An edge-topological defect-rich carbon catalyst, a preparation method and application thereof

Abstract

The application provides a kind of rich edge-topological defect carbon catalyst and its preparation method, application, the preparation method includes the following steps: (1) biomass raw material is carried out in inert atmosphere and is sectioned pyrolysis, and graphite carbon precursor is obtained;(2) the graphite carbon precursor is mixed with the aqueous solution of nitrogen-containing compound, and wet ball milling is obtained, and nitrogen-doped intermediate;(3) nitrogen-doped intermediate is annealed in inert atmosphere, and carbon catalyst rich in edge-topological intrinsic defect is obtained.The rich edge-topological defect carbon catalyst of the application has excellent broad-spectrum degradation capacity and high stability, and the active center is derived from the intrinsic carbon defect with stable structure, and the site accessibility is high, and the removal efficiency of various organic pollutants such as phenolic compounds, bisphenols, chlorinated phenols and dyes is ≥98%.

Description

Technical Field

[0001] This invention relates to the fields of environmental functional materials and water treatment technology, and in particular to a carbon catalyst rich in edge-topological defects, its preparation method, and its application. Background Technology

[0002] With the acceleration of industrialization, the problem of persistent organic pollutants (such as antibiotics and endocrine disruptors) remaining in water bodies is becoming increasingly serious. Advanced oxidation technologies based on persulfate (PDS / PMS) are considered effective means of degrading these persistent organic pollutants due to their high oxidation potential and wide pH range. While traditional transition metal catalysts have high activity, they suffer from drawbacks such as secondary pollution caused by metal ion leaching and difficulties in recovery. Metal-free carbon-based catalysts have become a research hotspot due to their environmental friendliness and high chemical stability.

[0003] Existing technologies still have the following limitations: First, the carbon framework construction and defect introduction processes are highly coupled. In the traditional one-step co-thermal decomposition synthesis method, the doping process of nitrogen heteroatoms often hinders the dehydrogenation condensation and aromatization of the carbon precursor, resulting in low graphitization of the final product. This causes a large number of active defect sites to be deeply buried or encapsulated inside amorphous carbon, leading to a sharp contradiction between "high defect abundance" and "low catalytic efficiency".

[0004] Second, the construction of intrinsic defects lacks spatial selectivity. Some studies have attempted to create defects using a two-stage high-temperature annealing denitrification process, but due to the lack of prior interface activation, the distribution of nitrogen atoms in the carbon matrix exhibits a high degree of randomness. This results in a disordered distribution of non-hexagonal topological defects induced after denitrification, making it difficult to achieve spatial electronic synergy with the edge defects of carbon materials.

[0005] Third, the methods for regulating microstructure are too simplistic. Existing research is mostly limited to relying on "thermal-driven" mechanisms (such as thermal denitrification) to reconstruct the carbon skeleton, seriously neglecting the enormous potential of mechanochemistry (such as high-energy shearing) in breaking lattice symmetry and locally activating carbon atoms.

[0006] In summary, there is an urgent need in this field to develop a novel carbon-based catalyst synthesis strategy to decouple the carbon framework growth and defect construction processes, achieve precise spatial distribution and synergistic reconstruction of specific active defects, and fundamentally overcome the technical limitations of existing carbon catalytic materials in that "structural stability and high catalytic activity are difficult to achieve simultaneously". Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a carbon catalyst rich in edge-topological defects, its preparation method, and its application, so as to solve the problem that it is difficult to achieve both structural stability and high catalytic activity in existing carbon catalysts.

[0008] To achieve the above and other related objectives, the present invention provides a method for preparing a carbon catalyst rich in edge-topological defects, comprising the following steps:

[0009] (1) Biomass raw materials are subjected to staged pyrolysis under an inert atmosphere to obtain graphitized carbon precursor;

[0010] (2) The graphitized carbon precursor is mixed with an aqueous solution of a nitrogen-containing compound and wet ball milled to obtain a nitrogen-doped intermediate. In this step, mechanical shearing force is used to expose the carbon skeleton edge of the graphitized carbon precursor and anchor the liquid nitrogen source.

