A chemical detoxification method for p-nitrophenol

Abstract

A chemical detoxification method of p-nitrophenol comprises the following steps: S1, adding p-nitrophenol solution, reducing agent and carbon-doped boron nitride non-metal photocatalyst into a quartz reaction tube, stirring uniformly, discharging oxygen and maintaining atmosphere by nitrogen; S2, placing the mixed reaction system into a light reaction instrument, opening a xenon lamp as a light source, opening circulating water, and reacting for 8-60 min at normal temperature; S3, filtering the reaction liquid, and obtaining low-toxicity p-aminophenol compound. The present application uses carbon-doped boron nitride as a non-metal photocatalyst, ethanol or glucose as a reducing agent, and a xenon lamp to simulate sunlight, and reduces p-nitrophenol to p-aminophenol in a nitrogen atmosphere, without using sodium borohydride and metal or noble metal-containing catalysts, and realizing green and efficient detoxification of p-nitrophenol.

Description

TECHNICAL FIELD

[0001] The present application relates to a chemical detoxification method of p-nitrophenol, belonging to the technical field of photocatalytic treatment of organic pollutants. BACKGROUND

[0002] Highly stable p-nitrophenol (4-NP) has genetic toxicity and carcinogenic effect on humans and animals, and its influence on human and animal health has attracted widespread attention. Artificial 4-NP is widely used in industrial manufacturing and processing, such as leather coloring, pesticide production, bactericide and dye manufacturing, etc., and is one of the most commonly used organic pollutants. At present, there is no evidence that 4-NP exists naturally, so it is the responsibility of mankind to detoxify it. People have developed various methods to catalytically convert 4-NP into p-aminophenol (4-AP). 4-AP is an important industrial intermediate, which has important application value in the manufacture of dyes, photographic developers and antipyretic drugs. It can be seen that reducing 4-NP to 4-AP is an effective and eco-friendly way.

[0003] 4-NP reduction to 4-AP reaction needs to add a reducing agent in addition to adding a catalyst. However, the existing method mostly relies on sodium borohydride (NaBH4) as a reducing agent to reduce 4-NP to 4-AP; if there is no NaBH4 in the solution, the reaction cannot proceed. According to the Material Safety Data Sheet (MSDS), excessive use of NaBH4 may have a negative impact on the environment due to its corrosive and irritating properties. In addition, the existing method often uses metal or noble metal catalysts for 4-NP catalytic reduction reactions, making the use cost higher. For example: Wang et al. prepared a Cu-Ag bimetallic nano-catalyst (Cu-Ag / PVA) for catalytic reduction of 4-nitrophenol (Cu-Ag bimetallic nano-catalyst anchored on polyvinyl alcohol sponge for catalytic reduction of 4-nitrophenol. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2023, vol. 677, no. 132450: 1-8). But this method uses a large amount of NaBH4 in the catalytic process (400 mol of NaBH4 is needed to catalytically reduce 1 mol of 4-NP), so the solution after the reaction contains a large amount of residual NaBH4, which will cause significant pollution to the water environment; in addition, the catalyst contains 10.1 wt% of metal Cu and Ag, and the metal content is high; the paper shows that about 0.7 g of Cu and Ag is needed to catalytically reduce 1 mmol of 4-NP, resulting in very high production and use costs. At the same time, the reaction dynamic constant of Cu-Ag / PVA is 0.54 min -1 Compared with the catalytic performance of most similar catalysts, the reaction rate of the catalyst is low.

[0004] In recent years, the method of photocatalytic reduction of 4-NP to 4-AP has also attracted the attention of researchers. Song et al. prepared CN / 800NiCNTs photocatalyst (N-doped carbon nanotubes enhanced charge transport between Ni nanoparticles and g-C3N4 nanosheets for photocatalytic H2 generation and 4-nitrophenol removal. Carbon. 2023, Vol. 210, pp. 118052: 1-8), which requires 10 min to reduce 4-NP to 4-AP under light conditions with NaBH4 as the reducing agent. The reaction kinetic constant of CN / 800NiCNTs is 0.47 min -1 It can be seen that the reaction rate of this catalyst is not high. In addition, for catalysts without Ni metal, such as CN and CN / CNTs catalysts, under the same photocatalytic conditions, even if a large amount of NaBH4 is added, 4-NP cannot be reduced to 4-AP.

