Method for preparing g-C3N4 loaded Fe and Mn bimetallic catalyst with high efficiency and low cost

Abstract

The invention discloses a method for preparing a g-C3N4 loaded Fe and Mn bimetallic catalyst with high efficiency and low cost, and belongs to the technical field of catalysts. Manganese ferrite is adopted as a bimetal source, a melamine one-step calcination method is combined, synthesis of g-C3N4 and loading of Fe and Mn are synchronously achieved, manganese ferrite is decomposed into FeOx and MnOx nanoparticles in the calcination process, the FeOx and MnOx nanoparticles and nitrogen sites of g-C3N4 form strong coordinate bonds, metal atomic-scale dispersion can be achieved, and metal ion migration is inhibited; through the bimetallic synergistic effect of Fe and Mn, the oxidation-reduction capacity of the catalyst can be remarkably improved; through the unique thermal decomposition characteristic, the bimetallic synergistic effect and the strong chemical bonding of the manganese ferrite and g-C3N4, the efficient exposure of active sites, the remarkable improvement of the oxidation reduction capacity and the effective inhibition of metal dissolution are realized, and the preparation method also has the advantages of high efficiency, low cost and small secondary pollution risk.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a method for efficiently and low-costly preparing a g-C 3 N 4 supported Fe, Mn bimetallic catalyst. Background Art

[0002] With the acceleration of the industrialization process, the accumulation of refractory organic pollutants (such as dyes, pesticides, drug residues, etc.) in water bodies has become increasingly serious, posing a serious threat to the ecological environment and human health. Traditional physical, chemical, and biological treatment methods are often inefficient or costly in treating refractory organic compounds. Therefore, the development of efficient, economical, and environmentally friendly catalytic degradation technologies has become the focus and hotspot in the current fields of water treatment and environmental governance.

[0003] Heterogeneous catalytic oxidation technology is considered to be one of the effective means for treating refractory organic pollutants due to its advantages such as high efficiency, good selectivity, easy 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, Mn) catalysts can significantly improve the catalytic performance through the synergistic effect of bimetals. Research shows that Fe-Mn bimetallic catalysts exhibit significant advantages in advanced oxidation processes (AOPs) based on persulfate (PMS / PDS), and can effectively degrade organic pollutants such as phenol, dyes, and emerging pollutants such as antibiotics. However, existing Fe-Mn bimetallic catalysts still have some problems, such as poor loading uniformity, catalytic activity limited by pH value, and high metal ion dissolution rate leading to secondary pollution, etc.

[0004] In recent years, carbon-based materials (such as graphitic carbon nitride, g-C 3 N 4 ) have become ideal carriers for loading transition metals due to their high specific surface area, good chemical stability, and adjustable electronic structure. g-C 3 N 4 As a new type of carbon-based material, it has a unique layered structure and good photocatalytic performance. It can anchor metal active sites through π-π interaction and surface functional groups, effectively inhibit the dissolution of metal ions, and can also further improve the redox ability of the catalyst through the conductivity and photocatalytic performance of g-C 3 N 4 . Although there have been studies exploring g-C 3 N 4 supported single-metal or heterojunction catalysts, regarding g-C 3 N 4There is still a blank in the report of the supported Fe-Mn bimetallic catalyst. In the prior art, the synthesis of bimetallic catalysts mostly uses the stepwise loading or physical mixing method. Its preparation process requires multiple calcination steps and complex post-treatment, with high costs and difficulty in achieving uniform dispersion of metals. In addition, the traditional method has insufficient regulation of the interaction between the support and the metal, resulting in limited catalytic stability and pH adaptability. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a method for efficiently and low-costly preparing a g-C 3 N 4 supported Fe, Mn bimetallic catalyst. The preparation method provided by the present invention has the advantages of high efficiency, low cost, and low risk of secondary pollution, and the prepared catalyst exhibits excellent degradation performance for refractory organic pollutants.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for efficiently and low-costly preparing a g-C 3 N 4 supported Fe, Mn bimetallic catalyst, comprising the following steps: dissolving manganese ferrite and melamine in an organic solvent, performing ultrasonic treatment and stirring to obtain a precursor mixture; then sequentially calcining, grinding, and washing the precursor mixture to obtain the g-C 3 N 4 supported Fe, Mn bimetallic catalyst.

