invention.

[0025] Figure 9 This describes the cycling performance of the dual-activated nitrogen-oxygen co-doped biocarbon PIBC800-1 prepared in Example 1 of this invention. Detailed Implementation

[0026] Example 1

[0027] The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar in this embodiment is as follows: S1. After freezing the penicillin bacterial residue at -20±5℃ for 36 hours, it was then vacuum freeze-dried at -55±5℃ for 24 hours to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, pass it through a 100-mesh sieve to obtain penicillin residue powder. S3. Anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 are mixed in a mass ratio of 1:1:1 to obtain a mixture; S4. The mixture obtained in S3 is transferred to a corundum magnetic boat and pyrolyzed in a tube furnace under a nitrogen atmosphere. Specifically, under a nitrogen atmosphere with a flow rate of 30 mL / min, the mixture obtained in S3 is heated from room temperature to 800℃ at a heating rate of 10℃ / min and pyrolyzed at a constant temperature for 2 hours. Then, it is naturally cooled to room temperature, ground, passed through a 100-mesh sieve, and transferred to a desiccator for later use to obtain penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar, denoted as PIBC800-1.

[0028] The structural regulation described in this embodiment is an effective strategy for improving the adsorption performance of biochar. This invention employs a dual-activation structural regulation method using ferric chloride and potassium oxalate. Ferric chloride primarily functions as a pore-forming agent during pyrolysis, etching the carbon framework to create abundant micropores and mesopores, contributing a high specific surface area. Potassium oxalate decomposes into K₂CO₃ at high temperatures, further reacting with carbon to generate K₂O and CO₂, producing a pore-expanding effect and widening some micropores into mesopores. This hierarchical pore structure of "micropores + mesopores" retains the high specific surface area advantage of micropores while providing rapid transport channels through mesopores, facilitating the diffusion of antibiotic molecules into the pore interior. This dual-activation regulation strategy provides a new technical pathway for the resource utilization of bacterial residue.

[0029] This embodiment also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method. The penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0030] 18 mg of PIBC800-1 was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the amount of antibiotics adsorbed by PIBC800-1 was calculated.

[0031] To assess the environmental safety of biochar, the penicillin content in PIBC800-1 was determined in this embodiment. 1 g of PIBC800-1 was weighed, added to 10 mL of deionized water, mixed thoroughly, and sonicated for 10 min. The supernatant was collected by centrifugation, and the extraction was repeated twice. The combined extract was adjusted to pH 4.0 and passed through an activated solid-phase extraction column at a flow rate of 5 mL / min. The column was then eluted with 5 mL of 0.1% formic acid solution, and all eluent was discarded. After drying under reduced pressure for 5 min, penicillin was eluted with 6 mL of methanol solution. The eluent was dried under nitrogen, reconstituted with 1 mL of water, filtered through a 0.22 µm filter, and quantified using liquid chromatography-mass spectrometry. The results showed that penicillin was undetectable, indicating that the pyrolysis process completely removed residual antibiotics.

[0032] Example 2

[0033] The preparation method of penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar in this embodiment is the same as that in Example 1, except that the mass ratio of anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 in step S3 is 1:0.5:1. The final prepared penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is denoted as PIBC800-0.5.

[0034] This embodiment also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method. The penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0035] 18 mg of PIBC800-0.5 was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the amount of antibiotics adsorbed by PIBC800-0.5 was calculated.

[0036] Example 3

[0037] The preparation method of penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar in this embodiment is the same as that in Example 1, except that the mass ratio of anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in step S3 is 1:2:1. The final prepared penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is denoted as PIBC800-2.

[0038] This embodiment also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method. The penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0039] 18 mg of PIBC800-2 was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the adsorption capacity of PIBC800-2 for the antibiotics was calculated.

[0040] Example 4

[0041] The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar in this embodiment is as follows: S1. After freezing the penicillin bacterial residue at -20±5℃ for 24 hours, it was then vacuum freeze-dried at -55±5℃ for 12 hours to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, pass it through a 100-mesh sieve to obtain penicillin residue powder. S3. Anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 are mixed in a mass ratio of 1:1:1 to obtain a mixture; S4. The mixture obtained in S3 is transferred to a corundum magnetic boat and pyrolyzed in a tube furnace under a nitrogen atmosphere. Specifically, under a nitrogen atmosphere with a flow rate of 20 mL / min, the mixture obtained in S3 is heated from room temperature to 600℃ at a heating rate of 5℃ / min and pyrolyzed at a constant temperature for 2 hours. Then, it is naturally cooled to room temperature, ground, passed through a 100-mesh sieve, and transferred to a desiccator for later use to obtain penicillin bacterial residue-based double-activated nitrogen-oxygen co-doped biochar, denoted as PIBC600-1.