[0011] (3) The nitrogen-doped intermediate is annealed under an inert atmosphere to obtain a carbon catalyst rich in edge-topological intrinsic defects. This step removes nitrogen from the carbon lattice by annealing and induces non-hexagonal topological defect structures in situ at the edges through reconstruction.

[0012] This application creatively breaks through the coupling bottleneck between "carbon skeleton construction" and "defect introduction": it adopts the strategy of "first forming the skeleton and then creating the defect". In step (1), a highly conductive graphitized substrate is pre-constructed, and the subsequent ball milling and denitrification are only performed for "local fine etching", which maintains excellent sp while possessing high density intrinsic defects. 2 Conjugated network. The edge-topological defect-rich carbon catalyst prepared in this application is based on the synergistic construction of edge-topological dual defects. A large number of edge defects are pre-created through the mechanochemical action in step (2), providing "targeting sites" for the insertion and removal of nitrogen atoms in step (3), so that the topological defects are distributed near the active edge, forming an edge-enhanced topological defect structure. The edge-topological defect-rich carbon catalyst prepared in this application has excellent broad-spectrum degradation ability and high stability. The active center originates from the structurally stable intrinsic carbon defects, and the site accessibility is high.

[0013] Preferably, in step (1), before the segmented pyrolysis, the biomass raw materials are also cleaned and dried.

[0014] Preferably, in step (1), the biomass raw material is selected from at least one of wood waste, crop straw, nut shells, bamboo and fallen leaves.

[0015] Preferably, in step (1), the segmented pyrolysis is to first raise the temperature to 300~500℃ and hold it for 1~3h, and then raise the temperature to 800~1000℃ and hold it for 3~5h.

[0016] Preferably, in step (2), the nitrogen-containing compound is at least one of melamine, urea and dicyandiamide; the aqueous solution of the nitrogen-containing compound is a homogeneous solution without solid-phase crystallization.

[0017] Preferably, in step (2), the mass ratio of the graphitized carbon precursor to the nitrogen-containing compound is 1:(0.5~3).

[0018] Preferably, in step (2), during the wet ball milling process, the solid-liquid ratio of the total mass of the graphitized carbon precursor and nitrogen-containing compound to water is controlled to be 1g:(20~150)mL, and the ball mass ratio of the grinding balls to the total solid material is (20~100):1.

[0019] Preferably, in step (2), the rotation speed of the wet ball mill is 300~800 rpm, and the ball milling time is 4~40h.

[0020] Preferably, in step (3), the annealing temperature is 800~1100℃ and the annealing time is 1~5h.

[0021] The present invention also provides a carbon catalyst rich in edge-topological defects prepared by the above preparation method.

[0022] The catalyst has a graphitized carbon framework and its surface is rich in edge defects introduced by high-energy ball milling and non-hexagonal topological defect structures induced by nitrogen atom removal.

[0023] The present invention also provides an application of the above-mentioned edge-topological defect-rich carbon catalyst in the removal of organic pollutants in water.

[0024] Preferably, the carbon catalyst rich in edge-topological defects is used in combination with an oxidant.

[0025] Preferably, the organic pollutant is selected from at least one of antibiotics, phenols, and dye compounds.

[0026] Preferably, the oxidant is selected from at least one of persulfate, hydrogen peroxide, calcium peroxide, and percarbonate.

