High-nitrogen carbon quantum dot composite biochar as well as preparation method and application thereof

Abstract

The application discloses high-nitrogen carbon quantum dot composite biochar as well as a preparation method and application thereof, aims to provide high-nitrogen carbon quantum dot composite agaric biochar obtained by high-temperature co-carbonization of agaric as a carbon source and high-nitrogen carbon quantum dots as a nitrogen source, the preparation method is simple and low in cost, the high-nitrogen carbon quantum dot composite agaric biochar can realize degradation of naphthyl in water by dithionate with a small amount, so as to solve the problems of low catalytic efficiency and large dosage in current transition metal catalysts, the high-nitrogen carbon quantum dot composite agaric biochar is simple in preparation process, the synthesis of carbon quantum dots is simple, agaric, a precursor raw material of the biochar, is rich in source and cheap and easy to obtain, the prepared product is high in catalytic capacity and high in degradation rate, and can achieve the purpose of efficient pollution treatment.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation technology, specifically relating to a carbon quantum dot and a biochar catalyst, specifically relating to a high-nitrogen carbon quantum dot composite black fungus biochar, and also relating to the preparation method and application of the catalyst. Background Technology

[0002] Naproxen, a commonly used nonsteroidal anti-inflammatory drug (NSAID) such as acetaminophen, aspirin, and ibuprofen, is frequently detected in natural and engineered aquatic environments (such as oceans, drinking water, rivers, tap water, and wastewater) and even sediments. Long-term intake of trace levels of naproxen can cause significant harm to the human body, such as pulmonary toxicity, stroke, and heart disease. Therefore, it is necessary to remove naproxen from water bodies. Currently, mature technologies for removing naproxen from water include adsorption, photo-Fenton oxidation, and advanced oxidation processes (AOPs) based on sulfate radical technology. AOPs technology has attracted widespread interest from researchers.

[0003] Advanced persulfate oxidation processes (PS-AOPs) can absorb energy to gain an electron, generating sulfate radicals, which further generate hydroxyl radicals in water. These free radicals utilize their electron-donating ability to attack organic pollutants, breaking them down into smaller molecules. PDS activation methods include transition metal ion catalytic activation, radiation, thermal activation, carbon material activation, and other combined activation methods.

[0004] Biochar, as a stable and carbon-rich material, boasts advantages such as simple and abundant sourcing, large specific surface area, low cost, simple synthesis process, and environmental friendliness. Furthermore, the carbon matrix surface of biochar, with its numerous delocalized π electrons and electron-rich functional groups, can serve as an electron donor and regulator in the persulfate activation process. Nitrogen, in particular, possesses electronic regulation activity over carbon topology; therefore, it is typically doped into the carbon matrix to enhance its catalytic activity.

[0005] CQDs are quasi-spherical carbon nanoparticles composed of a spherical carbon core and abundant functional groups distributed on its surface. They have attracted considerable attention due to their abundant raw materials (all biochar can be used as a carbon source), ease of preparation, non-toxicity, high biocompatibility, and excellent electron transport properties. By synthesizing CQDs rich in nitrogen-containing functional groups and combining them with biochar, the overall specific surface area, functional group diversity, and number of microscopic defects of biochar can be effectively increased, thereby promoting the catalytic activation of PS by biochar materials to degrade naproxen pollution in the aquatic environment. Summary of the Invention

[0006] The first objective of this invention is to provide a method for obtaining high-nitrogen carbon quantum dot composite wood ear biochar by using wood ear fungus as a carbon source and high-nitrogen carbon quantum dots as a nitrogen source through high-temperature co-heating carbonization. This preparation method is simple to operate and low in cost.

[0007] The second objective of this invention is to provide a high-nitrogen carbon quantum dot composite black fungus biochar that can achieve the degradation of naproxen in water by persulfate with a very small amount, thereby solving the problems of low catalytic efficiency and large dosage in current transition metal catalysts.

[0008] The final objective of this invention is to provide the application of the above-mentioned biochar in the degradation of naproxen in water by activated PDS.

