A method for efficient and low-cost preparation of g-C3N4 supported Fe and Mn bimetallic catalysts

Abstract

This invention discloses a highly efficient and low-cost method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts, belonging to the field of catalyst technology. This invention uses manganese ferrite as the bimetallic source, combined with a one-step calcination method using melamine, to simultaneously achieve the synthesis of g-C3N4 and the loading of Fe and Mn. During calcination, manganese ferrite decomposes into FeO. x and MnO x Nanoparticles form strong coordination bonds with the nitrogen sites of g-C3N4, enabling atomic-level dispersion of metals and inhibiting metal ion migration. Through the bimetallic synergistic effect of Fe and Mn, the redox capacity of the catalyst can be significantly improved. Manganese ferrite, through its unique thermal decomposition characteristics, bimetallic synergistic effect, and strong chemical bond with g-C3N4, achieves efficient exposure of active sites, significant improvement of redox capacity, and effective inhibition of metal dissolution. It also has the advantages of high efficiency, low cost, and low risk of secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts with high efficiency and low cost. Background Technology

[0002] With the acceleration of industrialization, the accumulation of recalcitrant organic pollutants (such as dyes, pesticides, and drug residues) in water bodies is becoming increasingly serious, posing a severe threat to the ecological environment and human health. Traditional physical, chemical, and biological treatment methods are often inefficient or costly in treating recalcitrant organic matter. Therefore, developing efficient, economical, and environmentally friendly catalytic degradation technologies has become a key focus and hot topic in the fields of water treatment and environmental governance.

[0003] Heterogeneous catalytic oxidation technology is considered an effective means of treating recalcitrant organic pollutants due to its advantages such as high efficiency, good selectivity, ease of separation, and reusability. Among them, transition metal catalysts have shown great potential in the field of heterogeneous catalysis due to their unique electronic structure and catalytic activity. In particular, binary transition metal (such as Fe and Mn) catalysts can significantly improve catalytic performance through bimetallic synergistic effects. Studies have shown that Fe-Mn bimetallic catalysts have shown significant advantages in advanced oxidation processes (AOPs) based on persulfate (PMS / PDS), effectively degrading organic pollutants such as phenol and dyes, as well as emerging pollutants such as antibiotics. However, existing Fe-Mn bimetallic catalysts still have some problems, such as poor loading uniformity, pH-limited catalytic activity, and high metal ion dissolution rates leading to secondary pollution.

[0004] In recent years, carbon-based materials (such as graphitic carbon nitride, g-C3N4) have become ideal supports for loading transition metals due to their high specific surface area, good chemical stability, and tunable electronic structure. g-C3N4, as a novel carbon-based material, possesses a unique layered structure and excellent photocatalytic performance. It can effectively inhibit metal ion dissolution by anchoring metal active sites through π-π interactions and surface functional groups. Furthermore, the conductivity and photocatalytic properties of g-C3N4 can further enhance the redox capacity of catalysts. Although existing studies have explored g-C3N4-supported monometallic or heterojunction catalysts, reports on g-C3N4-supported Fe-Mn bimetallic catalysts remain scarce. In current technologies, the synthesis of bimetallic catalysts often employs stepwise loading or physical mixing methods, requiring multiple calcination steps and complex post-processing, resulting in high costs and difficulty in achieving uniform metal dispersion. Moreover, traditional methods lack sufficient control over the interaction between the support and the metal, leading to limitations in catalytic stability and pH adaptability. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a highly efficient and low-cost method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts. The preparation method provided by this invention has the advantages of high efficiency, low cost, and low risk of secondary pollution, and the resulting catalyst exhibits excellent degradation performance for recalcitrant organic pollutants.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts at high efficiency and low cost, comprising the following steps: dissolving manganese ferrite and melamine in an organic solvent and subjecting them to ultrasonication and stirring to obtain a precursor mixture; then subjecting the precursor mixture to calcination, grinding and washing in sequence to obtain the g-C3N4 supported Fe and Mn bimetallic catalyst.

