Defect-rich iron-nitrogen co-doped porous carbon, preparation method thereof and application thereof in degrading harmful pollutants

Abstract

The present application belongs to the technical field of harmful pollutant removal, and relates to defect-rich iron-nitrogen co-doped porous carbon, a preparation method thereof and application of the defect-rich iron-nitrogen co-doped porous carbon in degradation of harmful pollutants. The defect-rich iron-nitrogen co-doped porous carbon is prepared by a "cage encapsulation precursor pyrolysis" strategy, and the material has high crystallinity, rich nitrogen / carbon defects, large specific surface area and hierarchical porous structure, and can in-situ continuously generate high-selectivity 1 O2 under no external energy or oxidant conditions. The defect-rich iron-nitrogen co-doped porous carbon of the present application can degrade more than 99.8% of AFB1 in an aqueous solution within 5 min, has a wide pH application range (3-8), strong anti-ion interference ability, and AFB1 degradation products have no cytotoxicity, and can also efficiently degrade harmful pollutants such as vomitoxin, rhodamine B, fluorene and phosalone, thereby providing a green, safe and efficient feasible solution for environmental and food pollution control.

Description

Technical Field

[0001] This invention belongs to the field of hazardous pollutant removal technology, specifically relating to defect-rich iron / nitrogen co-doped porous carbon (D-Fe / N-PC), its preparation method, and its application in degrading hazardous pollutants. Background Technology

[0002] Organic pollutants such as mycotoxins, dyes, polycyclic aromatic hydrocarbons (PAHs), and pesticides are common harmful contaminants in food and the environment, posing serious threats to food safety, human health, and the ecological environment. Among them, aflatoxin B1 (AFB1) is a naturally occurring, highly toxic, and strongly carcinogenic secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus fungi. It is widely found in grains, feed, soil, food, and environmental water, and is difficult to remove due to its high chemical / thermal stability and the complexity of its matrix. Furthermore, organic pollutants such as vomitoxin, rhodamine B dye, fluorene, and phosmet pesticides are also difficult to completely remove due to their complex benzene ring structures. Therefore, developing green, safe, and efficient methods for degrading harmful pollutants in food and the environment is crucial.

[0003] Degradation methods are considered an effective way to eliminate organic pollutants because they can alter or completely destroy the toxic sites of organic matter. Traditional degradation methods, such as irradiation, alkaline treatment, and ozone treatment, often require harsh conditions and / or high energy consumption, and their degradation efficiency is unsatisfactory. In recent years, advanced oxidation processes (AOPs), such as photocatalysis, persulfate activation, and Fenton / Fenton-like processes, have been widely used in the oxidation and mineralization of recalcitrant organic pollutants. Currently, AOPs for degrading harmful pollutants often require an external light source or oxidant (such as PMS and H2O2), and SO4 is among the oxidation products. 2- The residues and reusability of the degradation system are limited. Efficient degradation requires the rapid and effective generation of reactive oxygen species, which leads to the rapid consumption of the oxidant and its inability to maintain long-term activity. Therefore, developing a new strategy to achieve in-situ continuous generation of reactive oxygen species without external energy or oxidants, and to greenly, safely, and efficiently degrade harmful pollutants in the environment and food, has become an urgent need.

[0004] Metal-organic frameworks (MOFs) contain abundant carbon, nitrogen, and oxygen elements. Porous carbon materials produced by the pyrolysis of MOFs under high temperature and inert atmospheres (such as nitrogen and argon) possess advantages such as high specific surface area, abundant pore capacity, ease of doping with heteroatoms, tunable active sites (metal and carbon), and controllable morphology, offering significant advantages in the adsorption and degradation of organic pollutants. The doping and defect construction of transition metal iron helps alter the number and distribution of electrons at catalyst active sites, promoting electron transfer, and can also directly act as active sites, providing an effective means of controlling the chemical state of catalyst surfaces. Chinese invention patent application CN 117399005 A discloses a method for removing AFB1 using ZIF-8-derived ferromagnetic iron-doped nano-porous carbon (FM-Fe-NPC). FM-Fe-NPC can achieve a removal rate of 99.8% of AFB1 in water within 90 minutes, but it still suffers from slow removal speed, unknown safety of degradation products, and limited application in complex real-world samples such as food.

