Oxygen-doped iron monatomic carbon nitride composite catalyst as well as preparation method and application thereof

Abstract

The invention discloses an oxygen-doped iron monatomic carbon nitride composite catalyst and a preparation method and application thereof.The preparation method of the catalyst comprises the steps that after an iron source, oxalic acid hydrate, polyvinylpyrrolidone, 2-methylimidazole, Pluronic F127 and an alcohol solution are mixed and subjected to ball milling, filtering, washing, drying and grinding are conducted, and a precursor is obtained; and mixing the precursor with melamine, carrying out anaerobic calcination, cooling, grinding and sieving. Through the synergistic effect of polyvinylpyrrolidone, 2-methylimidazole and Pluronic F127, the dispersion effect of iron single atoms on carbon nitride is improved, and the prepared catalyst has excellent degradation efficiency in application of activating PMS to degrade BPA.

Description

Technical Field

[0001] The invention relates to an oxygen-doped iron single-atom carbon nitride composite catalyst and a preparation method and application thereof, belonging to the technical field of water pollution control. Background Art

[0002] Activated carbon, biochar, graphene, carbon nanotubes, graphitic carbon nitride (gC 3 N 4 ) have been widely used to activate persulfate to degrade phenolic pollutants. Among them, graphite carbon nitride is favored due to its simple synthesis method, low price, and good acid and alkali tolerance. However, the original gC 3 N 4 The transfer rate of surface electrons is low and its performance in activating persulfate is not ideal.

[0003] Metal single atom doped carbon nitride exhibits excellent chemical properties through its unique electronic structure, in which isolated metal atoms interact closely with surrounding coordinated atoms. This structure not only achieves efficient utilization of metal atoms and improves the catalytic efficiency at the atomic level, but also ensures high activity and stability of the catalyst. Under the doping of metal single atoms, non-metal atoms are further doped to enhance the adsorption and activation performance of the catalyst for peroxymonosulfate (PMS) by doping electronegative heteroatoms and adjusting the electron density of the metal center.

[0004] For example, iron single atom carbon nitride composite catalysts are prepared by oxygen doping, and the doped oxygen is used to increase the electron transfer rate, thereby improving the catalytic activity. However, due to the distribution problem of iron single atoms, the efficiency of activating PMS to degrade BPA is only 90%. Therefore, how to improve the dispersion effect of iron single atoms on carbon nitride to improve the degradation efficiency of BPA is still an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide an oxygen-doped iron single atom carbon nitride composite catalyst and its preparation method and application, and to utilize the synergistic effect of polyvinylpyrrolidone, 2-methylimidazole and Pluronic F127 to improve the dispersion effect of iron single atoms on carbon nitride to improve the efficiency of activating PMS to degrade BPA.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An oxygen-doped iron single-atom carbon nitride composite catalyst (SAFe-OgC 3 N 4) is prepared by mixing an iron source, oxalic acid hydrate, polyvinylpyrrolidone, 2-methylimidazole, Pluronic F127 and an alcohol solution, and then ball-milling the mixture, filtering, washing, drying and grinding the mixture to obtain a precursor; then mixing the precursor with melamine, calcining the mixture in the absence of oxygen, and grinding and sieving the mixture after cooling.

[0008] Preferably, the iron source is FeSO 4 7H 2 O, oxalic acid hydrate is: C 2 H 2 O 4 ·2H 2 O;

[0009] And FeSO 4 7H 2 O and C 2 H 2 O 4 ·2H 2 The molar ratio of O is 1:(1-10);

[0010] The mass ratio of the total mass of the iron source and oxalic acid hydrate to the mass ratio of polyvinylpyrrolidone, 2-methylimidazole, and Pluronic F127 is (2-4):(3-5):(4-6):(2-4).

[0011] Preferably, the drying conditions are: under vacuum conditions, 60-100° C., 10-15 h.

[0012] Preferably, the mass ratio of the precursor to melamine is 1:(3-8).

[0013] Preferably, the conditions for oxygen-free calcination are: in a nitrogen atmosphere, 500-800° C. for 2-5 h, and a heating rate of 1-5° C. / min.

[0014] An oxygen-doped iron single-atom carbon nitride composite catalyst is prepared by any of the above methods.

[0015] The application of the oxygen-doped iron single-atom carbon nitride composite catalyst prepared by any of the above methods in activating PMS to degrade phenol pollutants in water bodies is to add the catalyst to the water body containing phenol pollutants, and then add PMS for degradation after reaching adsorption-desorption equilibrium.

[0016] Preferably, the phenolic pollutant is bisphenol A.

[0017] Preferably, the dosage of the catalyst is 0.1-4 g / L, the dosage of PMS is 160-1600 μM, the concentration of bisphenol A in the water is 10-80 mg / L, and the pH of the water is 3-11.

[0018] Preferably, the adsorption-desorption equilibrium time is 20-30 min; and the degradation reaction time is 30-120 min.

