Preparation method of cobalt-nitrogen doped carbon nano composite material based on cuttlebone template

Abstract

The invention discloses a preparation method of a cobalt-nitrogen doped carbon nano composite material based on a cuttlebone template, and relates to the field of environment functional materials, and the preparation method comprises the following steps: S1, using ultrapure water to wash and remove cuttlebones, removing viscous impurities and shells on the top surfaces of the cuttlebones, and drying the cleaned cuttlebones in a vacuum environment of 60 DEG C for 10 hours to obtain dried cuttlebones; cutting and decomposing the dried cuttlefish bones into blocks of 0.5 cm * 0.5 cm * 0.5 cm, immersing the cut cuttlefish bone blocks into a 0.1 mol / L-1 hydrochloric acid solution, stirring for 15 minutes, washing the pickled cuttlefish bone blocks with ultrapure water until the cuttlefish bone blocks are neutral, and drying to obtain pretreated cuttlefish bones; according to the invention, the natural cuttlebone is used as the template, and the natural three-dimensional porous skeleton structure of the natural cuttlebone is used for replacing the traditional artificially synthesized template, so that the preparation cost is obviously reduced, the biomass resource utilization is realized, and the defect that the traditional template needs an additional pore-forming process is avoided in combination with the self-supporting structure characteristic of the natural cuttlebone.

Description

Technical Field

[0001] The present invention relates to environmental functional material technology, and in particular to a method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template. Background Art

[0002] Metronidazole (MTZ), a broad-spectrum antibiotic, is widely used in human medicine, livestock breeding, and aquatic parasite control. However, it is carcinogenic and mutagenic, damaging lymphocyte DNA and posing a serious threat to the ecological environment and human health. Currently, the removal of MTZ from aquatic environments relies primarily on carbon adsorption, reverse osmosis, and biological treatment. However, these technologies suffer from low removal efficiency and inability to completely mineralize the pollutant.

[0003] In recent years, Fenton-like advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) activation have attracted much attention due to their ability to efficiently generate active free radicals. However, conventional H2O2 systems suffer from high preparation costs, a narrow pH range (pH 3-5), and low free radical utilization, which limit their practical application. In contrast, PMS can overcome pH limitations when catalyzed by transition metals (such as Co and Fe). However, existing cobalt-based catalysts still face the following challenges: cobalt nanoparticles are prone to ion leaching and particle aggregation during the reaction, resulting in a reduction in active sites and the risk of secondary contamination; the catalyst structure easily collapses under high temperature or acidic conditions, significantly reducing cyclic performance; and traditional supports (such as clays and zeolites) have weak anchoring capabilities for metals, making it difficult to achieve high dispersion loading.

[0004] To address the above problems, researchers have tried to fix metal atoms through carbon-based materials (such as nitrogen-doped carbon) to improve stability. For example, Zhang et al. prepared single-atom iron-doped carbon materials by coating α-FeOOH nanorods with polydopamine (PDA) and carbonizing them, but the process is complex and depends on the synthetic precursor. Cuttlefish bone, as a natural biological template, has unique advantages. Its porous network structure (pore size 10-80 μm) and low density can achieve CO 2- The main component is calcium carbonate, which can form through-holes after acid leaching to increase the specific surface area of ​​the material.

[0005] However, traditional cobalt-based catalysts have poor metal dispersion and are easily deactivated. The synthesis process is complex and relies on expensive precursors. The structure and function of biological template materials have not been fully explored. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template, so as to solve the above-mentioned deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solution: a method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template, comprising the following steps:

[0008] S1. Use ultrapure water to rinse and remove the cuttlefish bone, and remove the sticky impurities and shell on the top surface. Dry the cleaned cuttlefish bone in a vacuum environment at 60°C for 10 hours, cut the dried cuttlefish bone into 0.5cm×0.5cm×0.5cm blocks, and immerse the cuttlefish bone blocks in 0.1mol / L -1 Stirring in a hydrochloric acid solution for 15 minutes, washing the acid-washed cuttlefish bone block with ultrapure water until neutral and then drying to obtain a pretreated cuttlefish bone;

[0009] S2, weighing 1 g of the pretreated cuttlefish bone in S1, immersing it in a CoCl2 solution with a pH of 9.0, and shaking it in a water bath constant temperature oscillator at a constant temperature of 30° C. for 48 hours to obtain a cuttlefish bone adsorbed with Co(II), filtering the cuttlefish bone solid adsorbed with Co(II), and drying the filtered cuttlefish bone solid adsorbed with Co(II) in a vacuum environment at 60° C. for 10 hours to obtain a Co(II) cuttlefish bone;