[0005] In summary, current materials for removing harmful pollutants suffer from drawbacks such as long degradation times, unknown safety of the degradation process, limited application in aqueous samples, and difficulty in use in complex samples such as real-world environments and food. Furthermore, no methods have been reported for utilizing defect-rich materials to continuously generate reactive oxygen species in situ without external energy or oxidants, and for the green, safe, and efficient degradation of harmful pollutants in complex environmental and food samples. Summary of the Invention

[0006] This invention proposes for the first time a method for preparing defect-rich iron-nitrogen co-doped porous carbon (D-Fe / N-PC) using a "cage-encapsulated precursor pyrolysis" strategy. This porous carbon can continuously generate active oxygen in situ and safely and efficiently degrade harmful pollutants without external energy or oxidants, providing a green, safe, and efficient feasible solution for environmental and food pollution control.

[0007] The technical solution of this invention is as follows: In a first aspect, this invention provides a defect-rich iron-nitrogen co-doped porous carbon. This porous carbon possesses high crystallinity, abundant nitrogen / carbon defects, a large specific surface area, and a hierarchical porous structure (micropores, mesopores, and macropores), which facilitates electron transfer and mass transfer of reactants to accelerate the degradation kinetics of harmful pollutants. This porous carbon has a dodecahedral structure and is composed of Zn... 2+ZIF-8 molecular-level cages with a cavity diameter of 11.6 Å and a pore size of 3.4 Å are first self-assembled with 2-methylimidazole to form ZIF-8 molecular-level cages. Each molecular-level cage traps a 9.7 Å diameter iron triacetylacetone (Fe(acac)3) metal precursor molecule. The mixture is then pyrolyzed at 800–1000 °C under a protective gas atmosphere to obtain the final product. After pyrolysis, ZIF-8 is transformed into a nitrogen-doped porous carbon material, while the Fe(acac)3 within the molecular cages is carbonized and reduced through organic ligands. This porous carbon contains a lattice with lattice spacings of 0.171, 0.229, 0.241, and 0.356 nm, corresponding to the Fe3N(112), Fe3C(002), Fe2N(110), and graphitic carbon(002) crystal planes, respectively.

[0008] Secondly, the present invention provides a method for preparing defect-rich iron-nitrogen co-doped porous carbon, which utilizes a unique "cage-encapsulated precursor pyrolysis" strategy to prepare defect-rich iron-nitrogen co-doped porous carbon.

[0009] Specifically, the "cage-encapsulated precursor" strategy refers to Zn 2+ During self-assembly with 2-methylimidazole, ZIF-8 molecular-level cages with a cavity diameter of 11.6 Å and a pore size of 3.4 Å are formed. Due to the limitations of pore size and cavity size, each cage can only trap one Fe(acac)3 metal precursor molecule (with a molecular diameter of approximately 9.7 Å) (denoted as Fe(acac)3@ZIF-8). After high-temperature pyrolysis under an argon atmosphere, ZIF-8 is transformed into nitrogen-doped porous carbon. Simultaneously, the Fe(acac)3 within the ZIF-8 cages undergoes carbonization and reduction via organic ligands, yielding defect-rich iron-nitrogen co-doped porous carbon. Both the Fe(acac)3@ZIF-8 before pyrolysis and the defect-rich iron-nitrogen co-doped porous carbon obtained after pyrolysis have a dodecahedral structure, and the elements iron, nitrogen, carbon, and oxygen are uniformly spatially distributed throughout the dodecahedral structure of the defect-rich iron-nitrogen co-doped porous carbon.

[0010] Specifically, the following steps are included: Step 1: The 2-methylimidazole solution, Fe(acac)3 solution, and Zn(NO3)2·6H2O solution are mixed and reacted to obtain Fe(acac)3@ZIF-8. Preferably, in this step, the 2-methylimidazole solution, Fe(acac)3 solution, and Zn(NO3)2·6H2O solution are respectively a 2-methylimidazole methanol solution, a Fe(acac)3 methanol solution, and a Zn(NO3)2·6H2O methanol solution; the molar ratio of 2-methylimidazole, Fe(acac)3, and Zn(NO3)2·6H2O in this step is 40:1:10.

[0011] Step 2: Fe(acac)3@ZIF-8 is pyrolyzed at 800℃~1000℃ under a protective gas atmosphere to obtain defect-rich iron-nitrogen co-doped porous carbon. Preferably, the heating rate in this step is 5℃ / min, the pyrolysis temperature is 900℃, and the pyrolysis time is 3 h. The protective gas can be argon or nitrogen.

[0012] Thirdly, the present invention provides the application of the above-mentioned defect-rich iron-nitrogen co-doped porous carbon in the preparation of highly selective reactive oxygen species.

[0013] Specifically, by dispersing defect-rich iron-nitrogen co-doped porous carbon in an aqueous solution and oscillating it, reactive oxygen species can be continuously generated in situ. 1 O2). Electron paramagnetic resonance (EPR) experiments have observed that TEMP-... 1 The significantly enhanced signal of the O2 characteristic triplet (1:1:1) indicates that defect-rich iron-nitrogen co-doped porous carbon can be continuously generated in situ. 1 O2.