[0042] This embodiment also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method. The penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0043] 18 mg of PIBC600-1 was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the adsorption capacity of IBC600-1 for the antibiotics was calculated.

[0044] Example 5

[0045] The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar in this embodiment is as follows: S1. After freezing the penicillin bacterial residue at -20℃±5℃ for 48 hours, it was then vacuum freeze-dried at -55℃±5℃ for 48 hours to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, pass it through a 100-mesh sieve to obtain penicillin residue powder. S3. Anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 are mixed in a mass ratio of 1:1:1 to obtain a mixture; S4. The mixture obtained in S3 is transferred to a corundum magnetic boat and pyrolyzed in a tube furnace under a nitrogen atmosphere. Specifically, under a nitrogen atmosphere with a flow rate of 50 mL / min, the mixture obtained in S3 is heated from room temperature to 400℃ at a heating rate of 8℃ / min and pyrolyzed at a constant temperature for 2 hours. Then, it is naturally cooled to room temperature, ground, passed through a 100-mesh sieve, and transferred to a desiccator for later use to obtain penicillin bacterial residue-based double-activated nitrogen-oxygen co-doped biochar, denoted as PIBC400-1.

[0046] This embodiment also provides the application of the penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the above preparation method. The penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater. The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

[0047] 18 mg of PIBC400-1 was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the adsorption capacity of PIBC400-1 for the antibiotics was calculated.

[0048] Comparative Example 1 The method for preparing penicillin bacterial residue-based single-activated nitrogen-oxygen co-doped biochar in this embodiment is as follows: S1. After freezing the penicillin bacterial residue at -20±5℃ for 36 hours, it was then vacuum freeze-dried at -55±5℃ for 24 hours to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, pass it through a 100-mesh sieve to obtain penicillin residue powder. S3. Mix anhydrous ferric chloride and the penicillin bacterial residue powder obtained in S2 at a mass ratio of 1:1 to obtain a mixture; S4. The mixture obtained in S3 is transferred to a corundum magnetic boat and pyrolyzed in a tube furnace under a nitrogen atmosphere. Specifically, under a nitrogen atmosphere with a flow rate of 30 mL / min, the mixture obtained in S3 is heated from room temperature to 800℃ at a heating rate of 10℃ / min and pyrolyzed at a constant temperature for 2 hours. Then, it is naturally cooled to room temperature, ground, passed through a 100-mesh sieve, and transferred to a desiccator for later use to obtain penicillin bacterial residue-based single activated nitrogen-oxygen co-doped biochar, denoted as IBC.

[0049] 18 mg of IBC was added to 60 mL of antibiotic solutions with an initial concentration of 10 mg / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC), and adsorbed for 24 h at 25 °C and 200 rpm. The concentration of the remaining antibiotics was measured, and the amount of antibiotics adsorbed by IBC was calculated.

[0050] Comparative Example 2 Commercially available activated carbon (AC) was passed through a 100-mesh sieve and added to antibiotic solutions with an initial concentration of 10 mg / L at a dosage of 0.3 g / L (sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, tetracycline TC). Adsorption was carried out at 25℃ and 200 rpm for 24 h. After filtering to separate the commercially available activated carbon, the concentration of the remaining antibiotics in the solution was measured, and the adsorption capacity of the commercially available activated carbon for the antibiotics was calculated.

[0051] The organic elemental composition of each biochar sample was determined using CHNS and O elemental analysis modes, and the results are shown in Table 1. In Comparative Example 2, the nitrogen (N) and oxygen (O) contents were 0.31% and 10.47%, respectively; while in Comparative Example 1 and Example 1, the N contents reached 3.41% and 1.29%, respectively, and the O contents were 15.55% and 18.11%, respectively. This indicates that nitrogen and oxygen co-doping can be successfully achieved through pyrolysis using penicillin bacterial residue as a precursor. The nitrogen mainly originates from the abundant crude protein in the penicillin bacterial residue, and this in-situ doping method is beneficial for improving the adsorption capacity of biochar for antibiotics.