[0005] In summary, the commonly used catalytic methods still have the problems of using a large amount of NaBH4 to reduce 4-NP to 4-AP, the catalyst containing metal or noble metal, poor catalytic activity, and high use cost.

[0006] Therefore, it is particularly urgent and important to find a green and environmentally friendly chemical method to safely and efficiently convert the toxic 4-NP in water into low-toxic 4-AP.

[0007] Photocatalytic technology is a method that can convert abundant and green clean solar energy in nature into chemical energy. It is considered as one of the ideal methods for treating water and air pollutants due to its green and clean, strong spectral, and mild reaction conditions.

[0008] Hexagonal boron nitride (h-BN) is known as "white graphene" and is widely used in different fields due to its high thermal conductivity, high mechanical strength, and good chemical stability. Although h-BN has many advantages, it is a wide-bandgap semiconductor (~ 5.5 eV) that can only absorb ultraviolet light and is not suitable for use as a photocatalyst. Studies have shown that the band gap of h-BN can be adjusted by element doping to broaden the visible light absorption range, making it a suitable photocatalyst. Among them, h-BN doped with carbon atoms has attracted special attention due to its simple preparation process and excellent photocatalytic performance. In addition, B, C, and N raw materials are cheap and easy to obtain, making BCN nanometer semiconductor materials a very promising non-metallic photocatalyst.

[0009] However, there is no report on the application of carbon-doped boron nitride non-metallic photocatalyst to the green and efficient reduction of p-nitrophenol pollutants without using NaBH4 as a reducing agent and without using a metal-containing catalyst. SUMMARY

[0010] The present application is to overcome the drawbacks of the prior art, and provides a chemical detoxification method of p-nitrophenol, which uses carbon-doped boron nitride as a non-metallic photocatalyst, ethanol or glucose as a reducing agent, and a xenon lamp to simulate sunlight, and reduces p-nitrophenol to p-aminophenol in a nitrogen atmosphere. The method does not need to use sodium borohydride and a metal or noble metal-containing catalyst, and realizes green and efficient detoxification of p-nitrophenol.

[0011] The technical solution adopted by the present application to solve its technical problems is:

[0012] A chemical detoxification method of p-nitrophenol, the method comprising the following steps:

[0013] S1, adding a p-nitrophenol solution, a reducing agent and a carbon-doped boron nitride non-metallic photocatalyst into a quartz reaction tube, stirring uniformly, and purging oxygen with nitrogen to maintain the atmosphere;

[0014] S2, placing the mixed reaction system into a light reaction instrument, turning on a xenon lamp as a light source, and opening a circulating water, and reacting for 8-60 min at room temperature;

[0015] S3, filtering the reaction solution to obtain a low-toxicity p-aminophenol compound.

[0016] The chemical detoxification method of p-nitrophenol, the reducing agent is one of ethanol or glucose, and the ethanol and glucose are analytical pure.

[0017] The chemical detoxification method of p-nitrophenol, in step S1, when the reducing agent is ethanol, first adding ethanol into the p-nitrophenol solution to prepare a 0.12 mmol / L p-nitrophenol reaction solution containing ethanol, wherein the volume percentage of ethanol is 10-30%, then mixing the p-nitrophenol reaction solution containing ethanol with carbon-doped boron nitride, and the dosage ratio of the two is 40 mL: 5-20 mg; when the reducing agent is glucose, the dosage ratio of the p-nitrophenol solution, glucose and carbon-doped boron nitride is 40 mL: 10-30 mg: 5-20 mg, and the concentration of the p-nitrophenol solution is 0.12 mmol / L.

