Preparation method of high-mesoporous-rate carbon adsorbent with high proportion and six-membered nitrogen configuration

Abstract

The invention relates to a preparation method of a high-mesoporous-rate carbon adsorbent with a high proportion and a six-membered nitrogen configuration, which solves the problems of low adsorption capacity and slow diffusion rate of the existing adsorbent, and comprises the following steps: (1) carrying out hydrothermal treatment on calcium citrate in a sugar solution, filtering, and freeze-drying to obtain a carbon film solid; (2) grinding the solid and nitrogen species, and pyrolyzing in an inert atmosphere to obtain carbide; and (3) soaking the carbide in a humic acid solution, filtering, drying, carrying out thermal reaction at 950 DEG C for 2 hours, and carrying out acid pickling, water washing and drying to obtain the high-mesoporous-rate nitrogen-doped carbon material. The mesoporous rate of the material reaches 76%, and the material is rich in pyridine nitrogen, can be manufactured on a large scale and has excellent performance in the aspect of purification of high-concentration dye wastewater. When the material is used as an adsorbent, dye can be rapidly removed within 50 min, the maximum adsorption capacity of methylene blue at room temperature reaches 680 mg / g, the removal rate of methylene blue after 10 cycles still reaches 80%, and the cycle stability is good.

Description

Technical field:

[0001] The present invention relates to the field of adsorbent preparation, and in particular to a preparation method and application of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen. Background technology:

[0002] Dye wastewater has complex composition and high chromaticity, and has become a key problem that needs to be solved in environmental governance. Trace dyes in water bodies seriously affect the photosynthesis of aquatic plants and may also pose a threat to human health through the food chain. The adsorption method has low energy consumption in dye removal. Traditional adsorbents such as activated carbon have been widely used in dye wastewater treatment, but their porosity is relatively low and the pore size distribution is wide. The diffusion rate of dye molecules is slow, and the adsorption performance will drop significantly after several cycles. Therefore, it is necessary to develop an adsorbent with fast adsorption and diffusion and high adsorption capacity.

[0003] Nitrogen-doped mesoporous carbon materials have well-developed pores, stable structures, and nitrogen-rich surfaces. They have excellent performance in energy storage, catalytic conversion, gas adsorption, and sewage treatment. When adsorbing pollutants in water, mesopores can provide transmission channels for adsorption and diffusion, and nitrogen can induce electron migration and create additional active sites. Nitrogen-doped mesoporous carbon materials are mainly prepared by combining templates and chemical activation. This process involves the use and removal of a large amount of non-renewable templates. Patent CN112619608B synthesizes a precursor by hydrothermal reaction of glucose, iron powder, and mesitylene at 160-170°C, and then KOH activation and acid treatment are used to obtain a 2370m 2 / g of carbon material and performs well in VOCs adsorption and separation. Although the patent claims that glucose is used as a carbon precursor, in the actual process, glucose does not form solids during the hydrothermal reaction at 160-170°C. The process mainly forms Fe-MOF crystals. After centrifugal washing, only some glucose carbon species remain on the surface of Fe-MOF. However, KOH-based chemical activation is indeed a conventional method for obtaining high-porosity carbon materials.