[0027] As described above, the present invention has the following beneficial effects:

[0028] (1) Breaking through the coupling bottleneck between "carbon skeleton construction" and "defect introduction": adopting the strategy of "first forming the skeleton and then creating defects", in step (1) a highly conductive graphitized substrate is pre-constructed, and the subsequent ball milling and denitrification are only performed for "local fine etching", which maintains excellent sp while possessing high density intrinsic defects. 2 Conjugate networks;

[0029] (2) Collaborative construction of edge-topology dual defects: A large number of edge defects are pre-created through the mechanochemical action of step (2) to provide "target sites" for the insertion and removal of nitrogen atoms in step (3), so that the topological defects are distributed near the active edge to form an edge-enhanced topological defect structure;

[0030] (3) Excellent broad-spectrum degradation ability and high stability: The active center originates from the intrinsic carbon defect with stable structure and has high site accessibility. It shows a removal efficiency of ≥98% for a variety of organic pollutants such as phenols, bisphenols, chlorophenols and dyes; and the catalytic activity can be quickly restored by combining with a simple low-temperature thermal regeneration process, making it suitable for long-term operation in complex wastewater systems. Attached Figure Description

[0031] Figure 1 The X-ray diffraction (XRD) pattern of NBMC-900-24h prepared in Example 1.

[0032] Figure 2 The images are scanning electron microscope (SEM) images of Comparative Example 3(a) and Example 1(b).

[0033] Figure 3 The image (a) is a spherical aberration corrected transmission electron microscope (AC-HRTEM) image of Example 1 and its inverse Fourier transform (IFFT) image (b).

[0034] Figure 4 Comparison of the fine peaks of X-ray photoelectron spectroscopy (XPS) N1s spectrum of Example 1 and NBMC-24h (Comparative Example 4).

[0035] Figure 5 Comparison of fine C1s peak diagrams of X-ray photoelectron spectroscopy (XPS) for Example 1 and Comparative Example 4.

[0036] Figure 6 The image shows a comparison of the Raman spectra of Example 1 and Comparative Examples 1-3.

[0037] Figure 7 The concentration-time curves of Example 1 and Comparative Examples 1-4 during the degradation of tetracycline by activated PDS are shown (based on normalization after adsorption equilibrium).

[0038] Figure 8 The figures show the pseudo-first-order kinetic fitting curves of tetracycline degradation by activated PDS in Example 1 and Comparative Examples 1-4.

[0039] Figure 9 The bar chart shows the tetracycline removal rate during multiple direct cycles and thermal regeneration cycles. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0042] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0043] Example 1

[0044] This embodiment provides a method for preparing a carbon catalyst rich in edge-topological defects, including:

[0045] (1) Pre-structure of graphitized carbon framework:

[0046] Wood waste was collected, thoroughly washed with deionized water to remove impurities, and dried at 80 °C for 48 h. The dried wood waste was then transferred to a tube furnace for pyrolysis under a flowing nitrogen atmosphere. A two-stage heat treatment process was employed: first, heating to 400 °C at a heating rate of 10 °C / min and holding for 2 h; then, further heating to 850 °C at a heating rate of 5 °C / min and holding for 4 h. After natural cooling, graphitized carbon precursor was obtained.

[0047] (2) Mechanochemical shearing and molecular-level anchoring:

[0048] Add 0.2 g of melamine (nitrogen source) to 60 mL of deionized water and stir thoroughly under heating until completely dissolved, then cool to room temperature. Mix 0.2 g of the graphitized carbon precursor obtained in step (1) into this solution (at this point, the mass ratio of graphitized carbon precursor to nitrogen source is 1:1; the volume ratio of total solid mass to water is 1 g: 150 mL, forming a uniform graphitized carbon precursor suspension). Place the mixture in a 100 mL agate ball mill jar containing 20 g of agate balls (at this point, the ball-to-material ratio is 50:1). Ball mill at 600 rpm for 24 h using a planetary ball mill. After ball milling, wash until the pH of the filtrate is 6-8, and dry at 60 ℃ for 12 h to obtain nitrogen-doped high-energy ball-milled carbon intermediate (NBMC-24h).

[0049] (3) Cooperative reconstruction of topological defects:

[0050] The NBMC-24h obtained in step (2) was placed in a tube furnace and heated to 900℃ at a rate of 10℃ / min under a nitrogen atmosphere, and held at that temperature for 2 hours. Under high temperature, the nitrogen atoms that were previously anchored were removed in situ from the carbon lattice, and their occupancy effect induced the rearrangement of surrounding carbon atoms, thereby constructing a high-density topological defect on the basis of edge defects. After natural cooling, a carbon catalyst rich in edge-topological intrinsic defects was obtained and named NBMC-900-24h.