[0008] Technical Principle:

[0009] The present invention uses manganese ferrite (MnFe 2 O 4 ) as the bimetallic source, combined with the one-step calcination method of melamine, to simultaneously realize the synthesis of g-C 3 N 4 and the loading of Fe and Mn. Among them, manganese ferrite decomposes into FeO x and MnO x nanoparticles during the calcination process, forming strong coordination bonds with the nitrogen sites of g-C 3 N 4 , which can achieve atomic-level dispersion of metals and inhibit the migration of metal ions; secondly, through the bimetallic synergistic effect of Fe and Mn, the redox ability of the catalyst can be significantly improved; therefore, manganese ferrite, through its unique thermal decomposition characteristics, bimetallic synergistic effect, and interaction with g-C 3 N 4The strong chemical bonding realizes the efficient exposure of active sites, the significant improvement of redox ability and the effective inhibition of metal dissolution. This design not only solves the defects of poor loading uniformity, pH - value - limited catalytic activity and high metal ion dissolution rate existing in the existing catalysts, but also greatly reduces the cost through process simplification, and has the advantages of 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 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.

[0012] Furthermore, the soluble iron salt is selected from FeCl 3 ·6H 2 O, and the soluble manganese salt is selected from MnCl 2 ·4H 2 O; the molar ratio of FeCl 3 ·6H 2 O to MnCl 2 ·4H 2 O is (1 - 2)∶1; the temperature of the hydrothermal reaction is 80 - 100 °C, and the time is 2 - 4 h.

[0013] Furthermore, the frequency of the ultrasonic wave is 40000 Hz, and the time 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 °C, the time is 5 - 6 h, and the heating rate is 5 °C·min -1 .

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

[0017] The present invention provides the g - C 3 N 4 supported Fe, Mn bimetallic catalyst prepared by the method for efficiently and low - cost preparing the g - C 3 N 4 supported Fe, Mn bimetallic catalyst.

[0018] The present invention also provides the application of the g - C 3 N 4 supported Fe, Mn bimetallic catalyst 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-C 3 N 4 supported Fe, Mn bimetallic catalyst prepared by the present invention exhibits excellent degradation performance for refractory organic pollutants, and the degradation efficiency is significantly improved compared with the prior art, and it can effectively remove various types of refractory organic pollutants, such as polycyclic aromatic hydrocarbons, halogenated organic compounds, etc.

[0021] The method for preparing the g-C 3 N 4 supported Fe, Mn bimetallic catalyst provided by the present invention has low cost, thus greatly reducing the production cost of the catalyst, has good economic benefits and market competitiveness, has significant technological innovation and potential for industrial application, and is conducive to large-scale industrial application.

[0022] The catalyst prepared by the present invention does not produce secondary pollution during the degradation of organic pollutants, meets the requirements of green chemistry and sustainable development, and provides a green and environmentally friendly solution for environmental governance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 1 The physical picture of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1;

[0025] Figure 2 The SEM image (30μm) of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1;

[0026] Figure 3 The SEM image (10μm) of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1;

[0027] Figure 4 The C element surface distribution map of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1;

[0028] Figure 5 The Fe-Mn / g-C 3 N4 N elemental surface distribution map of the catalyst;

[0029] Figure 6 Fe-Mn / g-C prepared for Example 1 3 N 4 O elemental surface distribution map of the catalyst;

[0030] Figure 7 Fe-Mn / g-C prepared for Example 1 3 N 4 Fe elemental surface distribution map of the catalyst;

[0031] Figure 8 Fe-Mn / g-C prepared for Example 1 3 N 4 Mn elemental surface distribution map of the catalyst;

[0032] Figure 9 Fe-Mn / g-C prepared for Example 1 3 N 4 All elemental surface distribution map of the catalyst;

[0033] Figure 10 Fe-Mn / g-C prepared for Example 1 3 N 4 EDS spectrum of the catalyst, and the inset shows the atomic percentage and weight percentage of each element;

[0034] Figure 11 Degradation rate graph of methylene blue catalyzed by the catalysts prepared for Example 1 and Comparative Examples 1-5;

[0035] Figure 12 Fe-Mn / g-C prepared for Example 1 3 N 4 Degradation curve of methylene blue catalyzed by the catalyst;

[0036] Figure 13 Degradation rate graph of methylene blue catalyzed by the catalysts prepared for Examples 1-5 and Comparative Examples 1, 6-9;

[0037] Figure 14 Fe-Mn / g-C prepared for Example 1 3 N 4 Degradation rate graph of norfloxacin hydrochloride catalyzed by the catalyst;

[0038] Figure 15 Fe-Mn / g-C prepared for Example 1 3 N 4 Degradation rate graph of rhodamine B catalyzed by the catalyst. Detailed implementation method

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

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

[0041] An embodiment of the present invention provides a method for efficiently and low-cost preparing a g-C 3 N 4 supported Fe, Mn bimetallic catalyst, comprising the following steps: dissolving manganese ferrite and melamine in an organic solvent, performing ultrasonic treatment and stirring to obtain a precursor mixture; then calcining, grinding, and washing the precursor mixture in sequence to obtain the g-C 3 N 4 supported Fe, Mn bimetallic catalyst (Fe-Mn / g-C 3 N 4 ).