[0052] Table 1. Bio-carbon elemental composition in PIBC800-1, IBC and commercial activated carbon To further investigate the properties of nitrogen-oxygen co-doped biochar, the morphology, structure, and elemental distribution of the biochar were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Comparative Example 2 ( Figure 1 The AC sample in the comparative example had a relatively smooth and flat surface with limited porosity. Figure 2 In Example 1, the surface of the IBC sample became rough, exhibiting a lamellar structure and obvious pore structure. The pore walls were thinner, and the pore distribution was more uniform, displaying typical micropore and mesopore characteristics, indicating that the introduction of ferric chloride significantly promoted pore development. In contrast, Example 1 ( Figure 3 The PIBC800-1 sample exhibits a more developed pore structure, displaying a more complex pore network, thinner pore walls, and a honeycomb-like structure in some areas, indicating better pore connectivity. This is because potassium oxalate releases gas and creates an alkaline environment during pyrolysis, further activating the carbon structure and promoting the development of mesoporous structures. EDS spectroscopy results ( Figures 4-6 This also confirms that IBC and PIBC800-1 contain 1.92%–2.50% nitrogen doping and 12.16%–17.64% oxygen doping. Figure 7 The N2 adsorption-desorption isotherms of the biochar samples are shown in Table 2. The calculated specific surface area and pore structure data are also presented. In Comparative Example 2, AC is predominantly microporous, with an overall underdeveloped pore structure. In Comparative Example 1, the specific surface area of ​​IBC is 372.59 m². 2 / g, but its specific surface area is mainly contributed by the microporous structure, with micropores accounting for 0.46% of the specific surface area and an average pore size of 2.49 nm. This indicates that ferric chloride activation effectively promotes pore development, forming a mixed pore structure dominated by micropores and mesopores. The specific surface area (PIBC800-1: 330.68 m²) in Examples 1 and 2 is shown in the figure. 2 / g; PIBC800-0.5: 347.45 m 2 The specific surface area ( / g) was slightly lower than that of IBC, but the proportion of microporous specific surface area decreased to 0.27 and 0.39, respectively, while the average pore size increased to 2.83 nm and 2.57 nm, respectively, and the pore volume remained basically unchanged. In Example 3, the specific surface area of ​​PIBC800-2 was 387.45 m². 2 / g, with an average pore size of 2.51 nm. The specific surface areas of PIBC600-1 and PIBC400-1 in Examples 4 and 5 were 337.48 m², respectively. 2 / g and 394.15 m 2 / g, the microporous specific surface area and microporous pore volume ratio are both lower than those of IBC in Comparative Example 1, while maintaining a relatively high pore volume (0.24 cm³). 3 / g and 0.27 cm 3The average pore sizes were 2.53 nm and 2.61 nm, respectively. Overall, the average pore sizes of Examples 1-5 (2.51-2.83 nm) were larger than those of Comparative Examples 1-2 (1.84-2.49 nm), and the pore volume did not decrease significantly. This indicates that the introduction of potassium oxalate as an activator in Examples 1-5 played a pore-expanding role, widening some micropores (<2 nm) into mesopores (2-50 nm) while maintaining a high pore volume. This evolution from microporous to mesoporous structure is more conducive to the rapid diffusion of antibiotic molecules into the pores, reducing pore blockage and improving the accessibility of active sites.

[0053] Table 2. Specific surface area and pore size data of penicillin bacterial residue-based biochar and commercial activated carbon. Figure 8 The images show the FTIR spectra of the biochar samples. Compared to AC, the CH absorption intensities of the IBC and PIBC800-1 samples are weaker, while the C=C absorption intensities are more significant. This indicates that dehydrogenation condensation and aromatization reconstruction occurred during the pyrolysis of penicillin bacterial residue, forming a highly conjugated aromatic carbon framework. This structure is beneficial for enhancing the hydrophobic interaction and π-π conjugation between biochar and antibiotics, thereby improving the adsorption performance for antibiotics. The 1031–1032 cm⁻¹ values ​​in the IBC and PIBC800-1 samples are also significant. -1 The CN bond at the site can enhance the antibiotic adsorption performance of biochar through hydrogen bonding. In addition, nitrogen-containing groups can easily change the charge distribution, which is beneficial to strengthening the electrostatic interaction between biochar and antibiotics.