[0018] The chemical detoxification method of p-nitrophenol, the preparation method of the carbon-doped boron nitride non-metallic photocatalyst comprises the following steps:

[0019] a, adding melamine, boric acid and glucose into deionized water, and heating to 95℃ to completely dissolve them;

[0020] b. 90℃ water bath for 6h, then cooled to room temperature, precipitate crystals, filter, oven dried at 70℃ to constant weight, to obtain the precursor;

[0021] c. The precursor is heated to 900℃ at a rate of 5℃ / min in a tube furnace under the protection of N2 with a flow rate of 50-200mL / min, and kept for 4h to obtain the carbon-doped boron nitride non-metal photocatalyst.

[0022] The chemical detoxification method of p-nitrophenol, the use amount ratio of the melamine, boric acid, glucose and deionized water is: 18.92g: 18.550g: (4.5-13.5)g: 800mL.

[0023] The chemical detoxification method of p-nitrophenol, in step S2, a 300W xenon lamp is used as a light source to simulate sunlight.

[0024] The beneficial effects of the present application are:

[0025] The present application selects carbon-doped boron nitride as a photocatalyst, which does not contain metal, and is used for photocatalytic reduction of p-nitrophenol, and uses ethanol or glucose as a reducing agent, without NaBH4, avoiding the large use of NaBH4, and having high photocatalytic activity, with an apparent kinetic constant as high as 1.53min -1 , and the conversion rate and selectivity of 4-NP reach 100%. The detoxification method is simple, has low environmental pollution, and the catalyst raw material is cheap and easy to obtain, which will be beneficial to subsequent large-scale industrial production, and has significant economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is the UV-Vis spectrum of 4-NP solution in ethanol solution and in the presence of ethanol and BCN-2 photocatalyst.

[0027] Figure 2 It is the UV-Vis absorption spectrum of the photocatalytic reduction process of 4-NP when the photocatalyst is BCN-2 and the reducing agent is 20% ethanol.

[0028] Figure 3 It is the UV-Vis absorption spectrum of the photocatalytic reduction process of 4-NP when the photocatalyst is BCN-2 and the reducing agent is 10mg glucose.

[0029] Figure 4 It is the UV-Vis spectrum of the photocatalytic reduction process of 4-NP when the photocatalyst is BCN-3 and the reducing agent is 20% ethanol.

[0030] Figure 5UV-Vis spectra of 4-NP photocatalytic reduction process with BCN-3 as photocatalyst and 10 mg glucose as reductant.

[0031] Figure 6 UV-Vis spectra of 4-NP photocatalytic reduction process with BCN-1 as photocatalyst and 20% ethanol as reductant.

[0032] Figure 7 HPLC of 4-NP photocatalytic reduction process with BCN-2 as photocatalyst and 20% ethanol as reductant.

[0033] Figure 8 Photocatalytic activity of different BCN as photocatalyst and ethanol or glucose as reductant.

[0034] Figure 9 TEM of BCN-2 non-metallic photocatalyst.

[0035] Figure 10 HRTEM of BCN-2 non-metallic photocatalyst

[0036] Figure 11 N2 adsorption-desorption isotherm of BCN-2 non-metallic catalyst.

[0037] Figure 12 DRS of BCN-2 non-metallic photocatalyst.

[0038] When the reductant is ethanol: 10% to 30% ethanol refers to its content in the solution of p-nitrophenol. For example, the preparation of 0.12 mmol / L 4-NP reaction solution containing 20% ethanol: mix 10 mL of 1.2 mmol / L 4-NP solution and 20 mL of anhydrous ethanol, and add deionized water to 100 mL.

[0039] When the reductant is glucose, the preparation of 0.12 mmol / L 4-NP reaction solution: take 10 mL of 1.2 mmol / L 4-NP solution, add deionized water to 100 mL, and then take a certain amount of 0.12 mmol / L 4-NP reaction solution and add 10 to 30 mg of glucose for reaction. DETAILED DESCRIPTION

[0040] The minimum potential difference required for the reduction of p-nitrophenol to p-aminophenol is -0.76 eV, which requires: 1) the selected catalyst semiconductor has a suitable band gap (generally less than 2.95 eV), which can generate electron holes under visible light irradiation; 2) the selected catalyst must have a conduction band lower than -0.76 eV, in order to have sufficient reduction potential to reduce p-nitrophenol to p-aminophenol.