[0010] S3, immersing the Co(II) cuttlefish bone in S2 in a Tris buffer solution at pH = 8.5 and stirring, adding a dopamine hydrochloride solution, and stirring at room temperature for 12 hours to obtain a cuttlefish bone mixture completely coated with dopamine hydrochloride, filtering the mixture through a 0.22 μm filter membrane, and drying it in a vacuum environment at 60° C. for 10 hours to obtain a dried cuttlefish bone coated with dopamine hydrochloride;

[0011] S4, grinding the cuttlefish bone coated with dopamine hydrochloride dried in S3 into powder, heating the powder to 550°C at 5°C / min in a nitrogen atmosphere, maintaining the constant temperature for 2 hours, then heating to 700°C at 5°C / min, maintaining the constant temperature for 1 hour, and then naturally cooling to obtain a carbonized material;

[0012] S5. Immerse the carbonized material in S4 in a hydrochloric acid solution (0.1 M, 100 ml) for 4 hours to remove CaCO3 in the carbonized material. Wash the acid-washed carbonized material with ultrapure water until it is neutral and dry it to obtain a cobalt-nitrogen doped carbon nanocomposite material.

[0013] Furthermore, the concentration of the CoCl2 solution in S2 is 0.03 M, and the volume of the solution is 100 mL.

[0014] Furthermore, the concentration of the Tris buffer in S3 is 1 mM, the volume of the Tris buffer is 200 ml, and the dopamine hydrochloride buffer is a buffer in which 500 mg of dopamine hydrochloride is completely dissolved in 20 mL of solvent.

[0015] Furthermore, the pyrolysis process in S4 is divided into two stages: the first stage is to heat up to 550°C at 5°C / min and keep warm for 2 hours; the second stage is to heat up to 700°C at 5°C / min and keep warm for 1 hour.

[0016] Furthermore, the cuttlefish bone after pickling is dried in a vacuum environment at 60° C. for 10 hours.

[0017] A cobalt-nitrogen-doped carbon nanocomposite prepared by any of the above methods for preparing cobalt-nitrogen-doped carbon nanocomposite materials based on cuttlebone templates, wherein Co is dispersed in the nitrogen-doped carbon skeleton in the form of single atoms, the Co content is 1.0-1.2wt%, and the specific surface area is ≥200m 2 / g, and has a porous network structure.

[0018] Furthermore, the pollutants include one or more of metronidazole, sulfamethoxazole and bisphenol A.

[0019] Compared with the existing technology, the method for preparing a cobalt-nitrogen-doped carbon nanocomposite material based on a cuttlebone template provided by the present invention uses natural cuttlebone as a template, utilizing its natural three-dimensional porous skeleton structure to replace traditional synthetic templates, significantly reducing preparation costs while realizing biomass resource utilization. The aragonite-phase calcium carbonate skeleton formed after acid washing of the cuttlebone provides a natural site for metal ion adsorption. Combined with its self-supporting structural characteristics, it avoids the defect of traditional templates requiring additional pore-forming steps.

[0020] Through molecular layer encapsulation technology using dopamine hydrochloride, cobalt ions are uniformly embedded in the nitrogen-doped carbon framework at the single-atom level. This "atomic-level anchoring" effect completely solves the problems of metal particle agglomeration and insufficient exposure of active sites in traditional catalysts. It is like "seeding" cobalt atoms on the carbon substrate, allowing each cobalt atom to independently participate in the catalytic reaction.

[0021] Through the molecular layer encapsulation technology of dopamine hydrochloride, cobalt ions are evenly embedded in the nitrogen-doped carbon skeleton at the single-atom level, completely solving the problem of easy agglomeration of metal particles and insufficient exposure of active sites in traditional catalysts. It is like "planting" cobalt atoms on the carbon substrate, allowing each cobalt atom to participate in the catalytic reaction independently. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0023] Figure 1 The SEM spectrum of Co-CN provided in the embodiment of the present invention;

[0024] Figure 2 (a) is the XRD spectrum of Co-CN, and (b) is the Raman spectrum of Co-CN;

[0025] Figure 3 (a) is the XPS graph of Co-CN, (b) is the C1s graph of Co-CN, (c) is the N1s graph of Co-CN, and (d) is the Co2p graph of Co-CN;