[0014] In a further scheme, the concentration of defect-rich iron-nitrogen co-doped porous carbon added to the aqueous solution is 10–50 mg / L, and active oxygen is continuously generated in situ for at least 72 days.

[0015] Fourthly, this invention provides the application of the defect-rich iron-nitrogen co-doped porous carbon in the degradation of harmful pollutants; the harmful pollutants are AFB1, vomitoxin, rhodamine B dye, fluorene, or phosmet pesticide. Specifically, the defect-rich iron-nitrogen co-doped porous carbon is dispersed in an aqueous solution containing harmful pollutants such as AFB1, vomitoxin, rhodamine B dye, fluorene, or phosmet pesticide, and the harmful pollutants are degraded by shaking at room temperature.

[0016] Furthermore, the initial pH of the aqueous solution containing AFB1 is 3–8. The initial concentration of AFB1 in the aqueous solution is 1250–5000 μg / L, and the amount of defect-rich iron-nitrogen co-doped porous carbon added is 10–250 mg / L. Even if the aqueous solution contains anions and cations including KCl, K2CO3, K2SO4, KNO3, KH2PO4, NaCl, CaCl2, and MgCl2, it does not affect the degradation of AFB1 by the defect-rich iron-nitrogen co-doped porous carbon. The defect-rich iron-nitrogen co-doped porous carbon of the present invention can degrade AFB1 not only in aqueous solutions, but also in complex environmental samples (such as lake water and irrigation water) and food samples (such as rice vinegar and sorghum liquor). Neither the defect-rich iron-nitrogen co-doped porous carbon material nor the AFB1 degradation products have significant cytotoxicity.

[0017] Furthermore, in the aqueous solution containing vomitoxin, rhodamine B dye, fluorene, or phosmet, the initial concentration of vomitoxin, rhodamine B dye, fluorene, or phosmet is 2000–2500 μg / L, and the amount of defect-rich iron-nitrogen co-doped porous carbon added is 50–150 mg / L.

[0018] The beneficial effects of this invention are as follows: 1. The defect-rich iron-nitrogen co-doped porous carbon of the present invention has high crystallinity, abundant nitrogen / carbon defects, large specific surface area and hierarchical porous structure (micropores, mesopores and macropores), which is beneficial to promoting electron transfer and mass transfer of reactants to accelerate the degradation reaction kinetics of harmful pollutants.

[0019] 2. The defect-rich iron-nitrogen co-doped porous carbon prepared by the "cage-encapsulated precursor pyrolysis" strategy of this invention can continuously generate active oxygen in situ without the need for external energy or oxidants; the rate of active oxygen generation (in "H2O2" equivalent) is 4786 μmol g over 60 min. -1 h -1 .

[0020] 3. The defect-rich iron-nitrogen co-doped porous carbon of the present invention degrades AFB1 at an extremely fast rate, degrading more than 99.8% of 2500 μg / L AFB1 in aqueous solution within 5 min, which is faster than the degradation rate of currently known materials; it can continuously degrade AFB1 for at least 7 cycles, with a total AFB1 degradation amount of 350 mg / g.

[0021] 4. The defect-rich iron-nitrogen co-doped porous carbon involved in this invention has strong resistance to interference from anions and cations. Commonly used anions and cations (such as KCl, K2CO3, K2SO4, KNO3, KH2PO4, NaCl, CaCl2 and MgCl2) have almost no effect on the degradation performance of D-Fe / N-PC on AFB1.

[0022] 5. The defect-rich iron-nitrogen co-doped porous carbon of the present invention has a wide pH range (pH=3 to 8) and can efficiently and rapidly degrade AFB1 with an initial concentration of 1250 to 5000 μg / L under different pH conditions.

[0023] 6. The defect-rich iron-nitrogen co-doped porous carbon of the present invention can not only efficiently degrade AFB1 in a variety of complex environmental and food samples such as lake water, irrigation water, rice vinegar and sorghum wine, but also efficiently degrade a variety of harmful pollutants in water such as vomitoxin, rhodamine B, fluorene and phosmet.

[0024] 7. The defect-rich iron-nitrogen co-doped porous carbon and the products of pollutant degradation optimization by the defect-rich iron-nitrogen co-doped porous carbon of the present invention do not have obvious cytotoxicity, and have the characteristics of being green, safe and pollution-free, providing a green, safe and efficient feasible solution for environmental and food pollution control. Attached Figure Description

[0025] Figure 1 A schematic diagram of the synthesis of D-Fe / N-PC using the "cage-encapsulated precursor pyrolysis" strategy.