[0041] However, pure boron nitride has a bandgap of 5.5-6.0 eV, which can only absorb light in the ultraviolet region. Carbon-doped boron nitride can reduce the bandgap to some extent. Specifically:

[0042] 1. Change of lattice structure: After the introduction of carbon elements, the lattice structure of boron nitride (BN) will be distorted to some extent. This is because the atomic radius and electronegativity of carbon atoms are different from those of nitrogen and boron, leading to changes in lattice parameters. Changes in lattice structure will affect the energy state of electrons, thereby changing the bandgap of the material.

[0043] 2. Introduction of impurity energy levels: The introduction of carbon atoms will introduce new impurity energy levels in the energy band structure of BN, which will affect the energy difference between the conduction band and the valence band, thereby changing the bandgap. For example, carbon atoms may form chemical bonds different from the main lattice of BN, and the energy level distribution of these new bonds may cause the rearrangement of energy bands.

[0044] 3. Electron-electron and electron-ion interactions: After doping carbon elements, the electron-electron and electron-ion interactions in BN will be different. These interactions will affect the electronic state density of the material, and in turn affect the bandgap. For example, the doping elements may cause changes in local charge distribution, leading to modifications of the energy band structure.

[0045] 4. Local stress and strain: The introduction of carbon atoms into the BN lattice will cause local stress and strain, and this mechanical strain will affect the electronic band structure. Stress and strain can change the atomic spacing and bond angles, thereby affecting the width and position of the energy band.

[0046] In summary, after the introduction of carbon elements into BN, the bandgap of BN changes through changes in lattice structure, introduction of impurity energy levels, influence on electron interactions, and local stress and strain, etc.

[0047] As mentioned above, in order to successfully reduce p-nitrophenol to p-aminophenol, carbon-doped boron nitride with a bandgap lower than 2.95 eV is required. If it is higher than 2.95 eV, the catalyst will not respond under visible light irradiation and cannot produce electron holes for photocatalysis. In addition, if the carbon-doped boron nitride prepared has a bandgap lower than 2.95 eV, but its conduction band is higher than -0.76 eV, it is not high enough to reduce p-nitrophenol to p-aminophenol, and it will also cause the formation of intermediate by-products (reaction path as follows).

[0048]

[0049] Therefore, in the preparation method of the present application, the carbon-doped boron nitride band gap is finely controlled by controlling the selection of the carbon source and the amount of carbon source incorporated, so that it not only has absorption in the visible light, but also has a low enough conduction band to reduce 4-NP. The present application controls the amount of melamine, boric acid, glucose and deionized water as follows: 18.92g: 18.550g: 4.5-13.5g: 800mL, so as to change the band gap and conduction band of boron nitride (BN), specifically:

[0050] 1. Too little carbon is incorporated, less than the limited amount of the present application.

[0051] A, weak influence: a small amount of carbon incorporation may not significantly change the lattice structure and electronic properties of BN, because the introduction of a small amount of impurity is not enough to significantly change the overall electronic state density and lattice parameters.

[0052] B, local defects: incorporation of a small amount of carbon atoms may form local defects or impurity levels in the BN lattice, which can introduce a small amount of state density in the band gap, but the overall effect on the band gap width may be small.

[0053] 2. Moderate amount of carbon is incorporated, within the limited amount range of the present application.

[0054] A, adjust the band gap: the appropriate amount of carbon incorporation can effectively adjust the band gap of BN. This is because the appropriate amount of carbon atoms can be uniformly distributed in the lattice, resulting in optimized adjustment of the lattice parameters and electronic structure, thereby effectively controlling the band gap width.

[0055] B, improve material performance: appropriate amount of carbon incorporation can optimize the electrical and optical properties of the material. For example, appropriate doping can improve the conductivity of BN or broaden the light absorption range, making it perform better in photocatalytic applications.

[0056] 3. Too much carbon is incorporated, i.e. beyond the amount range of the present application.

