Preparation method and application of bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material

Abstract

The application discloses a preparation method of a bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material, which comprises the following steps: adding bamboo powder into a basic methanol solution, heating and refluxing at 60-80 DEG C for 3-6h, cooling to room temperature, adding Bi(NO3)3 and FeCl3.6H2O into the reaction product, stirring and uniformly mixing, placing in a reaction kettle, sealing, reacting at 100-140 DEG C for 20-25h, cooling, solid-liquid separation, drying the solid, placing in a nitrogen atmosphere, calcining at 550-650 DEG C for 3h, and washing, drying and obtaining the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material; the material is a mesoporous material, has excellent catalytic activity in the application of photocatalytic degradation of antibiotics, has ferromagnetism, and can be 100% recycled; the catalyst structure is stable, can be recycled and reused, the bamboo charcoal matrix makes the catalyst have excellent light corrosion resistance and antioxidant corrosion resistance.

Description

Technical Field

[0001] This invention relates to a method for preparing a bimetallic-doped porous magnetic bamboo charcoal composite photocatalytic material, belonging to the field of organic pollutant treatment. Background Technology

[0002] With the development of global industrialization, water pollution has attracted widespread attention worldwide. Various organic pollutants, such as organic dyes, antibiotics, and endocrine disruptors, have been widely detected in water. Traditional methods for removing organic pollutants from water utilize adsorbents; however, adsorbents can only transfer organic pollutants from the aqueous phase to the solid phase, not completely decompose them. Therefore, there is an urgent need to develop efficient and environmentally friendly methods for the rapid and complete removal of organic pollutants from water. Currently, many technologies have been developed for removing organic pollutants from water, among which advanced oxidation processes (AOPs) are considered a water treatment technology with great application potential. AOPs utilize active free radicals to completely oxidize and decompose organic pollutants into carbon dioxide and water, achieving high efficiency and without generating secondary pollution.

[0003] Bamboo charcoal (BC) has shown great potential in aquatic remediation due to its low cost, large specific surface area, high porosity, and high electrical conductivity. Biochar-assisted advanced oxidation processes (BC-AOPs) have attracted increasing attention in recent years for the remediation of organic pollutants in water. However, the impact of biochar properties on catalytic performance still needs further investigation, the reaction mechanism remains controversial and knowledge gaps exist, and the recycling and regeneration of biochar catalysts are relatively difficult. Therefore, it is necessary to develop a bamboo charcoal composite catalytic material doped with multiple active centers for the efficient degradation of organic pollutants in water. Summary of the Invention

[0004] This invention provides a method for preparing a bimetallic-doped porous magnetic bamboo charcoal composite photocatalyst. This method utilizes bamboo powder as a carbon source and employs a solvothermal and thermal decomposition method to prepare a bismuth-iron bimetallic-doped porous magnetic bamboo charcoal composite photocatalyst (Bi-BiOCl-Fe3N / BC). When this composite material is applied to the photocatalytic degradation of sulfonamide antibiotics, experimental results show that the bimetallic-doped porous magnetic bamboo charcoal composite photocatalyst exhibits good degradation ability for sulfadiazine, making it a promising water treatment material.

[0005] The preparation method of the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material of the present invention is as follows: bamboo powder is added to an alkaline methanol solution, heated under reflux at 60-80℃ for 3-6 hours, cooled to room temperature, Bi(NO3)3 and FeCl3·6H2O are added to the reaction product, stirred and mixed, placed in a reaction vessel and reacted at 100-140℃ for 20-25 hours under a sealed environment, cooled and separated into solid and liquid components, the solid is dried and calcined at 550-650℃ for 3 hours under a nitrogen atmosphere, washed and dried to obtain the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material.

[0006] The alkaline methanol solution is prepared by adding N,N-dimethylformamide to methanol, stirring and mixing, then adding NaOH and mixing again. The volume ratio of N,N-dimethylformamide to methanol is 1-3:2-4, and the mass-volume ratio of NaOH to N,N-dimethylformamide (mg:mL) is 1:1-2.

[0007] The mass-to-volume ratio of bamboo powder to alkaline methanol solution (g:mL) is 1:10-20.

[0008] The mass ratio of Bi(NO3)3 to bamboo powder is 1-2:1, and the mass ratio of FeCl3·6H2O to bamboo powder is 1-2:1.

[0009] The bamboo powder is from Giant Dragon Bamboo.