[0008] Technical principle:

[0009] This invention utilizes manganese ferrite (MnFe2O4) as a bimetallic source, combined with a one-step calcination method using melamine, to simultaneously achieve the synthesis of g-C3N4 and the loading of Fe and Mn. During calcination, manganese ferrite decomposes into FeO. x and MnO x Nanoparticles form strong coordination bonds with the nitrogen sites of g-C3N4, enabling atomic-level dispersion of metals and inhibiting metal ion migration. Secondly, the bimetallic synergistic effect of Fe and Mn significantly enhances the catalyst's redox capacity. Therefore, manganese ferrite, through its unique thermal decomposition characteristics, bimetallic synergistic effect, and strong chemical bond with g-C3N4, achieves efficient exposure of active sites, a significant improvement in redox capacity, and effective inhibition of metal dissolution. This design not only solves the defects of existing catalysts, such as poor loading uniformity, pH-limited catalytic activity, and high metal ion dissolution rate, but also significantly reduces costs through process simplification, offering advantages such as high efficiency, low cost, and low risk of secondary pollution.

[0010] Furthermore, the mass ratio of manganese ferrite to melamine is 1:(20-50).

[0011] Furthermore, the method for preparing manganese ferrite includes the following steps: dissolving soluble iron salt and soluble manganese salt in water, adding NaOH solution under stirring conditions, and then carrying out a hydrothermal reaction to obtain the manganese ferrite.

[0012] Furthermore, the soluble iron salt is selected from FeCl3·6H2O, and the soluble manganese salt is selected from MnCl2·4H2O; the molar ratio of FeCl3·6H2O to MnCl2·4H2O is (1-2):1; the hydrothermal reaction temperature is 80-100℃, and the time is 2-4h.

[0013] Furthermore, the frequency of the ultrasound is 40,000 Hz, and the duration is 45-60 min.

[0014] Furthermore, the stirring rate is 120-150 r / min, and the time is 18-24 h.

[0015] Furthermore, the calcination temperature is 525-600℃, the time is 5-6 hours, and the heating rate is 5℃·min. -1 .

[0016] Furthermore, the calcination temperature is 550-575℃.

[0017] This invention provides a method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts using the above-described efficient and low-cost method.

[0018] This invention also provides the application of the g-C3N4 supported Fe and Mn bimetallic catalyst described in the above technical solution in the degradation of organic pollutants.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] The g-C3N4 supported Fe and Mn bimetallic catalyst prepared in this invention exhibits excellent degradation performance for recalcitrant organic pollutants, with a significantly improved degradation efficiency compared to existing technologies. It can effectively remove various types of recalcitrant organic pollutants, such as polycyclic aromatic hydrocarbons and halogenated organic compounds.

[0021] The method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts provided by this invention has low cost, thereby significantly reducing the production cost of the catalyst. It has good economic benefits and market competitiveness, significant technological innovation and industrial application potential, and is conducive to large-scale industrial application.

[0022] The catalyst prepared by this invention does not generate secondary pollution during the degradation of organic pollutants, which meets the requirements of green chemistry and sustainable development, and provides a green and environmentally friendly solution for environmental governance. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 A photograph of the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0025] Figure 2 SEM image (30 μm) of the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0026] Figure 3 SEM image (10 μm) of the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0027] Figure 4 The carbon elemental distribution diagram of the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0028] Figure 5 The N element surface distribution diagram of the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0029] Figure 6 The surface distribution diagram of O element in the Fe-Mn / g-C3N4 catalyst prepared in Example 1;

[0030] Figure 7 The surface distribution of Fe element in the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is shown.

[0031] Figure 8 The surface distribution of Mn element in the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is shown.

[0032] Figure 9 The image shows the surface distribution of all elements in the Fe-Mn / g-C3N4 catalyst prepared in Example 1.

[0033] Figure 10 The image shows the EDS spectrum of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. The inset shows the atomic percentage and weight percentage of each element.

[0034] Figure 11 The degradation rate of methylene blue catalyzed by the catalysts prepared in Example 1 and Comparative Examples 1-5 is shown in the graph.

[0035] Figure 12 The degradation curve of methylene blue catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is shown.

[0036] Figure 13 The degradation rate of methylene blue catalyzed by the catalysts prepared in Examples 1-5 and Comparative Examples 1 and 6-9 is shown in the graph.