[0042] In a preferred embodiment, the mass ratio of the manganese ferrite to the melamine is 1:(20 - 50). The present invention uses manganese ferrite as the manganese source and iron source for preparing the g-C 3 N 4 supported Fe, Mn bimetallic catalyst, which is beneficial to obtaining a catalyst with high catalytic activity.

[0043] In a preferred embodiment, the preparation method of the manganese ferrite comprises the following steps: dissolving a soluble iron salt and a soluble manganese salt in water, adding a NaOH solution under stirring conditions, and then performing a hydrothermal reaction to obtain the manganese ferrite.

[0044] In a preferred embodiment, the soluble iron salt is selected from FeCl 3 ·6H 2 O, and the soluble manganese salt is selected from MnCl 2 ·4H 2 O; the molar ratio of the FeCl 3 ·6H 2 O to the MnCl 2 ·4H 2 O is (1 - 2):1.

[0045] In a preferred embodiment, a soluble iron salt and a soluble manganese salt are dissolved in water and stirred for 30 min. Then, a NaOH solution is added dropwise while continuously stirring for 1 h. In the present invention, by continuously stirring for 1 h, it is ensured that iron ions and manganese ions react fully with hydroxide ions, making the generated manganese ferrite precursor more complete and stable. If the stirring is stopped in advance, some ions may not participate in the reaction, resulting in inaccurate composition of the precursor and affecting the performance of the manganese ferrite material.

[0046] In a preferred embodiment, the concentration of the NaOH solution is 1.5 mo1 / L; the amount of the NaOH solution is used to adjust the pH value of the solution to 11 - 12; the addition method of the NaOH solution is dropwise addition.

[0047] In a preferred embodiment, the temperature of the hydrothermal reaction is 80 - 100 °C and the time is 2 - 4 h; 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, it further includes: cooling the product of the hydrothermal reaction at room temperature, then performing centrifugal washing and drying to obtain the manganese ferrite; the reagent for centrifugal washing is deionized water, the rotation speed of centrifugal washing is 4500 r / min, and the time is 10 min; the drying temperature is 65 °C, and the drying equipment is an oven.

[0049] In a preferred embodiment, the organic solvent is selected from methanol. The present invention has no special limitation on the amount of the organic solvent, and it can cover the manganese ferrite and melamine.

[0050] In a preferred embodiment, the frequency of the ultrasound is 40000 Hz and the time is 45 - 60 min.

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

[0052] In a preferred embodiment, the calcination temperature is 525 - 600 °C, more preferably 550 - 575 °C; the calcination time is 5 - 6 h; the heating rate of the calcination is 5 °C·min -1 . In the present invention, the calcination temperature affects the catalytic activity of the catalyst. Calcination within the above temperature range is beneficial to 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 rotation speed is 4500 r / min, the washing time is 15 min, and the number of washing times is three. In the present invention, washing is used to remove unbound Fe and Mn ions and excess impurities.

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

[0055] The present invention provides the g-C prepared by the method of the above technical solution 3 N 4 supported Fe, Mn bimetallic catalyst 3 N 4 supported Fe, Mn bimetallic catalyst.

[0056] The present invention also provides the application of the g-C 3 N 4 supported Fe, Mn bimetallic catalyst in the degradation of organic pollutants.

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

[0058] In the embodiments of the present invention, room temperature refers to "25 ± 2 °C".

[0059] Unless otherwise specified, the raw materials in the embodiments of the present invention are all obtained through commercial channels.

