Nitrogen-rich porous carbon, preparation method thereof and application of nitrogen-rich porous carbon in ibuprofen adsorption

Abstract

The invention belongs to the technical field of biochar materials, and particularly relates to nitrogen-rich porous carbon, a preparation method thereof and application of the nitrogen-rich porous carbon in ibuprofen adsorption. The method comprises the following steps: carrying out pyrolytic reaction on duckweed in a nitrogen atmosphere to obtain pyrolytic biochar; mixing the pyrolytic biochar, inorganic strong base and water to obtain a suspension of the pyrolytic biochar; drying the turbid liquid of the pyrolytic biochar to obtain a dipping mixture; and activating the impregnated mixture in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon. According to the present invention, the fixation and the enrichment of the duckweed endogenous nitrogen and the pore forming of the biochar are achieved, and the high nitrogen element content in the obtained nitrogen-rich porous carbon is ensured while the preparation of the high-porosity porous structure can be achieved, such that the obtained nitrogen-rich porous carbon has the good adsorption property on the ibuprofen, and the resourceful treatment of the duckweed is further achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of biochar materials, and in particular relates to nitrogen-rich porous carbon and a preparation method thereof and application thereof in ibuprofen adsorption. Background Art

[0002] Ibuprofen is one of the most frequently detected non-steroidal anti-inflammatory drugs in the global environment. Trace amounts of ibuprofen can be enriched through the food chain and accumulated in plants and animals. Studies have shown that ibuprofen is chronically toxic to aquatic organisms. Effectively removing ibuprofen from water bodies has become an urgent problem to be solved. At present, the commonly used methods for removing ibuprofen include chemical methods, biological methods, and adsorption methods. The chemical method has high efficiency and high investment costs, and chemical agents will cause secondary pollution to the water body. The biological method has low cost, but the operation is unstable and the effect is poor. The traditional activated sludge method of sewage treatment plants cannot effectively remove ibuprofen. The adsorption method has stable effects, low prices, and a wide range of materials. It has been widely used in the removal of wastewater containing ibuprofen.

[0003] As an emerging renewable resource, biochar has the advantages of low price, wide source, large specific surface area and rich functional groups. It has been widely used in wastewater treatment in recent years. Chinese patent application number CN201810632589.5 discloses a preparation of biochar and its adsorption of ibuprofen. The specific method is to dry, crush and screen the rice husk, mix it with deionized water, put it into a reactor and heat it for carbonization, clean and dry it, activate it with H2O2, and dry it again to form carbonized rice husk. Carbonized rice husk can be used to treat wastewater containing ibuprofen to remove ibuprofen from the wastewater. However, the adsorption effect is poor. The hydrothermal carbonized rice husk provided in the patent has a concentration of 100 mg·L -1 The adsorption amount of ibuprofen in the ibuprofen solution was only 15.92 mg·g -1 . Summary of the invention

[0004] The purpose of the present invention is to provide a nitrogen-rich porous carbon and a preparation method thereof and application in ibuprofen adsorption. The nitrogen-rich porous carbon provided by the present invention has good adsorption performance for ibuprofen and can simultaneously realize the resource processing of duckweed.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing nitrogen-rich porous carbon, comprising the following steps:

[0007] The duckweed is subjected to pyrolysis reaction in a nitrogen atmosphere to obtain pyrolysis biochar;

[0008] The pyrolysis biochar, inorganic strong base and water are mixed to obtain a suspension of pyrolysis biochar; the pyrolysis biochar suspension is dried to obtain an impregnation mixture;

[0009] The impregnation mixture is activated in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon.

[0010] Preferably, the temperature of the pyrolysis reaction is 400-600°C, and the time is 3-4h; the heating rate from room temperature to the temperature of the pyrolysis reaction is 5-10°C / min.

[0011] Preferably, during the pyrolysis reaction, the flow rate of the nitrogen is 150 to 200 mL / min.