[0037] Figure 14 The graph shows the degradation rate of norfloxacin hydrochloride catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1.

[0038] Figure 15The graph shows the degradation rate of Rhodamine B catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] This invention provides a method for preparing a g-C3N4-supported Fe and Mn bimetallic catalyst at high efficiency and low cost, comprising the following steps: dissolving manganese ferrite and melamine in an organic solvent and subjecting them to ultrasonication and stirring to obtain a precursor mixture; then subjecting the precursor mixture to calcination, grinding and washing in sequence to obtain the g-C3N4-supported Fe and Mn bimetallic catalyst (Fe-Mn / g-C3N4).

[0042] In a preferred embodiment, the mass ratio of manganese ferrite to melamine is 1:(20-50). This invention uses manganese ferrite as both a manganese and iron source to prepare a g-C3N4-supported Fe / Mn bimetallic catalyst, which is beneficial for obtaining a catalyst with high catalytic activity.

[0043] In a preferred embodiment, the method for preparing manganese ferrite includes the following steps: dissolving soluble iron salt and soluble manganese salt in water, adding NaOH solution under stirring conditions, and then carrying out a hydrothermal reaction to obtain manganese ferrite.

[0044] In a preferred embodiment, the soluble iron salt is selected from FeCl3·6H2O, and the soluble manganese salt is selected from MnCl2·4H2O; the molar ratio of FeCl3·6H2O to MnCl2·4H2O is (1-2):1.

[0045] In a preferred embodiment, soluble iron and manganese salts are dissolved in water and stirred for 30 minutes. Then, while continuing stirring for 1 hour, NaOH solution is added dropwise. This invention ensures that iron and manganese ions react fully with hydroxide ions by continuing stirring for 1 hour, resulting in a more complete and stable manganese ferrite precursor. If stirring is stopped prematurely, some ions may not participate in the reaction, leading to inaccurate precursor composition and affecting the performance of the manganese ferrite material.

[0046] In a preferred embodiment, the concentration of the NaOH solution is 1.5 mol / L; the amount of NaOH solution used is to adjust the pH of the solution to 11-12; and the NaOH solution is added dropwise.

[0047] In a preferred embodiment, the hydrothermal reaction is carried out at a temperature of 80-100°C for 2-4 hours; the equipment for the hydrothermal reaction is a constant temperature water bath, and the hydrothermal reaction is carried out under mechanical stirring.

[0048] In a preferred embodiment, after the hydrothermal reaction is completed, the process further includes: cooling the product of the hydrothermal reaction at room temperature, then centrifuging, washing and drying to obtain the manganese ferrite; the centrifugation washing reagent is deionized water, the centrifugation speed is 4500 r / min, and the time is 10 min; the drying temperature is 65℃, and the drying equipment is an oven.

[0049] In a preferred embodiment, the organic solvent is selected from methanol. The present invention does not have a particular limitation on the amount of organic solvent used, as long as it is sufficient to cover the manganese ferrite and melamine.

[0050] In a preferred embodiment, the frequency of the ultrasound is 40,000 Hz and the duration is 45-60 min.

[0051] In a preferred embodiment, the stirring rate is 120-150 r / min and the stirring time is 18-24 h.

[0052] In a preferred embodiment, the calcination temperature is 525-600℃, more preferably 550-575℃; the calcination time is 5-6 hours; and the calcination heating rate is 5℃·min. -1 In this invention, the calcination temperature affects the catalytic activity of the catalyst. Calcination within the above-mentioned temperature range is beneficial for obtaining a catalyst with high catalytic activity.

[0053] In a preferred embodiment, the washing method is centrifugal washing, the washing reagent is deionized water, the washing speed is 4500 r / min, the washing time is 15 min, and the washing is performed three times. This invention removes unbound Fe and Mn ions and excess impurities through washing.

[0054] In a preferred embodiment, the washing process further includes drying and re-grinding steps; the drying temperature is 80°C, and the drying equipment is an oven.

[0055] This invention provides a method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts using the above-described efficient and low-cost method.

[0056] This invention also provides the application of the g-C3N4 supported Fe and Mn bimetallic catalyst described in the above technical solution in the degradation of organic pollutants.