[0060] Example 1

[0061] A method for efficiently and low-costly preparing a g-C 3 N 4 supported Fe, Mn bimetallic catalyst, the specific steps are as follows:

[0062] (1) Dissolve 2.7029 g of FeCl 3 ·6H 2 O and 0.9892 g of MnCl 2 ·4H 2 O (the molar ratio of FeCl 3 ·6H 2 O and MnCl 2 ·4H 2 O is 2:1) in deionized water, stir for 30 min, then while continuously stirring for 1 h, dropwise add a NaOH solution with a concentration of 1.5 mo1 / L until the pH value of the solution is 11 - 12 to obtain a manganese ferrite precursor mixture; heat the obtained manganese ferrite precursor mixture in a 100 °C constant temperature water bath, while starting mechanical stirring, after 4 h, the reaction ends, cool the reaction product at room temperature, and then perform centrifugal washing with deionized water, the rotation speed of centrifugal washing is 4500 r / min, the time of centrifugal washing is 10 min, after centrifugal washing ends, place the sample in an oven at 65 °C for drying to obtain manganese ferrite MnFe 2O 4 。

[0063] (2) Using methanol as the solvent, add 0.4 g of MnFe obtained in step (1) 2 O 4 and 12 g of melamine (the mass ratio of MnFe 2 O 4 to melamine is 1:30), ultrasonicate at 40000 Hz for 45 min, then stir at a rate of 150 r / min for 18 h to obtain a precursor mixture; transfer the obtained precursor mixture to a muffle furnace, heat it to 550 °C at a heating rate of 5 °C·min -1 , calcine for 5 h, after the calcined product cools, grind it into a fine and uniform powder with a mortar, then transfer it to a centrifuge tube and add deionized water for centrifugal washing. The rotation speed of the centrifugal washing is 4500 r / min, and the time of the centrifugal washing is 15 min. Repeat the above centrifugal washing three times. Then put the washed sample into an oven and dry it at a temperature of 80 °C. After cooling to room temperature, grind it again to obtain a g-C 3 N 4 supported Fe, Mn bimetallic catalyst (Fe-Mn / g-C 3 N 4 catalyst), denoted as GCDCS-6.

[0064] Figure 1 is a physical picture of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1. As can be seen from Figure 1 , the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 is in the form of black particles.

[0065] Figure 2 is the SEM image (30 μm) of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1, Figure 3 is the SEM image (10 μm) of the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1. As can be seen from Figure 2 and Figure 3 , the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 is a typical aggregated layered structure. The surface of g-C 3 N 4 is smooth and has a layered stacking structure with a large specific surface area, which is beneficial to the loading of Fe and Mn.

[0066] Figure 4The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of C element of the catalyst, Figure 5 The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of N element of the catalyst, Figure 6 The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of O element of the catalyst, Figure 7 The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of Fe element of the catalyst, Figure 8 The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of Mn element of the catalyst, Figure 9 The Fe-Mn / g-C prepared for Example 1 3 N 4 Elemental surface distribution map of all elements of the catalyst. From Figures 4 - 9 It can be seen that the Fe-Mn / g-C prepared in Example 1 3 N 4 The catalyst contains C, N, O, Fe, and Mn elements.

[0067] Figure 10 The Fe-Mn / g-C prepared for Example 1 3 N 4 EDS spectrum of the catalyst, and the inset shows the atomic percentage and weight percentage of each element. From Figure 10 It can be seen that the Fe-Mn / g-C prepared in Example 1 3 N 4 The catalyst contains 0.4 wt% of Mn element and 0.8 wt% of Fe element.

[0068] Comparative Example 1

[0069] Weigh 1 g of ferric chloride, 1 g of manganese chloride, and 10 g of melamine, mix them, grind them and put them into a crucible. Place the crucible in a muffle furnace and heat it at a heating rate of 5 °C·min -1 to 550 °C, calcine for 5 h and then cool naturally to obtain a calcined product; after grinding the obtained calcined product into a uniform powder in a mortar, transfer it to a centrifuge tube and add deionized water for centrifugal washing. The rotation speed of centrifugal washing is 4500 r / min, and the time of centrifugal washing is 15 min. Repeat the above centrifugal washing three times, and then put the washed sample into an oven and dry it at a temperature of 65 °C. After cooling to room temperature, grind it again to obtain the catalyst DS-1.

[0070] Comparative Example 2

[0071] Weigh 1g of ferric chloride, 1g of potassium permanganate 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 -1 The mixture was heated to 550°C at a heating rate of 1000 ℃, calcined for 5 hours and then naturally cooled to obtain a calcined product; the calcined product was ground into uniform powder in a mortar, transferred into a centrifuge tube and centrifuged with deionized water for washing at a speed of 4500 r / min and a time of 15 minutes. The above centrifugal washing was repeated three times, and the washed sample was then placed in an oven and dried at 65°C. After cooling to room temperature, it was ground again to obtain catalyst DS-2.