[0026] Figure 2 Scanning electron microscope images of Fe(acac)3@ZIF-8 (a) and D-Fe / N-PC (b); high-resolution transmission electron microscope images (cd, il) and EDS distribution maps (eh) of Fe, N, C and O elements in D-Fe / N-PC.

[0027] Figure 3 Electron paramagnetic resonance (a), Raman spectrum (b), nitrogen adsorption-desorption curve and pore size distribution (c) of D-Fe / N-PC.

[0028] Figure 4 (a) EPR detection of reactive oxygen species generated by D-Fe / N-PC-900 in water; (b) Reactive oxygen species generated by D-Fe / N-PC-900 in water and AFB1 system (in "H2O2" equivalent).

[0029] Figure 5 (a) Effect of D-Fe / N-PC materials prepared at different pyrolysis temperatures on the degradation of AFB1; (b) Effect of different amounts of D-Fe / N-PC-900 materials on the degradation of AFB1; (c) High performance liquid chromatograms of AFB1 (2500 μg / L) treated with D-Fe / N-PC-900 (0.2 mg) for different times; (d) Degradation of AFB1 with different initial concentrations by D-Fe / N-PC-900 (1 mg).

[0030] Figure 6 (a) Effect of D-Fe / N-PC-900 on the degradation of AFB1 at different pH values; (b) Effect of D-Fe / N-PC-900 on the degradation of AFB1 under different ion conditions; (c) Continuous degradation of AFB1 by D-Fe / N-PC-900; (d) Degradation of AFB1 by D-Fe / N-PC-900 in lake water, irrigation water, rice vinegar and sorghum liquor; In Figure (d), a and b represent D-Fe / N-PC-900 dosages of 1 mg and 5 mg, respectively.

[0031] Figure 7Cytotoxicity of D-Fe / N-PC-900 (a) and AFB1 degradation products (b).

[0032] Figure 8 D-Fe / N-PC-900 degrades vomitoxin, rhodamine B dye, polycyclic aromatic hydrocarbons fluorene, and phosmet pesticides in water. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] The AFB1 standard used in the examples was purchased from Shanghai Maclean Biotechnology Co., Ltd., with a purity of ≥98%.

[0035] Example 1 The "cage-encapsulated precursor pyrolysis" strategy for preparing defect-rich iron-nitrogen co-doped porous carbon (D-Fe / N-PC) includes the following steps: Step 1: Dissolve 28.8 mmol of 2-methylimidazole in 20 mL of methanol; dissolve 0.72 mmol of Fe(acac)3 and 7.2 mmol of Zn(NO3)2·6H2O in 30 mL of methanol; mix the two solutions, stir, let stand, and crystallize. Wash the product with methanol, centrifuge, and vacuum dry to obtain Fe(acac)3@ZIF-8.

[0036] Step 2: Fe(acac)3@ZIF-8 was heated to 800 ℃, 900 ℃, and 1000 ℃ respectively at a rate of 5 ℃ / min under an argon atmosphere and pyrolyzed for 3 h to obtain D-Fe / N-PC-800, D-Fe / N-PC-900, and D-Fe / N-PC-1000. A schematic diagram of the synthesis of D-Fe / N-PC using the "cage-encapsulated precursor pyrolysis" strategy is shown below. Figure 1 As shown.

[0037] Figure 2 Scanning electron microscopy (SEM) of (a) and (b) and Figure 2High-resolution transmission electron microscopy (HRTEM) images (cd) show that both the Fe(acac)3@ZIF-8 before pyrolysis and the D-Fe-NPC-900 material after pyrolysis have a dodecahedral morphology. This dodecahedral structure not only effectively maintains the passivation of the Fe atom surface but also provides abundant accessible active sites, thereby minimizing the mass / charge transfer distance, which is crucial for achieving efficient and sustainable catalytic performance. High-angle annular dark-field transmission electron microscopy and corresponding EDS images reveal that Fe, C, N, and O elements are uniformly distributed throughout the porous structure. Figure 2 Furthermore, the HRTEM images show that the D-Fe-NPC-900 material contains abundant and ordered lattice fringes (eh). Figure 2 The lattice spacings of the lattice planes are 0.171, 0.229, 0.241 and 0.356 nm, respectively, which may correspond to the Fe3N(112), Fe3C(002), Fe2N(110) and graphitic carbon(002) crystal planes, respectively, indicating that the material has abundant crystallinity.