[0057] In a preferred embodiment, the organic pollutant includes methylene blue, norfloxacin hydrochloride, or rhodamine B.

[0058] In this embodiment of the invention, room temperature refers to "25±2℃".

[0059] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0060] Example 1

[0061] A method for efficiently and cost-effectively preparing g-C3N4-supported Fe and Mn bimetallic catalysts, comprising the following specific steps:

[0062] (1) Dissolve 2.7029g FeCl3·6H2O and 0.9892g MnCl2·4H2O (the molar ratio of FeCl3·6H2O and MnCl2·4H2O is 2:1) in deionized water and stir for 30 min. Then, while stirring continuously for 1 h, add NaOH solution with a concentration of 1.5 mol / L dropwise until the pH of the solution is 11-12 to obtain a manganese ferrite precursor mixture. Heat the obtained manganese ferrite precursor mixture in a 100℃ constant temperature water bath while turning on mechanical stirring. After 4 h, the reaction ends. Cool the reaction product at room temperature and then centrifuge and wash it with deionized water at a speed of 4500 r / min for 10 min. After centrifugation and washing, place the sample in an oven at 65℃ to dry to obtain manganese ferrite MnFe2O4.

[0063] (2) Using methanol as a solvent, add 0.4g of MnFe2O4 obtained in step (1) and 12g of melamine (the mass ratio of MnFe2O4 to melamine is 1:30), sonicate at 40000Hz for 45min, and then stir at a rate of 150r / min for 18h to obtain a precursor mixture; transfer the obtained precursor mixture to a muffle furnace and heat at 5℃·min -1 The temperature was increased to 550℃ and calcined for 5 hours. After cooling, the calcined product was ground into a fine and uniform powder using a mortar and pestle. The powder was then transferred to a centrifuge tube and deionized water was added for centrifugal washing. The centrifugal washing speed was 4500 r / min and the centrifugal washing time was 15 min. The above centrifugal washing was repeated three times. After washing, the sample was placed in an oven and dried at 80℃. After cooling to room temperature, it was ground again to obtain g-C3N4 supported Fe and Mn bimetallic catalyst (Fe-Mn / g-C3N4 catalyst), denoted as GCDCS-6.

[0064] Figure 1 This is a photograph of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. (From...) Figure 1 As can be seen, the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is in the form of black granules.

[0065] Figure 2 The image shows a SEM image (30 μm) of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 3 SEM image (10 μm) of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. From... Figure 2 and Figure 3 It can be seen that the Fe-Mn / g-C3N4 catalyst prepared in Example 1 has a typical aggregated layered structure. The g-C3N4 has a smooth surface and a layered stacked structure with a large specific surface area, which is beneficial for loading Fe and Mn.

[0066] Figure 4 The image shows the carbon elemental distribution of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 5 The image shows the N element surface distribution of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 6 The image shows the surface distribution of O element in the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 7 The image shows the surface distribution of Fe element in the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 8 The image shows the surface distribution of Mn in the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 9 This is an elemental surface distribution diagram of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. From... Figure 4-9 It can be seen that the Fe-Mn / g-C3N4 catalyst prepared in Example 1 contains C, N, O, Fe, and Mn elements.

[0067] Figure 10 The image shows the EDS spectrum of the Fe-Mn / g-C3N4 catalyst prepared in Example 1. The inset shows the atomic and weight percentages of each element. Figure 10 It can be seen that the Fe-Mn / g-C3N4 catalyst prepared in Example 1 contains 0.4 wt% Mn and 0.8 wt% Fe.

[0068] Comparative Example 1

[0069] Weigh out 1g of ferric chloride, 1g of manganese chloride and 10g of melamine, mix them, grind them and put them into a crucible. Place the crucible in a muffle furnace and heat at 5℃·min. -1The temperature was raised to 550℃ at a heating rate, calcined for 5 hours, and then naturally cooled to obtain the calcined product. The obtained calcined product was ground into a uniform powder in a mortar and then transferred into a centrifuge tube and deionized water was added for centrifugal washing. The centrifugal washing speed was 4500 r / min and the centrifugal washing time was 15 min. The above centrifugal washing was repeated three times. After that, the washed sample was placed in an oven and dried at a temperature of 65℃. After cooling to room temperature, it was ground again to obtain catalyst DS-1.