[0012] Preferably, the inorganic strong base comprises an alkali metal hydroxide; the mass ratio of the pyrolysis biochar to the inorganic strong base is 1:(3-4);

[0013] The ratio of the mass of the inorganic strong base to the volume of the water is 6 g: (15-20) mL;

[0014] The drying temperature is 100-105° C. and the drying time is 12-24 hours.

[0015] Preferably, the activation temperature is 700-750° C., and the time is 2-3 h; the heating rate from room temperature to the activation temperature is 5-10° C. / min.

[0016] The present invention provides nitrogen-rich porous carbon prepared by the preparation method described in the above technical scheme.

[0017] Preferably, the nitrogen content of the nitrogen-rich porous carbon is 1.6-4.11 wt %.

[0018] Preferably, the total specific surface area of ​​the nitrogen-rich porous carbon is 1908 to 2807 m 2 / g; micropore specific surface area is 617~967m 2 / g.

[0019] The present invention provides the use of the nitrogen-rich porous carbon described in the above technical solution in the adsorption of ibuprofen.

[0020] Preferably, the ibuprofen is ibuprofen in water, and the initial mass concentration of ibuprofen in the water is 0.1 to 0.5 g / L.

[0021] The present invention provides a method for preparing nitrogen-rich porous carbon, comprising the following steps: subjecting duckweed to pyrolysis reaction in a nitrogen atmosphere to obtain pyrolysis biochar; mixing the pyrolysis biochar, an inorganic strong base and water to obtain a suspension of pyrolysis biochar; drying the suspension of pyrolysis biochar to obtain an impregnation mixture; activating the impregnation mixture in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon. The present invention pyrolyzes duckweed in a nitrogen atmosphere containing nitrogen, and obtains nitrogen-rich pyrolysis biochar using the nitrogen element contained in duckweed; then activates the impregnation mixture obtained by the nitrogen-rich pyrolysis biochar and the inorganic strong base in a nitrogen atmosphere to obtain the target product, nitrogen-rich porous carbon. The present invention uses duckweed as a raw material, and through pyrolysis and activation, the fixation and enrichment of endogenous nitrogen in duckweed and the pore formation of biochar are achieved, while ensuring that the nitrogen content in the obtained nitrogen-rich porous carbon is high, the preparation of a porous structure with high porosity can be achieved, so that the obtained nitrogen-rich porous carbon has good adsorption performance for ibuprofen, and also realizes the resource processing of duckweed. In summary, the preparation method provided by the present invention has a simple process, and the nitrogen-rich porous carbon has excellent adsorption performance, which is suitable for industrial production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM image of duckweed-based biochar prepared in an embodiment of the present invention. Figure 1 (a) and (b) are SEM images of the product of Example 1. Figure 1 (c) and (d) are SEM images of the product of Example 2. Figure 1 (e) and (f) are SEM images of the product of Example 3;

[0023] Figure 2 This is the absorbance curve of ibuprofen solution at different concentrations. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing nitrogen-rich porous carbon, comprising the following steps:

[0025] The duckweed is subjected to pyrolysis reaction in a nitrogen atmosphere to obtain pyrolysis biochar;

[0026] The pyrolysis biochar, inorganic strong base and water are mixed to obtain a suspension of pyrolysis biochar; the pyrolysis biochar suspension is dried to obtain an impregnation mixture;

[0027] The impregnation mixture is activated in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon.