[0054] As shown in Table 3, in Comparative Example 1, the removal rates of sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, and tetracycline TC by IBC were 70.34%, 56.27%, 63.17%, and 66.87%, respectively. In Comparative Example 2, the removal rates of sulfamethoxazole SMX, norfloxacin NOR, oxytetracycline OTC, and tetracycline TC by AC were 9.44%, 18.22%, 25.71%, and 8.86%, respectively. The removal rates of the four antibiotics in Examples 1-5 were 98.45%-99.65%, 73.60%-93.29%, 85.28%-88.67%, 64.82%-96.14%, and 58.48%-81.25%, respectively, all significantly higher than those of Comparative Example 1 (IBC, 56.27%-70.34%) and Comparative Example 2 (AC, 8.86%-25.71%). These results indicate that the dual activation process of ferric chloride and potassium oxalate significantly improved the physicochemical properties of the biochar samples. FeCl3 can act as a Lewis acid catalyzing the recombination of the carbon skeleton, while its reduction product, Fe... 0 or Fe x O yThe carbon layer can be etched to form micropores and mesopores. In Examples 1-5, the pore-expanding effect of potassium oxalate further promoted the formation of a hierarchical porous structure dominated by mesopores and supplemented by micropores, demonstrating a synergistic effect of dual activation. This structure retains the high specific surface area advantage of micropores while providing rapid transport channels through mesopores, achieving a dual improvement in adsorption kinetics and capacity. Among them, PIBC800-1 in Example 1 exhibited the best antibiotic adsorption performance, which is related to the mesoporous structure and large average pore size of PIBC800-1.

[0055] Table 3 Adsorption capacity of penicillin bacterial residue-based biochar and commercial activated carbon for antibiotics 18 mg of PIBC800-1 was added to 60 mL of sulfamethoxazole SMX solution with an initial concentration of 10 mg / L. After adsorption equilibrium was reached, PIBC was separated and desorbed in methanol for 4 h. The adsorption-desorption process was repeated 5 times as one cycle. The removal rate and adsorption capacity were calculated based on the residual sulfamethoxazole SMX concentration in each cycle. The results are as follows: Figure 9 As shown in the figure, within 5 cycles, the removal rate of sulfamethoxazole (SMX) by PIBC800-1 remained in the range of 87.14% to 98.57%, and the adsorption capacity was 29.05 to 32.86 mg / g, indicating that PIBC800-1 has good regeneration performance.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar, characterized in that, The method is as follows: S1. Freeze the penicillin bacterial residue and then freeze-dry it under vacuum to obtain the dried penicillin bacterial residue. S2. After pulverizing the dried penicillin residue obtained in S1, sieve it to obtain penicillin residue powder. S3. Anhydrous ferric chloride, potassium oxalate and penicillin bacterial residue powder obtained in S2 are mixed to obtain a mixture; S4. Under a nitrogen atmosphere, the mixture obtained in S3 is pyrolyzed at a temperature of 400~800℃, then naturally cooled to room temperature, and after grinding and sieving, penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar is obtained.

2. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, The freezing temperature of the penicillin bacterial residue described in S1 is -20±5℃, and the freezing time is 24~48h; the vacuum freeze-drying temperature is -55±5℃, and the time is 12~48h.

3. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, In S2, the sieve is 100 mesh.

4. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, The mass ratio of anhydrous ferric chloride, potassium oxalate, and penicillin bacterial residue powder in S3 is 1:(0.5~2):

1.

5. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, The nitrogen flow rate described in S4 is 20–50 mL / min.

6. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, The pyrolysis conditions in S4 are: heating to 400~800℃ at a heating rate of 5~10℃ / min, and pyrolyzing at a constant temperature for 2h.

7. The method for preparing penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar according to claim 1, characterized in that, In S4, the sieve is 100 mesh.

8. The application of penicillin bacterial residue-based dual-activated nitrogen-oxygen co-doped biochar prepared by the preparation method according to any one of claims 1-7, characterized in that, The penicillin bacterial residue-based double-activated nitrogen-oxygen co-doped biochar is used for the treatment of antibiotic wastewater.

9. The application according to claim 8, characterized in that, The antibiotics in the antibiotic wastewater include sulfamethoxazole, norfloxacin, oxytetracycline, and / or tetracycline.

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