[0051] Example 2

[0052] This embodiment provides a method for preparing a carbon catalyst rich in edge-topological defects, including:

[0053] (1) Pre-structure of graphitized carbon framework:

[0054] Crop straw was collected, thoroughly washed with deionized water to remove impurities, and dried at 80 °C for 48 h. The dried crop straw was then transferred to a tube furnace for pyrolysis under a flowing argon atmosphere. A two-stage heat treatment process was employed: first, the temperature was increased to 300 °C at a rate of 10 °C / min and held for 3 h; then, the temperature was further increased to 800 °C at a rate of 5 °C / min and held for 5 h. After natural cooling, graphitized carbon precursor was obtained.

[0055] (2) Mechanochemical shearing and molecular-level anchoring:

[0056] Add 0.2 g of dicyandiamide (nitrogen source) to 30 mL of deionized water and stir thoroughly at room temperature until completely dissolved. Mix 0.4 g of the graphitized carbon precursor obtained in step (1) into the solution (at this point, the mass ratio of graphitized carbon precursor to nitrogen source is 1:0.5; the volume ratio of total solid mass to water is 1 g:50 mL, forming a uniform graphitized carbon precursor suspension). Place the mixture in a 100 mL agate ball mill jar containing 12 g of agate balls (at this point, the ball-to-material ratio is 20:1). Ball mill at 300 rpm for 40 h using a planetary ball mill. After ball milling, wash until the pH of the filtrate is 6-8, and dry at 60℃ for 12 h to obtain nitrogen-doped high-energy ball-milled carbon intermediate (DBMC-40h).

[0057] (3) Cooperative reconstruction of topological defects:

[0058] The DBMC-40h obtained in step (2) was placed in a tube furnace and heated to 800℃ at 10℃ / min under an argon atmosphere, and held at that temperature for 5h. Under high temperature, the nitrogen atoms that were previously anchored were removed in situ from the carbon lattice, and their occupancy effect induced the rearrangement of surrounding carbon atoms, thereby constructing a high-density topological defect on the basis of edge defects. After natural cooling, a carbon catalyst rich in edge-topological intrinsic defects was obtained and named DBMC-800-40h.

[0059] Example 3

[0060] This embodiment provides a method for preparing a carbon catalyst rich in edge-topological defects, including:

[0061] (1) Pre-structure of graphitized carbon framework:

[0062] Bamboo was collected, thoroughly washed with deionized water to remove impurities, and dried at 80 °C for 48 h. The dried bamboo was then transferred to a tube furnace for pyrolysis under a flowing nitrogen atmosphere. A two-stage heat treatment process was employed: first, the temperature was increased to 500 °C at a rate of 10 °C / min and held for 1 h; then, the temperature was further increased to 1000 °C at a rate of 5 °C / min and held for 3 h. After natural cooling, a graphitized carbon precursor was obtained.

[0063] (2) Mechanochemical shearing and molecular-level anchoring:

[0064] Add 0.375 g of urea (nitrogen source) to 10 mL of deionized water and stir thoroughly at room temperature until completely dissolved. Mix 0.125 g of the graphitized carbon precursor obtained in step (1) into the solution (at this point, the mass ratio of graphitized carbon precursor to nitrogen source is 1:3; the volume ratio of total solid mass to water is 1 g: 20 mL, forming a homogeneous carbon precursor suspension). Place the mixture in a 100 mL agate ball mill jar containing 50 g of agate balls (at this point, the ball-to-material ratio is 100:1). Ball mill at 800 rpm for 4 h using a planetary ball mill. After ball milling, wash until the pH of the filtrate is 6-8, and dry at 60 ℃ for 12 h to obtain nitrogen-doped high-energy ball-milled carbon intermediate (UBMC-4h).