[0038] Single-electron information and defects on the surface of D-Fe-NPC were analyzed using electron paramagnetic resonance (EPR) spectroscopy. The results are as follows: Figure 3 As shown in (a), a symmetrical Lorentz-type signal appears at a g value of 2.003, indicating the possible presence of nitrogen defects in D-Fe-NPC-900. This may be due to the alteration of electron distribution on the catalyst by Fe lattice doping. The change in electron distribution also leads to the formation of electron-rich Fe and electron-depleted C(π) microregions in D-Fe-NPC-900. The internal chemical structure of the material was analyzed by measuring its Raman spectrum using confocal micro-Raman spectroscopy. Figure 3 The Raman spectrum in (b) shows the characteristic D peak (1350 cm⁻¹) of D-Fe-NPC. −1 ) and G peak (1580 cm) −1 The D peak originates from sp. 3 The lattice defects or distortions in hybrid C atoms, while the G peak represents graphite sp. 2 The ordered structure of carbon reflects the graphene-like structural characteristics (C(π) structure) of the catalyst. Furthermore, the intensity ratio of the D peak to the G peak (I0) is... D / I G The higher the value, the more defects and disordered structures exist in the carbon material. Calculation results show that the Ig of D-Fe / N-PC-900... D / I G The value (3.48) is significantly higher than that of D-Fe / N-PC-800 (3.09), indicating that more defective carbon structures are formed in D-Fe / N-PC-900, which helps to regulate the surface and electronic structure (i.e. increase electron exchange) and thus optimize the reactivity.

[0039] The surface area and pore size of D-Fe / N-PC were analyzed using a surface area and porosity analyzer. The results are shown in Table 1. The specific surface area of ​​D-Fe / N-PC-900 and D-Fe / N-PC-1000 is approximately twice that of D-Fe / N-PC-800. The larger surface area and pore size in D-Fe / N-PC-900 allow for more active sites to be exposed, thereby enhancing the performance of the catalyst. Figure 3 (c) The nitrogen adsorption-desorption isotherms of D-Fe / N-PC-900 are typical type IV isotherms with an H4 type hysteresis loop, indicating the presence of abundant mesoporous structures in the material. Iron ions, acting as mesoporous forming agents, induce the Kirkendall effect during pyrolysis, generating relatively large voids within the final derived carbon material. 3+ The dopant is transformed into atomic Fe-Nx sites, which are well dispersed in the carbon matrix. (From Zn) 2+ Reduced zinc (boiling point 908 °C) volatilizes at high temperatures, leaving behind a large number of micropores. This hierarchical porous structure accelerates reaction kinetics by promoting mass transfer of reactants.

[0040] Table 1. Specific surface area, pore volume, and pore size of D-Fe / N-PC materials prepared at different pyrolysis temperatures. Example 2: Identification of reactive oxygen species and their in-situ continuous generation 5 mg of D-Fe / N-PC-900 was dispersed in 1 mL of water, and 2,2,6,6-tetramethyl-4-piperidinone (TEMP) was used as a paramagnetic trapping agent. The results were analyzed using EPR. Figure 4 As shown in (a), typical TEMP- was detected in the D-Fe / N-PC-900 system after 5 min and 20 min of reaction. 1 The O2 characteristic triplet (1:1:1) and the triplet signal increasing with increasing reaction time indicate that... 1 O2 continues to be generated in situ. 1 O2 is a highly selective reactive oxygen species that can selectively oxidize and degrade target pollutants.

[0041] Weigh 1.5 mg of D-Fe / N-PC-900 and disperse it in 10 mL of deionized water or 2500 μg / L AFB1 aqueous solution. Add 10 mL of a mixed solution containing 0.4 mol / L potassium iodide, 0.16 mmol / L ammonium molybdate, and 0.05 mol / L NaOH, and 10 mL of 0.1 mol / L potassium hydrogen phthalate solution. Shake the solution, periodically sample and filter the solution, and detect the concentration of reactive oxygen species (in "H2O2" equivalent) using a UV-Vis spectrophotometer at a detection wavelength of 351 nm. The results are as follows. Figure 4 As shown in (b), the concentration of reactive oxygen species generated by D-Fe / N-PC-900 increased with time, reaching a rate as high as 4786 μmol g in deionized water at 60 min. -1 h -1 The rate of reactive oxygen species in AFB1 aqueous solution (3790 μmol g) -1 h -1 The concentration of AFB1 was significantly lower than that of the deionized water system, which is due to the consumption of reactive oxygen species during AFB1 degradation.