[0009] Therefore, the first technical solution provided by this invention is as follows:

[0010] A method for preparing high-nitrogen carbon quantum dot composite black fungus biochar includes the following steps:

[0011] 1) Grind and mix high-nitrogen carbon quantum dots and wood ear biochar at a mass ratio of 1:(4-8) thoroughly, and grind the mixed solid into a uniform fine powder as much as possible;

[0012] 2) Transfer the mixed solids from 1) to a ceramic boat for a tube furnace, then transfer it to the tube furnace and react at a constant temperature of 700-900℃ for 1-3 hours. After cooling, remove the solids to obtain crude biochar.

[0013] 3) Wash the crude biochar obtained in step 2) thoroughly with 2-5M hydrochloric acid for 6-12 hours;

[0014] 4) Wash the acid-washed biochar from step 3) with excess deionized water until neutral and grind it into powder. Store it in a refrigerator at 4°C for later use.

[0015] Step 4) The water washing process can be completed during repeated filtration. The product is ground through a 100-200 mesh sieve to make the material particles more uniform and more conducive to subsequent reactions.

[0016] Furthermore, in the above-mentioned method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, the high-nitrogen carbon quantum dots are prepared by the following method:

[0017] 1) Weigh out urea and ammonium citrate according to a molar ratio of (16-18):1, add deionized water, and mix thoroughly to dissolve;

[0018] 2) Transfer the mixed product from 1) to a reaction vessel and perform hydrothermal treatment at 120-200℃ for 2-6 hours. After cooling, remove the product and perform centrifugation and filtration in sequence. Collect the filtrate and freeze-dry it to obtain high-nitrogen carbon quantum dots.

[0019] Furthermore, in the above-mentioned method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, deionized water is added during dissolution in step 1) at a ratio of 3 to 4 times the total mass of the mixture.

[0020] Furthermore, in the above-mentioned method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, in step 2), after cooling to room temperature, the centrifugation speed is 10000 rpm / min and the centrifugation time is 30 min; the filter membrane used for vacuum filtration is 0.22 μm; and the filtrate is freeze-dried for 48 h.

[0021] Furthermore, in the above-mentioned method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, in step 2), the heating rate of the tube furnace is 5℃ / min, the protective gas is nitrogen, and the furnace is continuously ventilated to ensure that it is filled with nitrogen.

[0022] Furthermore, in the above-mentioned method for preparing a high-nitrogen carbon quantum dot composite black fungus biochar, the black fungus biochar is prepared through the following steps:

[0023] 1) Cut the black fungus into small pieces. Wash the cut fungus repeatedly with deionized water and anhydrous ethanol to remove surface impurities, and then dry it for later use.

[0024] 2) Transfer the black fungus from step 1) to a ceramic boat for a tube furnace, then transfer it to the tube furnace and react at a constant temperature of 200-400℃ for 1-3 hours. After cooling, remove the fungus and wash it to obtain pre-carbonized black fungus biochar.

[0025] 3) According to the mass ratio of 1:(4-8), 2) weigh the pre-carbonized wood ear biochar and KOH, add water and mix evenly. Continue to stir vigorously at 70-90℃ until it becomes a gel and dry it for later use.

[0026] Furthermore, in the above-mentioned method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, in step 2), the heating rate of the tubular furnace is 10℃ / min, the protective gas is nitrogen, and the furnace is continuously ventilated to ensure that it is filled with nitrogen.

[0027] The second technical solution provided by the present invention is a high-nitrogen carbon quantum dot composite black fungus biochar, which is prepared by the method described in the first technical solution.

[0028] The third technical solution provided by this invention is the application of the above-mentioned high-nitrogen carbon quantum dot composite black fungus biochar in catalyzing the degradation of naproxen in water by persulfate.

[0029] The fourth technical solution provided by this invention is a method for degrading naproxen in water with persulfate. The high-nitrogen carbon quantum dot composite black fungus biochar described in the third technical solution is used as a catalyst. Under dark conditions, the high-nitrogen carbon quantum dot composite black fungus biochar and persulfate are added to the water to be treated containing naproxen and thoroughly mixed and stirred until the organic pollutants are completely degraded.