[0065] (3) Cooperative reconstruction of topological defects:

[0066] The UBMC-4h obtained in step (2) was placed in a tube furnace and heated to 1100℃ at a rate of 10℃ / min under a nitrogen atmosphere, and held at that temperature for 1h. Under high temperature, the nitrogen atoms anchored in the early stage were removed in situ from the carbon lattice, and their occupancy effect induced the rearrangement of surrounding carbon atoms, thereby constructing a high-density topological defect on the basis of edge defects. After natural cooling, a carbon catalyst rich in edge-topological intrinsic defects was obtained and named UBMC-1100-4h.

[0067] Comparative Example 1: Weak shear nitrogen-free reference carbon material (BMC-900-4h).

[0068] The preparation process is the same as in Example 1, except that melamine is not added in step (2) and the ball milling time is only 4 hours.

[0069] The obtained sample was named BMC-900-4h. This comparative example was set as the most basic control line for the entire catalytic system. Due to insufficient total energy input from ball milling and lack of exogenous nitrogen, the material basically maintained the original state of the pre-graphitized carbon skeleton, with very little edge exposure and a lack of topological defects inside the lattice, which was intended to reflect the intrinsic inertness of the biomass-based carbon skeleton when it is not effectively activated.

[0070] Comparative Example 2: High-shear nitrogen-free carbon material (BMC-900-24h).

[0071] The preparation process is the same as in Example 1, except that melamine is not added in step (2).

[0072] The resulting sample was named BMC-900-24h. This comparative example aims to verify the upper limit of contribution from simple high-intensity mechanical shearing (physical "edge-making"). By comparing with Example 1, it can be confirmed that, in the absence of atomic-level nitrogen template-assisted etching, simple mechanical ball milling, while able to break the carbon layer and expose edge defects, cannot induce the generation of highly active topological defects at a deep level within the carbon plane.

[0073] Comparative Example 3: Weak shear nitrogen-containing carbon material (NBMC-900-4h).

[0074] The preparation process is the same as in Example 1, except that the ball milling time in step (2) is shortened to 4 hours.

[0075] The resulting sample was named NBMC-900-4h. This comparative example was set up to reveal the sequential dependence between "mechanical edge formation" and "nitrogen source anchoring". The experimental results will demonstrate that, because short-duration low-energy ball milling failed to provide sufficient mechanical shear force to tear the carbon layer, there was a lack of sufficient "edge dangling bonds" to anchor melamine molecules; under this premise, even with the introduction of a nitrogen source and high-temperature annealing, the generation of topological defects could not be effectively stimulated.

[0076] Comparative Example 4: Undeniably denitrified ball-milled intermediate (NBMC-24h).

[0077] The preparation process is the same as in Example 1, except that the high-temperature annealing treatment in step (3) is omitted.

[0078] The nitrogen-doped ball-milled carbon intermediate (ball-milled for 24 hours) obtained in step (2) of Example 1 was directly used as the final catalyst, and the resulting sample was named NBMC-24h. This comparative example was set up to verify the core "denitrification and reconstruction" mechanism of the present invention. Although the sample underwent sufficient mechanical shearing and successfully introduced a large number of nitrogen heteroatoms, the carbon skeleton failed to undergo secondary rearrangement because it was not removed in situ driven by a high temperature of 900°C. By comparing the activity of this sample with that of Example 1, it was intended to confirm that the "nitrogen doping" in the conventional concept is not the true source of the catalytic activity of the present invention, and the real catalytic center is the "intrinsic topological defect" left after the nitrogen atom overflows.

[0079] Microstructure characterization and mechanism analysis were performed on NBMC-900-24h prepared in Example 1 and its comparative examples:

[0080] XRD analysis results are as follows: Figure 1 As shown, NBMC-900-24h exhibits characteristic broad peaks of graphitic carbon (002) and (100) at 23° and 43°, indicating that after pyrolysis at 850°C and annealing at 900°C, biomass is transformed into a graphitic microcrystalline framework with sp² conjugated network, providing a structural basis for rapid electron transfer.