[0010] The Bi-BiOCl-Fe3N / BC catalyst prepared in this invention is a multifunctional organic composite material that integrates five functions: photocatalysis, magnetism, electron transfer, adsorption, and corrosion resistance through structural innovation. This functional integration is not achieved by simple mixing, but by combining the chemical bonds between atoms through the modification process of bamboo powder and the high-temperature pyrolysis process. Specifically, the functional integration is achieved through the following mechanisms: (1) The N atom in the Fe3N structure is stably inserted into the six-membered ring structure of bamboo charcoal to form a CN bond; the N atom continues to coordinate with three Fe atoms. This structure endows the material with both photocatalytic activity and ferromagnetism. Due to the ferromagnetism, the catalyst can be 100% recovered. Using bamboo charcoal prepared at 600℃ as a matrix, the composite material has a mesoporous structure, thereby obtaining good adsorption performance of sulfadiazine. Bamboo charcoal matrix serves as a carrier for immobilizing Bi atoms and BiOCl, providing a transfer channel for photogenerated electrons and enhancing the photocatalytic activity of Bi-BiOCl-Fe3N / BC. The chemically stable properties of bamboo charcoal matrix protect the photocatalytic active centers and magnetic centers doped within it, thus giving the Bi-BiOCl-Fe3N / BC catalyst excellent resistance to photocorrosion and oxidant corrosion, and excellent recyclability.

[0011] Advantages and technical effects of the present invention:

[0012] This invention uses *Phyllostachys edulis*, a bamboo species rich in fiber, with well-developed pores and low cost, as raw material. A bimetallic-doped porous magnetic bamboo charcoal composite material is prepared using a solvothermal method and a thermal decomposition method. The composition and structure of the composite material are analyzed using X-ray powder diffraction and X-ray photoelectron spectroscopy. The microstructure of the composite material is studied using scanning electron microscopy, and the pore structure is investigated using nitrogen adsorption-desorption. The results show that the material is mesoporous and contains Bi. 0 The composite material of this invention contains three catalytic active centers: Fe3N and BiOCl, which are doped onto the bamboo charcoal matrix through stable chemical bonds. When applied to the photocatalytic degradation of antibiotics, the experimental results show that a degradation rate of over 90% can be obtained in 20 minutes, and the degradation rate can still reach over 85% after the material is recycled 4 times. Attached Figure Description

[0013] Figure 1 XRD patterns of bamboo charcoal composite materials prepared under different pyrolysis temperature conditions;

[0014] Figure 2 X-ray photoelectron spectra of Fe, Bi, N, Cl, O and C elements in bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600;

[0015] Figure 3 Scanning electron microscope image of bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600;

[0016] Figure 4 EDX spectrum of bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600;

[0017] Figure 5 Nitrogen adsorption-desorption isotherm (a) and pore size distribution curve (b) of bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600;

[0018] Figure 6 The catalytic degradation rate of sulfadiazine by the bamboo charcoal composite material Bi-BiOCl-Fe3N / BC prepared under different conditions is shown in the figure.

[0019] Figure 7 The graph shows the effect of Bi-BiOCl-Fe3N / BC-600 in the degradation of sulfadiazine after 4 cycles.

[0020] Figure 8 The X-ray powder diffraction pattern of Bi-BiOCl-Fe3N / BC-600 after 4 cycles of use. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the contents described.

[0022] Example 1:

[0023] 1. Add 40 mL of DMF to 60 mL of methanol and stir for 5 min to mix thoroughly. Then weigh 40 mg of NaOH and add it to the mixed solution. Stir magnetically for 30 min to completely dissolve the NaOH and obtain an alkaline methanol solution.

[0024] 2. Preparation of bamboo charcoal composite materials

[0025] 1g of *Bambusa textilis* powder was added to 15mL of alkaline methanol solution and refluxed at 60℃ for 1h. After cooling to room temperature, the reaction product was transferred to a stainless steel reactor. 5mmol Bi(NO3)3 and 5mmol FeCl3·6H2O were added to the reactor, and the mixture was magnetically stirred for 30min. The reactor was then sealed and heated at 120℃ for 24h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. After filtration, the solid was dried at 60℃. The dried product was placed in a quartz crucible and calcined at 500℃, 600℃, and 700℃ for 3h in a nitrogen atmosphere and a tube furnace, respectively. After washing and drying, the bamboo charcoal composite materials Bi-BiOCl-Fe3N / BC-500, Bi-BiOCl-Fe3N / BC-600, and Bi-BiOCl-Fe3N / BC-700 were obtained. The XRD patterns of the bamboo charcoal composite materials are shown below. Figure 1 As can be seen from the figure, Bi diffraction peaks were found in all three materials, mainly at 2θ = 27.1°, 37.9°, 39.6°, 48.7° and 64.5°, which correspond to the (012), (104), (110), (202) and (122) crystal planes of Bi, respectively. The results are consistent with the Bi standard card (JCPDS: No. 85-1329).

