Nickel-bismuth composite nitrogen-doped carbon materials, their preparation methods and applications

Abstract

This invention belongs to the field of catalysts, specifically relating to a nickel-bismuth composite nitrogen-doped carbon material, its preparation method, and its application. The preparation method includes the following steps: 1) adding a ligand to a mixed metal source of nickel and bismuth and mixing it uniformly in a solvent; 2) adding a nitrogen source to the mixture obtained in step 1) and performing a solvothermal reaction to obtain a precursor; 3) calcining the precursor to obtain the nickel-bismuth composite nitrogen-doped carbon material. The catalyst of this application organically combines adsorption and photocatalytic functions, resulting in a Bi-Ni / NC composite adsorption photocatalyst exhibiting excellent adsorption capacity for tetracycline in water and good visible light photocatalytic degradation performance.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to a nickel-bismuth composite nitrogen-doped carbon material, its preparation method, and its application. Background Technology

[0002] Antibiotics are indispensable drugs in medical and animal husbandry fields, with widespread and far-reaching applications. However, in recent years, the overuse of antibiotics has become increasingly serious, leading to growing antibiotic pollution and its resulting ecological risks, posing a global environmental challenge. Tetracycline, as a broad-spectrum and relatively inexpensive antibiotic, is particularly common in the prevention and treatment of animal diseases in livestock farming, with both its production and usage being substantial. Due to their stable molecular structure, tetracycline antibiotics are difficult to fully metabolize and degrade in animals, resulting in large amounts of residues being released into the environment through feces. Because of their high stability and antibacterial properties in the environment, tetracycline is not easily biodegraded, thus accumulating continuously.

[0003] Tetracycline is currently widely detected in surface water, groundwater, and drinking water sources. Unfortunately, traditional water treatment methods are ineffective in removing tetracycline from water. Tetracycline pollution not only has chronic toxicological effects on aquatic organisms and disrupts the ecological balance of aquatic ecosystems, but it can also enter the human body through drinking water and the food chain, affecting immunity and potentially leading to health problems such as kidney issues, joint diseases, endocrine disorders, and central nervous system abnormalities. Furthermore, it can promote antibiotic resistance in pathogens, leading to the emergence of "superbugs." Given these increasingly serious health threats and ecological risks, developing a highly efficient and low-energy-consumption technology for removing tetracycline from water is particularly important and urgent, considering the widespread distribution and long-term effects of antibiotic pollution in water bodies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nickel-bismuth composite nitrogen-doped carbon material, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The present invention includes a method for preparing a nickel-bismuth composite nitrogen-doped carbon material, comprising the following steps: 1) adding a ligand to a mixed metal source of nickel and bismuth and mixing it uniformly in a solvent; 2) adding a nitrogen source to the mixture obtained in step 1) and performing a solvothermal reaction to obtain a precursor; 3) calcining the precursor to obtain the nickel-bismuth composite nitrogen-doped carbon material.

[0007] The nitrogen source is g-C3N4; the nitrogen source is prepared by calcining dicyandiamide at 500-600℃ for 2-6 hours, cooling to room temperature, and grinding the obtained product into powder to obtain nitrogen source g-C3N4; preferably, calcining at 550℃ for 4 hours.

[0008] The nickel source is nickel nitrate hexahydrate; the bismuth source is bismuth nitrate pentahydrate; and the solvent is N,N-dimethylformamide.

[0009] The molar ratio of nickel source to bismuth source in the mixed metal source is 3:1.

[0010] The ligand is a mixture of terephthalic acid and triethylenediamine in a molar ratio of 1:1; the molar ratio of the ligand to the metal source is 2:(0.32-0.68); preferably 2:0.32.

[0011] The ratio of the mass of nitrogen source added to the mass of metal source added is 8:(1-2.3); preferably 8:1.

[0012] In step 2), the temperature of the solvothermal reaction is room temperature, and the reaction time is 2-6 hours.

[0013] The calcination temperature in step 3) is 700-900℃, preferably 800℃; the calcination time is 0.5-2h, preferably 1h.

[0014] The present invention also includes a nickel-bismuth composite nitrogen-doped carbon material obtained by the preparation method described above.