[0028] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0029] The present invention conducts a pyrolysis reaction on duckweed in a nitrogen atmosphere to obtain pyrolysis biochar. In the present invention, before the pyrolysis reaction, the present invention preferably pre-treats the duckweed, and the pre-treatment preferably includes: drying and crushing the duckweed in sequence, and the specific implementation of the drying is preferably baking, and the drying temperature is preferably 100-105°C, and the time is preferably 24h. The crushing is preferably carried out in a crusher, and the present invention has no special requirements for the specific implementation of the crushing. The pyrolysis reaction is preferably carried out in a tubular furnace. The present invention preferably places the duckweed in a quartz hanging basket, and then places the quartz hanging basket containing duckweed in a tubular furnace for the pyrolysis reaction. In the present invention, the temperature of the pyrolysis reaction is preferably 400-600°C, and specifically preferably 400°C, 500°C or 600°C. The insulation time of the pyrolysis reaction is preferably 3-4h, and specifically preferably 3h; the heating rate from room temperature to the temperature of the pyrolysis reaction is preferably 5-10°C / min, and specifically preferably 10°C / min. In the present invention, the pyrolysis reaction is carried out in a nitrogen atmosphere, and during the pyrolysis reaction, the flow rate of the nitrogen is preferably 150 to 200 mL / min, and specifically preferably 200 mL / min. After the pyrolysis reaction is completed, the present invention preferably cools the product obtained by the pyrolysis reaction to room temperature to obtain pyrolysis biochar.

[0030] After obtaining the pyrolysis biochar, the present invention preferably grinds and sieves the pyrolysis biochar to obtain pyrolysis biochar with a particle size of less than 0.15 mm before performing subsequent steps. The present invention has no special requirements for the specific implementation process of the grinding and sieving.

[0031] After obtaining the pyrolytic biochar, the present invention mixes the pyrolytic biochar, an inorganic strong base and water to obtain a suspension of the pyrolytic biochar; and dries the suspension of the pyrolytic biochar to obtain an impregnation mixture. In the present invention, the particle size of the pyrolytic biochar is preferably <.15 mm. The inorganic strong base preferably includes an alkali metal hydroxide, and is preferably KOH. The water is preferably deionized water. The mass ratio of the pyrolytic biochar to the inorganic strong base is preferably 1: (3-4), and is preferably 1: 3. The ratio of the mass of the inorganic strong base to the volume of the water is preferably 6g: (15-20) mL. The mixing preferably includes: dissolving the inorganic strong base in water to obtain a strong base solution; and impregnating the pyrolytic biochar in the strong base solution. The impregnation is preferably carried out under stirring. The drying is preferably carried out in a blast drying oven. The drying temperature is preferably 100-105°C, and the drying time is preferably 12-24h.

[0032] After obtaining the impregnation mixture, the present invention activates the impregnation mixture in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon. In the present invention, the activation is preferably carried out in a tubular furnace. The activation temperature is preferably 700-750°C, and the activation insulation time is preferably 2-3h. The heating rate from room temperature to the activation temperature is preferably 5-10°C / min. During the activation, the flow rate of nitrogen is preferably 150-200mL / min, and specifically preferably 200mL / min.

[0033] The present invention provides nitrogen-rich porous carbon prepared by the preparation method described in the above technical scheme.

[0034] In the present invention, the mass content of nitrogen in the nitrogen-rich porous carbon is 1.6-4.11wt%, more preferably 1.6-4wt%, further preferably 1.6-3wt%, most preferably 1.6-2.5wt%, specifically preferably 1.6wt%, 2wt% or 1.99wt%.

[0035] In the present invention, the total specific surface area of ​​the nitrogen-rich porous carbon is 1908-2807 m 2 / g, more preferably 2000 to 2807 m 2 / g, more preferably 2500 to 2807 m 2 / g, preferably 2589m 2 / g or 2807m 2 The micropore specific surface area of ​​the nitrogen-rich porous carbon is preferably 617 to 967 m 2 / g, more preferably 700 to 967 m 2 / g, more preferably 800 to 967 m 2 / g, preferably 851m 2 / g or 967m 2 / g.

[0036] The present invention provides the use of the nitrogen-rich porous carbon described in the above technical solution in the adsorption of ibuprofen.

[0037] In the present invention, the ibuprofen is preferably ibuprofen in water, and the initial mass concentration of ibuprofen in water is preferably 0.1-0.5 g / L, specifically preferably 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L or 0.5 g / L.