[0026] The characteristic diffraction peaks of BiOCl appear at 2θ = 12.0° (001), 24.1° (002), 28.9° (101), 32.5° (110), 33.5° (102), 40.9° (112), 46.7° (200), and 58.6° (212). The crystal planes corresponding to the different diffraction peaks are shown in parentheses, which is consistent with the BiOCl standard card (JCPDS: No. 85-0861). Notably, no diffraction peaks of BiOCl were found in the Bi-BiOCl-Fe3N / BC-700 diffraction pattern prepared at 700℃, because BiOCl has already decomposed under heat at 700℃. Diffraction peaks of Fe3N were found in the XRD patterns of both Bi-BiOCl-Fe3N / BC-600 and Bi-BiOCl-Fe3N / BC-700. The main characteristic peaks appeared at 2θ = 38.1°, 40.8°, 43.4°, 57.0°, and 68.8°, which is consistent with the Fe3N standard card (JCPDS: No. 83-0876).

[0027] The surface elemental composition and chemical valence state of the Bi-BiOCl-Fe3N / BC composite material were investigated using X-ray photoelectron spectroscopy. The X-ray photoelectron spectrum (XPS) of the porous magnetic bamboo charcoal Bi-BiOCl-Fe3N / BC-600 is shown below. Figure 2 In the full spectrum of Bi-BiOCl-Fe3N / BC-600, characteristic peaks of Fe, Bi, N, Cl, O, and C can be clearly observed. The C1s spectrum shows three peaks: the peak at 284.80 eV belongs to surface contaminants (carbon), the peak at 286.11 eV belongs to inorganic carbides, and the peak at 288.38 eV belongs to metal-carbonyl bonds. The high-fine O1s spectrum shows three peaks: the peaks at 530 eV and 530.6 eV indicate that oxygen is a metal-oxide bond; while the binding energies at 531.67 eV and 533.29 eV belong to ClO. 3- The presence of chemical bonds further confirms the presence of BiOCl in the material. The peak at 398.64 eV in the N1s hyperfine spectrum is attributed to Fe3N, confirming the presence of iron nitride in the prepared sample. The peak at 198.16 eV in the Cl 2p spectrum belongs to Cl... - The peak at 199.88 eV belongs to ClO. 3- The peaks at 710.72 eV and 713.31 eV in the Fe 2p spectrum are attributed to the binding energy of the Fe-N bond. A set of peaks at 159.35 / 164.66 eV in the Bi 4f spectrum is attributed to elemental bismuth. The presence of Bi in the material can be confirmed by XPS high-resolution spectra of each element. 0 The presence of Fe3N and BiOCl is consistent with the XRD results.

[0028] The morphology of the porous magnetic bamboo charcoal composite material was analyzed by scanning electron microscopy. The scanning electron micrograph of the porous magnetic bamboo charcoal Bi-BiOCl-Fe3N / BC-600 is shown in the figure. Figure 3 The image shows that the surface of the composite material consists of a loose structure formed by numerous nanoparticles, which is beneficial for increasing the specific surface area. Furthermore, to determine the elemental information and interactions within the material, elemental analysis of the Bi-BiOCl-Fe3N / BC-600 sample was performed using EDX energy dispersive spectroscopy. Figure 4 The results showed that the sample was mainly composed of five elements: Fe, Bi, Cl, O, and C, with atomic percentages of 9.43%, 2.17%, 1.52%, 11.74%, and 75.15%, respectively. Moreover, Cl, O, and C elements were evenly distributed throughout the material.

[0029] The specific surface area and pore structure of porous magnetic bamboo charcoal were characterized using N2 adsorption-desorption technology. Figure 5 ), Figure 5 a is the N2 adsorption-desorption curve of Bi-BiOCl-Fe3N / BC-600. According to the IUPAC classification standard, the N2 adsorption-desorption curve of the sample is a type IV isotherm, indicating that Bi-BiOCl-Fe3N / BC-600 is a typical mesoporous material with pore sizes mainly distributed between 2 and 10 nm. Figure 5 b) Specific surface area is 23.2811 m² 2 / g, this hierarchical porous structure that runs through the entire surface of the material can promote the transformation of reactants on the inner surface of the pores, thereby improving the photo-Fenton catalytic activity of the material.