[0015] The present invention also includes an application of the aforementioned nickel-bismuth composite nitrogen-doped carbon material for removing antibiotics from water, preferably tetracycline.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] When light of a specific wavelength irradiates a plasmonic metal, the free electrons within the metal are induced by the electromagnetic field to undergo collective oscillations, leading to a strong resonance phenomenon known as the surface plasmon resonance (SPR) effect. By stimulating the SPR effect in transition metals Bi and Ni, not only can the absorption capacity of photocatalysts for visible light be significantly enhanced, but high-energy hot electrons are also generated to participate in the photocatalytic reaction. Bi and Ni plasmonic metals are relatively inexpensive and have greater potential for practical applications. The synergistic effect between the two metals enables alloy nanoparticles to exhibit a stronger promoting effect.

[0018] At the interface between transition metals and nitrogen-doped carbon supports, a distinct metal-deficient region and a carbon-support-rich region are formed due to the rectified electron effect, effectively promoting the catalytic reaction. Furthermore, the carbon-nitrogen support exhibits good structural stability, effectively preventing the aggregation of active sites, and also possesses a large specific surface area, allowing for the full exposure of active sites during catalysis.

[0019] Therefore, the technical solution of this application selects nitrogen-doped carbon material as a carrier and combines it with plasma transition metals Bi and Ni to construct a highly efficient catalyst.

[0020] 1. The nickel-bismuth composite nitrogen-doped carbon material proposed in this invention fully considers the integration and complementarity of adsorbent components and photocatalytic functions in its design. On the one hand, the porous structure and large specific surface area of ​​the nitrogen-doped carbon support exhibit excellent adsorption capacity for tetracycline. On the other hand, by fully utilizing the SPR effect of Ni metal and Bi-Ni alloy, the catalyst can generate abundant photogenerated electrons and holes. Combined with the excellent conductivity of the nitrogen-doped carbon support, these photogenerated electrons and holes can be separated more effectively, further improving the catalytic efficiency of the catalyst under visible light, thus promoting more efficient visible light photocatalytic performance. This design organically combines the adsorption and photocatalytic functions of the catalyst, enabling the Bi-Ni / NC composite adsorption photocatalyst to have excellent adsorption capacity for tetracycline in water and good visible light photocatalytic degradation performance.

[0021] 2. The nickel-bismuth composite nitrogen-doped carbon material prepared by this invention exhibits significant adsorption and visible-light photocatalytic removal effects on tetracycline in water. For example, in the preferred embodiment 1, when the catalyst dosage is only 0.12 g / L, the adsorption and visible-light degradation removal rates for 100 mL of a 20 mg / L tetracycline solution can reach 87%. The adsorption performance for tetracycline is outstanding; in Example 1, with a catalyst dosage of 0.12 g / L, the dark adsorption equilibrium removal rate for 100 mL of a 40 mg / L tetracycline solution can reach 69%, and the equilibrium adsorption capacity reaches 219.28 mg·g⁻¹. -1 After further exposure to visible light, the removal rate can be further increased to 75%. The nickel-bismuth composite nitrogen-doped carbon photocatalyst is an adsorption photocatalyst capable of efficiently removing tetracycline pollutants from water under visible light. Attached Figure Description

[0022] Figure 1 This is the XPS spectrum of the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of this invention;

[0023] Figure 2 The XRD pattern of the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of this invention;

[0024] Figure 3 This is a SEM image of the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of this invention;

[0025] Figure 4 This is an adsorption and removal curve of tetracycline by the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of the present invention.

[0026] Figure 5 This is the curve showing the change in adsorption capacity of the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of this invention as a function of adsorption time.

[0027] Figure 6 The visible light catalytic degradation curve of tetracycline by the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst obtained in Example 1 of this invention is shown.

[0028] Figure 7 The graphs show the removal curves of tetracycline by the composite adsorption photocatalysts of the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅰ) obtained in Example 1, the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅱ) obtained in Example 2, and the nickel-bismuth composite nitrogen-doped carbon material Bi-Ni / NC(Ⅲ) obtained in Example 3. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0030] Example 1

[0031] A method for preparing a nickel-bismuth composite nitrogen-doped carbon (Bi-Ni / NC) composite adsorption photocatalyst, the specific operation of which is as follows:

[0032] (1) Place 10g of dicyandiamide into a 100mL covered crucible, heat it to 550℃ in a muffle furnace for 4h under an air atmosphere and keep it for 4h, then cool it naturally to room temperature, grind the obtained product into powder, and collect the sample to obtain nitrogen source g-C3N4.