[0072] Comparative Example 3

[0073] Weigh 1g of ferric 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 -1 The mixture was heated to 550°C at a heating rate of , calcined for 5 hours and then naturally cooled to obtain a calcined product; the calcined product was ground into uniform powder in a mortar, transferred into a centrifuge tube and centrifuged with deionized water for washing at a speed of 4500 r / min and a time of 15 minutes. The above centrifugal washing was repeated three times, and the washed sample was then placed in an oven and dried at 65°C. After cooling to room temperature, it was ground again to obtain catalyst DS-3.

[0074] Comparative Example 4

[0075] Weigh 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 it at 5℃·min -1 The mixture was heated to 550°C at a heating rate of 1000 ℃, calcined for 5 hours and then naturally cooled to obtain a calcined product; the calcined product was ground into uniform powder in a mortar, transferred into a centrifuge tube and centrifuged with deionized water for washing at a speed of 4500 r / min and a time of 15 minutes. The above centrifugal washing was repeated three times, and the washed sample was then placed in an oven and dried at 65°C. After cooling to room temperature, it was ground again to obtain catalyst DS-4.

[0076] Comparative Example 5

[0077] Weigh 10 g of melamine into a crucible, transfer it to a muffle furnace, and heat it at 5 °C min -1 The temperature was raised to 550℃ and kept at this temperature for 5h to obtain blocky gC 3 N 4 ; The obtained block gC 3 N 4 Grind to obtain powdered gC 3 N4 , weigh 0.5 g of powdered g-C 3 N 4 , place it in 40 mL of deionized water, and add 1 g of ferric chloride, 0.732 g of manganese chloride and 1.2333 g of sodium hydroxide for mixing. After stirring for 24 h, transfer it to a muffle furnace and heat it to 550 °C at a heating rate of 5 °C·min -1 for 5 h of calcination, and cool it naturally to obtain the calcined product; after grinding the obtained calcined product into a uniform powder in a mortar, transfer it to a centrifuge tube and add deionized water for centrifugal washing. The rotation speed of centrifugal washing is 4500 r / min, and the time of centrifugal washing is 15 min. Repeat the above centrifugal washing three times, and then put the washed sample into an oven and dry it at 80 °C. After cooling to room temperature, grind it again to obtain the catalyst GCD-5.

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

[0079] The reaction conditions are set at room temperature, pH value of 7, and carried out in a glass conical flask with an effective volume of 500 mL. The specific experimental process is as follows:

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

[0081] 2) Accurately weigh 0.1 g of the catalysts prepared in Example 1 and Comparative Examples 1-5 on an analytical balance, add them to the conical flask, and then place them on a magnetic stirrer and stir for 30 min. After 30 min, take 5 mL of the sample as the zero-point sample, denoted as C 0 .

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

[0083] 4) During the reaction, take a sample every 1 min, each time taking 5 mL of the sample. After the obtained sample is filtered through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 554 nm, denoted as C.

[0084] Figure 11 is the degradation rate diagram of the catalysts prepared in Example 1 and Comparative Examples 1-5 for the catalytic degradation of methylene blue. From Figure 11 it can be seen that when comparing the catalysts prepared by 6 different preparation methods of Example 1 and Comparative Examples 1-5 for the catalytic degradation of methylene blue by persulfate PMS, the Fe-Mn / g-C prepared in Example 1 3 N 4The degradation rate of the catalyst is the highest, reaching 99.04%. Followed by the catalyst DS-1 prepared in Comparative Example 1, with a degradation rate of 91.71%.

[0085] Figure 12 For the Fe-Mn / g-C prepared in Example 1 3 N 4 Degradation curve of methylene blue catalyzed by the catalyst. From Figure 12 It can be seen that when using the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 to catalyze the degradation of methylene blue, the concentration of methylene blue drops rapidly within the first 2 minutes, and the reaction proceeds rapidly at this time. The curve flattens out within 2 - 3 minutes after the start of the reaction, and the reaction rate is slow at this time. After the 3rd minute of the start of the reaction, the reaction basically reaches an equilibrium state, and the final degradation rate reaches 99.04%.

[0086] Examples 2 - 5

[0087] The difference from Example 1 is that in step (2), it is heated to 500 °C (Example 2), 525 °C (Example 3), 575 °C (Example 4), 600 °C (Example 5) at a heating rate of 5 °C·min -1 respectively, and the others are the same as Example 1.