[0004] In addition to porosity, nitrogen doping also significantly affects the amount of dye adsorption. Pyridine nitrogen can undergo a strong conjugation reaction with the dye and has excellent adsorption performance. Patent CN112452310A reported the use of ammonium citrate hydrothermal method to achieve green nitrogen doping on the surface of porous carbon materials, but the mesoporous structure collapsed during high-temperature pyrolysis and the material recyclability was poor. The paper (Micro. Meso. Mater., 2019, 279: 439-445) mixed sucrose and disodium zinc ethylenediaminetetraacetic acid and dissolved them, then freeze-dried them, and then pyrolyzed them at high temperature and treated them with acid to obtain a 1638m 2 / g and a nitrogen-doped carbon material with a mesoporosity of 66%, Na 2 CO 3The ZnO and ZnO play the dual role of template and activator during the reaction. The nitrogen content is 2.1 at.%, and the pentapyrrolyl nitrogen is the main component. The paper (Micro. Meso. Mater., 2021, 310: 110662) uses low-temperature hydrothermal glucose as a modifier to coat the surface of ZIF-8 to form a complex, and high-temperature pyrolysis obtains a 1000m 2 / g and a multi-level porous carbon material rich in pyridine nitrogen, with a methylene blue adsorption capacity of 383mg / g. However, the production cost of ZIF is relatively high. Although it has a high porosity and better adsorption performance when pyrolyzed into carbon, it is difficult to achieve industrial production and the nitrogen doping amount at high temperature is usually less than 10at.%. The paper (CCS Chemistry, 2021, 3: 870-881.) reported a method using 2,6-diaminopyridine as a monomer, spherical micelles formed by PS-b-PEO as a template, and graphene as a structure-directing agent. After self-assembly to form a polymer, it was pyrolyzed at 700°C to obtain a specific surface area of ​​324m 2 / g, a carbon material rich in mesopores with a nitrogen content of 19at.%, 2,6-diaminopyridine itself contains nitrogen atoms in the pyridinic nitrogen configuration, and the hexapyridinic nitrogen accounts for 49.9% of the 19at.% total nitrogen. For adsorption applications, it is still necessary to seek economical, efficient, sustainable and green adsorbents. How to obtain mesoporous carbon materials with high porosity and rich in pyridinic nitrogen configuration while avoiding the use of corrosive activators is a problem that needs to be solved at present. Summary of the invention:

[0005] In response to the problems of the prior art, the present invention provides a method for preparing a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration and its application. Calcium citrate is used as a self-template and self-activator to avoid the use of corrosive chemical reagents, and humic acid is used to regulate the nitrogen coordination configuration. The prepared high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration has the characteristics of high adsorption capacity and rapid diffusion for dye pollutants in water bodies.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A method for preparing a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration comprises the following steps:

[0008] (1) Preparation of carbon membrane solids, specifically: low-temperature hydrothermal reaction of calcium citrate in a sugar solution, centrifugation filtration and freeze-drying of the carbon membrane solids after the reaction is completed;

[0009] (2) Preparation of carbides, specifically: grinding the carbon film solid obtained in step (1) with nitrogen species and then subjecting it to a heat treatment reaction under a nitrogen atmosphere;

[0010] (3) The carbide obtained in step (2) is soaked in a humic acid solution, filtered, dried, and then thermally reacted at 950° C. for 2 h. After continuous acid washing, water washing, and drying, a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration is obtained.

[0011] Preferably in the above technical scheme, when preparing the carbon film solid material in step (1), the sugar is at least one of glucose, fructose, sucrose and xylose and the solution concentration is 5 to 20 wt.%; the mass ratio of sugar to calcium citrate is 1:1 to 5:1; the hydrothermal reaction temperature is 140 to 170°C; and the hydrothermal reaction time is 10 to 24 hours.

[0012] Preferably in the above technical scheme, when preparing the carbide in step (2), the nitrogen species is at least one of hexamethylenetetramine, urea, bipyridine, melamine, dicyandiamide, ethylenediamine and thiourea; the mass ratio of the carbon film solid to the nitrogen species is 1:0.5 to 1:4.0; the heat treatment reaction temperature is 500 to 750°C, and the reaction time is 0.5 to 2h.

[0013] Preferably, in the above technical solution, the mass ratio concentration of humic acid when the carbide described in step (3) is immersed in the humic acid solution is 5 to 20 wt.%, and the mass ratio of carbide to humic acid is 25:1 to 100:1.

[0014] The application of the high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration prepared by the above method in removing dye pollutants in water bodies comprises the following specific steps: adding the material to an aqueous solution containing a dye, performing oscillating adsorption at room temperature of 25°C, and stirring at a constant temperature until adsorption equilibrium is reached, thereby completing dye adsorption.

[0015] Preferably, the concentration of the material in the aqueous solution containing the dye is 0.02-0.1 g / L, the volume of the solution is 20-100 mL, the concentration of the dye in the aqueous solution is 200-800 mg / L, and the dye is methylene blue.