[0030] The concentration of the catalyst is 0.05–0.3 g / L, and the concentration of persulfate is 5 mM.

[0031] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0032] 1. The high-nitrogen carbon quantum composite black fungus biochar provided by the present invention uses black fungus as the carbon source of biochar and high-nitrogen carbon quantum dots as the nitrogen source. It is obtained by high-temperature co-heating carbonization. The preparation method is simple to operate and the materials are easy to obtain. It has a high cost advantage compared with metal catalysts.

[0033] 2. The high-nitrogen carbon quantum dots provided by this invention can create more microscopic defects by leaving various vacancies due to the overflow of heteroatoms during the high-temperature synthesis of biochar, which is beneficial for the activation of PDS in the material. 1 O2, SO4 ·- The ·OH radical oxidizes and degrades organic pollutants in water. At the same time, the surface of biochar materials can also adsorb naproxen pollutants, promoting the in-situ degradation of pollutants on the biochar surface, thereby improving the overall degradation efficiency.

[0034] 3. The high-nitrogen carbon quantum dot composite black fungus biochar provided by this invention successfully possesses a large number of microporous structures, which accelerates the contact between the material and PDS and naproxen, thereby improving the pollutant removal rate. The high-nitrogen carbon quantum dot composite black fungus biochar of this invention can provide a theoretical reference for the development of efficient and promising advanced oxidation technologies, and has good practical application prospects. Attached Figure Description

[0035] Figure 1 XPS image of the high-nitrogen carbon quantum dot composite black fungus biochar prepared in Example 1;

[0036] Figure 2 Raman spectroscopy images of the high-nitrogen carbon quantum dot composite black fungus biochar prepared in Example 1 before and after the reaction;

[0037] Figure 3 SEM image of the high-nitrogen carbon quantum dot composite black fungus biochar prepared in Example 1;

[0038] Figure 4 The degradation effects of naproxen in different systems are shown in the diagram.

[0039] Figure 5 The graph shows the degradation effect of naproxen by PMS under different concentrations of the high-nitrogen carbon quantum dot composite black fungus biochar prepared in Example 1. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and specific examples. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, and the reagents used in these embodiments are all commercially available products but do not constitute a limitation of the present invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Example 1

[0042] This invention provides a method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, the preparation steps of which are as follows:

[0043] (1) Synthesis of high-nitrogen carbon quantum dots

[0044] Accurately weigh 9.729g of urea and 2.178g of citric acid and dissolve them in 45mL of deionized water. Then transfer the solution to a polytetrafluoroethylene reactor and perform a hydrothermal reaction at 180℃ for 3 hours in an oven. After the reaction is complete, cool to room temperature, centrifuge at 10000rpm / min for 30min, collect the supernatant and filter it through a 0.22m filter membrane. Freeze (-50℃) the filtered liquid for 48 hours to dry it. The resulting blue-green powder is N-CODs. Seal and store it in a refrigerator at 4℃ for later use.

[0045] (2) Pretreatment of crude biochar from black fungus

[0046] Dried black fungus was purchased from a farmers' market, chopped, and repeatedly rinsed with deionized water and ethanol before drying. The dried sample was placed in a tube furnace and heated to 300℃ at 10℃ / min and held at that temperature for 2 hours. Nitrogen gas was introduced to ensure the tube was filled with nitrogen. After cooling, the sample was removed and ground into a fine powder. The soluble impurities of the material were repeatedly rinsed with deionized water and ethanol. Finally, the solid material was filtered out and dried (60-80℃) to obtain crude black fungus biochar.

[0047] (3) Activation treatment of crude biochar from black fungus

[0048] After pre-carbonization, the coarse biochar material of wood ear fungus is mixed with KOH at a mass ratio of 1:6 and placed in a container. Three times the solid mass of deionized water is added, and the mixture is stirred vigorously at 80°C until a gel-like viscous liquid is formed. Then, it is placed in an oven and dried at 70°C for later use.