[0019] The beneficial effects of the present invention are:

[0020] The PPO and PEO segments of Pluronic F127 (block copolymer) can self-assemble to form micelles, which can encapsulate Fe 2+ , forming a nano-scale dispersion system, thereby inhibiting the aggregation of iron ions. PluronicF127 can also use its hydrophilic chain segment to interact with polyvinylpyrrolidone (PVP) to enhance the stability of the system, and the pyrrolidone ring in PVP can also interact with Fe 2+ The formation of coordination bonds, combined with the flexibility of the polymer, dynamically adjusts the dispersion state of iron atoms; at the same time, 2-methylimidazole can coordinate with iron ions through the N atom in the imidazole ring to form a stable Fe-N 4 The systemic interaction between Pluronic F127 and F127 optimizes the coordination environment and enhances the metal-carrier interaction. That is, the micellar dispersion of F127 is combined with the coordination ability of PVP and 2-methylimidazole to form a triple mechanism of "micelle encapsulation-coordination fixation-thermal decomposition confinement", and finally achieves the uniform distribution of single iron atoms. In oxygen-free calcination, the decomposition gas can also facilitate the formation of porous structures. These porous structures not only provide abundant anchoring sites, but also prevent the migration and agglomeration of iron atoms through physical confinement.

[0021] The obtained catalyst SAFe-OgC 3 N 4 It shows a disordered carbon layer stacking structure, with no obvious iron clusters or nanoparticles, showing a typical carbon nitride stacking structure. 3 N 4 The entire gC 3 N 4 The uniform distribution in the matrix does not change the skeleton structure of carbon nitride.

[0022] In the application of degradation of bisphenol A in water, the prepared SAFe-OgC 3 N 4 The catalyst exhibits excellent catalytic performance. It has strong catalytic activity against persulfate, can quickly degrade bisphenol A in water, and has wide applicability to phenolic substances in water. At the same time, the preparation method is simple, low-cost, and has strong potential for industrial application, providing a solution with significant social, economic and technical benefits for the field of water treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1XRD diffraction patterns of the original carbon nitride prepared in Comparative Example 1 and the oxygen-doped iron single-atom carbon nitride prepared in Example 1;

[0024] Figure 2 The infrared spectra (FT-IR) of the original carbon nitride prepared in Comparative Example 1 and the oxygen-doped iron single-atom carbon nitride prepared in Example 1;

[0025] Figure 3 This is a transmission electron microscope (TEM) image of the oxygen-doped iron single-atom carbon nitride prepared in Example 1;

[0026] Figure 4 This is an EDS mapping image of the oxygen-doped iron single-atom carbon nitride prepared in Example 1;

[0027] Figure 5 The effect diagram of catalytic degradation of BPA by the original carbon nitride prepared in Comparative Example 1 and the oxygen-doped iron single-atom carbon nitride prepared in Example 1;

[0028] Figure 6 1:4SAFe-OgC 3 N 4 Effect diagram of catalytic degradation of BPA at different catalyst dosages;

[0029] Figure 7 1:4SAFe-OgC 3 N 4 The effect diagram of catalytic degradation of BPA under different PMS concentrations;

[0030] Figure 8 1:4SAFe-OgC 3 N 4 The effect diagram of catalytic degradation of BPA at different BPA concentrations;

[0031] Fig. 9 1:4SAFe-OgC 3 N 4 Effect diagram of catalytic degradation of BPA under different pH conditions;

[0032] Fig.10 3D response surface plot designed using Design-Expert 8.0.6 software;

[0033] Fig.11 1:4SAFe-OgC 3 N 4 Effect diagram of catalytic degradation of BPA under the final optimized conditions;

[0034] Fig.12For three anion pairs 1:4SAFe-OgC 3 N 4 Effect diagram of catalytic degradation of BPA;

[0035] Fig.13 1:4SAFe-OgC 3 N 4 Degradation effect diagram of different pollutants;

[0036] Fig.14 1:4SAFe-OgC 3 N 4 Degradation curves of BPA by catalytic degradation in tap water and actual water bodies;

[0037] Fig.15 1:4SAFe-OgC 3 N 4 Effect diagram of catalytic degradation of BPA after four cycles;

[0038] Fig.16 This is a diagram showing the effect of the catalyst prepared in Comparative Example 2 being cycled four times to catalyze the degradation of BPA. DETAILED DESCRIPTION

[0039] Example 1

[0040] Preparation of oxygen-doped iron single-atom carbon nitride, the steps are as follows:

[0041] With FeSO 4 7H 2 O and C 2 H 2 O 4 ·2H 2 O in a molar ratio of 1:2, 1:4, and 1:8, respectively, and weigh 3.335 g of the corresponding mass of FeSO 4 7H 2 O and C 2 H 2 O 4 ·2H 2 O, and then placed in a ball mill with 4.320g polyvinylpyrrolidone K-30, 4.720g 2-methylimidazole, 3.280g Pluronic F127 and 12mL methanol for 2h. After filtering, the sample was centrifuged and washed with ethanol for 4 times, and then dried in a vacuum drying oven at 80℃ for 12h. After drying, the sample was taken out and ground and sieved to obtain a precursor.