[0057] A, lattice distortion: excessive carbon incorporation will cause serious distortion of the lattice structure, destroying the original crystal structure of BN. This distortion will cause the deterioration of material properties, and may even lead to instability of the material structure.

[0058] B, significant change in energy band structure: the introduction of a large amount of carbon atoms may cause serious energy band rearrangement, forming a new energy band structure, and even causing a significant narrowing of the band gap or closing of the band gap, making the material change from a semiconductor to a conductor.

[0059] C, local phase separation: excessive carbon may cause carbon to aggregate in BN, forming local carbon-rich regions, leading to phase separation. This phase separation will introduce more defects and interfaces, further reducing the performance of the material.

[0060] D. Reduced material properties: Excessive carbon doping usually leads to the deterioration of material properties, such as reduced mechanical strength, thermal stability and chemical stability, thereby limiting its effectiveness in practical applications.

[0061] In summary, the amount of carbon incorporated has a significant impact on the properties of boron nitride. Appropriate carbon incorporation can adjust the bandgap and optimize the material's performance, but too little or too much carbon will adversely affect the material's structure and properties. Therefore, controlling the concentration and uniformity of carbon incorporation is crucial for optimizing material performance.

[0062] In the photocatalytic reduction of 4-NP to 4-AP, a reducing agent is required to initiate the reaction. This invention uses carbon-doped boron nitride as the photocatalyst and ethanol or glucose as the reducing agent, making it more environmentally friendly. The photocatalytic reduction process is as follows:

[0063] Both ethanol and glucose molecules contain hydroxyl groups. Their hydroxyl hydrogen atoms have reducing properties. During photocatalytic reactions, the hydroxyl group provides reducing hydrogen, and combined with electrons generated by visible light irradiation of carbon-doped boron nitride, 4-NP can be reduced to 4-AP. The hydroxyl groups in ethanol and glucose molecules are oxidized to carbonyl or carboxyl groups.

[0064] The photocatalytic reduction of 4-NP to 4-AP by carbon-doped boron nitride can be divided into three steps: (i) adsorption of reactants (ethanol and 4-NP) on the surface of the carbon-doped boron nitride photocatalyst; the high specific surface area and porous structure of carbon-doped boron nitride can provide more activation adsorption sites, which helps to increase the adsorption amount of the reaction substrate and thus improve its catalytic performance. (ii) As a semiconductor, carbon-doped boron nitride generates electrons and holes during photoirradiation. The holes in its valence band oxidize and decompose ethanol into aldehydes or carboxylic acids and H+. + It transfers electrons from the conduction band to the acceptor 4-NP molecule and transfers H+ to the acceptor molecule. + (iii) The product 4-AP is transferred to 4-NP, causing it to be reduced to 4-AP. The reaction is as follows:

[0065] BCN+hv→h + +e - (1-1)

[0066] CH3CH2OH + H2O + h + →CH3CHO+H + +OH (1-2)

[0067]

[0068] The prepared carbon-doped boron nitride non-metallic photocatalyst needs to be ground when used in photocatalysis. After grinding, the obtained carbon-doped boron nitride sample is a fiber with a diameter of 2.0-3.3 μm and a length of 4.7-30 μm.

[0069] The application will be further described below in combination with examples.

[0070] Example 1

[0071] Preparation of carbon-doped boron nitride (BCN) non-metallic catalyst: first, 18.92 g of melamine, 18.550 g of boric acid and 9 g of glucose were added to 800 mL of deionized water, heated to 95 ℃ to completely dissolve them. Then, 90 ℃ water bath for 6 h, and then naturally cooled to room temperature, and the crystals were separated, filtered and dried in an oven at 70 ℃ to constant weight to obtain a precursor. Finally, under the protection of N2 with a flow rate of 50 mL / min, the precursor was heated to 900 ℃ at a rate of 5 ℃ / min in a tube furnace, and kept for 4 h to obtain the carbon-doped boron nitride non-metallic catalyst, which is denoted as BCN-2.