[0026] Figure 4 (a) is the effect of different reaction conditions on MTZ degradation (all MTZ initial concentrations are 20 mg / L -1 ; Catalyst concentration: 0.1gL -1 ; PMS concentration: 0.2 gL -1 ; pH = 7), (b) is the fitting diagram of MTZ degradation by different reactions, (c) is the effect of the initial pH value of the reaction solution on MTZ degradation, (d) is the effect of the PMS concentration of the reaction solution on MTZ degradation, (e) is the effect of the catalyst concentration on MTZ degradation, and (f) is the effect of Co-CN catalyst on the degradation of different pollutants;

[0027] Figure 5 (a) is the cycle diagram of MTZ degradation by Co-CN (the initial MTZ concentration is 20 mg L-1; the Co-CN concentration is 0.1 g L-1 -1 ; PMS concentration is 0.2 gL -1 , pH = 7), (b) is the XPS total spectrum before and after the Co-CN reaction;

[0028] Figure 6 (a) is the effect of different quenching conditions on MTZ degradation, (b) is the first-order kinetic curve of different quenching conditions (Co-CN: 0.1gL -1 ; PMS: 0.2gL - 1; MTZ: 20mgL -1 ; pH = 7);

[0029] Figure 7 Diagram of the Co-CN catalytic degradation mechanism. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Example 1:

[0032] See also Figure 1 , a method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template, comprising:

[0033] S1. Use ultrapure water to rinse and remove the cuttlefish bone, and remove the sticky impurities and shell on the top surface. Dry the cleaned cuttlefish bone in a vacuum environment at 60°C for 10 hours, cut the dried cuttlefish bone into 0.5cm×0.5cm×0.5cm blocks, and immerse the cuttlefish bone blocks in 0.1mol / L -1 Stirring in a hydrochloric acid solution for 15 minutes, washing the acid-washed cuttlefish bone block with ultrapure water until neutral and then drying to obtain a pretreated cuttlefish bone;

[0034] S2, weighing 1 g of the pretreated cuttlefish bone in S1, immersing it in a CoCl2 solution with a pH of 9.0, and shaking it in a water bath constant temperature oscillator at a constant temperature of 30° C. for 48 hours to obtain a cuttlefish bone adsorbed with Co(II), filtering the cuttlefish bone solid adsorbed with Co(II), and drying the filtered cuttlefish bone solid adsorbed with Co(II) in a vacuum environment at 60° C. for 10 hours to obtain a Co(II) cuttlefish bone;

[0035] S3, immersing the Co(II) cuttlefish bone in S2 in a Tris buffer solution at pH = 8.5 and stirring, adding a dopamine hydrochloride solution, and stirring at room temperature for 12 hours to obtain a cuttlefish bone mixture completely coated with dopamine hydrochloride, filtering the mixture through a 0.22 μm filter membrane, and drying it in a vacuum environment at 60° C. for 10 hours to obtain a dried cuttlefish bone coated with dopamine hydrochloride;

[0036] S4, grinding the cuttlefish bone coated with dopamine hydrochloride dried in S3 into powder, heating the powder to 550°C at 5°C / min in a nitrogen atmosphere, maintaining the constant temperature for 2 hours, then heating to 700°C at 5°C / min, maintaining the constant temperature for 1 hour, and then naturally cooling to obtain a carbonized material;

[0037] S5. Immerse the carbonized material in S4 in a hydrochloric acid solution (0.1 M, 100 ml) for 4 hours to remove CaCO3 in the carbonized material. Wash the acid-washed carbonized material with ultrapure water until it is neutral and dry it to obtain a cobalt-nitrogen doped carbon nanocomposite material.

[0038] In this embodiment, the concentration of the CoCl2 solution in S2 is 0.03 M, and the volume of the solution is 100 mL.

[0039] In this embodiment, the concentration of the Tris buffer in S3 is 1 mM, the volume of the Tris buffer is 200 ml, and the dopamine hydrochloride buffer is a buffer in which 500 mg of dopamine hydrochloride is completely dissolved in 20 mL of solvent.

[0040] In this embodiment, the S4 pyrolysis process is divided into two stages: the first stage is to heat up to 550°C at 5°C / min and keep warm for 2 hours; the second stage is to heat up to 700°C at 5°C / min and keep warm for 1 hour.