[0070] Comparative Example 2

[0071] Weigh out 1g of ferric chloride, 1g of potassium permanganate, and 10g of melamine, mix them, grind them, and place them in a crucible. Place the crucible in a muffle furnace and heat at 5℃·min. -1 The temperature was increased to 550℃ at a heating rate, and calcined for 5 hours. After natural cooling, the calcined product was obtained. The obtained calcined product was ground into a uniform powder in a mortar and then transferred into a centrifuge tube. Deionized water was added for centrifugal washing at a speed of 4500 r / min for 15 min. The centrifugal washing was repeated three times. After that, the washed sample was placed in an oven and dried at 65℃. After cooling to room temperature, it was ground again to obtain catalyst DS-2.

[0072] Comparative Example 3

[0073] Weigh out 1g of ferric chloride and 10g of melamine, mix them, grind them, and place them in a crucible. Place the crucible in a muffle furnace and heat at 5℃·min. -1 The temperature was raised to 550℃ at a heating rate, calcined for 5 hours, and then naturally cooled to obtain the calcined product. The obtained calcined product was ground into a uniform powder in a mortar and then transferred into a centrifuge tube and deionized water was added for centrifugal washing. The centrifugal washing speed was 4500 r / min and the centrifugal washing time was 15 min. The above centrifugal washing was repeated three times. After that, the washed sample was placed in an oven and dried at a temperature of 65℃. After cooling to room temperature, it was ground again to obtain catalyst DS-3.

[0074] Comparative Example 4

[0075] Weigh out 1g of manganese chloride and 10g of melamine, mix them, grind them, and place them in a crucible. Place the crucible in a muffle furnace and heat at 5℃·min. -1 The temperature was raised to 550℃ at a heating rate, calcined for 5 hours, and then naturally cooled to obtain the calcined product. The obtained calcined product was ground into a uniform powder in a mortar and then transferred into a centrifuge tube and deionized water was added for centrifugal washing. The centrifugal washing speed was 4500 r / min and the centrifugal washing time was 15 min. The above centrifugal washing was repeated three times. After that, the washed sample was placed in an oven and dried at a temperature of 65℃. After cooling to room temperature, it was ground again to obtain catalyst DS-4.

[0076] Comparative Example 5

[0077] Weigh 10g of melamine and place it in a crucible. Transfer it to a muffle furnace and heat at 5℃·min. -1 The temperature was increased to 550℃ and held for 5 hours to obtain lumpy g-C3N4. The obtained lumpy g-C3N4 was ground to obtain powdered g-C3N4. 0.5 g of powdered g-C3N4 was weighed and placed in 40 mL of deionized water, and 1 g of ferric chloride, 0.732 g of manganese chloride and 1.2333 g of sodium hydroxide were added and mixed. After stirring for 24 hours, the mixture was transferred to a muffle furnace and heated at 5℃·min. -1 The product was heated to 550℃ for 5 hours and calcined. After natural cooling, the calcined product was obtained. The calcined product was ground into a uniform powder in a mortar and transferred into a centrifuge tube. Deionized water was added for centrifugal washing at a speed of 4500 r / min for 15 min. The centrifugal washing was repeated three times. After washing, the sample was placed in an oven and dried at 80℃. After cooling to room temperature, it was ground again to obtain catalyst GCD-5.

[0078] The catalysts prepared in Example 1 and Comparative Examples 1-5 catalyze the degradation of methylene blue by PMS.

[0079] The reaction conditions were set at room temperature and pH 7, and the experiment was carried out in a 500mL glass conical flask. The specific experimental procedure was as follows:

[0080] 1) Prepare a 500mL glass conical flask, add 5mg of methylene blue and 500mL of deionized water to the conical flask to prepare a 10mg / L methylene blue solution.

[0081] 2) Accurately weigh 0.1g of the catalyst prepared in Example 1 and Comparative Examples 1-5 on an analytical balance, add them to an Erlenmeyer flask, and then stir on a magnetic stirrer for 30min. After 30min, take 5mL of sample as the zero point sample and record it as CO.