[0030] Example 2: Degradation experiment of sulfadiazine antibiotic by porous magnetic bamboo charcoal composite material Bi-BiOCl-Fe3N / BC

[0031] A 300W xenon lamp was used as the light source, and ultraviolet light was filtered out using a filter. 100 mL of sulfadiazine aqueous solution (20 mg / L) and 0.2 mL of hydrogen peroxide (H₂O₂) were added to a jacketed beaker as an oxidant, followed by 40 mg of porous magnetic bamboo charcoal composite material. A control group without the composite material was used. The mixture was stirred and mixed in the dark for 30 min to allow the catalyst to reach adsorption equilibrium. 3 mL of the reaction solution was taken, centrifuged at 6000 r / min, and the absorbance of the sulfadiazine solution was measured and recorded as A₀. The xenon lamp light source and circulating water cooling system were turned on to start the photocatalytic reaction. 3 mL of the reaction solution was taken at intervals to test the absorbance and recorded as A₀. t The formula for calculating the degradation rate of sulfadiazine is: (A0-A t ) / A0×100%;

[0032] The results of photo-Fenton degradation of sulfadiazine by porous magnetic bamboo charcoal Bi-BiOCl-Fe3N / BC are attached. Figure 6 As can be seen, Bi-BiOCl-Fe3N / BC-600 achieved a 90% degradation rate of sulfadiazine within 20 minutes. However, under the same 20-minute illumination, the degradation rates of sulfadiazine by Bi-BiOCl-Fe3N / BC-500 and Bi-BiOCl-Fe3N / BC-700 were only 30% and 54%, respectively. The experiment shows that the porous magnetic bamboo charcoal composite material prepared by pyrolysis at 600℃ exhibits the best photo-Fenton catalytic activity. This is because the composite material contains Fe3N and BiOCl, where BiOCl has excellent visible light-responsive catalytic ability, and Fe3N can catalyze the decomposition of H2O2 to generate a high concentration of hydroxyl radicals.

[0033] The cyclic performance of the porous magnetic bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600 in photocatalytic degradation of sulfadiazine was tested. The results are shown in [Figure number missing]. Figure 7 It can be seen that the photodegradation removal rates of sulfadiazine at 20 min within the four cycles were 89.7%, 86.2%, 85.5%, and 85.1%, respectively. The results indicate that the porous magnetic bamboo charcoal composite material Bi-BiOCl-Fe3N / BC-600 maintains good catalytic activity during multiple cycles, making it an excellent recyclable photo-Fenton catalyst. To verify the structural stability of Bi-BiOCl-Fe3N / BC-600, X-ray powder diffraction analysis was performed on the catalyst after four cycles, and the results are as follows. Figure 8 As shown in the X-ray powder diffraction pattern, the positions of the Bi-BiOCl-Fe3N / BC-600 diffraction peaks of the porous magnetic bamboo charcoal after four cycles of use remain almost unchanged, indicating that the porous magnetic bamboo charcoal has good structural stability during the photo-Fenton reaction process and can resist photo-corrosion and oxidant corrosion.

Claims

1. A method for preparing a bimetallic-doped porous magnetic bamboo charcoal composite photocatalytic material, characterized in that: Bamboo powder was added to an alkaline methanol solution and heated under reflux at 60-80℃ for 3-6 hours. After cooling to room temperature, Bi(NO3)3 and FeCl3·6H2O were added to the reaction product and stirred until well mixed. The mixture was then placed in a reaction vessel and reacted at 100-140℃ for 20-25 hours under a sealed environment. After cooling, the solid and liquid were separated. The solid was dried and then calcined at 550-650℃ for 3 hours under a nitrogen atmosphere. After washing and drying, the bimetallic doped porous magnetic bamboo charcoal composite photocatalyst material Bi-BiOCl-Fe3N / BC was obtained.

2. The preparation method of the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material according to claim 1, characterized in that: The alkaline methanol solution is prepared by adding N,N-dimethylformamide to methanol, stirring and mixing, then adding NaOH and mixing again. The volume ratio of N,N-dimethylformamide to methanol is 1-3:2-4, and the mass-volume ratio of NaOH to N,N-dimethylformamide (mg:mL) is 1:1-2.

3. The preparation method of the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material according to claim 1, characterized in that: The mass-to-volume ratio of bamboo powder to alkaline methanol solution (g:mL) is 1:10-20.

4. The preparation method of the bimetallic doped porous magnetic bamboo charcoal composite photocatalytic material according to claim 1, characterized in that: The mass ratio of Bi(NO3)3 to bamboo powder is 1-2:1, and the mass ratio of FeCl3·6H2O to bamboo powder is 1-2:

1.

5. The application of the bimetallic doped porous magnetic bamboo charcoal composite photocatalyst material Bi-BiOCl-Fe3N / BC prepared by the preparation method of the bimetallic doped porous magnetic bamboo charcoal composite photocatalyst material according to any one of claims 1-4 in the photocatalytic degradation of sulfonamide antibiotics.

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