[0038] The preparation method of nitrogen-rich porous carbon provided by the present invention realizes the fixation of endogenous nitrogen in duckweed. Nitrogen-rich high-performance porous carbon is prepared by a two-step method of pyrolysis and activation, which ensures the nitrogen content and high void structure while realizing the resource processing of duckweed. The obtained nitrogen-rich porous carbon has good adsorption performance for ibuprofen.

[0039] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0040] In order to study the adsorption performance of the prepared nitrogen-rich porous carbon product in the following examples, ibuprofen (IB) solutions of different concentrations were experimentally prepared as simulated ibuprofen-containing wastewater. 0.01 g of IB powder was dissolved in 1 L of ethanol-water (the volume ratio of ethanol to water was 8:2) to prepare an IB reference solution (0.01 g / L). The IB reference solution was then diluted to a certain concentration range with different volumes of deionized water. The absorbance of IB solutions of different concentrations was measured at λmax = 220 nm (the maximum absorption wavelength of IB) using a spectrophotometer (Mapada UV-1600, China), and a standard curve of the IB solution was further drawn, as shown in FIG. Figure 2 As shown in Figure 2, within the IB mass concentration range of 0.01-0.05 g / L, the concentration of IB solution at 220 nm and its corresponding absorbance show an obvious linear relationship.

[0041] Example 1

[0042] Take 5g of duckweed and put it into a drying oven for baking. The baking temperature is 105℃ and the baking time is 24h. Then break it up. Take 5g of the broken duckweed raw material and put it into a quartz hanging basket at room temperature. Then put the hanging basket into a tube furnace for pyrolysis treatment. The pyrolysis is carried out in a nitrogen atmosphere with a nitrogen flow rate of 200mL / min and a heating rate of 10℃ / min. The temperature is raised from room temperature to 400℃ and kept warm for 3h. After the pyrolysis is completed, take out the hanging basket when the sample is cooled to room temperature, record the mass of the sample (hereinafter referred to as "pyrolytic carbon"), grind the sample into a mortar and sieve it to obtain a sample with a size greater than 100 mesh (<0.15mm).

[0043] Take 6g of KOH solid and dissolve it in 15mL of deionized water to obtain a KOH solution, then take 2g of the prepared pyrolytic carbon and add it to the KOH solution, and stir the solution with a glass rod until the pyrolytic carbon is completely immersed in the solution. Then place the suspension containing pyrolytic carbon in a forced air drying oven and dry it for 24h at a drying temperature of 105°C. Then take out the dried sample that has been impregnated with KOH and collect it for subsequent use.

[0044] The impregnated samples were activated in a tubular furnace with a nitrogen flow rate of 200 mL / min, a heating rate of 10 °C / min, and a holding time of 2 h after heating to 750 °C. After the pyrolysis was completed, the samples were taken out and pickled to remove the alkali in the samples. During the pickling, the hydrochloric acid was first diluted to prepare a hydrochloric acid with a molar concentration of 1.5 mol / L. The sample to be washed was placed in a beaker, and the prepared hydrochloric acid was added to the beaker. At the same time, it was stirred with a glass rod. When there were no more bubbles in the beaker, the pH value of the solution was tested with a pH test paper to ensure that the solution was weakly acidic, and then the solution was filtered. After the filtration was completed, the sample was placed in a drying oven and dried for 3 h, and then the sample was collected and ground to obtain the activated nitrogen-rich high-performance porous carbon (denoted as AFP-4).

[0045] Figure 1 (a) and Figure 1 (b) is a scanning electron microscope image of the nitrogen-rich porous carbon prepared in Example 1. Figure 1 It can be seen from (a) and (b) that the nitrogen-rich porous carbon material prepared in Example 1 has a good pore structure.

[0046] The nitrogen content (i.e., nitrogen doping amount) of the nitrogen-rich porous carbon prepared in Example 1 is 4.11 wt %, and the total specific surface area is 1908 m 2 / g, micropore specific surface area is 617m 2 / g.