[0049] (4) Synthesis of high-nitrogen carbon quantum dot composite black fungus biochar

[0050] Weigh the high-nitrogen carbon quantum dots prepared in step (1) and the activated wood ear biochar in step (3) at a mass ratio of 1:6. Grind and mix them evenly, transfer them to a special ceramic boat for tube furnace, and then transfer them to tube furnace. React at 800℃ for 2 hours. After cooling, take them out and wash them thoroughly with 3M hydrochloric acid for 12 hours. Then wash them repeatedly with deionized water until neutral and filter them. Dry them and finally grind the biochar until it can pass through a 200-mesh sieve. The product obtained is the high-nitrogen carbon quantum dot composite wood ear biochar.

[0051] Example 2

[0052] This invention provides a method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, the preparation steps of which are as follows:

[0053] (1) Synthesis of high-nitrogen carbon quantum dots

[0054] Accurately weigh 9.729g of urea and 2.178g of citric acid and dissolve them in 45mL of deionized water. Then transfer the solution to a polytetrafluoroethylene reactor and perform a hydrothermal reaction at 180℃ for 4 hours in an oven. After the reaction is complete, cool to room temperature, centrifuge at 10000rpm / min for 30min, collect the supernatant and filter it through a 0.22m filter membrane. Freeze (-50℃) the filtered liquid for 72 hours to dry it. The resulting blue-green powder is N-CODs. Seal and store it in a refrigerator at 4℃ for later use.

[0055] (2) Pretreatment of crude biochar from black fungus

[0056] Dried black fungus was purchased from a farmers' market, chopped, and repeatedly rinsed with deionized water and ethanol before drying. The dried sample was placed in a tube furnace and heated to 300℃ at 10℃ / min and held at that temperature for 2 hours. Nitrogen gas was introduced to ensure the tube was filled with nitrogen. After cooling, the sample was removed and ground into a fine powder. The soluble impurities of the material were repeatedly rinsed with deionized water and ethanol. Finally, the solid material was filtered out and dried (60-80℃) to obtain crude black fungus biochar.

[0057] (3) Activation treatment of crude biochar from black fungus

[0058] After pre-carbonization, the coarse biochar material of wood ear fungus is mixed with KOH at a mass ratio of 1:6 and placed in a container. Three times the solid mass of deionized water is added, and the mixture is stirred vigorously at 90°C until a gel-like viscous liquid is formed. Then, it is placed in an oven and dried at 70°C for later use.

[0059] (4) Synthesis of high-nitrogen carbon quantum dot composite black fungus biochar

[0060] Weigh the high-nitrogen carbon quantum dots prepared in step (1) and the activated wood ear biochar in step (3) at a mass ratio of 1:4. Grind and mix them evenly, transfer them to a special ceramic boat for a tube furnace, and then transfer them to a tube furnace. React at a constant temperature of 800℃ for 1 hour. After cooling, take them out and wash them thoroughly with 3M hydrochloric acid for 12 hours. Then wash them repeatedly with deionized water until neutral and filter them. Dry them and finally grind the biochar until it can pass through a 200-mesh sieve. The product obtained is the high-nitrogen carbon quantum dot composite wood ear biochar.

[0061] Example 3

[0062] This invention provides a method for preparing high-nitrogen carbon quantum dot composite black fungus biochar, the preparation steps of which are as follows:

[0063] (1) Synthesis of high-nitrogen carbon quantum dots

[0064] Accurately weigh 9.729g of urea and 2.178g of citric acid and dissolve them in 45mL of deionized water. Then transfer the solution to a polytetrafluoroethylene reactor and perform a hydrothermal reaction at 190℃ for 3 hours in an oven. After the reaction is complete, cool to room temperature, centrifuge at 9000rpm / min for 30min, collect the supernatant and filter it through a 0.22m filter membrane. Freeze-dry the filtered liquid for 48 hours. The resulting blue-green powder is N-CODs, which should be sealed and stored in a refrigerator at 4℃ for later use.