[0081] SEM analysis results are as follows: Figure 2 As shown, compared to the carbon particles in Comparative Example 3 that underwent only 4 hours of wet ball milling, the carbon particles in Example 1, prepared by 24 hours of high-energy wet ball milling, exhibited significantly smaller sizes and rich exfoliated, layered, and fragmented structures on their surfaces and edges. This indicates that sufficient mechanical shear force effectively broke up the bulk graphitized framework, increased the exposed interfaces at the nanoscale, and provided more accessible sites for the anchoring of nitrogen-containing species.

[0082] AC-HRTEM analysis results are as follows: Figure 3 As shown: Significant distortions were observed in the carbon lattice of Example 1, revealing non-hexagonal carbon ring structures (such as pentagonal and octagonal rings), which are the topological defects described in this invention. These defects disrupt charge neutrality, becoming highly active sites for activating PDS.

[0083] XPS analysis results are as follows: Figure 4 and Figure 5 As shown: Comparative Example 4 (NBMC-24h) had a nitrogen content of 3.5 at%, indicating successful nitrogen source anchoring; after annealing at 900℃, the total nitrogen content of Example 1 decreased to 0.5 at%. Figure 4 This confirms that high temperature drives nitrogen atoms to escape from the carbon lattice. Simultaneously, the proportion of sp² hybridized carbon in the C1s spectrum increased from 82.5% to 84.9%. Figure 5 This indicates that the order of the carbon framework is further improved after annealing, and the graphitization network is maintained or repaired. Combined with... Figure 3 The non-hexagonal carbon ring structure directly observed by AC-HRTEM confirms that the removal of nitrogen atoms leaves unsaturated topological defects in the carbon lattice, realizing the transformation from "heterogeneous doping" to "intrinsic topological defects".

[0084] The Raman analysis results are as follows: Figure 6 As shown: The Raman spectrum was subjected to four-peak fitting, which are: D1 peak (approximately 1186 cm⁻¹). -1 (corresponding to a non-ideal graphite layer structure), D2 peak (approximately 1340 cm⁻¹) -1 (corresponding to disordered graphite lattice), D3 peak (approximately 1500 cm⁻¹) -1 (corresponding to heteroatom-induced defects and topological defects) and the G peak (approximately 1590 cm⁻¹). -1 (corresponding to the sp² carbon vibration of an ideal graphite framework). Through A D2 / A G (Total Defect Level) and A D3 / A G Analysis was conducted on the degree of topological defects. Comparison of Comparative Example 1 (BMC-900-4h) and Comparative Example 2 (BMC-900-24h) revealed that when the ball milling time was extended from 4h to 24h, A... D2 / AG Instead, it decreased from 1.76 to 1.72, indicating that simple mechanical ball milling cannot effectively construct deep intrinsic defects. Comparative Example 3 (NBMC-900-4h) A D2 / A G =1.73, A D3 / A G =0.46, almost identical to Comparative Example 1, indicating that short-time ball milling failed to expose sufficient edge dangling bonds, the nitrogen source could not be anchored, and annealing did not induce topological reconstruction. Only when high-energy mechanical shearing (24h) and nitrogen source etching are simultaneously satisfied can the A of Example 1 (NBMC-900-24h) be obtained. D2 / A G Rising to 1.82, A D3 / A G The value jumped to 0.55 (an increase of approximately 30.6% compared to Comparative Example 3). This fully demonstrates that only by anchoring the nitrogen source with a large number of edge dangling bonds created by 24-hour high-energy ball milling, and then expelling nitrogen atoms from the lattice at a high temperature of 900℃, can a high density of intrinsic topological defects be formed inside the carbon framework.

[0085] Performance evaluation of PDS catalyst for tetracycline degradation:

[0086] The materials prepared in Example 1 and Comparative Examples 1-4 were compared and tested.