[0047] The nitrogen-rich porous carbon prepared in Example 1 was mixed with 50 mL of ibuprofen solution at room temperature, the solvent used in the ibuprofen solution was ethanol-water (the volume ratio of ethanol to water was 8:2), and placed in a shaker for mixed adsorption for 3 hours. The adsorption capacity of the nitrogen-rich porous carbon prepared in Example 1 for ibuprofen was 0.000 g / g (initial concentration 0.1 g / L), 0.163 g / g (initial concentration 0.2 g / L), 0.504 g / g (initial concentration 0.3 g / L), 0.876 g / g (initial concentration 0.4 g / L) and 1.345 g / g (initial concentration 0.5 g / L).

[0048] Example 2

[0049] Take 5g of duckweed and put it into a drying oven for baking. The baking temperature is 105℃ and the baking time is 24h. Then break it up. Take 5g of the broken duckweed raw material and put it into a quartz hanging basket at room temperature. Then put the hanging basket into a tube furnace for pyrolysis treatment. The pyrolysis is carried out in a nitrogen atmosphere with a nitrogen flow rate of 200mL / min and a heating rate of 10℃ / min. The temperature is raised from room temperature to 500℃ and kept warm for 3h. After the pyrolysis is completed, take out the hanging basket when the sample is cooled to room temperature, record the mass of the sample (hereinafter referred to as "pyrolytic carbon"), grind the sample into a mortar and sieve it to obtain a sample with a size greater than 100 mesh (<0.15mm).

[0050] Take 6g of KOH solid and dissolve it in 15mL of deionized water to obtain a KOH solution, then take 2g of the prepared pyrolytic carbon and add it to the KOH solution, and stir the solution with a glass rod until the pyrolytic carbon is completely immersed in the solution. Then place the suspension containing pyrolytic carbon in a forced air drying oven and dry it for 24h at a drying temperature of 105°C. Then take out the dried sample that has been impregnated with KOH and collect it for subsequent use.

[0051] The impregnated samples were activated in a tubular furnace with a nitrogen flow rate of 200 mL / min, a heating rate of 10 °C / min, and a holding time of 2 h after heating to 750 °C. After the pyrolysis was completed, the samples were taken out and pickled to remove the alkali in the samples. During the pickling, the hydrochloric acid was first diluted to prepare a hydrochloric acid with a molar concentration of 1.5 mol / L. The sample to be washed was placed in a beaker, and the prepared hydrochloric acid was added to the beaker. At the same time, it was stirred with a glass rod. When there were no more bubbles in the beaker, the pH value of the solution was tested with a pH test paper to ensure that the solution was weakly acidic, and then the solution was filtered. After the filtration was completed, the sample was placed in a drying oven and dried for 3 h, and then the sample was collected and ground to obtain the activated nitrogen-rich high-performance porous carbon (denoted as AFP-5).

[0052] Figure 1 (c) and Figure 1 (d) is a scanning electron microscope image of the nitrogen-rich porous carbon prepared in Example 2. Figure 1 It can be seen from (c) and (d) that the nitrogen-rich porous carbon material prepared in Example 2 has a good pore structure.

[0053] The nitrogen content (i.e., nitrogen doping amount) of the nitrogen-rich porous carbon prepared in Example 2 is 1.6 wt % and the total specific surface area is 2589 m 2 / g, micropore specific surface area is 851m 2 / g.

[0054] The nitrogen-rich porous carbon prepared in Example 2 was mixed with 50 mL of ibuprofen solution at room temperature, the solvent used in the ibuprofen solution was ethanol-water (the volume ratio of ethanol to water was 8:2), and placed in a shaker for mixed adsorption for 3 hours. The adsorption capacity of the nitrogen-rich porous carbon prepared in Example 2 for ibuprofen was 0.117 g / g (initial concentration 0.1 g / L), 0.338 g / g (initial concentration 0.2 g / L), 0.766 g / g (initial concentration 0.3 g / L), 0.923 g / g (initial concentration 0.4 g / L) and 1.360 g / g (initial concentration 0.5 g / L).