[0016] The principle of the present invention is:

[0017] The high mesoporous carbon adsorbent with a high proportion of six-membered nitrogen configuration described in the present invention uses calcium citrate as a raw material, which acts as a self-activator and self-template in the reaction process. It can form a carboxyl-rich carbon film on the surface by utilizing the reducing property of sugar through a low-temperature hydrothermal reaction in a sugar solution. After the carboxyl functional groups of the carbon film are fully cross-linked with nitrogen species, they are pyrolyzed to form a nitrogen-doped carbon material rich in micropores and calcium species, which is then adsorbed with humic acid. The high mesoporous carbon adsorbent with a high proportion of six-membered nitrogen configuration is obtained by utilizing the co-thermal decomposition reaction of calcium species and humic acid during high-temperature pyrolysis and acid treatment to remove calcium species. Although the oxygen and nitrogen volatiles in humic acid will reduce the nitrogen content, they can effectively regulate the coordination environment of the nitrogen element to form a rich six-membered pyridine nitrogen configuration. The synergistic effect of the pyridine nitrogen conjugated π system and the lone electron pair of the nitrogen atom effectively increases the interaction force between the dye molecule and the adsorbent surface, significantly increasing the adsorption amount. The position occupied by the calcium species is fully released after acid treatment, thereby showing a rich mesoporous scale. This characteristic accelerates the kinetic diffusion during the adsorption of dye molecules.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1). The present invention uses calcium citrate as a self-template and self-activator to avoid the use of corrosive chemical reagents. The carbon film formed by low-temperature hydrothermal reaction of sugars can inhibit the loss of calcium species and form carboxyl functional groups on the surface to enhance hydrophilicity. The raw materials of the entire reaction process are cheap and easy to obtain, and the preparation process is green, environmentally friendly and economical.

[0020] 2) The present invention makes full use of waste humic acid to obtain a high-porosity mesoporous carbon material rich in hexapyridine nitrogen configuration under the premise of maintaining a high concentration of nitrogen doping (12.1 at.%), with a specific surface area of ​​948 m 2 / g, this structural feature makes it exhibit high adsorption capacity and rapid diffusion characteristics for methylene blue dye.

[0021] 3). The equilibrium time for adsorption treatment of high-concentration methylene blue wastewater is only 60 minutes, and the maximum adsorption capacity at room temperature is 680 mg / g. Due to the synergistic effect of the pyridine nitrogen conjugated π system and the lone electron pair of the nitrogen atom, the methylene blue removal rate after 10 cycles remains above 80%, with good stability and great application prospects in the field of water treatment. Description of the drawings:

[0022] Figure 1 This is a pore structure diagram of the high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration described in Example 1.

[0023] Figure 2 This is a scanning electron microscope image of the high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration described in Example 1.

[0024] Figure 3This is the nitrogen coordination configuration of the high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration as described in Example 1.

[0025] Figure 4 This is the methylene blue kinetic curve of the high mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration described in Example 1.

[0026] Figure 5 The methylene blue adsorption isotherms of the materials described in Example 1 and Comparative Example 1 are shown.

[0027] Figure 6 This is a pore structure diagram of the nitrogen-doped mesoporous carbon material described in Comparative Example 1.

[0028] Figure 7 This is a comparison of the nitrogen coordination configuration of the nitrogen-doped mesoporous carbon material described in Example 1.

[0029] Figure 8 This is the methylene blue kinetic curve of the nitrogen-doped mesoporous carbon material described in Comparative Example 1. Specific implementation method:

[0030] The present invention is described below by specific embodiments. It should be noted that the embodiments of the present invention are only for further explanation of the content of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art can implement the invention in various combinations defined and covered by the claims.