[0072] Take 40 mL of 0.12 mmol / L 4-NP reaction solution containing 20% ethanol and 20 mg of ground BCN-2 non-metallic catalyst and add them to the reaction tube, mix thoroughly and maintain a nitrogen atmosphere; put it into the light reaction instrument, turn on the xenon lamp light and open the circulating water to make the reaction proceed at room temperature. Take the reaction solution and filter it every certain time interval, and analyze the filtrate using a UV-visible spectrophotometer or high-performance liquid chromatography (HPLC), and the conversion rate and selectivity of 4-NP are both 100%. The apparent kinetic constant is 0.81 min -1 .

[0073] Example 2

[0074] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as in Example 1.

[0075] Take 40 mL of 0.12 mmol / L 4-NP solution, 10 mg of glucose and 20 mg of ground BCN-2 non-metallic catalyst and add them to the reaction tube, mix thoroughly and maintain a nitrogen atmosphere; put it into the light reaction instrument, turn on the xenon lamp light and open the circulating water to make the reaction proceed at room temperature. Take the reaction solution and filter it every certain time interval, and analyze the filtrate using a UV-visible spectrophotometer, and the apparent kinetic constant is 0.41 min -1 .

[0076] Example 3

[0077] Preparation of carbon-doped boron nitride (BCN) non-metallic catalyst: first, 18.92 g of melamine, 18.550 g of boric acid and 4.5 g of glucose were added to 800 mL of deionized water, heated to 95 ℃ to completely dissolve them. Then, 90 ℃ water bath for 6 h, then naturally cool to room temperature, precipitate crystals, filter, dry to constant weight in an oven at 70 ℃, to obtain the precursor. Finally, under the protection of N2 with a flow rate of 50 mL / min, the precursor was heated to 900 ℃ at a rate of 5 ℃ / min in a tube furnace, and kept for 4 h to obtain the carbon-doped boron nitride non-metallic catalyst, which is denoted as BCN-1.

[0078] Take 40 mL of 0.12 mmol / L 4-NP reaction solution containing 20% ethanol and 20 mg of BCN-1 non-metallic catalyst after grinding, mix thoroughly, maintain a nitrogen atmosphere; put into the light reaction instrument, turn on the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction solution and filter, using ultraviolet visible spectrophotometer to analyze the filtrate, the apparent kinetic constant is 0.11 min -1 .

[0079] Example 4

[0080] Preparation of carbon-doped boron nitride (BCN) non-metallic catalyst: first, 18.92 g of melamine, 18.550 g of boric acid and 4.5 g of glucose were added to 800 mL of deionized water, heated to 95 ℃ to completely dissolve them. Then, 90 ℃ water bath for 6 h, then naturally cool to room temperature, precipitate crystals, filter, dry to constant weight in an oven at 70 ℃, to obtain the precursor. Finally, under the protection of N2 with a flow rate of 50 mL / min, the precursor was heated to 900 ℃ at a rate of 5 ℃ / min in a tube furnace, and kept for 4 h to obtain the carbon-doped boron nitride non-metallic catalyst, which is denoted as BCN-1.

[0081] Take 40 mL of 0.12 mmol / L 4-NP reaction solution containing 20% ethanol and 20 mg of BCN-1 non-metallic catalyst after grinding, mix thoroughly, maintain a nitrogen atmosphere; put into the light reaction instrument, turn on the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction solution and filter, using ultraviolet visible spectrophotometer to analyze the filtrate, the apparent kinetic constant is 0.11 min -1 .

[0082] Example 5

[0083] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as that of Example 3.

[0084] Take 40 mL of 0.12 mmol / L 4-NP solution, 10 mg of glucose and 20 mg of BCN-1 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer for analysis, apparent kinetic constant is 0.02 min -1 .

[0085] Example 6

[0086] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as example 4.

[0087] Take 40 mL of 0.12 mmol / L 4-NP solution, 10 mg of glucose and 20 mg of BCN-1 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer for analysis, apparent kinetic constant is 0.02 min -1 .

[0088] Example 7

[0089] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as example 1.