[0041] In this embodiment, the S5 pickling process is performed at room temperature, and the Ca residual content of the material after pickling is ≤0.5wt%.

[0042] In this embodiment, the cuttlefish bone after pickling is dried in a vacuum environment at 60° C. for 10 hours;

[0043] Specifically, first, the cuttlefish bone was rinsed with ultrapure water to remove sticky impurities and shells on the top surface of the bone, and the cleaned cuttlefish bone was vacuum dried at 60°C for 10 hours. Then, the cleaned cuttlefish bone was cut into cubes of about 0.5 cm in size and soaked in 0.1 mol / L -1 HCl and continued stirring for 15 minutes, and washed with ultrapure water until the pH of the filtered water was 7, and dried to obtain pretreated cuttlefish bones;

[0044] 1g of pretreated cuttlefish bone was weighed and added to a 100mL CoCl2 solution (0.03M, pH=9.0). The solution was shaken in a water bath at 30°C for 48 hours to allow the cuttlefish bone to fully adsorb Co(II). The Co(II)-adsorbed cuttlefish bone was filtered and vacuum-dried at 60°C for 10 hours. The resulting material was ground and added to a Tris buffer solution (200mL, 1mM, pH=8.5). Stirring was continued, and a dopamine hydrochloride solution (20mL, 500mg) was added. The mixture was stirred at room temperature for 12 hours, at which point the dopamine hydrochloride completely coated the cuttlefish bone. The mixture was filtered through a 0.22μm filter membrane and vacuum-dried at 60°C for 10 hours. Finally, the obtained material was ground into powder and calcined at high temperature under N2, the temperature was increased to 550℃ at 5℃ per minute, and the constant temperature was maintained for 2 hours. Then the temperature was increased to 700℃ at 5℃ per minute and the constant temperature was maintained for 1 hour. After natural cooling, the obtained material was acid-leached in HCl solution (0.1M, 100mL) for 4 hours to further remove CaCO3 in the material, washed with ultrapure water until the pH of the filtered water was 7, and dried to obtain the Co-CN catalyst.

[0045] In this embodiment, Co in the material is dispersed in the nitrogen-doped carbon skeleton in the form of single atoms, the Co content is 1.0-1.2 wt%, and the specific surface area is ≥200 m 2 / g, and has a porous network structure.

[0046] In this embodiment, the pollutants include one or more of metronidazole, sulfamethoxazole and bisphenol A.

[0047] Example 2:

[0048] XRD and Raman analysis of Co-CN materials:

[0049] See also Figure 2 , Figure 2 (a) shows the X-ray diffraction spectrum (XRD) of Co-CN material. In the figure, two diffraction peaks of Graphite-2H can be observed at 26.381° and 44.391°, which are {002} and {101} crystal planes, respectively, proving that Co-CN material has a graphite structure. The diffraction peaks of aragonite phase calcium carbonate are found in the XRD spectrum, which are located at 29.12°, 47.14°, 55.74°, 68.68°, and 75.80°, corresponding to the {104}, {024} , {211}, {217}, and {220} crystal planes, indicating that a small amount of calcium carbonate is still present in the Co-CN catalyst. The acid leaching process has not completely removed the calcium carbonate in the material. However, in experiments and characterization, we found that the Ca content accounts for about 1% of the material, and after a single cycle experiment, its content is less than 0.5%. Therefore, it is believed that the Ca in the material can be basically removed after multiple cycles, while the material still maintains high recyclability. Therefore, the impact of trace calcium carbonate in the material is temporarily ignored here. The excellent adsorption properties of cuttlefish bones uniformly adsorb Co(Ⅱ). By adding dopamine hydrochloride (DPH), the cuttlefish bones further wrap the Co(Ⅱ) to form CoCl2@DPH / Cuttlefishbones. After carbonization, DPH is converted into a CN layer. CoCl2 slowly converts to Co atoms on the DPH layer, and Co and CN have a strong interaction.

[0050] Figure 2 (b) shows the local structure of Co-CN catalyst and graphene material characterized by Raman spectroscopy at 1333 cm -1 、1587cm -1 There are two characteristic peaks on the left and right, corresponding to the D band and G band of its graphite structure. Both can produce in-plane stretching vibrations, which are induced by carbon atom lattice defects or disorder, as well as by sp 2 The intensity ratio of the D peak to the G peak (ID / IG) indicates the amount of defects in the carbon material. The calculated values ​​for Co-CN and Graphene are 1.250 and 1.033, respectively. A larger ratio indicates greater material disorder and more lattice defects, resulting in more active sites for binding to contaminant molecules.