[0033] (2) Add 0.24 mmol of nickel nitrate hexahydrate and 0.08 mmol of bismuth nitrate pentahydrate to 25 mL of N,N-dimethylformamide, and stir vigorously until a homogeneous solution is formed. Then add 0.151 g of terephthalic acid (1 mmol) and 0.108 g (1 mmol) of triethylenediamine, and sonicate for 1 h and stir for 1 h. Then add 0.8 g of nitrogen source g-C3N4 to the above liquid and stir magnetically for 3 h. After stirring, separate the precipitate, dry it in an oven at 80 °C for 12 h, and grind it into powder. Collect the precursor powder A and store it for later use.

[0034] (3) The precursor powder A was transferred to a covered quartz boat and calcined at 800℃ under nitrogen protection at a heating rate of 1.6℃ / min for 1 h. After cooling to room temperature, the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst was collected.

[0035] The XPS spectrum of the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst prepared in this embodiment is as follows: Figure 1 As shown, by Figure 1 It can be seen that the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst has peaks of C, N, O, Ni and Bi, and the N peak is obvious, indicating that nitrogen is successfully doped on the carbon support.

[0036] The XRD pattern of the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst prepared in this embodiment is as follows: Figure 2 As shown, by Figure 2 It can be seen that the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst has characteristic peaks of graphite carbon, Bi3Ni alloy and Ni metal on carbon support, which confirms that Bi3Ni alloy and Ni metal were successfully loaded on nitrogen-doped carbon support.

[0037] The SEM image of the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst prepared in this embodiment is as follows: Figure 3 As shown, by Figure 3 It can be seen that the metal particles in the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst are loaded onto a nitrogen-doped carbon support, and the material has a porous structure. The abundant pore structure gives it a large specific surface area, and the BET specific surface area of ​​the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst is 232.476 m². 2 ·g -1 .

[0038] The adsorption and visible light photocatalytic performance of the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst prepared in Example 1 were tested. The experimental process and results are as follows:

[0039] Adsorption Experiment: 12 mg of Bi-Ni / NC(Ⅰ) composite photocatalyst was added to 100 mL of a 40 mg / L tetracycline solution. Under dark conditions, the solution was continuously stirred for adsorption. At different adsorption times, 4 mL samples of the reaction mixture were taken, filtered through a 0.22 μm filter membrane, and the absorbance of the solution was measured at 357 nm using a UV-Vis spectrophotometer to obtain the remaining concentration of tetracycline after adsorption. The adsorption and removal curves of tetracycline by the Bi-Ni / NC(Ⅰ) composite photocatalyst were obtained, as shown below. Figure 4 As shown, the adsorption equilibrium removal rate of tetracycline in water by Bi-Ni / NC(Ⅰ) is 69%, and the adsorption equilibrium time is 3 hours. The adsorption capacity as a function of adsorption time can be calculated from the adsorption experimental results, as shown in the figure. Figure 5 As shown, the equilibrium adsorption capacity of Bi-Ni / NC(Ⅰ) is approximately 219.28 mg·g⁻¹. -1 This demonstrates that the Bi-Ni / NC(Ⅰ) composite photocatalyst exhibits excellent adsorption performance for tetracycline in water.

[0040] Visible light catalytic degradation experiment: 12 mg of Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst was added to 100 mL of a 40 mg / L tetracycline solution. Under dark conditions, the solution was continuously stirred for 3 h to reach adsorption equilibrium. Then, under xenon lamp irradiation with a total light power of 50 W and a visible light emission spectrum of 420–780 nm, visible light catalytic degradation was carried out. The irradiation time was 60 min, with sampling intervals of 10 min. 4 mL of the reaction mixture was drawn using a syringe, filtered through a 0.22 μm filter, and the absorbance was measured at 357 nm using a UV-Vis spectrophotometer to assess the remaining tetracycline concentration in the solution. The visible light catalytic degradation curve of tetracycline by the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst was obtained, as shown below. Figure 6 As shown, it can be seen that after Bi-Ni / NC(Ⅰ) removed 69% of tetracycline in water through adsorption equilibrium, it can further degrade tetracycline through visible light photocatalysis, increasing the removal rate to 75%. This indicates that the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst has good visible light photocatalytic degradation ability.