[0090] Take 40 mL of 0.12 mmol / L 4-NP solution containing 10% ethanol and 20 mg of BCN-2 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer for analysis, apparent kinetic constant is 0.56 min -1 .

[0091] Example 8

[0092] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as example 1.

[0093] Take 40 mL of 0.12 mmol / L 4-NP solution containing 30% ethanol and 20 mg of BCN-2 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer for analysis, apparent kinetic constant is 1.53 min -1 .

[0094] Example 9

[0095] The preparation of the carbon-doped boron nitride non-metallic catalyst is the same as that of Example 1.

[0096] Take 40 mL of 0.12 mmol / L 4-NP reaction solution containing 10% ethanol and 10 mg of BCN-2 non-metallic catalyst after grinding, mix thoroughly, maintain a nitrogen atmosphere; put into the photochemical reactor, turn on the xenon lamp light, open the circulating water to make the reaction at room temperature. Take the reaction solution and filter every interval, analyze the filtrate by ultraviolet visible spectrophotometer, the apparent kinetic constant is 0.36 min -1 .

[0097] Example 10

[0098] The preparation of the carbon-doped boron nitride non-metallic catalyst is the same as that of Example 1.

[0099] Take 40 mL of 0.12 mmol / L 4-NP reaction solution containing 30% ethanol and 10 mg of BCN-2 non-metallic catalyst after grinding, mix thoroughly, maintain a nitrogen atmosphere; put into the photochemical reactor, turn on the xenon lamp light, open the circulating water to make the reaction at room temperature. Take the reaction solution and filter every interval, analyze the filtrate by ultraviolet visible spectrophotometer, the apparent kinetic constant is 1.43 min -1 .

[0100] Example 11

[0101] The preparation of the carbon-doped boron nitride non-metallic catalyst is the same as that of Example 1.

[0102] Take 40 mL of 0.12 mmol / L 4-NP solution, 20 mg of glucose and 20 mg of BCN-2 non-metallic catalyst after grinding, mix thoroughly, maintain a nitrogen atmosphere; put into the photochemical reactor, turn on the xenon lamp light, open the circulating water to make the reaction at room temperature. Take the reaction solution and filter every interval, analyze the filtrate by ultraviolet visible spectrophotometer, the apparent kinetic constant is 0.76 min -1 .

[0103] Example 12

[0104] The preparation of the carbon-doped boron nitride non-metallic catalyst is the same as that of Example 1.

[0105] Take 40 mL of 0.12 mmol / L 4-NP solution, 30 mg of glucose and 20 mg of BCN-2 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; Put into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer to analyze the filtrate, apparent kinetic constant is 1.36 min -1 .

[0106] Example 13

[0107] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as that in Example 1.

[0108] Take 40 mL of 0.12 mmol / L 4-NP solution, 20 mg of glucose and 10 mg of BCN-2 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; Put into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer to analyze the filtrate, apparent kinetic constant is 0.53 min -1 .

[0109] Example 14

[0110] The preparation of carbon-doped boron nitride non-metallic catalyst is the same as that in Example 1.

[0111] Take 40 mL of 0.12 mmol / L 4-NP solution, 30 mg of glucose and 10 mg of BCN-2 non-metallic catalyst after grinding into the reaction tube, mix evenly, maintain nitrogen atmosphere; Put into the light reaction instrument, open the xenon lamp light, open the circulating water to make the reaction at room temperature. Reaction every interval a certain time to take the reaction liquid and filter, using ultraviolet visible spectrophotometer to analyze the filtrate, apparent kinetic constant is 1.12 min -1 .

[0112] Photocatalytic test:

[0113] 1) 4-NP is added to the ethanol solution, and 4-NP is added to the ethanol solution containing BCN-2, and UV-Vis spectrum test is carried out on the two mixed solutions, which can be seen from Figure 1 that the characteristic absorption peak of 4-NP in the ethanol solution is 318 nm, and after adding BCN-2, the solution is alkaline, and the characteristic peak of 4-NP is right shifted to 400 nm.