[0087] All degradation experiments were conducted in 100 mL glass beakers containing 100 mL of a 0.045 mM tetracycline (TC) aqueous solution at room temperature (approximately 25 °C). The initial solution pH was unadjusted (the initial natural pH was determined to be approximately 6.8). First, the catalyst (0.1 g / L) was added to the TC solution, and the mixture was magnetically stirred for 240 min to establish adsorption equilibrium. Subsequently, persulfate (PDS) was added to achieve a final concentration of 1.0 mM, initiating the catalytic oxidation reaction. 1.0 mL samples were taken at 0, 5, 10, 20, 30, 40, and 60 min, immediately filtered through a 0.22 μm syringe filter, and quenched with sodium thiosulfate solution. The residual TC concentration was determined by high-performance liquid chromatography (HPLC). All experiments were repeated three times, and the data were averaged.

[0088] like Figure 7 and Figure 8 As shown, to visually compare the apparent reaction rate constants of PDS activated by different catalysts, the degradation curve data have been normalized based on the concentration after adsorption equilibrium (i.e., at t=0, c). t / c0=1.0). To further quantify the reaction kinetics of each catalytic system, a pseudo-first-order kinetic model was used to fit the reaction data, and the apparent reaction rate constant (k) of each system was calculated. obs ).

[0089] k of the weak shear nitrogen-free reference material (Comparative Example 1, BMC-900-4h) system obs The value is only 0.0119 min. -1 This indicates that the intrinsic catalytic activity of the carbon skeleton that has not been effectively activated is extremely low.

[0090] When only the ball milling time is increased (Comparative Example 2, BMC-900-24h), k obs The value slightly increased to 0.0151, indicating that although simple physical mechanical crushing can increase the edge contact area to a certain extent, it cannot fundamentally construct highly active deep defect sites.

[0091] k of the weak shear nitrogen-containing material (Comparative Example 3, NBMC-900-4h) obs The value actually decreased to 0.0089 min. -1 This confirms that without sufficient mechanical shear to "create edges," nitrogen sources cannot be effectively anchored and induce topological reconstruction, and may even lead to the ineffective occupation of some pores or intrinsic sites.

[0092] Furthermore, the k of the ball-milled intermediate (Comparative Example 4, NBMC-24h) without denitrification and reconstruction... obs The value is 0.0110min -1 This proves that "heterogeneous nitrogen doping" in the traditional sense is not the true source of activity for activating PDS in this system.

[0093] k in Embodiment 1 of the present invention (NBMC-900-24h) obs The value is 0.0365 min. -1 These are the reference materials (k of Comparative Example 1). obs Value 0.0119 min -1 ) and traditional non-nitrogen-removing materials (comparative example 4, k obs Value 0.0110 min -1 The energy barrier for PDS activation was 3.07 times and 3.32 times that of PDS, respectively. This indicates that the present invention significantly reduces the reaction energy barrier for PDS activation through a synergistic strategy of edge-topological dual defects, achieving highly efficient catalytic degradation.

[0094] Catalyst cycle stability and thermal regeneration performance:

[0095] To verify the long-term operational stability and industrial application potential of the catalyst of the present invention under conditions closer to actual aquatic environments, the NBMC-900-24h prepared in Example 1 was subjected to low-concentration load recycling and thermal regeneration tests.

[0096] Except for adjusting the initial TC concentration to 5 mg / L (approximately 0.011 mM), the reaction volume, catalyst dosage (0.1 g / L), PDS concentration (1.0 mM), and operating procedures remained consistent with the above. After each round of degradation reaction (reaction time 60 min), the catalyst was recovered by filtration. The recovered catalyst was rinsed with only a small amount of deionized water, dried in a 60 °C oven, and then directly added to the next round of reaction system containing fresh TC solution (5 mg / L) and PDS. When repeated cycles resulted in a significant decrease in catalyst activity, the recovered and dried catalyst was placed in a tube furnace and heat-treated at 400 °C for 1 h under a nitrogen atmosphere to remove accumulated organic intermediates on the surface and in the pores, followed by subsequent cycle tests.