[0042] Example 3: Degradation of AFB1 D-Fe / N-PC, prepared under different conditions and of varying mass, was dispersed into aqueous solutions, environmental samples, or food samples containing different concentrations of AFB1. The initial pH or anion / cation concentrations of the mixed solutions were adjusted, and AFB1 degradation was induced by shaking at room temperature. All experiments were conducted under environmental conditions without external oxidant input. Samples were taken at specific time points and filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane. The residual amount of AFB1 was determined by high-performance liquid chromatography (HPLC).

[0043] (1) Degradation of AFB1 by D-Fe / N-PC prepared at different pyrolysis temperatures D-Fe / N-PC-800, D-Fe / N-PC-900, and D-Fe / N-PC-1000, prepared at a heating rate of 5 °C / min, a pyrolysis time of 3 h, and different pyrolysis temperatures (800 °C, 900 °C, and 1000 °C), were dispersed in 20 mL of 2500 μg / L AFB1 aqueous solution and shaken. Results were measured at regular intervals. Figure 5 As shown in (a), D-Fe / N-PC-900 showed the best effect in degrading AFB1, degrading 99.8% of AFB1 within 5 min and completely removing AFB1 within 10 min.

[0044] (2) Degradation of AFB1 by different amounts of D-Fe / N-PC-900 0.2 mg, 0.5 mg, 0.7 mg, and 1.0 mg of D-Fe / N-PC-900 were dispersed in 20 mL of an aqueous solution containing 2500 μg / LAFB1, respectively, and shaken. Data were collected at regular intervals for detection. The results are as follows: Figure 5 As shown in (b), the degradation efficiency of AFB1 significantly increased with increasing D-Fe / N-PC-900 dosage, and the 1.0 mg material exhibited the fastest degradation rate of AFB1. This is likely because more material provides more active sites. Furthermore, with prolonged time... Figure 5 (c) The HPLC chromatogram shows that the concentration of AFB1 is decreasing while the concentration of newly appearing products is increasing, indicating that AFB1 has been degraded.

[0045] (3) Degradation of AFB1 at different initial concentrations 1.0 mg D-Fe / N-PC-900 was dispersed in 20 mL of aqueous solutions containing 1250 μg / L, 2500 μg / L, 3750 μg / L, or 5000 μg / L AFB1, respectively, and shaken. Data were collected at regular intervals. The results of D-Fe / N-PC-900 treatment with different initial concentrations of AFB1 are shown below. Figure 5 As shown in (d), when the initial concentration of AFB1 is 1250–5000 μg / L, 1.0 mg of D-Fe / N-PC-900 can efficiently degrade it, indicating that the material has wide applicability.

[0046] (4) Degradation of AFB1 by D-Fe / N-PC-900 under different pH conditions 1.0 mg D-Fe / N-PC-900 was dispersed in 20 mL aqueous solutions containing 2500 μg / L AFB1 at pH values ​​of 3, 4, 5, 6, 7, and 8, respectively, and the solutions were shaken. Results were measured at regular intervals. Figure 6 As shown in (a), the degradation effect of D-Fe / N-PC-900 on AFB1 did not differ significantly within the pH range of 3 to 8, indicating that the material has excellent applicability across a wide pH range.

[0047] (5) Degradation of AFB1 by D-Fe / N-PC-900 under different anion and cation conditions 1.0 mg of D-Fe / N-PC-900 was dispersed in 20 mL of aqueous solutions containing 2500 μg / L AFB1 with different cations and anions (10 mM KCl, K2CO3, K2SO4, KNO3, KH2PO4, NaCl, CaCl2, and MgCl2), and the solutions were shaken. Data were collected periodically for analysis. The results of AFB1 degradation by D-Fe / N-PC-900 under different cation and anion conditions are shown below. Figure 6 As shown in (b), compared with the control group, the degradation efficiency of D-Fe / N-PC-900 on AFB1 did not change significantly after the addition of anions and cations, indicating that the material has a strong resistance to anion and cation interference.

[0048] (6) Continuous degradation of AFB1 In a long-term, continuous degradation experiment, 1 mg of D-Fe / N-PC-900 was dispersed in 20 mL of a 2500 μg / L AFB1 aqueous solution and shaken. The reaction solution was analyzed periodically. When the degradation efficiency reached over 98%, AFB1 was added to the system to maintain a concentration of 2500 μg / L, and degradation continued, repeating the above steps. Results are as follows: Figure 6 As shown in (c), D-Fe / N-PC-900 can continuously degrade AFB1 7 times within 1730 hours (72 days), with a total removal of 350 mg / g, and the degradation efficiency in the last cycle is still higher than 98%, indicating that D-Fe / N-PC-900 still has the potential to continue degrading AFB1.