[0051] Example 3:

[0052] See also Figure 3 ,like Figure 3As shown in Figure a, five elements, C, N, O, Co, and Ca, were observed in the overall spectrum. A small amount of Ca (about 0.4%) still exists in the material. This may be because the acid leaching process failed to completely remove the CaCO3 inside the material. This also explains the strong O peak in the overall spectrum, which may come not only from the O2 / H2O participating in the pyrolysis process, but also from CaCO3. Figure 3 b and Figure 3 c are the XPS spectra of carbon and nitrogen elements in Co-CN, respectively. It can be observed that the electronic structures of the two elements are in different environments. Figure 3 C1 in b s The spectrum shows that carbon can be convoluted into three peaks. From right to left, the first peak is 284.50eV, which corresponds to sp 2 hybridized C-C bond; the second peak is 285.51eV, corresponding to the C-O-C bond; the third peak is 288.64eV, belonging to the sp2 hybridized carbon in NC=N. Figure 3 N1 in c s The spectrum shows that nitrogen can be convoluted into four peaks. The first peak from right to left is 398.05 eV, corresponding to the CN=C structure, that is, sp bonded to the carbon atom. 2 Hybridized aromatic nitrogen; the second peak is 399.12eV, corresponding to the Co-N bond, proving that Co is bonded to N on graphite; the third peak is 400.60eV, the characteristic peak corresponds to the CNH structure; the fourth peak is 402.46eV, the characteristic peak corresponds to oxidizedN. Figure 3 d shows the XPS spectrum of Co2p, Co 2p 3 / 2 The binding energy is 780.7eV and the 2p1 / 2 binding energy is 796.3eV, which is attributed to the binding energy of Co(Ⅱ) in Co-Nx material and metallic Co (Co2p 3 / 2 :778.10eV,Co2p1 / 2:793.30) compared with Co2p in Co-CN. 3 / 2 With Co2p 1 / 2 A small chemical shift occurs toward higher binding energy.

[0053] Example 4:

[0054] See also Figure 4 In order to evaluate the catalytic performance of Co-CN catalysts, control experiments under different systems can be carried out, such as Figure 4 The black line in a shows the degradation effect of MTZ when only oxidant (PMS) is added without catalyst. It is found that only 9.4% of MTZ is degraded. The reason is that there is no catalyst in the reaction, which cannot produce effective active free radicals, and PMS is not activated to generate enough SO4. 2-The red, blue, green, and pink lines represent the MTZ degradation curves of Co-CN catalysts doped with 0.00M, 0.01M, 0.03M, and 0.10M CoCl2, respectively. Overall, the material's adsorption of MTZ was not as strong as that of Mn-C3N4, with the highest adsorption amount being only 7%. In the degradation experiments, 0.00M Co-CN exhibited relatively low catalytic activity (degrading only 53% of MTZ within 15 minutes). Due to the addition of metal, the Co-doped materials all exhibited excellent catalytic effects. The higher the metal doping level, the better the degradation performance. The degradation rate of 0.03M Co-CN reached 100% after 15 minutes of reaction, demonstrating that Co-CN can activate PMS to produce sufficient active free radicals to participate in the reaction. Figure 4 b is the relationship curve between -ln(C / C0) and reaction time t, where C0 is the initial concentration of MTZ (mgL -1 ), C is the MTZ reaction concentration (mgL -1 ), t is the reaction time (min). From the figure, we can see that there is a good linear relationship between -ln(C / C0) and reaction time t, and the graph conforms to the pseudo-first-order kinetic model:

[0055] -ln(C / Co)=kt;

[0056] k is the kinetic rate constant (min-1), and the K value of 0.03MCo-CN catalyst for PMS activation is 0.4863min -1 , which are 1.73 times, 11.67 times and 66.61 times of the k values ​​of 0.01MCo-CN / PMS, 0.00MCo-CN / PMS and PMS systems respectively. This shows that the carbon-nitrogen nanocomposite material loaded with cobalt has stronger catalytic efficiency, and the higher the loading amount, the higher the catalytic efficiency.