[0041] Example 2

[0042] The difference between Example 2 and Example 1 is that the amount of nickel nitrate hexahydrate added in step (2) is 0.36 mmol; the amount of bismuth nitrate pentahydrate is 0.12 mmol. This example ultimately yields a Bi-Ni / NC(Ⅱ) composite adsorption photocatalyst.

[0043] Example 3

[0044] The difference between Example 3 and Example 1 is that the amount of nickel nitrate hexahydrate added in step (2) is 0.51 mmol; the amount of bismuth nitrate pentahydrate is 0.17 mmol. This example finally yields a Bi-Ni / NC(Ⅲ) composite adsorption photocatalyst.

[0045] The performance of the three composite adsorption photocatalysts, Bi-Ni / NC(Ⅰ), Bi-Ni / NC(Ⅱ), and Bi-Ni / NC(Ⅲ), prepared in Examples 1, 2, and 3 were tested and compared. The experimental process and results are as follows:

[0046] 12 mg each of Bi-Ni / NC(Ⅰ), Bi-Ni / NC(Ⅱ), and Bi-Ni / NC(Ⅲ) were added to 100 mL of a 20 mg / L tetracycline solution. The mixture was stirred continuously for 30 min under dark conditions for dark adsorption. Then, a visible light catalytic degradation reaction was carried out under irradiation with a visible light emission spectrum of 420–780 nm. The irradiation time was 60 min, with sampling intervals of 10 min. 4 mL of the reaction mixture was drawn up using a syringe, filtered through a 0.22 μm filter, and the absorbance was measured at 357 nm using a UV-Vis spectrophotometer to assess the remaining tetracycline concentration in the solution. Removal curves of tetracycline by the three composite adsorption photocatalysts were obtained, as shown in the figure. Figure 7 As shown. By Figure 7 It can be seen that after 30 min of dark adsorption and 60 min of light irradiation, Bi-Ni / NC(Ⅰ), Bi-Ni / NC(Ⅱ), and Bi-Ni / NC(Ⅲ) all showed removal effects on tetracycline in water, with 88%, 53%, and 52% respectively. Among them, the Bi-Ni / NC(Ⅰ) composite adsorption photocatalyst had the highest removal efficiency, not only having the best tetracycline adsorption capacity, but also exhibiting the best visible light removal effect.

[0047] In summary, the nickel-bismuth composite nitrogen-doped carbon material proposed in this invention fully considers the integration and complementarity of adsorbent components and photocatalytic functions in its design. On the one hand, the porous structure and large specific surface area of ​​the nitrogen-doped carbon support exhibit excellent adsorption capacity for tetracycline. On the other hand, by fully utilizing the SPR effect of Ni metal and Bi-Ni alloy, the catalyst can generate abundant photogenerated electrons and holes. Combined with the excellent conductivity of the nitrogen-doped carbon support, these photogenerated electrons and holes can be separated more effectively, further improving the catalytic efficiency of the catalyst under visible light, thus promoting more efficient visible light photocatalytic performance. This design organically combines the adsorption and photocatalytic functions of the catalyst, enabling the Bi-Ni / NC composite adsorption photocatalyst to have excellent adsorption capacity for tetracycline in water and good visible light photocatalytic degradation performance.