[0049] (7) Degradation of AFB1 in different environmental and food samples AFB1 was added to lake water, irrigation water, rice vinegar, and sorghum liquor (both with alcohol content of 15% and 40%) to prepare samples containing 2500 μg / L AFB1. 1 mg of D-Fe / N-PC-900 was dispersed in 20 mL of lake water (from Xiliu Lake, Zhongyuan District, Zhengzhou City, Henan Province), irrigation water (from farmland irrigation water in Xinyang City, Henan Province), rice vinegar (purchased from Zhenjiang Danhe Vinegar Industry Co., Ltd., with a total acidity ≥5.00 g / 100 mL), and sorghum liquor (purchased from Chongqing Jiangji Winery Co., Ltd., specifically 15% vol Guolifang and 40% vol Jiangxiaobai, respectively) containing 2500 μg / L AFB1, and the samples were shaken. Samples were taken periodically, and the AFB1 content was determined by HPLC. The degradation effect of AFB1 in the lake water, irrigation water, rice vinegar, and sorghum liquor samples is as follows: Figure 6 As shown in (d), 1 mg of D-Fe / N-PC-900 can completely degrade AFB1 in lake water and irrigation water within 180 min. However, in rice vinegar and sorghum liquor with alcohol contents of 15% and 40%, respectively, only 86.47%, 76.32%, and 66.64% of AFB1 can be degraded, respectively. This may be because the carbohydrates, organic acids, ethanol, and other components in rice vinegar or sorghum liquor compete with AFB1 for the active sites of D-Fe / N-PC-900, resulting in lower AFB1 degradation efficiency. Furthermore, when the dosage of catalyst D-Fe / N-PC-900 is increased to 5 mg, the AFB1 degradation efficiency in both rice vinegar and sorghum liquor can reach over 98%, indicating that D-Fe / N-PC has good prospects for practical application.

[0050] (8) Cytotoxicity of D-Fe / N-PC and AFB1 degradation products The effects of D-Fe / N-PC-900 on HeLa cells (purchased from Cybio Shanghai Biotechnology Co., Ltd.) were evaluated using in vitro cytotoxicity assays. Specifically, HeLa cells were incubated with D-Fe / N-PC-900 for 48 hours, and viable cell concentration was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Results are as follows: Figure 7 As shown in (a), when the concentration of D-Fe / N-PC-900 is from 0.01 mg / mL to 1.25 mg / mL, the cell survival rate after incubation with D-Fe / N-PC-900 exceeds 90%, indicating that D-Fe / N-PC-900 has low biotoxicity.

[0051] In addition, the toxicity of AFB1 standard solution, AFB1 degradation products, untreated irrigation water, irrigation water containing AFB1, and irrigation water containing AFB1 after detoxification treatment to cells was investigated. The AFB1 standard solution is prepared by dissolving AFB1 in a small amount of acetonitrile and then adding water to obtain a solution of 2500 μg / L. The AFB1 degradation product refers to the solution after complete AFB1 degradation, obtained by degrading the 2500 μg / L AFB1 standard solution with 1 mg D-Fe / N-PC-900 for 3 h and then filtering to remove D-Fe / N-PC-900. Untreated irrigation water refers to irrigation water that does not contain AFB1. Irrigation water containing AFB1 refers to the solution containing 2500 μg / L AFB1 obtained by diluting the 0.5 mg / L AFB1 standard solution with irrigation water as a solvent. The detoxification treatment of irrigation water containing AFB1 refers to the treatment of detoxified irrigation water containing AFB1 by degrading the irrigation water containing AFB1 with 1 mg D-Fe / N-PC-900 for 3 h (complete degradation of AFB1) and then filtering to remove D-Fe / N-PC-900.

[0052] like Figure 7 As shown in (b), after treatment with AFB1 standard solution and irrigation water containing AFB1, cell viability decreased to 12.85% and 11.86%, respectively, indicating that AFB1 has high toxicity. Notably, the cell viability after detoxification treatment with AFB1 degradation products, untreated irrigation water, and irrigation water containing AFB1 were 97.97%, 98.92%, and 99.91%, respectively. This indicates that the AFB1 degradation products and irrigation water containing AFB1, after detoxification treatment with D-Fe / N-PC-900, showed no significant cytotoxicity. D-Fe / N-PC can greenly and safely degrade harmful pollutants in real samples. This characteristic makes D-Fe / N-PC a friendly choice for environmental and food sample processing.