[0031] Example 1

[0032] A method for preparing a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration comprises the following steps:

[0033] (1) Preparation of carbon membrane solids, specifically: weighing 6 g of calcium citrate in 60 mL of an aqueous solution containing 6 g of glucose, stirring for 10 min, placing in a polytetrafluoroethylene-lined reactor and hydrothermally reacting at 170° C. for 12 h, cooling to room temperature after the reaction, centrifuging, filtering, and freeze-drying to obtain a carbon membrane solid;

[0034] (2) Preparation of carbide, specifically: weighing 1 g of carbon film solid and 2 g of melamine, mixing and grinding, pyrolyzing at 700 °C in a nitrogen atmosphere for 2 h at a heating rate of 4 °C / min, and cooling to room temperature to obtain carbide after the reaction is completed;

[0035] (3) Weigh 0.1 g of carbide and soak it in 20 mL of an aqueous solution containing 10% humic acid for 10 h. After the aqueous solution becomes clear, centrifuge and filter it, dry it, and then heat react at 950 ° C for 2 h at a heating rate of 4 ° C / min. After the reaction is completed and cooled to room temperature, it is continuously acid-washed, washed with water, and dried to obtain a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration.

[0036] Figure 1 The pore size structure diagram of the sample prepared in Example 1. From the nitrogen adsorption isotherm in the figure, it can be seen that at P / P 0 >0.45 contains an obvious hysteresis loop. The pore size distribution curve shows that the main peaks of the pore size are located at 18.6 and 40 nm. The calculated specific surface area is 948 m 2 / g, and the mesoporosity reaches 76%.

[0037] Figure 2 This is a scanning electron microscope image of the material prepared in Example 1. From the image, a spherical structure with a diameter of about 5 μm can be seen, indicating that glucose successfully condensed into carbon microspheres during the low-temperature hydrothermal reaction and coated on the surface of calcium citrate, and the structure remained stable during the high-temperature pyrolysis-self-activation process.

[0038] Figure 3 This is the nitrogen coordination configuration diagram of the material prepared in Example 1. The nitrogen doping amount reaches 12.1 at.%. The fitting results show that the hexapyridine nitrogen configuration at 398.1 eV accounts for 54.7% of the total nitrogen. This structural feature may enable it to exhibit excellent dye adsorption performance.

[0039] The high mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen obtained in this embodiment is used to remove methylene blue dye pollutants in water, with an initial concentration of 200-800 mg / L and a test temperature of 25°C. The specific method is:

[0040] 0.02 g of the above-mentioned high-proportion hexavalent nitrogen-containing high-mesoporous carbon adsorbent was weighed and placed in a 50 mL glass bottle, and then 20 mL of an aqueous solution of methylene blue with an initial concentration of 200 mg / L and 400 mg / L was added respectively. Samples were taken at different time points, centrifuged to obtain the supernatant, and the equilibrium adsorption amount was determined by measuring the absorbance change at 667 nm using an ultraviolet spectrophotometer. The specific results are shown in the figure. Figure 4 .Depend on Figure 4 The kinetic curve shows that the adsorption rate of methylene blue is fast, approaching dynamic equilibrium in 30 minutes, and completely achieving adsorption equilibrium when the contact time reaches 45 minutes, with a removal rate of 100%. The material adsorbed with dye was treated with 0.1M NaOH as the eluent, and then washed with deionized water, dried, and the dye adsorption was measured again. The operation was repeated in this way. The results showed that the removal rate was still 85% after 10 cycles of adsorption.

[0041] Weigh 0.02 g of the high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen prepared above into a 50 mL glass bottle, add 20 mL of methylene blue aqueous solution with different initial concentrations (200-800 mg / L), stir thoroughly at 25 ° C for 6 h to ensure full adsorption, take samples and centrifuge to obtain the supernatant, use an ultraviolet spectrophotometer at a wavelength of 667 nm to measure the absorbance changes at different initial concentrations to obtain the adsorption isotherms at different concentrations. The specific results are as follows: Figure 5 As shown. Figure 5 It can be seen from the isotherm that the adsorption process of methylene blue conforms to the Lagmuir model, and the maximum adsorption amount obtained by fitting at room temperature reaches 680 mg / g.

[0042] Example 2

[0043] The difference between Example 2 and Example 1 is that the glucose concentration is different when preparing the carbon membrane solid in step (1). Specifically, 6 g of calcium citrate is weighed and stirred in 60 mL of an aqueous solution containing 3 g of glucose for 10 min, then placed in a polytetrafluoroethylene-lined reactor and subjected to a hydrothermal reaction at 170 ° C for 12 h. After the reaction is completed and cooled to room temperature, centrifugation, filtration, and freeze-drying are performed to obtain the carbon membrane solid. The subsequent steps (2) and (3) are the same as those in Example 1. The specific surface area of ​​the prepared high-proportion hexavalent nitrogen configuration high-mesoporous carbon adsorbent is 926 m 2 / g, the mesoporosity is 71%, and the nitrogen doping concentration is 10.4at.%.