[0057] Figure 4 c is the effect of the initial pH concentration of the reaction on the degradation of MTZ. Before the dark reaction, 0.1M hydrochloric acid and sodium hydroxide were used to adjust the pH to 3, 4, 5, 6, 7, 8, 9, and 10, respectively. As can be seen from the figure, MTZ has a good degradation effect under different pH conditions after 30 minutes of reaction, which shows that the pH application range of the catalyst is relatively strong. At pH = 7, the degradation effect of MTZ is most obvious, and the removal rate of MTZ reaches 99.7% after 6 minutes of reaction. When the pH increases to 10, the reaction effect decreases significantly. This is because under alkaline conditions, the PMS substance will undergo self-decomposition (SO4 ·- +SO4 ·- →S2O8 2-) and some sulfate radicals are converted into hydroxyl radicals. Because sulfate radicals have greater stability and a longer half-life than hydroxyl radicals, they are more effective in degrading antibiotic-related organic micropollutants. When the solution pH drops to 4, the degradation effect of MTZ begins to decline, likely because the superacidic conditions hinder the activation of PMS.

[0058] Figure 4 d. The effect of PMS concentration on the degradation of MTZ was investigated. When [PMS] increased from 0.01 g L-1 to 0.20 g L-1, the sulfate radicals and hydroxyl radicals produced by PMS increased, and the removal efficiency of MTZ gradually increased. However, when [PMS] increased from 0.20 g L-1 to 0.20 g L-1, the sulfate radicals and hydroxyl radicals produced by PMS increased, and the removal efficiency of MTZ gradually increased. -1 Increase by 0.30 g / L -1 When the concentration of MTZ increases, the degradation rate of MTZ no longer increases, and even decreases slightly. According to the conclusion of the previous experiment, as the concentration increases, the number of PMS molecules and active free radicals will increase, but PMS molecules will undergo quenching reactions with free radicals, and free radicals will also undergo quenching reactions with each other, which is obviously not conducive to the reaction.

[0059] Figure 4 e reflects the effect of catalyst concentration on MTZ degradation. Without catalyst, PMS failed to effectively generate active free radicals and MTZ was only degraded by 9.4%. As shown in the figure, the degradation effect of MTZ was significantly improved after adding catalyst. When the catalyst concentration was 0.01, 0.05, 0.10, and 0.20 g / L -1 When the catalyst concentration increased, the adsorption efficiency of MTZ on the catalyst was 0.36%, 5.113%, 5.453% and 1.14% respectively. It can be seen that with the increase of catalyst concentration, the adsorption amount of MTZ on the catalyst gradually increased. However, when the amount of catalyst gradually increased to 0.20 gL -1 When the catalyst adsorbs MTZ, the amount is reduced. This is because too many suspended particles overlap with each other, which in turn reduces the effective contact area between the pollutant and the catalyst. Overall, the addition of catalysts can effectively activate PMS to produce active free radicals. The catalyst concentrations are 0.01, 0.05, 0.10, and 0.20 gL-1. After 15 minutes of reaction, the degradation rates of MTZ are 96.60%, 99.18%, 100%, and 100%, respectively, which have excellent catalytic effects. In short, considering efficiency and cost, this experiment proposed three optimal reaction conditions, namely pH = 7, [PMS] = 0.2 gL-1, and [PMS] = 0.2 gL-1. -1 , the concentration of 0.03MCo-CN catalyst is 0.1gL -1 The experiment also evaluated several other common pollutants, such as Figure 4f, including sulfamethoxazole (SMX), meropenem (MEM), and bisphenol A (BPA), it can be seen that 20mgL -1 The degradation rates of SMX and BPA can reach more than 99% after 6 minutes, 20mgL -1 SMX can be completely degraded in 10 minutes.

[0060] Stability and reusability play a vital role in the practical application of catalysts. This application studies the cyclic degradation effect of MTZ by 0.03MCo-CN catalyst, such as Figure 5 As shown in Figure a, after the first, second, third, fourth and fifth cycle experiments, the degradation rates of MTZ reached 100%, 100%, 100%, 99.9% and 99.8% respectively, indicating that the Co-CN material prepared by the cuttlebone template method improved the shortcomings of the original catalyst such as poor chemical stability. After five cycle experiments, it still had a catalytic efficiency of 99.8%, with excellent reusability. The experiment also analyzed the XPS total spectrum of the Co-CN catalyst after the cycle experiment, as shown in Figure 5. Figure 5 As shown in Figure b, before the sequential experiment, the content of Co in the catalyst was 1.07%, and after the sequential experiment, the content of Co was 1.06%, which remained basically unchanged, proving that there was no metal ion leaching in the Co-CN catalyst, further proving that the catalyst had good stability.