[0088] Comparative Examples 6 - 9

[0089] The difference from Comparative Example 1 is that it is heated to 500 °C (Comparative Example 6), 525 °C (Comparative Example 7), 575 °C (Comparative Example 8), 600 °C (Comparative Example 9) at a heating rate of 5 °C·min -1 respectively, and the others are the same as Comparative Example 1.

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

[0091] Figure 13 Degradation rate diagram of methylene blue catalyzed by the catalysts prepared in Examples 1 - 5 and Comparative Examples 1, 6 - 9. From Figure 13 It can be seen that when using the preparation method of Comparative Example 1, the catalyst shows the best catalytic performance in the calcination temperature range of 550 - 600 °C, while the preparation method of Example 1 shows excellent catalytic activity in the range of 525 - 600 °C. By comparing the catalytic performance of the catalysts obtained by the two preparation methods, it is found that the catalyst prepared in Example 1 has a significantly better degradation effect on methylene blue than Comparative Example 1, which may be due to the formation of a more suitable crystal structure and surface characteristics of the catalyst prepared in Example 1, thus improving the catalytic activity.

[0092] The Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 for catalytic degradation of the antibiotic - norfloxacin hydrochloride

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

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

[0095] 2) Accurately weigh 0.2 g of the Fe-Mn / g-C 3 N 4 (GCDCS-6) catalyst and add it to the conical flask, 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.

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

[0097] 4) During the reaction, take a sample every 1 min, each time taking 5 mL of the sample. After the obtained sample is filtered through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 273 nm.

[0098] Figure 14 The degradation rate graph of norfloxacin hydrochloride catalyzed by the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1. As can be seen from Figure 14 it, when using the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 to catalyze the degradation of norfloxacin hydrochloride, the concentration of norfloxacin hydrochloride drops rapidly within the first 3 minutes, and the reaction proceeds rapidly at this time. The curve tends to be flat within 3 - 11 minutes after the start of the reaction, and the reaction rate is slow at this time. After the 11th minute of the start of the reaction, the reaction basically reaches an equilibrium state, and the final degradation rate reaches 84.9%.

[0099] The Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 for catalytic degradation of rhodamine B

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

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

[0102] 2) Accurately weigh 0.1 g of the Fe-Mn / g-C 3 N 4 (GCDCS-6) catalyst prepared in Example 1 and add it to the conical flask, 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) Then weigh 0.1 g of PMS and add it to the conical flask, and start timing while adding PMS.

[0104] 4) During the reaction, take a sample every 1 min, each time taking 5 mL of the sample. After the obtained sample is filtered through a 0.45 μm filter membrane, use a spectrophotometer to measure its absorbance at a wavelength of 554 nm.

[0105] Figure 15 It is the degradation rate diagram of Rhodamine B catalyzed by the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1. From Figure 15 it can be seen that when using the Fe-Mn / g-C 3 N 4 catalyst prepared in Example 1 to catalyze the degradation of Rhodamine B, the concentration of Rhodamine B drops rapidly within the first 3 minutes, and the reaction proceeds rapidly at this time. The curve flattens out within 3 - 9 minutes after the start of the reaction, and the reaction rate is slow at this time. After the 9th minute of the start of the reaction, the reaction basically reaches an equilibrium state, and the final degradation rate reaches 86.6%.

[0106] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost, characterized in that: The method comprises the following steps: dissolving manganese ferrite and melamine in an organic solvent, performing ultrasound and stirring to obtain a precursor mixed liquid; and then sequentially calcining, grinding and washing the precursor mixed liquid to obtain the g-C3N4 loaded Fe, Mn bimetallic catalyst.

2. The method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost according to claim 1, characterized in that: The mass ratio of the manganese ferrite to melamine is 1:(20-50).

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

4. The method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost according to claim 3, 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 temperature of the hydrothermal reaction is 80-100° C. and the time is 2-4 hours.

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

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

7. The method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost according to claim 1, characterized in that: The calcination temperature is 525-600°C, the time is 5-6h, and the heating rate is 5°C·min -1 .

8. The method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost according to claim 7, characterized in that: The calcination temperature is 550-575°C.

9. A g-C3N4 loaded Fe, Mn bimetallic catalyst prepared by the method for preparing g-C3N4 loaded Fe, Mn bimetallic catalyst with high efficiency and low cost as described in any one of claims 1 to 8.

10. Use of the g-C3N4 loaded Fe, Mn bimetallic catalyst as claimed in claim 9 in the degradation of organic pollutants.

Images