[0044] Example 3

[0045] The difference between Example 3 and Example 1 is that the pyrolysis reaction temperature is different when preparing carbide in step (2). Specifically, 1g of carbon film solid is weighed and mixed with 2g of melamine, and then pyrolyzed for 2h in a nitrogen atmosphere at 600℃, with a heating rate of 4℃ / min. After the reaction is completed and cooled to room temperature, carbide is obtained. The remaining steps (1) and (3) are the same as those in Example 1. The specific surface area of ​​the prepared high-proportion hexavalent nitrogen configuration high-mesoporous carbon adsorbent is 756m 2 / g, the mesoporosity is 65%, and the nitrogen doping concentration is as high as 14.2%.

[0046] Example 4

[0047] The difference between Example 4 and Example 1 is that: in step (3), the mass ratio concentration of humic acid is different when the carbide is immersed in the humic acid solution. Specifically, 0.1g of carbide is weighed and immersed in 20mL of an aqueous solution containing 20% ​​humic acid for 10 hours. When the color of the aqueous solution no longer changes, centrifugal filtration and drying are performed, and then a thermal reaction is performed at 950°C for 2 hours, with a heating rate of 4°C / min. After the reaction is completed and cooled to room temperature, it is continuously acid-washed, washed with water and dried to obtain a high-proportion hexavalent nitrogen configuration high-mesoporous carbon adsorbent. The remaining steps (1) and (2) are the same as those in Example 1. The specific surface area of ​​the prepared high-proportion hexavalent nitrogen configuration high-mesoporous carbon adsorbent is 1034m 2 / g, the mesoporosity is 70%, and the nitrogen doping concentration is 12.8%.

[0048] The high mesoporous carbon adsorbent with a high proportion of hexapyridine nitrogen configuration prepared in Examples 2-4 also showed a faster diffusion rate and adsorption amount during the adsorption of methylene blue. Compared with Example 1, the adsorption amount was slightly lower and the equilibrium time was slightly longer, but the maximum adsorption amount was also above 600 mg / g, and the adsorption equilibrium was completely reached within 50 minutes. This is due to the strong conjugation between the hexapyridine nitrogen configuration and the dye molecules. The high mesoporosity provides a guarantee for the rapid diffusion of the dye molecules. The adsorption amount after 10 cycles is basically above 80%.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that no humic acid solution is used for modification during the reaction of step (3). Specifically, 0.1 g of carbide is weighed and soaked in 20 mL of deionized water for 10 h, and then subjected to a thermal reaction at 950°C for 2 h after centrifugation, filtration, and drying, with a heating rate of 4°C / min. After the reaction is completed and cooled to room temperature, it is continuously acid-washed, washed with water, and dried to obtain a high mesoporous nitrogen-doped carbon adsorbent. The remaining steps (1) and (2) are the same as those in Example 1.

[0051] The material prepared by the above method was characterized and its structural characteristics are as follows:

[0052] Figure 6 The pore size structure diagram of the sample prepared in Comparative Example 1. From the nitrogen adsorption isotherm in the figure, it can be seen that the P / P 0 >0.45 contains an obvious hysteresis loop. The pore size distribution curve shows that the main peak of the pore size is located at 40nm, and there is a wide distribution in the range of 2.7-18.6nm. The calculated specific surface area is 1195m 2 / g, and the mesoporosity reaches 65%.

[0053] Figure 7It is the nitrogen coordination configuration diagram of the sample prepared in Comparative Example 1. The nitrogen doping amount is as high as 18.6at.%, and the fitting results show that the material contains both five-membered pyrrolic nitrogen (399.9eV) and six-membered pyridinic nitrogen (398.3eV), accounting for 64.6% and 35.4% of the total nitrogen, respectively, further illustrating that humic acid can effectively regulate the coordination configuration of nitrogen.