[0061] Embodiment 5:

[0062] In order to explore the active free radicals generated during the degradation of MTZ by Co-CN catalyst, we studied the free radical quenching method. The quenchers used included isopropanol, methanol, disodium ethylenediaminetetraacetic acid, sodium azide, such as Figure 6 As shown in a and 6b, when IPA or NaN3 was added, the degradation rates of MTZ were 82.3% and 81.7%, and the reaction rate constants were 0.1273min-1 and 0.1030min-1, respectively. Compared with 0.4954min-1 without quencher, the degradation of MTZ tended to be inhibited, but it was weak, indicating that ·OH and 1 O2 participates in the degradation of MTZ, but it is not the main active free radical. 1 O2 had the lowest degradation activity. When MeOH was added, a stronger inhibitory effect was observed, and the degradation efficiency of MTZ was greatly suppressed to only 47.8%, with a reaction rate constant of 0.0288 min -1 , showing that SO4 in the reaction ·- Once quenched, the reaction effect will be greatly reduced, proving that SO4 ·-It has stronger activity and is the main active free radical in the degradation process. When EDTA-2Na is added, the MTZ degradation rate is almost zero, and the reaction rate constant is 2.2287×10-4min-1, indicating that H+ plays a key role in the reaction. The kinetic parameters of MTZ catalytic degradation in different quenching systems are shown in Table 1 below:

[0063]

[0064] Table 1 (Kinetic parameters of catalytic degradation of MTZ in different quenching systems)

[0065] Under neutral conditions, the persulfate ions of PMS react with cobalt ions to produce sulfate radicals, which can be further converted into hydroxyl radicals. ·- Under the action of excited electrons, it is converted into superoxide free radicals. From the quenching experiment, it can be concluded that in O2 ·- / SO4 ·- / ·OH degrade MTZ. Based on the above results, we proposed the degradation mechanism of MTZ in Co-CN+PMS system, such as Figure 7 shown.

[0066] First, the peroxymonosulfate (HSO5 - ) under the action of catalyst and Co2 + The reaction produces SO4 ·- Free radicals and Co3 + (Equation 3.2), and at the same time, the generated Co3 + Continue with HSO5 - The reaction produces SO4 ·- Free radicals (Equation 3.3), the above two reactions can promote each other to produce more SO4 ·- Free radicals. SO4 ·- Free radicals can react with OH - The reaction produces OH radicals (Equation 3.4), and at the same time, O2 in the reaction reacts with the electrons (e-) on Co-CN to produce O2 ·- Free radical (Equation 3.5), O2 ·- The free radicals react with OH radicals in the solution to produce singlet oxygen (O2 ·- )(Equation 3.6). Finally, through SO4 ·- Free radicals, OH radicals, singlet oxygen 1 O2 acts on pollutants and is ultimately converted into H2O and CO2 (Equation 3.7).

[0067] HSO5-+Co2+→SO4·—+Co3++OH-(3.2);

[0068] HSO5-+Co3+→SO5·—+Co2++H+(3.3);

[0069] SO4·—+OH-→SO42—+·OH(3.4);

[0070] O2+e-→O2·-(3.5);

[0071] O2·-+·OH→1O2+OH-(3.6);

[0072] 1O2 / SO4·— / ·OH+MTZ→degradationproducts→H2O+CO2(3.7);

[0073] In summary, a highly efficient catalyst of cobalt-based carbon-nitrogen nanocomposite material was successfully prepared by the cuttlebone template method, named Co-CN, and the material was characterized by SEM, XRD, XPS, Raman and other techniques. Co-CN exhibits the characteristics of high porosity and high dispersibility, and no particle aggregation is found. The content of Co metal in the material does not decrease after repeated use, and there is no metal leaching, indicating that the metal-loaded material prepared by the cuttlebone template method has advantages such as high stability. In the catalytic degradation experiment, it was found that this material has stronger catalytic activity than existing catalysts such as carbon nitride and graphene, and overcomes the disadvantage of low reuse rate of graphite and graphene structural materials. After multiple cycle experiments, it still maintains a high catalytic degradation efficiency. This experiment also studied the catalysts (Fe-CN) of iron-based carbon-nitrogen nanocomposite materials and the catalysts (Cu-CN) of iron-based carbon-nitrogen nanocomposite materials prepared by the cuttlebone template method, both of which have strong catalytic degradation capabilities. At the same time, Co-CN exhibits excellent catalytic degradation performance for endocrine disruptors, brominated flame retardants, sulfonamide antibiotics, etc. The research in this experiment provides a new method to solve the shortcomings of existing catalysts such as obvious metal leaching and serious particle aggregation, and opens up new ideas for the synthesis of nanocatalysts by template method.