[0065] (2) Pretreatment of crude biochar from black fungus

[0066] Dried black fungus was purchased from a farmers' market, chopped, and repeatedly rinsed with deionized water and ethanol before drying. The dried sample was placed in a tube furnace and heated to 300°C at a rate of 10°C / min and held at that temperature for 2 hours. Nitrogen gas was introduced to ensure the tube was filled with nitrogen. After cooling, the sample was removed and ground into a fine powder. The soluble impurities in the material were repeatedly rinsed with deionized water and ethanol. Finally, the solid material was filtered out and dried to obtain coarse black fungus biochar.

[0067] (3) Activation treatment of crude biochar from black fungus

[0068] After pre-carbonization, the crude biochar material of wood ear fungus is mixed with KOH at a mass ratio of 1:6 and placed in a container. Five times the solid mass of deionized water is added, and the mixture is stirred vigorously at 85°C until a gel-like viscous liquid is formed. Then, it is placed in an oven and dried at 0°C for later use.

[0069] (4) Synthesis of high-nitrogen carbon quantum dot composite black fungus biochar

[0070] Weigh the high-nitrogen carbon quantum dots prepared in step (1) and the activated wood ear biochar in step (3) at a mass ratio of 1:8. Grind and mix them evenly, transfer them to a special ceramic boat for a tube furnace, and then transfer them to a tube furnace. React at a constant temperature of 800℃ for 2.5h. After cooling, take them out, wash them thoroughly with 1M hydrochloric acid for 12h, wash them repeatedly with deionized water until neutral, filter them, dry them, and finally grind the biochar until it can pass through a 100-mesh sieve. The product obtained is the high-nitrogen carbon quantum dot composite wood ear biochar.

[0071] Comparative Example 1

[0072] This case study provides a method for preparing carbonized high-nitrogen carbon quantum dots, the preparation steps of which are as follows:

[0073] (1) Synthesis of high-nitrogen carbon quantum dots

[0074] Accurately weigh 9.729g of urea and 2.178g of citric acid and dissolve them in 45mL of deionized water. Then transfer the solution to a polytetrafluoroethylene reactor and perform a hydrothermal reaction at 180℃ for 3 hours in an oven. After the reaction is complete, cool to room temperature, centrifuge at 10000rpm / min for 30min, collect the supernatant and filter it through a 0.22m filter membrane. Freeze-dry the filtered liquid for 48 hours. The resulting blue-green powder is N-CODs, which should be sealed and stored in a refrigerator at 4℃ for later use.

[0075] (2) Preparation of carbonized high-nitrogen carbon quantum dots

[0076] The high-nitrogen carbon quantum dots synthesized in step (1) were ground evenly and transferred to a special ceramic boat for tube furnace. Then, they were transferred to a tube furnace and reacted at a constant temperature of 800℃ for 2 hours. After cooling, they were taken out and washed thoroughly with 3M hydrochloric acid for 12 hours. They were then repeatedly washed with deionized water until neutral and filtered. After drying, the biochar was ground until it could pass through a 200-mesh sieve. The resulting product is carbonized high-nitrogen carbon quantum dots (C-NCQDs).

[0077] Comparative Example 2

[0078] This case provides a method for preparing wood ear mushroom biochar, the preparation steps of which are as follows:

[0079] (1) Pretreatment of crude biochar from black fungus

[0080] Dried black fungus was purchased from a farmers' market, chopped, and repeatedly rinsed with deionized water and ethanol before drying. The dried sample was placed in a tube furnace and heated to 300°C at a rate of 10°C / min and held at that temperature for 2 hours. Nitrogen gas was introduced to ensure the tube was filled with nitrogen. After cooling, the sample was removed and ground into a fine powder. The soluble impurities in the material were repeatedly rinsed with deionized water and ethanol. Finally, the solid material was filtered out and dried to obtain coarse black fungus biochar.