[0048] 2. The nickel-bismuth composite nitrogen-doped carbon material prepared by this invention exhibits significant adsorption and visible-light photocatalytic removal effects on tetracycline in water. For example, in the preferred embodiment 1, when the catalyst dosage is only 0.12 g / L, the adsorption and visible-light degradation removal rates for 100 mL of a 20 mg / L tetracycline solution can reach 87%. The adsorption performance for tetracycline is outstanding; in Example 1, with a catalyst dosage of 0.12 g / L, the dark adsorption equilibrium removal rate for 100 mL of a 40 mg / L tetracycline solution can reach 69%, and the equilibrium adsorption capacity reaches 219.28 mg·g⁻¹. -1 Further exposure to visible light can further increase the removal rate to 75%. Nickel-bismuth composite nitrogen-doped carbon photocatalysts are adsorption photocatalysts capable of efficiently removing tetracycline pollutants from water under visible light.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nickel-bismuth composite nitrogen-doped carbon material for photocatalytic removal of antibiotics in water, characterized in that, The method comprises the following steps: 1) mixing a nickel source and a bismuth source with a ligand in a solvent to obtain a mixed metal source; the ligand is a mixture of terephthalic acid and triethylenediamine, and the molar ratio of the two is 1:1; 2) adding a nitrogen source to the mixed solution obtained in step 1) and performing a solvothermal reaction at room temperature to obtain a precursor; the solvothermal reaction is performed at room temperature, and the reaction time is 2-6 hours; the nitrogen source is g-C3N4; and 3) calcining the precursor to obtain a nickel-bismuth composite nitrogen-doped carbon material.

2. The method for preparing nickel-bismuth composite nitrogen-doped carbon material according to claim 1, characterized in that, The nitrogen source is prepared by the following method: calcining dicyandiamide at 500-600 DEG C for 2-6 hours, cooling to room temperature, and grinding the obtained product into a powder to obtain the nitrogen source g-C3N4.

3. The method for preparing the nickel-bismuth composite nitrogen-doped carbon material according to claim 1, characterized in that, The nitrogen source is prepared by the following method: calcining dicyandiamide at 550 DEG C for 4 hours, cooling to room temperature, and grinding the obtained product into a powder to obtain the nitrogen source g-C3N4.

4. The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the steps of: preparing a nickel-bismuth composite material; and performing a carbonization process on the nickel-bismuth composite material. The nickel source is nickel nitrate hexahydrate, the bismuth source is bismuth nitrate pentahydrate, and the solvent is N, N-dimethylformamide.

5. The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the steps of: preparing a nickel-bismuth composite material; and performing a carbonization process on the nickel-bismuth composite material. The molar ratio of the nickel source to the bismuth source in the mixed metal source is 3:

1. 6.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the following steps: (1) preparing a nickel-bismuth composite material; (2) mixing the nickel-bismuth composite material with a carbon source; (3) heating the mixture to obtain the nickel-bismuth composite nitrogen-doped carbon material. The molar ratio of the ligand to the metal source is 2: (0.32-0.68). 7.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the following steps: (1) preparing a nickel-bismuth composite material; (2) mixing the nickel-bismuth composite material with a carbon source; (3) heating the mixture to obtain the nickel-bismuth composite nitrogen-doped carbon material. The molar ratio of the ligand to the metal source is 2:0.

32. 8.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the following steps: (1) preparing a nickel-bismuth composite material; (2) mixing the nickel-bismuth composite material with a carbon source; (3) heating the mixture to obtain the nickel-bismuth composite nitrogen-doped carbon material. The ratio of the added mass of the nitrogen source to the added mass of the metal source is 8: (1-2.3). 9.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the following steps: (1) preparing a nickel-bismuth composite material; (2) mixing the nickel-bismuth composite material with a carbon source; (3) heating the mixture to obtain the nickel-bismuth composite nitrogen-doped carbon material. The ratio of the added mass of the nitrogen source to the added mass of the metal source is 8:

1. 10.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the method comprising: preparing a nickel-bismuth composite material; and performing a carbonization process on the nickel-bismuth composite material. The calcination temperature in step 3) is 700-900 DEG C, and the calcination time is 0.5-2 hours. 11.The method of claim 1, wherein the nickel-bismuth composite nitrogen-doped carbon material is prepared by the following steps: (1) preparing a nickel-bismuth composite material; (2) mixing the nickel-bismuth composite material with a carbon source; (3) heating the mixture to obtain the nickel-bismuth composite nitrogen-doped carbon material. The calcination temperature in step 3) is 800 DEG C, and the calcination time is 1 hour.

12. A nickel-bismuth composite nitrogen-doped carbon material prepared by the preparation method of any one of claims 1-11.

13. Use of the nickel-bismuth composite nitrogen-doped carbon material according to claim 12, characterized in that Applied to photocatalytic removal of antibiotics in water.

14. The use of the nickel-bismuth composite nitrogen-doped carbon material according to claim 13, characterized in that, The antibiotic is tetracycline.

Images