[0074] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template, characterized in that: include: S1. Use ultrapure water to rinse and remove the cuttlefish bone, and remove the sticky impurities and shell on the top surface. Dry the cleaned cuttlefish bone in a vacuum environment at 60°C for 10 hours, cut the dried cuttlefish bone into 0.5cm×0.5cm×0.5cm blocks, and immerse the cuttlefish bone blocks in 0.1mol / L -1 Stirring in a hydrochloric acid solution for 15 minutes, washing the acid-washed cuttlefish bone block with ultrapure water until neutral and then drying to obtain a pretreated cuttlefish bone; S2, weighing 1 g of the pretreated cuttlefish bone in S1, immersing it in a CoCl2 solution with a pH of 9.0, and shaking it in a water bath constant temperature oscillator at a constant temperature of 30° C. for 48 hours to obtain a cuttlefish bone adsorbed with Co(II), filtering the cuttlefish bone solid adsorbed with Co(II), and drying the filtered cuttlefish bone solid adsorbed with Co(II) in a vacuum environment at 60° C. for 10 hours to obtain a Co(II) cuttlefish bone; S3, immersing the Co(II) cuttlefish bone in S2 in a Tris buffer solution at pH = 8.5 and stirring, adding a dopamine hydrochloride solution, and stirring at room temperature for 12 hours to obtain a cuttlefish bone mixture completely coated with dopamine hydrochloride, filtering the mixture through a 0.22 μm filter membrane, and drying it in a vacuum environment at 60° C. for 10 hours to obtain a dried cuttlefish bone coated with dopamine hydrochloride; S4, grinding the cuttlefish bone coated with dopamine hydrochloride dried in S3 into powder, heating the powder to 550°C at 5°C / min in a nitrogen atmosphere, maintaining the constant temperature for 2 hours, then heating to 700°C at 5°C / min, maintaining the constant temperature for 1 hour, and then naturally cooling to obtain a carbonized material; S5. Immerse the carbonized material in S4 in a hydrochloric acid solution (0.1 M, 100 ml) for 4 hours to remove CaCO3 in the carbonized material. Wash the acid-washed carbonized material with ultrapure water until it is neutral and dry it to obtain a cobalt-nitrogen doped carbon nanocomposite material.

2. The method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template according to claim 1, characterized in that: The concentration of the CoCl2 solution in S2 is 0.03 M, and the volume of the solution is 100 mL.

3. The method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template according to claim 1, characterized in that: The concentration of the Tris buffer in S3 is 1 mM, the volume of the Tris buffer is 200 ml, and the dopamine hydrochloride buffer is a buffer in which 500 mg of dopamine hydrochloride is completely dissolved in 20 mL of solvent.

4. The method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template according to claim 1, wherein: The pyrolysis process in S4 is divided into two stages: the first stage is to increase the temperature to 550°C at 5°C / min and keep it at that temperature for 2 hours; the second stage is to increase the temperature to 700°C at 5°C / min and keep it at that temperature for 1 hour.

5. The method for preparing cobalt-nitrogen doped carbon nanocomposite material based on cuttlebone template according to claim 1, characterized in that: The pickling process in S5 is carried out at room temperature, and the Ca residual content of the material after pickling is ≤0.5wt%.

6. The method for preparing a cobalt-nitrogen doped carbon nanocomposite material based on a cuttlebone template according to claim 1, characterized in that: The cuttlefish bones after pickling were dried in a vacuum environment at 60° C. for 10 hours.

7. A cobalt-nitrogen doped carbon nanocomposite material prepared by the method according to any one of claims 1 to 6, characterized in that: The Co in the material is dispersed in the nitrogen-doped carbon skeleton in the form of single atoms, with a Co content of 1.0-1.2wt% and a specific surface area of ​​≥200m 2 / g, and has a porous network structure.

8. Use of the cobalt-nitrogen doped carbon nanocomposite material according to claim 7 in activating peroxymonosulfate to degrade organic pollutants, characterized in that: The pollutants include one or more of metronidazole, sulfamethoxazole and bisphenol A.

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