[0081] (2) Activation treatment of crude biochar from black fungus

[0082] After pre-carbonization, the coarse biochar material of wood ear fungus is mixed with KOH at a mass ratio of 1:6 and placed in a container. Three times the solid mass of deionized water is added, and the mixture is stirred vigorously at 80°C until a gel-like viscous liquid is formed. Then, it is placed in an oven and dried at 70°C for later use.

[0083] (3) Synthesis of high-nitrogen carbon quantum dot composite black fungus biochar

[0084] The coarse biochar of black fungus prepared in step (2) was ground evenly and transferred to a special ceramic boat for tube furnace. Then it was transferred to tube furnace and reacted at a constant temperature of 800℃ for 2 hours. After cooling, it was taken out and washed thoroughly with 3M hydrochloric acid for 12 hours. Then it was repeatedly washed with deionized water until neutral and filtered and dried. The resulting product is black fungus biochar (a-BC-800).

[0085] The following are specific application examples of the carbon quantum dot composite transition metal catalysts provided in this application:

[0086] Application Example 1: High-nitrogen carbon quantum dot composite black fungus biochar catalyzes PDS degradation of naproxen.

[0087] Prepare a naproxen (NPX) aqueous solution (50 mg / L, pH = 9) and take 18 portions (50 mL) into 100 mL glass beakers using a magnetic stirrer (4 cm conical stir bar, 500 rpm). Then, add the prepared high-nitrogen carbon quantum dot composite biochar (Na-BC-800) from Example 1, carbonized high-nitrogen carbon quantum dots (C-NCQDs) from Comparative Example 1, and wood ear biochar (a-BC-800) from Comparative Example 3 to the glass beakers, so that the concentration of each material is 0.1 g / L. At the same time, add PDS to make the concentration 5 mM. A control group without PDS is used. Each group has 3 replicates. Stir thoroughly for 30 min under dark conditions. The degradation effect is as follows: Figure 2 As shown, the removal rate is almost 0% under PDS only, while the removal rate reaches 65% under composite biochar only. In the composite biochar / PDS system, the degradation rate of naproxen reaches more than 96% in 10 minutes, which is shorter than the time to reach equilibrium and the removal rate is also higher under the biochar / PDS system. This indicates that the composite biochar has a good effect on catalyzing the degradation of naproxen pollutants by PDS.

[0088] Application Example 2: High-nitrogen carbon quantum dot composite black fungus biochar catalyzes PDS degradation of naproxen.

[0089] Prepare 12 portions (50 mL each) of naproxen (NPX) aqueous solution (50 mg / L, pH = 9) and place them in 100 mL glass beakers with a magnetic stirrer (using a 4 cm conical stir bar at 500 rpm). Then, add the high-nitrogen carbon quantum dot composite biochar (Na-BC-800) prepared in Example 1 to the glass beakers, so that the concentrations of the composite biochar are 0.02 g / L, 0.04 g / L, 0.06 g / L, and 0.1 g / L, respectively. At the same time, add PDS to make the concentration 5 mM. Each group is repeated in 3 replicates. Stir thoroughly for 30 min in the dark. The degradation effect is as follows. Figure 3 As shown, the removal rate of naproxen pollutants gradually increases with the continuous increase of the concentration of composite biochar. It is worth noting that even when the biochar concentration is 0.02 g / L, the removal rate reaches nearly 80% or more, and when the biochar concentration reaches 0.04 g / L, the removal rate has reached more than 90%, achieving high efficiency with minimal amount.

[0090] The above experiments and application examples demonstrate that the high-nitrogen carbon quantum composite black fungus biochar of this invention is the first to use black fungus as the carbon source and high-nitrogen carbon quantum dots as the nitrogen source. It is obtained through high-temperature co-heating carbonization, which increases the specific surface area of ​​the material, helps accelerate electron transfer within the material, and forms a novel advanced oxidation technology system with PDS for efficient degradation of naproxen pollutants. This invention uses naproxen (NPX) as a model pollutant for catalytic degradation experiments. The results confirm that the high-nitrogen carbon quantum composite black fungus biochar can efficiently and rapidly degrade naproxen pollutants in wastewater. Furthermore, the effect of catalyst dosage was further investigated. Compared to traditional advanced oxidation technologies, this invention can improve the degradation efficiency of organic pollutants and has excellent practical application prospects.

