Preparation method of nitrogen vacancy-rich cobalt nitride nanowires and application thereof in deep treatment of antibiotic wastewater

Abstract

The present application relates to a preparation method of nitrogen vacancy-rich cobalt nitride nanowires and its application in deep treatment of antibiotic wastewater. The present application introduces a large number of nitrogen defects into cobalt nitride through metal doping method, enhances the adsorption capacity of cobalt nitride for oxygen-containing substances, and solves the main difficult problem restricting the application of cobalt nitride in advanced oxidation process. The catalytic material shows great application potential in peroxoacetic acid activation process, and the activation efficiency of peroxoacetic acid and the degradation efficiency of pollutants can reach 100% within 5 min. In addition, the introduction of nitrogen defects effectively controls the generation of selective oxidation species Co(IV)=O in the process, which can realize the selective removal of pollutants. It also shows strong pH tolerance and environmental background resistance, and is more suitable for the treatment of actual wastewater.

Description

Technical Field

[0001] This invention relates to a method for preparing cobalt nitride nanowires rich in nitrogen vacancies and their application in the advanced treatment of antibiotic wastewater, belonging to the field of new materials and environmental technology. Background Technology

[0002] In recent years, trace organic pollutants such as endocrine disruptors, pharmaceuticals, and personal care products have been frequently detected in the environment, posing a serious threat to water quality, the environment, and human health. Advanced oxidation processes are effective technologies for degrading trace organic pollutants, such as persulfate and hydrogen peroxide activation technologies. Among these, peracetic acid (PAA), with its excellent oxidation, disinfection, and sterilization functions, is attracting increasing attention from researchers. The dissociation energy of the O2O bond in peracetic acid is 159 kJ / mol. -1 The concentration of hydrogen peroxide (213 kJ / mol) is much lower than that of hydrogen peroxide. -1 ) and persulfate (317 kJ mol) -1 Peracetic acid can be activated more efficiently through various methods such as ultraviolet light, ultrasound, metal ions, and heterogeneous catalysts to generate various reactive oxygen species, such as hydroxyl radicals (·OH) and organic radicals (RO·). However, these activation technologies suffer from high costs, high energy consumption, and serious secondary pollution, which severely affect the stable and long-term operation of wastewater purification systems. Therefore, the development of efficient, green, and economical peracetic acid activation catalysts has become an urgent task.

[0003] Transition metal nitrides exhibit significant advantages in catalysis due to their unique electronic structure, high electrical conductivity, and acid-base chemical stability. Compared to common transition metal oxides, transition metal nitrides demonstrate more pronounced metallicity, with nitrogen atoms occupying interstitial positions in their metallic structures. This influences the local electronic structure and alters the chemical reaction properties. On one hand, they provide reactants and products with adsorption strength similar to noble metals; on the other hand, the bonding energy between the metal and nitrogen promotes more efficient electron transfer, resulting in higher conductivity. Furthermore, the reduced d-band electron center further enhances catalytic activity.

[0004] Currently, cobalt nitride is mainly used in photocatalysis and electrocatalysis, but its exploration and research in advanced oxidation processes have not yet begun. The main challenge lies in the limited adsorption capacity of cobalt nitride for oxygen-containing substances, which prevents it from effectively enriching oxidants and contaminants on the surface and triggering catalytic reactions. Introducing nitrogen defects into the catalyst is an effective way to solve this problem. In addition, defect engineering can also adjust the electronic structure, lower the activation energy barrier, and enhance electron transfer at the interface. Currently, commonly used methods for constructing defects include doping, reduction, etching, ball milling, and plasma methods. Among these, the method of introducing defects using lattice doping has advantages such as low cost, greenness, no pollution, and high stability, and can achieve precise control over the material structure. However, due to the special bonding mode and crystal structure of metal nitrides, lattice doping of metal ions on their matrix is ​​difficult to achieve.

[0005] Therefore, by introducing a large number of nitrogen defects into cobalt nitride through a novel, low-cost, and environmentally friendly method and applying it to advanced oxidation processes, ultra-efficient activation of peracetic acid and ultra-rapid degradation of pollutants have been achieved, which is of great significance for the degradation of pollutants. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing cobalt nitride nanowires rich in nitrogen vacancies and their application in the advanced treatment of antibiotic wastewater. Invention Overview:

[0008] This invention introduces a large number of nitrogen defects into cobalt nitride nanowires by in-situ doping with metals during the synthesis of the cobalt nitride precursor, and applies it to advanced oxidation processes for the first time. The construction of nitrogen defects effectively enhances the catalyst's adsorption capacity for oxygen-containing species and promotes the enrichment of oxidants, effectively solving the key challenges that have traditionally limited the application of metal nitrides in advanced oxidation processes. This material exhibits ultra-high peracetic acid utilization and pollutant removal rates in peracetic acid-based advanced oxidation processes, and can effectively resist interference from real-world environmental backgrounds, demonstrating great potential for practical applications. Furthermore, the entire preparation process utilizes readily available and inexpensive raw materials, is simple to operate, and is conducive to industrial-scale production.