[0055] Example 3

[0056] Take 5g of duckweed and put it into a drying oven for baking. The baking temperature is 105℃ and the baking time is 24h. Then break it up. Take 5g of the broken duckweed raw material and put it into a quartz hanging basket at room temperature. Then put the hanging basket into a tube furnace for pyrolysis treatment. The pyrolysis is carried out in a nitrogen atmosphere with a nitrogen flow rate of 200mL / min and a heating rate of 10℃ / min. The temperature is raised from room temperature to 600℃ and kept warm for 3h. After the pyrolysis is completed, take out the hanging basket when the sample is cooled to room temperature, record the mass of the sample (hereinafter referred to as "pyrolytic carbon"), grind the sample into a mortar and sieve it to obtain a sample with a size greater than 100 mesh (<0.15mm).

[0057] Take 6g of KOH solid and dissolve it in 15mL of deionized water to obtain a KOH solution, then take 2g of the prepared pyrolytic carbon and add it to the KOH solution, and stir the solution with a glass rod until the pyrolytic carbon is completely immersed in the solution. Then place the suspension containing pyrolytic carbon in a forced air drying oven and dry it for 24h at a drying temperature of 105°C. Then take out the dried sample that has been impregnated with KOH and collect it for subsequent use.

[0058] The impregnated samples were activated in a tubular furnace with a nitrogen flow rate of 200 mL / min, a heating rate of 10 °C / min, and a holding time of 2 h after heating to 750 °C. After the pyrolysis was completed, the samples were taken out and pickled to remove the alkali in the samples. During the pickling, the hydrochloric acid was first diluted to prepare a hydrochloric acid with a molar concentration of 1.5 mol / L. The sample to be washed was placed in a beaker, and the prepared hydrochloric acid was added to the beaker. At the same time, it was stirred with a glass rod. When there were no more bubbles in the beaker, the pH value of the solution was tested with a pH test paper to ensure that the solution was weakly acidic, and then the solution was filtered. After the filtration was completed, the sample was placed in a drying oven and dried for 3 h, and then the sample was collected and ground to obtain the activated nitrogen-rich high-performance porous carbon (denoted as AFP-6).

[0059] Figure 1 (e) and Figure 1 (f) is a scanning electron microscope image of the nitrogen-rich porous carbon prepared in Example 3. Figure 1 It can be seen from (e) and (f) that the nitrogen-rich porous carbon material prepared in Example 3 has a good pore structure.

[0060] The nitrogen content (i.e., nitrogen doping amount) of the nitrogen-rich porous carbon prepared in Example 3 is 1.99 wt % and the total specific surface area is 2807 m 2 / g, micropore specific surface area is 967m 2 / g.

[0061] The nitrogen-rich porous carbon prepared in Example 3 was mixed with 50 mL of ibuprofen solution at room temperature, the solvent used in the ibuprofen solution was ethanol-water (the volume ratio of ethanol to water was 8:2), and placed in a shaker for mixed adsorption for 3 hours. The adsorption capacity of the nitrogen-rich porous carbon prepared in Example 3 for ibuprofen was 0.173 g / g (initial concentration 0.1 g / L), 0.163 g / g (initial concentration 0.2 g / L), 0.594 g / g (initial concentration 0.3 g / L), 0.876 g / g (initial concentration 0.4 g / L) and 1.335 g / g (initial concentration 0.5 g / L).

[0062] Comparative Example 1

[0063] The preparation method is basically the same as that in Example 1, except that the duckweed raw material used in Example 1 is replaced by donkey dung, and the obtained porous carbon material is recorded as ALF-4.

[0064] Comparative Example 2

[0065] The preparation method is basically the same as that of Example 2, except that the duckweed raw material used in Example 2 is replaced by donkey dung, and the obtained porous carbon material is recorded as ALF-5.