[0082] 3) Next, weigh 0.1g of PMS and add it to the conical flask. Start timing while adding PMS.

[0083] 4) Take a sample every 1 minute during the reaction, with 5 mL of sample taken each time. After filtering the sample through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 554 nm, and record it as C.

[0084] Figure 11 The graph shows the degradation rate of methylene blue catalyzed by the catalysts prepared in Example 1 and Comparative Examples 1-5. From... Figure 11As can be seen, when comparing the catalysts prepared by the six different preparation methods of Comparative Example 1 and Comparative Examples 1-5, the Fe-Mn / g-C3N4 catalyst prepared in Example 1 showed the highest degradation rate of methylene blue when used to catalyze the degradation of persulfate PMS, reaching 99.04%, followed by the catalyst DS-1 prepared in Comparative Example 1, with a degradation rate of 91.71%.

[0085] Figure 12 The degradation curve of methylene blue catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is shown. From... Figure 12 As can be seen, when using the Fe-Mn / g-C3N4 catalyst prepared in Example 1 to catalyze the degradation of methylene blue, the concentration of methylene blue decreases rapidly within the first 2 minutes, indicating a rapid reaction. The curve flattens out within the first 2-3 minutes, indicating a slow reaction rate. After the third minute, the reaction essentially reaches equilibrium, with a final degradation rate of 99.04%.

[0086] Examples 2-5

[0087] The difference from Example 1 is that in step (2), the temperature is 5°C·min. -1 The heating rates were respectively raised to 500℃ (Example 2), 525℃ (Example 3), 575℃ (Example 4), and 600℃ (Example 5), with other conditions the same as in Example 1.

[0088] Comparative Examples 6-9

[0089] The difference from Comparative Example 1 is that, at 5℃·min -1 The temperature was increased to 500℃ (Comparative Example 6), 525℃ (Comparative Example 7), 575℃ (Comparative Example 8), and 600℃ (Comparative Example 9) at the same rate as Comparative Example 1.

[0090] The catalysts prepared in Examples 1-5, Comparative Examples 1, and Comparative Examples 6-9 were used to catalyze the degradation of methylene blue in PMS. The experimental methods were the same as above, and the experimental results are shown in [Figure 1]. Figure 13 .

[0091] Figure 13 The graph shows the degradation rate of methylene blue catalyzed by the catalysts prepared in Examples 1-5 and Comparative Examples 1 and 6-9. Figure 13It can be seen that when using the preparation method of Comparative Example 1, the catalyst exhibits the best catalytic performance in the calcination temperature range of 550-600℃, while the preparation method of Example 1 shows excellent catalytic activity in the range of 525-600℃. By comparing the catalytic performance of the catalysts obtained by the two preparation methods, it was found that the catalyst prepared in Example 1 has a significantly better degradation effect on methylene blue than that in Comparative Example 1. This may be because the catalyst prepared in Example 1 forms a more suitable crystal structure and surface characteristics, thereby improving catalytic activity.

[0092] Example 1: The Fe-Mn / g-C3N4 catalyst prepared for the catalytic degradation of the antibiotic norfloxacin hydrochloride

[0093] The reaction conditions were set at room temperature and pH 7, and the experiment was carried out in a 500mL glass conical flask. The specific experimental procedure was as follows:

[0094] 1) Prepare a 500mL glass conical flask, add 10mg norfloxacin hydrochloride and 500mL deionized water to the conical flask to prepare a 20mg / L norfloxacin hydrochloride solution.

[0095] 2) Accurately weigh 0.2g of the Fe-Mn / g-C3N4(GCDCS-6) catalyst prepared in Example 1 and add it to an Erlenmeyer flask. Then place it on a magnetic stirrer and stir for 30min. After 30min, take 5mL of sample as the zero-point sample.

[0096] 3) Next, weigh 0.2g of PMS and add it to the conical flask. Start timing while adding PMS.

[0097] 4) Take a sample every 1 minute during the reaction, with 5 mL of sample taken each time. After filtering the sample through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 273 nm.