Claims

1. Application of high-nitrogen carbon quantum dot composite agaric biochar in catalyzing perdisulfate to degrade naproxen in water, characterized in that, The high-nitrogen carbon quantum dot composite agaric biochar is prepared by the following steps in sequence: 1) The high-nitrogen carbon quantum dots and the agaric biochar are mixed in a mass ratio of 1: (4-8) and then fully ground; 2) The mixed solid in 1) is transferred into a tube furnace porcelain case and then into a tube furnace, and reacted at 700-900 ℃ for 1-3 h, and then taken out after cooling to obtain a crude biochar; 3) The crude biochar obtained in 2) is washed with 2-5 M hydrochloric acid for 6-12 h; 4) The biochar after acid washing in 3) is washed to neutral with excess deionized water and ground into powder, and placed in a refrigerator at 4 ℃ for standby.

2. The high-nitrogen carbon quantum dot composite agaric biochar for catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 1, characterized in that, The high-nitrogen carbon quantum dots are prepared by the following method: 1) Urea and ammonium citrate are weighed according to a molar ratio of (16-18): 1, deionized water is added, and the mixture is fully mixed and dissolved; 2) The mixed product in 1) is transferred into a reaction kettle, and hydrothermal treatment is carried out at 120-200 ℃ for 2-6 h, and then taken out after cooling, followed by centrifugation, suction filtration, collection of the filtrate, and freeze-drying to obtain the high-nitrogen carbon quantum dots.

3. The high-nitrogen carbon quantum dot composite agaric biochar for catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 2, characterized in that, In step 1), deionized water is added to be 3-4 times the total mass of the mixture during dissolution.

4. The high-nitrogen carbon quantum dot composite agaric biochar for catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 2, characterized in that, In step 2), after cooling to room temperature, the centrifugation speed is 10,000 rpm / min, and the centrifugation time is 30 min; the filter membrane used for suction filtration is 0.22 μm; and the freeze-drying time of the filtrate is 48 h.

5. The application of high-nitrogen carbon quantum dot composite agaric biochar in catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 1, characterized in that, In step 2), the tube furnace has a heating rate of 5 ℃ / min, and nitrogen is used as the protective gas, and the gas is continuously supplied to ensure that the furnace is filled with nitrogen.

6. The application of a high-nitrogen carbon quantum dot composite agaric biochar in catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 1, characterized in that, The agaric biochar is prepared by the following steps: 1) Black agaric is cut and washed for standby; 2) The black agaric in step 1) is transferred into a tube furnace, reacted at 200-400 ℃ for 1-3 h, taken out after cooling, and washed to obtain a pre-carbonized agaric biochar; 3) The pre-carbonized agaric biochar prepared in step 2) is weighed according to a mass ratio of 1: (4-8) and mixed with KOH and water, and then stirred at 70-90 ℃ until a jelly is formed, and then dried for standby.

7. The use of high-nitrogen carbon quantum dot composite agaric biochar in catalyzing the degradation of piroxicam in water by peroxymonosulfate according to claim 6, characterized in that, In step 2), the tube furnace has a heating rate of 10 ℃ / min, and nitrogen is used as the protective gas, and the gas is continuously supplied to ensure that the furnace is filled with nitrogen.

8. A method of degrading naproxen in water by peroxodisulfate, characterized by, The high-nitrogen carbon quantum dot composite agaric biochar in claim 1 is used as a catalyst, the high-nitrogen carbon quantum dot composite agaric biochar and peroxodisulfate are added to water containing naproxen to be treated under dark conditions, and the mixture is fully stirred until the organic pollutants are completely degraded. The concentration of the catalyst is 0.05-0.3 g / L, and the concentration of peroxodisulfate is 5 mM.

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