[0114] 2) UV-Vis of BCN-1, BCN-2 and BCN-3 photocatalysts prepared by the application are used as reducing agent to photocatalytically reduce 4-NP Figures 2 to 6The peak at 400 nm in each figure represents the characteristic absorption peak of 4-NP, and the peak at 297 nm represents the characteristic absorption peak of 4-AP. As the catalytic time is prolonged, the absorption peak of 4-NP gradually weakens, and the absorption peak of 4-AP gradually strengthens, indicating that 4-NP is successfully photocatalytically reduced to 4-AP.

[0115] 3) Test of 4-NP conversion rate: the high performance liquid chromatogram of the photocatalytic reduction process of 4-NP with BCN-2 as photocatalyst and 20% ethanol as reducing agent is as shown in Figure 7 It can be seen from Figure 7 that the conversion rate and selectivity of 4-NP are both 100%.

[0116] 4) The reaction rate of photocatalytic reduction of 4-NP with different carbon doping amounts of BCN catalysts (BCN-1, BCN-2 and BCN-3) prepared in Examples 1 to 6 in combination with different reducing agents (ethanol or glucose) is known from Figure 8 that the activity of BCN-2 as catalyst is the best.

[0117] 5) Morphology and structure test of BCN

[0118] As shown in Figure 9 , Figure 10 and Figure 11 , the morphology and structure of BCN are fibrous structure, there are a large number of mesopores, and have a large specific surface area, which can fully expose active sites and improve the photocatalytic efficiency. The lattice spacing of BCN is 0.361 nm, indicating that carbon elements are successfully doped into the BN lattice, which increases the lattice spacing. Figure 12 It is shown that after successful carbon doping, there is a obvious absorption peak at 450 nm, which significantly improves the absorption of the sample in the visible light region.

[0119] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. A method for chemical detoxification of p-nitrophenol, characterized by: The method comprises the following steps: S1, adding a p-nitrophenol solution, a reducing agent and a carbon-doped boron nitride non-metallic photocatalyst into a quartz reaction tube, stirring uniformly, discharging oxygen and maintaining an atmosphere by nitrogen; S2, placing the mixed reaction system into a light reaction instrument, turning on a xenon lamp as a light source, opening circulating water, and reacting for 8-60 min at room temperature; S3, filtering the reaction liquid to obtain a low-toxicity p-aminophenol compound; The preparation method of the carbon-doped boron nitride non-metallic photocatalyst comprises the following steps: a, adding melamine, boric acid and glucose into deionized water, heating to 95 ℃ to completely dissolve them; b, 90 ℃ water bath for 6 h, then naturally cooling to room temperature, precipitating crystals, filtering, and drying to constant weight in an oven at 70 ℃ to obtain a precursor; c, under the protection of N2 with a flow rate of 50-200 mL / min, heating the precursor to 900 ℃ at a rate of 5 ℃ / min in a tube furnace, and maintaining for 4 h to obtain the carbon-doped boron nitride non-metallic photocatalyst; The amount ratio of the melamine, boric acid, glucose and deionized water is: 18.92 g: 18.550 g: (4.5-13.5) g: 800 mL.

2. The method of chemical detoxification of p-nitrophenol according to claim 1, characterized by: The reducing agent is one of ethanol or glucose, and the ethanol is analytical pure.

3. The method of chemical detoxification of p-nitrophenol according to claim 2, characterized by that: In step S1, when the reducing agent is ethanol, first add ethanol into the p-nitrophenol solution to prepare a 0.12 mmol / L p-nitrophenol reaction liquid containing ethanol, wherein the volume percentage of ethanol is 10-30%, then mix the p-nitrophenol reaction liquid containing ethanol and the carbon-doped boron nitride, and the amount ratio of the two is: 40 mL: 5-20 mg; when the reducing agent is glucose, the amount ratio of the p-nitrophenol solution, glucose and carbon-doped boron nitride is: 40 mL: 10-30 mg: 5-20 mg, and the concentration of the p-nitrophenol solution is 0.12 mmol / L.

4. The method of chemical detoxification of p-nitrophenol according to claim 1, characterized by that: In step S2, a 300 W xenon lamp is used as a light source to simulate sunlight.

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