[0097] like Figure 9 As shown, under high-load continuous operation without any regeneration treatment and with the active sites continuously covered by intermediate products, the TC removal rate remained above 50% after 6 cycles. After low-temperature thermal regeneration, the removal rate rapidly recovered to 91.9%, almost reaching the level of the first cycle (95.2%). The activity decayed slowly in the subsequent 4 regeneration cycles. This indicates that the intrinsic defect active site structure of the catalyst is stable, and low-temperature thermal treatment can effectively achieve regeneration.

[0098] The catalyst exhibits broad-spectrum removal performance against various organic pollutants:

[0099] To verify the universality of the catalyst of the present invention for different types of organic pollutants, the catalysts prepared in Examples 1-3 were used to conduct degradation experiments on bisphenol A (BPA), phenol (PhOH), 4-chlorophenol (4-CP), and rhodamine B (RhB) under the same experimental conditions as above (catalyst dosage 0.1 g / L, PDS concentration 1.0 mM, initial pollutant concentration 0.045 mM, room temperature, stirring for 240 min to establish adsorption equilibrium, then adding PDS to start the reaction, reaction time 60 min).

[0100] The results are shown in Table 1:

[0101] Table 1. Universality of the catalysts prepared in Examples 1-3 for different types of organic pollutants

[0102]

[0103] As shown in Table 1, the edge-topological defect-rich carbon catalyst prepared in this invention exhibits extremely high removal efficiency for phenols, bisphenols, chlorophenols, and dyes, with removal rates exceeding 97% after 60 min of reaction. This indicates that the edge-topological intrinsic defect sites constructed in this invention possess broad-spectrum catalytic oxidation capabilities and are suitable for treating various types of recalcitrant organic wastewater.

[0104] The above embodiments are for illustrating the implementation schemes disclosed in this invention and should not be construed as limiting the invention. Furthermore, various modifications listed herein, as well as variations in the methods and compositions of the invention, will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been specifically described in conjunction with various specific preferred embodiments, it should be understood that the invention should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the invention should be included within the scope of this invention.

Claims

1. A method for preparing a carbon catalyst rich in edge-topological defects, characterized in that, Includes the following steps: (1) Biomass raw materials are subjected to staged pyrolysis under an inert atmosphere to obtain graphitized carbon precursor; (2) The graphitized carbon precursor is mixed with an aqueous solution of a nitrogen-containing compound and wet ball milled to obtain a nitrogen-doped intermediate; wherein the rotation speed of the wet ball mill is 300~800 rpm and the ball milling time is 24~40h; (3) The nitrogen-doped intermediate was annealed under an inert atmosphere to obtain a carbon catalyst rich in edge-topological intrinsic defects; In step (2), the nitrogen-containing compound is at least one of melamine, urea, and dicyandiamide; the aqueous solution of the nitrogen-containing compound is a homogeneous solution without solid-phase crystallization. In step (2), the mass ratio of the graphitized carbon precursor to the nitrogen-containing compound is 1:(0.5~3). In step (2), during the wet ball milling process, the solid-liquid ratio of the total mass of the graphitized carbon precursor and nitrogen-containing compound to water is controlled to be 1g:(20~150)mL, and the ball mass ratio of the grinding balls to the total solid material is (20~100):

1. In step (3), the annealing temperature is 800~1100℃ and the annealing time is 1~5h.

2. The preparation method according to claim 1, characterized in that: In step (1), the biomass raw material is selected from at least one of wood waste, crop straw, nut shells, bamboo and fallen leaves; the staged pyrolysis is to first raise the temperature to 300~500℃ and hold it for 1~3h, and then raise the temperature to 800~1000℃ and hold it for 3~5h.

3. A carbon catalyst rich in edge-topological defects prepared by the preparation method according to any one of claims 1 to 2.

4. The application of the edge-topological defect-rich carbon catalyst as described in claim 3 in the removal of organic pollutants from water.

5. The application according to claim 4, characterized in that: The edge-topological defect-rich carbon catalyst is used in combination with an oxidant, wherein the organic pollutant is selected from at least one of antibiotics, phenols and dye compounds; and the oxidant is selected from at least one of persulfate, hydrogen peroxide, calcium peroxide and percarbonate.

Images