[0009] The technical solution of the present invention is as follows:

[0010] A method for preparing cobalt nitride nanowires rich in nitrogen vacancies includes the following steps:

[0011] (1) Co(NO3)2, NH4F and CO(NH2)2 were dissolved together in water, and then a metal salt solution was added. After stirring evenly, a hydrothermal reaction was carried out. After cooling down, the mixture was washed with ethanol and water and dried to obtain metal-doped Co(CO3). 0.5 (OH)·0.11H2O precursor;

[0012] (2) Doping the metal with Co(CO3) 0.5 Cobalt nitride nanowires rich in nitrogen vacancies were prepared by calcining the (OH)·0.11H2O precursor under an ammonia atmosphere and then pyrolyzing it.

[0013] According to a preferred embodiment of the present invention, in step (1), the molar ratio of Co(NO3)2, NH4F and CO(NH2)2 is 1:(1-5):(4-10).

[0014] More preferably, in step (1), the molar ratio of Co(NO3)2, NH4F and CO(NH2)2 is 1:2:5.

[0015] According to a preferred embodiment of the present invention, in step (1), the molar ratio of Co(NO3)2 to the volume ratio of water is (1-3):(20-40), in mmol / mL.

[0016] According to a preferred embodiment of the present invention, in step (1), the metal salt solution is one of Cu(NO3)2 solution, Mn(NO3)2 solution, and Ni(NO3)2 solution.

[0017] Most preferably, in step (1), the metal salt solution is a Mn(NO3)2 solution.

[0018] More preferably, in step (1), the concentration of the metal salt solution is 0.05-0.3 mol / L, and the molar ratio of the metal salt to Co(NO3)2 in the metal salt solution is (0-0.13):1.

[0019] Most preferably, in step (1), the molar ratio of the metal salt to Co(NO3)2 in the metal salt solution is 0.07:1.

[0020] According to a preferred embodiment of the present invention, in step (1), the hydrothermal reaction temperature is 110-130°C and the hydrothermal time is 4-8h.

[0021] According to a preferred embodiment of the present invention, in step (1), washing with ethanol and water means washing with ethanol and water alternately by centrifugation three times each.

[0022] According to a preferred embodiment of the present invention, in step (1), the drying is performed at 50-70°C for 10-16 hours.

[0023] According to a preferred embodiment of the present invention, in step (2), the heating rate of calcination is 4-10℃ / min.

[0024] According to a preferred embodiment of the present invention, in step (2), the heating and calcination temperature is 400-500℃ and the calcination time is 100-160min.

[0025] More preferably, in step (2), the heating and calcination temperature is 460℃ and the calcination time is 120 min.

[0026] According to a preferred embodiment of the present invention, in step (2), the ammonia flow rate is 300-600 sccm, and after removing the sample, it is ground into powder and passed through a 100-mesh sieve.

[0027] A cobalt nitride nanowire rich in nitrogen vacancies was prepared using the method described above.

[0028] The above-mentioned cobalt nitride nanowires rich in nitrogen vacancies are used in the advanced treatment of antibiotic wastewater.

[0029] According to a preferred embodiment of the present invention, the specific application method steps are as follows: at room temperature, cobalt nitride catalyst rich in nitrogen vacancies and peracetic acid are added to the pollutant solution, and the mixture is stirred to carry out a catalytic degradation reaction.

[0030] According to a preferred embodiment of the present invention, the contaminant is an antibiotic or a phenolic contaminant, the contaminant concentration is 15-35 μmol / L, and the pH of the contaminant solution is 3-11.

[0031] According to a preferred embodiment of the present invention, the dosage of the catalyst is 0.01-0.2 g / L.

[0032] The most preferred catalyst dosage is 0.05 g / L.

[0033] According to a preferred embodiment of the present invention, the dosage of peracetic acid is 100-400 μmol / L.

[0034] The most preferred dosage of peracetic acid is 200 μmol / L.