[0054] The high mesoporous nitrogen-doped carbon adsorbent prepared in Comparative Example 1 was used to adsorb and treat methylene blue dye pollutants in water, and the test temperature was 25°C. The specific method was as follows:

[0055] Weigh 0.02g of the material prepared by the above method into a 50mL glass bottle, then add 20mL of an aqueous solution of methylene blue with an initial concentration of 200mg / L and 400mg / L. Sampling was performed at different time points, and the supernatant was obtained by centrifugation. The equilibrium adsorption capacity was determined by measuring the absorbance change at 667nm using an ultraviolet spectrophotometer. The specific results are shown in the figure. Figure 5 .Depend on Figure 5 From the kinetic curve, it can be seen that the adsorption equilibrium time of methylene blue is significantly prolonged, and the adsorption equilibrium is basically reached in about 60 minutes.

[0056] Similarly, methylene blue aqueous solutions with different initial concentrations (200-800 mg / L) were stirred at 25°C for 6 h to ensure sufficient adsorption. After sampling, the supernatant was centrifuged and the absorbance change was measured at a wavelength of 667 nm using an ultraviolet spectrophotometer to obtain the adsorption isotherms at different concentrations. The specific results are as follows: Figure 5 As shown. Figure 6 It can be seen from the isotherm that the adsorption process of methylene blue conforms to the Lagmuir model, and the maximum adsorption amount obtained by fitting at room temperature reaches 568 mg / g.

[0057] Obviously, compared with Example 1, the material described in Comparative Example 1 has a relatively high porosity and nitrogen doping amount, but the adsorption equilibrium time under the same conditions is significantly prolonged and shows a lower adsorption amount. The comparison results fully confirm that the porosity and nitrogen doping amount of the adsorbent do not play a decisive role in the dye adsorption amount, the mesopores of a specific size have a significant promoting effect on the diffusion of dye molecules, and the six-membered nitrogen configuration can increase the adsorption amount through a strong conjugation effect with the dye molecules.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration, characterized in that it comprises the following steps: (1) Preparation of carbon membrane solids, specifically: subjecting calcium citrate to low-temperature hydrothermal reaction in a sugar solution, and after the reaction is completed, centrifuging and filtering the carbon membrane solids, and freeze-drying them; (2) Preparation of carbides, specifically: grinding the carbon film solid obtained in step (1) with nitrogen species and then subjecting it to a heat treatment reaction under a nitrogen atmosphere; (3) The carbide obtained in step (2) is soaked in a humic acid solution, filtered, dried, and then subjected to a thermal reaction at 950° C. for 2 h. After continuous acid washing, water washing, and drying, a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration is obtained.

2. The preparation of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration according to claim 1 is characterized in that: the sugar in step (1) is at least one of glucose, fructose, sucrose and xylose; the concentration of the sugar solution is 5 to 20 wt.%, and the mass ratio of sugar to calcium citrate is 1:1 to 5:

1.

3. The preparation of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration according to claim 1, characterized in that: the hydrothermal reaction temperature in step (1) is 140-170° C.; and the hydrothermal reaction time is 10-24 h.

4. The preparation of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration according to claim 1 is characterized in that: the nitrogen species described in step (2) is at least one of hexamethylenetetramine, urea, bipyridine, melamine, dicyandiamide, ethylenediamine and thiourea; and the mass ratio of the carbon membrane solid to the nitrogen species is 1:0.5 to 1:4.

0.

5. The preparation of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen configuration according to claim 1, characterized in that: the heat treatment temperature in step (2) is 500-750°C, and the reaction time is 0.5-2h.

6. The preparation of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen according to claim 1, characterized in that: the mass ratio concentration of humic acid in step (3) is 5-20wt.%, and the mass ratio of carbide to humic acid is 25:1-100:

1.

7. Application of a high-mesoporous carbon adsorbent with a high proportion of hexavalent nitrogen obtained by the preparation method according to any one of claims 1 to 4 in the adsorption treatment of methylene blue dye wastewater, characterized in that high-concentration dye can be quickly purified by stirring at room temperature of 25°C, and the stirring time is 30 to 360 minutes.

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