[0066] Comparative Example 3

[0067] The preparation method is basically the same as that in Example 3, except that the duckweed raw material used in Example 3 is replaced by donkey dung, and the obtained porous carbon material is recorded as ALF-6.

[0068] The porous carbon materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were mixed with 50 mL of ibuprofen solution at room temperature, wherein the solvent used in the ibuprofen solution was ethanol-water (the volume ratio of ethanol to water was 8:2), and placed in a shaker for mixing and adsorption for 3 hours. The adsorption capacity of ibuprofen solutions of different mass concentrations is shown in Table 1.

[0069] Table 1 Adsorption capacity of products prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0070]

[0071] In Table 1: A: represents activated biochar; FP: the abbreviation of duckweed; LF: the abbreviation of donkey dung. Donkey dung has no adsorption effect at low concentrations and is not as good as duckweed at high concentrations.

[0072] From the above embodiments, it can be seen that the present invention pyrolyzes duckweed in a nitrogen atmosphere to prepare nitrogen-rich pyrolytic biochar; the nitrogen-rich pyrolytic biochar is mixed with potassium hydroxide, and activated in a nitrogen atmosphere to obtain a nitrogen-rich porous carbon product. The present invention uses duckweed as a raw material and performs high-temperature pyrolysis to achieve the preparation of nitrogen-rich porous carbon, thereby reducing the use of exogenous nitrogen; the present invention uses potassium hydroxide as an activator to form pores in the nitrogen-rich porous carbon to prepare nitrogen-rich high-performance porous carbon. The present invention can prepare nitrogen-rich high-performance porous carbon by a two-step method to fix endogenous nitrogen, and while ensuring the nitrogen content and high-void structure, it can also realize the resource processing of duckweed, and the resulting nitrogen-rich high-performance porous carbon has good adsorption properties for ibuprofen.

[0073] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing nitrogen-rich porous carbon, characterized in that: The following steps are involved: The duckweed is subjected to pyrolysis reaction in a nitrogen atmosphere to obtain pyrolysis biochar; The pyrolysis biochar, inorganic strong base and water are mixed to obtain a suspension of pyrolysis biochar; the pyrolysis biochar suspension is dried to obtain an impregnation mixture; The impregnation mixture is activated in a nitrogen atmosphere to obtain the nitrogen-rich porous carbon.

2. The preparation method according to claim 1, characterized in that: The temperature of the pyrolysis reaction is 400-600°C, and the time is 3-4h; the heating rate from room temperature to the temperature of the pyrolysis reaction is 5-10°C / min.

3. The preparation method according to claim 1 or 2, characterized in that: During the pyrolysis reaction, the flow rate of the nitrogen is 150-200 mL / min.

4. The preparation method according to claim 1, characterized in that: The inorganic strong base includes an alkali metal hydroxide; the mass ratio of the pyrolysis biochar to the inorganic strong base is 1:(3-4); The ratio of the mass of the inorganic strong base to the volume of the water is (15-20) mL; The drying temperature is 100-105° C. and the drying time is 12-24 hours.

5. The preparation method according to claim 1 or 4, characterized in that: The activation temperature is 700-750° C., and the time is 2-3 hours; the heating rate from room temperature to the activation temperature is 5-10° C. / min.

6. Nitrogen-rich porous carbon prepared by the preparation method according to any one of claims 1 to 5.

7. The nitrogen-rich porous carbon according to claim 6, characterized in that The nitrogen content of the nitrogen-rich porous carbon is 1.6-4.11 wt %.

8. The nitrogen-rich porous carbon according to claim 6 or 7, characterized in that: The total specific surface area of ​​the nitrogen-rich porous carbon is 1908-2807 m 2 / g; micropore specific surface area is 617~967m 2 / g.

9. Use of the nitrogen-rich porous carbon according to any one of claims 6 to 8 in the adsorption of ibuprofen.

10. The use according to claim 9, characterized in that: The ibuprofen is ibuprofen in water, and the initial mass concentration of ibuprofen in the water is 0.1-0.5 g / L.

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