[0035] The beneficial effects of this invention are:

[0036] 1. The raw materials selected in this invention are readily available and inexpensive. Through simple in-situ metal doping, the nitrogen defects of cobalt nitride materials can be controlled, thereby further improving their catalytic activity.

[0037] 2. This invention significantly improves the adsorption efficiency of cobalt nitride catalyst for oxygen-containing substances by introducing nitrogen defects into it, thereby enhancing its ability to activate peracetic acid and achieving ultra-efficient degradation of organic pollutants. In addition, the introduction of nitrogen defects also enhances the high efficiency and selectivity for reactive oxygen species, which is more conducive to the selective degradation of pollutants.

[0038] 3. The cobalt nitride nanowire system rich in nitrogen vacancies prepared in this invention for activating PAA has strong pH tolerance and can effectively resist the influence of natural environmental background, showing great potential in actual wastewater treatment. Attached Figure Description

[0039] Figure 1 The XRD patterns are those of cobalt nitrides containing different nitrogen vacancies prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention.

[0040] Figure 2 XPS spectra of cobalt nitride containing different nitrogen vacancies prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention.

[0041] Figure 3 The EPR spectra of cobalt nitride containing different nitrogen vacancies prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0042] Figure 4 This is a comparison chart showing the efficiency of cobalt nitride with different nitrogen vacancies in activating peracetic acid prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of the present invention.

[0043] Figure 5 This is a comparison chart showing the performance of cobalt nitride-activated peracetic acid with different nitrogen vacancies in degrading sulfonamides against methoxypyrimidine, prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of the present invention.

[0044] Figure 6 The effects of different cobalt nitride activated peracetic acid with different nitrogen vacancies prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention on PMSO consumption, PMSO2 generation and PMSO2 generation rate.

[0045] Figure 7 The effect of different catalyst dosages on the degradation performance of sulfonamides on methoxypyrimidine.

[0046] Figure 8 The effect of different peracetic acid dosages on the degradation performance of sulfonamides on methoxypyrimidine.

[0047] Figure 9 The effect of different pH values ​​on the degradation performance of sulfonamides on methoxypyrimidine.

[0048] Figure 10 The effect of different coexisting anions on the degradation performance of sulfonamides on methoxypyrimidine. Detailed Implementation

[0049] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

[0050] The raw materials used in the examples are all commercially available products.

[0051] Example 1

[0052] A method for preparing cobalt nitride nanowires rich in nitrogen vacancies, comprising the following steps:

[0053] (1) Dissolve 1.5 mmol Co(NO3)2, 3 mmol NH4F and 7.5 mmol CO(NH2)2 in 30 mL of water, and then add 1 mL of 0.1 mol / L Mn(NO3)2 solution and mix well.

[0054] (2) Transfer the solution obtained in step (1) to a hydrothermal reactor and hydrothermally react at 120°C for 5 hours. After cooling down, take it out and wash the sample three times each with ethanol and water. Place the obtained solid sample in an oven and dry it at 60°C for 12 hours.

[0055] (3) The sample obtained after drying in step (2) is placed in a tube furnace and heated to 450°C at a heating rate of 5°C / min under an ammonia atmosphere. It is then calcined at 450°C for 120 min and allowed to cool naturally to room temperature. After that, it is taken out, ground and sieved to obtain a cobalt nitride catalyst rich in nitrogen vacancies, denoted as Co4N / CoN-1Mn.

[0056] Application in the advanced treatment of antibiotic wastewater:

[0057] Take 5 mg of the nitrogen-vacancy-rich cobalt nitride catalyst synthesized in step (3) and add it to 100 mL of simulated wastewater with a sulfamethoxypyrimidine concentration of 20 μmol / L (pH = 7). Then add 200 μL of 0.1 mol / L peracetic acid solution to trigger the catalytic reaction.

[0058] During the reaction, samples were taken at certain time intervals, and the active substances in the samples were quenched with 0.05 mol / L Na2S2O3. The concentration of the samples was then determined by high performance liquid chromatography.

[0059] Example 2

[0060] The preparation method is the same as described in Example 1, except that in step (1), the volume of the 0.1 mol / L Mn(NO3)2 solution added is 0.5 mL. The rest of the operation and dosage are exactly the same as in Example 1. The obtained catalyst is denoted as Co4N / CoN-0.5Mn.

[0061] Example 3

[0062] The preparation method is the same as described in Example 1, except that in step (1), the volume of the 0.1 mol / L Mn(NO3)2 solution added is 1.5 mL. The rest of the operation and dosage are exactly the same as in Example 1. The obtained catalyst is denoted as Co4N / CoN-1.5Mn.