[0053] Example 7: Degradation of vomitoxin, rhodamine B dye, fluorene, and phosmet pesticide in water 3 mg D-Fe / N-PC-900 was dispersed in 20 mL of 2000 μg / L vomitoxin aqueous solution and shaken. Samples were taken periodically (5 min, 10 min, 15 min, 20 min, 30 min, 60 min, 90 min, 120 min, 180 min) and the concentration of vomitoxin was detected by HPLC at wavelengths of 254 nm and 220 nm.

[0054] 2 mg D-Fe / N-PC-900 was dispersed in 40 mL of 2500 μg / L Rhodamine B aqueous solution and shaken. Samples were taken periodically and the concentration of Rhodamine B was detected using a spectrophotometer with a detection wavelength of 554 nm.

[0055] 1 mg D-Fe / N-PC-900 was dispersed in 20 mL of 2500 μg / L fluorene or phosmet aqueous solution and shaken. Samples were taken periodically, and the concentration of fluorene or phosmet was determined by HPLC.

[0056] The results are as follows Figure 8 As shown, D-Fe / N-PC-900 can degrade 91.51% of Rhodamine B, 100% of fluorene, and 97.71% of phosmet within 5 min, and 100% of vomitoxin within 3 h, and the appearance of new products was observed. This indicates that the D-Fe / N-PC material of the present invention has a good degradation effect on vomitoxin, Rhodamine B, polycyclic aromatic hydrocarbon fluorene, and organophosphorus pesticide phosmet.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A defect-rich iron-nitrogen co-doped porous carbon, characterized in that, The porous carbon has a dodecahedral structure, which is composed of Zn 2+ 2-Methylimidazole first self-assembles to form ZIF-8 molecular-level cages with a cavity diameter of 11.6 Å and a pore size of 3.4 Å. Each molecular-level cage traps a triacetylacetone iron metal precursor molecule with a molecular diameter of 9.7 Å. Then, it is pyrolyzed at 800 ℃ to 1000 ℃ under a protective gas atmosphere to obtain the product. The porous carbon contains a lattice with lattice spacings of 0.171, 0.229, 0.241 and 0.356 nm, corresponding to Fe3N(112), Fe3C(002), Fe2N(110) and graphitic carbon(002) crystal planes, respectively; the defect-rich iron-nitrogen co-doped porous carbon has nitrogen / carbon defects.

2. The method for preparing defect-rich iron-nitrogen co-doped porous carbon according to claim 1, characterized in that, include: Step 1: Mix 2-methylimidazolium solution, iron triacetylacetone solution, and Zn(NO3)2·6H2O solution, react, allow to stand, and crystallize to obtain Fe(acac)3@ZIF-8; the 2-methylimidazolium solution, iron triacetylacetone solution, and Zn(NO3)2·6H2O solution are respectively 2-methylimidazolium methanol solution, iron triacetylacetone methanol solution, and Zn(NO3)2·6H2O methanol solution; the molar ratio of 2-methylimidazolium, iron triacetylacetone, and Zn(NO3)2·6H2O is 40:1:10; Step 2: Pyrolyze Fe(acac)3@ZIF-8 at 800℃~1000℃ under a protective gas atmosphere to obtain defect-rich iron-nitrogen co-doped porous carbon.

3. The method for preparing defect-rich iron-nitrogen co-doped porous carbon according to claim 2, characterized in that, In step 2, the heating rate is 5 °C / min, the pyrolysis temperature is 900 °C, and the pyrolysis time is 3 h.

4. The application of the defect-rich iron-nitrogen co-doped porous carbon according to claim 1 in the preparation of highly selective active oxygen.

5. The application according to claim 4, characterized in that, The porous carbon is dispersed in an aqueous solution and oscillated in situ to continuously generate active oxygen.

6. The application of the defect-rich iron-nitrogen co-doped porous carbon of claim 1 in the degradation of harmful pollutants; wherein the harmful pollutants are AFB1, vomitoxin, rhodamine B dye, polycyclic aromatic hydrocarbon fluorene, or phosmet pesticide.

7. The application according to claim 6, characterized in that, The porous carbon was dispersed in an aqueous solution containing AFB1, vomitoxin, rhodamine B dye, polycyclic aromatic hydrocarbon fluorene, or phosmet pesticide, and the harmful pollutants were degraded by shaking at room temperature.

8. The application according to claim 6, characterized in that, The initial pH of the aqueous solution containing AFB1 is 3-8, the initial concentration of AFB1 in the aqueous solution is 1250-5000 μg / L, and the amount of porous carbon added is 10-250 mg / L; the initial concentration of vomitoxin, rhodamine B dye, fluorene, or phosmet pesticide in the aqueous solution is 2000-2500 μg / L, and the amount of porous carbon added is 50-150 mg / L.

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