[0098] Figure 14 This is a graph showing the degradation rate of norfloxacin hydrochloride catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1. From... Figure 14 As can be seen, when the Fe-Mn / g-C3N4 catalyst prepared in Example 1 is used to catalyze the degradation of norfloxacin hydrochloride, the concentration of norfloxacin hydrochloride decreases rapidly within the first 3 minutes, indicating a rapid reaction. The curve flattens out within the first 3-11 minutes, indicating a slow reaction rate. After the first 11 minutes, the reaction reaches near equilibrium, with a final degradation rate of 84.9%.

[0099] Example 1: The Fe-Mn / g-C3N4 catalyst prepared for the catalytic degradation of Rhodamine B

[0100] The reaction conditions were set at room temperature and pH 7, and the experiment was carried out in a 500mL glass conical flask. The specific experimental procedure was as follows:

[0101] 1) Prepare a 500mL glass conical flask, add 5mg of Rhodamine B and 500mL of deionized water to the conical flask to prepare a 10mg / L Rhodamine B solution.

[0102] 2) Accurately weigh 0.1 g of the Fe-Mn / g-C3N4(GCDCS-6) catalyst prepared in Example 1 into an Erlenmeyer flask using an analytical balance, then place it on a magnetic stirrer and stir for 30 min. After 30 min, take 5 mL of the sample as the zero-point sample.

[0103] 3) Next, weigh 0.1g of PMS and add it to the conical flask. Start timing while adding PMS.

[0104] 4) Take a sample every 1 minute during the reaction, with 5 mL of sample taken each time. After filtering the sample through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 554 nm.

[0105] Figure 15 This is a graph showing the degradation rate of Rhodamine B catalyzed by the Fe-Mn / g-C3N4 catalyst prepared in Example 1. Figure 15 As can be seen, when using the Fe-Mn / g-C3N4 catalyst prepared in Example 1 to catalyze the degradation of Rhodamine B, the concentration of Rhodamine B decreases rapidly within the first 3 minutes, indicating a rapid reaction. The reaction curve flattens out within the first 3-9 minutes, indicating a slow reaction rate. After the 9th minute, the reaction essentially reaches equilibrium, with a final degradation rate of 86.6%.

[0106] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for efficiently and cost-effectively preparing g-C3N4-supported Fe / Mn bimetallic catalysts, characterized in that, The process includes the following steps: dissolving manganese ferrite and melamine in an organic solvent and then sonicating and stirring to obtain a precursor mixture; subsequently calcining, grinding, and washing the precursor mixture to obtain the g-C3N4-supported Fe / Mn bimetallic catalyst; the mass ratio of manganese ferrite to melamine is 1:(20-50); the calcination temperature is 525-600℃, the time is 5-6 h, and the heating rate is 5℃·min. -1 .

2. The method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts with high efficiency and low cost according to claim 1, characterized in that, The preparation method of the manganese ferrite includes the following steps: dissolving soluble iron salt and soluble manganese salt in water, adding NaOH solution under stirring conditions, and then carrying out a hydrothermal reaction to obtain the manganese ferrite.

3. The method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts with high efficiency and low cost according to claim 2, characterized in that, The soluble iron salt is selected from FeCl3·6H2O, and the soluble manganese salt is selected from MnCl2·4H2O; the molar ratio of FeCl3·6H2O to MnCl2·4H2O is (1-2):1; The hydrothermal reaction is carried out at a temperature of 80-100℃ for 2-4 hours.

4. The method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts with high efficiency and low cost according to claim 1, characterized in that, The ultrasound frequency is 40000Hz and the duration is 45-60min.

5. The method for preparing g-C3N4 supported Fe and Mn bimetallic catalysts with high efficiency and low cost according to claim 1, characterized in that, The stirring rate is 120-150 r / min, and the stirring time is 18-24 h.

6. The method for efficiently and cost-effectively preparing g-C3N4-supported Fe and Mn bimetallic catalysts according to claim 1, characterized in that, The calcination temperature is 550-575℃.

7. A g-C3N4-supported Fe and Mn bimetallic catalyst prepared by the method for preparing g-C3N4-supported Fe and Mn bimetallic catalysts according to any one of claims 1 to 6.

8. The application of the g-C3N4 supported Fe and Mn bimetallic catalyst as described in claim 7 in the degradation of organic pollutants.

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