[0063] Example 4

[0064] The preparation method is the same as described in Example 1, except that in step (1), the volume of the 0.1 mol / L Mn(NO3)2 solution added is 2 mL. The rest of the operation and dosage are exactly the same as in Example 1. The obtained catalyst is denoted as Co4N / CoN-2Mn.

[0065] Comparative Example 1

[0066] The preparation method is the same as described in Example 1, except that in step (1), Mn(NO3)2 solution is not added. The rest of the operation and dosage are exactly the same as in Example 1. The catalyst obtained is denoted as Co4N / CoN.

[0067] Experimental Example 1

[0068] The XRD patterns of the cobalt nitride catalysts prepared in Examples 1, 2, 3, 4 and Comparative Example 1 are shown below. Figure 1 As shown. (Through) Figure 1 It can be seen that the CoN / Co4N composite material was successfully synthesized. Furthermore, the manganese doping did not affect the material's structural species, indicating that the doping amount was extremely small.

[0069] XPS plots of the cobalt nitride catalysts prepared in Examples 1, 2, 3, 4 and Comparative Example 1 are shown below. Figure 2 As shown. With increasing manganese doping concentration, Co... 3+ The peak shifts to higher binding energies, which can be attributed to the increased degree of electron delocalization of Co atoms, confirming that the electronic structure is significantly affected by manganese doping.

[0070] The EPR spectra of the cobalt nitride catalysts prepared in Example 1 and Comparative Example 1 are as follows: Figure 3 As shown, manganese doping significantly increases nitrogen vacancies in cobalt nitride materials.

[0071] Experimental Example 2

[0072] Examples 1, 2, 3, 4 and Comparative Example 1 show different doping levels of Mn. 2+ The performance of catalysts in activating peracetic acid, for example Figure 4 As shown, the activation efficiency of peracetic acid increases significantly with increasing manganese doping, demonstrating the important role of nitrogen vacancies in the activation process of peracetic acid.

[0073] Experiment Example 3

[0074] Examples 1, 2, 3, 4 and Comparative Example 1 show different doping levels of Mn. 2+ The performance of catalyst-activated peracetic acid in degrading pollutants, for example Figure 5As shown, with increasing manganese doping, the removal efficiency of sulfonamides for methoxypyrimidine significantly improved, indicating that nitrogen defects promoted the activation of peracetic acid to generate more active substances that degrade pollutants.

[0075] Experiment Example 4

[0076] Using benzyl sulfoxide (PMSO) as a probe for high-metallic substances, and taking advantage of the characteristic that PMSO can undergo oxygen atom transfer with high-valence metals to form PMSO2, this study investigated the effects of different doping levels of Mn. 2+ The effect on the generation of high-valent cobalt during the activation of peracetic acid by catalyst. Figure 6 Examples 1, 2, 3, 4, and Comparative Example 1 show Mn with different doping amounts. 2+ Experimental results on the effect of catalyst-activated peracetic acid on PMSO conversion. The results show that as Mn... 2+ With the increase of doping amount, the nitrogen vacancy concentration in the catalyst increases, and the conversion rate of PMSO to PMSO2 is also significantly improved, indicating that the introduction of nitrogen defects promotes the catalyst's ability to selectively generate Co(IV)=O from peracetic acid.

[0077] Comparative Example 2

[0078] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0079] The catalyst was added at a mass of 0 mg, and the rest of the operation and dosage were exactly the same as in Example 1.

[0080] Comparative Example 3

[0081] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0082] The catalyst was added at a mass of 10 mg, and the rest of the operation and dosage were exactly the same as in Example 1.

[0083] Comparative Example 4

[0084] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0085] The catalyst was added at a mass of 20 mg, and the rest of the operation and dosage were exactly the same as in Example 1.

[0086] Experimental Example 5

[0087] The effects of different nitrogen-vacancy-rich cobalt nitride catalytic dosages on the degradation of pollutants by active peracetic acid, such as Figure 7As shown, when the catalyst dosage is 0.05 g / L, pollutants can be completely removed within 5 minutes. When the catalyst dosage exceeds 0.05 g / L, its pollutant removal efficiency decreases, which may be because excessive catalyst addition may cause catalyst agglomeration and block some active sites.

[0088] Comparative Example 5

[0089] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0090] The mass of 0.1 mol / L peracetic acid solution added was 0 μL, and the rest of the operation and dosage were exactly the same as in Example 1.

[0091] Comparative Example 6

[0092] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0093] The dosage of 0.1 mol / L peracetic acid solution was 100 μL, and the rest of the operation and dosage were exactly the same as in Example 1.

[0094] Comparative Example 7

[0095] The application of activated peracetic acid for removing pollutants from water as described in Example 1 differs in that...

[0096] The dosage of 0.1 mol / L peracetic acid solution was 300 μL, and the rest of the operation and dosage were exactly the same as in Example 1.

[0097] Experimental Example 6

[0098] The effect of different peracetic acid dosages on the degradation of pollutants by active peracetic acid, such as Figure 8 As shown, as the dosage of peracetic acid gradually increases, the system generates more active species, leading to a significant increase in the removal rate of methoxypyrimidine by sulfonamides.

[0099] Experiment Example 7

[0100] As described in Example 1, the only difference is that in step (4), the pH of the simulated wastewater is adjusted to 3, 5, 9, and 11, while the rest of the operation and dosage are exactly the same as in Example 1.

[0101] The effect of different pH values ​​on the degradation of pollutants by active peracetic acid, such as Figure 9 As shown, this oxidation system can efficiently remove pollutants across a wide pH range (3-11).

[0102] Example 8

[0103] As described in Example 1, the difference is that in step (4), various anions (Cl-) present in actual water bodies are added to the simulated wastewater. - HCO3 - H2PO4 - NO3 - SO4 2- The remaining operations and dosages are exactly the same as in Example 1.

[0104] Figure 10 The effects of different coexisting anions on the degradation of pollutants by the oxidation system are shown. This oxidation system effectively resists interference from various coexisting anions, indicating its suitability for pollutant removal in real-world water bodies.

Claims

1. A method for preparing nitrogen vacancy-rich cobalt nitride nanowires, comprising the following steps: (1) Co(NO3)2, NH4F and CO(NH2)2 are dissolved in water, then a metal salt solution is added, and after stirring, a hydrothermal reaction is carried out, and after cooling, the product is washed with ethanol and water, dried, and a metal-doped Co(CO3) 0.5 (OH)·0.11H2O precursor is obtained; the metal salt solution is one of Cu(NO3)2 solution, Mn(NO3)2 solution and Ni(NO3)2 solution; (2) The metal-doped Co(CO3) 0.5 The nitrogen vacancy-rich cobalt nitride nanowire material is prepared by heating and calcining the metal-doped Co(CO3) (OH)·0.11H2O precursor in an ammonia atmosphere and using ammonia pyrolysis.

2. The production method according to claim 1, characterized by, In step (1), the molar ratio of Co (NO3) 2, NH4F and CO (NH2) 2 is 1: (1-5): (4-10), and the molar amount of Co (NO3) 2 to the volume of water is (1-3): (20-40) mmol / mL.

3. The production method according to claim 1, characterized by, In step (1), the concentration of the metal salt solution is 0.05-0.3 mol / L, and the molar ratio of metal salt to Co (NO3) 2 in the metal salt solution is 0.07:

1.

4. The method of claim 1, wherein, In step (1), the hydrothermal reaction temperature is 110-130℃, and the hydrothermal time is 4-8 h.

5. The preparation method according to claim 1, characterized in that, Washing with ethanol and water means that each is washed three times alternately by centrifugation, and drying is carried out at 50-70℃ for 10-16 h.

6. The method of claim 1, wherein, In step (2), the heating rate of heating calcination is 4-10℃ / min, the heating calcination temperature is 400-500℃, and the calcination time is 100-160 min.

7. The preparation method according to claim 1, characterized in that, In step (2), the heating calcination temperature is 460℃, the calcination time is 120 min, the ammonia flow rate is 300-600 sccm, the sample is removed, ground into powder and sieved through a 100 mesh sieve. 8.Nitrogen vacancy-rich cobalt nitride nanowires prepared by the method of any one of claims 1-7. 9.The use of the nitrogen vacancy-rich cobalt nitride nanowires of claim 8 in the deep treatment of antibiotic wastewater.

10. Use according to claim 9, characterized in that, The specific application method comprises the following steps: at room temperature, nitrogen vacancy-rich cobalt nitride catalyst and peroxyacetic acid are added to the pollutant solution, and the catalytic degradation reaction is carried out by stirring. The pollutant is an antibiotic or a phenolic pollutant, the pollutant concentration is 15-35 µmol / L, the pollutant solution pH is 3-11, the catalyst dosage is 0.01-0.2 g / L, and the peroxyacetic acid dosage is 0.1-400 µmol / L.

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