[0042] The precursor and melamine were mixed in a mass ratio of 1:5 and placed in a quartz boat, which was then placed in a tube furnace for oxygen-free calcination (under a nitrogen atmosphere, with a nitrogen flow rate of 25 mL / min), and the temperature was raised to 600°C at a heating rate of 3°C / min, and maintained at 600°C for 3 hours. After the oxygen-free calcination was completed, the quartz boat was taken out after the temperature of the tube furnace dropped to room temperature, and the product was ground and sieved.

[0043] The catalysts prepared above are respectively denoted as 1:2SAFe-OgC 3 N 4 、1:4SAFe-OgC 3 N 4 、1:8SAFe-OgC 3 N 4 .

[0044] Comparative Example 1

[0045] Preparation of pristine carbon nitride:

[0046] Weigh 10g of melamine, place it in a tube furnace, heat it to 600℃ at a heating rate of 3℃ / min, and maintain 600℃ for 3h without oxygen. During the calcination process, ensure that the nitrogen flow rate is stable at 25mL / min to ensure the stability of the calcination environment. After the calcination is completed, grind and sieve the material to obtain gC 3 N 4 .

[0047] Comparative Example 2

[0048] Preparation of iron-oxygen co-doped carbon nitride:

[0049] With FeSO 4 7H 2 O and C 2 H 2 O 4 ·2H 2 O in a molar ratio of 1:4, weigh 3.335 g of FeSO 4 7H 2 O and C 2 H 2 O 4 ·2H 2 O, and then placed in a ball mill with 12 mL of methanol for 2 hours. After filtering, the sample was centrifuged and washed 4 times with ethanol, and then dried in a vacuum oven at 80°C for 12 hours. After drying, the sample was taken out and ground and sieved to obtain the precursor.

[0050] The precursor and melamine were mixed in a quartz boat at a mass ratio of 1:5, and then placed in a tube furnace for oxygen-free calcination (under nitrogen atmosphere, nitrogen flow rate 25mL / min), and the temperature was raised to 600℃ at a heating rate of 3℃ / min, and maintained at 600℃ for 3h. After the oxygen-free calcination, the quartz boat was taken out after the temperature of the tube furnace dropped to room temperature, and the product was ground and sieved. The obtained catalyst was recorded as Fe-OgC 3 N 4 .

[0051] Figure 1 The XRD diffraction patterns of the original carbon nitride prepared in Comparative Example 1 and the three oxygen-doped iron single-atom carbon nitrides prepared in Example 1 are shown in FIG. Figure 1 It can be seen that gC 3 N 4 and three SAFe-OgC 3 N 4 The characteristic diffraction peaks at 13.1 nm and 28.1 nm correspond to the in-plane vibration (100 crystal plane) and interlayer stacking (002 crystal plane) of the heptazine ring structure in the carbon nitride substrate, respectively. These two diffraction peaks are caused by the graphene layer stacking of the π conjugated plane, indicating that gC 3 N 4 It has a layered structure similar to graphite. SAFe-OgC 3 N 4 With gC 3 N 4 The similar XRD diffraction patterns of indicate that the doping of Fe and O does not change the gC 3 N 4 In addition, the three SAFe-OgC 3 N 4 No diffraction peaks of zero-valent iron or iron oxide were detected, indicating that Fe is dispersed in the gC in atomic form. 3 N 4 In the matrix.

[0052] Figure 2 The infrared spectra (FT-IR) of the original carbon nitride prepared in Comparative Example 1 and the three oxygen-doped iron single-atom carbon nitrides prepared in Example 1 are shown in FIG. Figure 2 It can be seen that gC 3 N 4 The absorption peaks of FT-IR are mainly concentrated at: 800, 1240-1640, 3100-3500cm -1 At 800cm -1 The absorption peaks near the triazine ring correspond to the characteristic absorption of the triazine ring; 1240-1640cm -1 The absorption peaks in the range 3100-3500cm-1 The absorption peaks in the range correspond to the characteristic absorption of NH bonds. 3 N 4 The three SAFe-OgC 3 N 4 The absorption peak of carbon nitride with heptazine ring structure still exists, which further indicates that the doping of Fe single atom and O atom does not change the gC 3 N 4 But SAFe-OgC 3 N 4 At 807cm -1 The intensity of the vibration peak at gC 3 N 4 There is a significant decrease, indicating that oxygen doping weakens the interaction between the heptazine ring structures.

[0053] Figure 3 The transmission electron microscope (TEM) images of the three oxygen-doped iron single-atom carbon nitrides prepared in Example 1 show that SAFe-OgC 3 N 4 Transmission electron microscopy (TEM) images show no obvious iron clusters or nanoparticles, revealing a typical carbon nitride stacking structure. Figure 4 The EDS mapping images of the three oxygen-doped iron single-atom carbon nitrides prepared in Example 1 reveal that Fe is 3 N 4 The entire gC 3 N 4 The uniform distribution of O in the matrix also proves that O is successfully doped into SAFe-OgC 3 N 4 In catalyst.

[0054] Experimental study on degradation of bisphenol A in water by activated persulfate (PMS)

[0055] First, a 20 mg / L bisphenol A aqueous solution was prepared, and 0.09 g of the catalyst prepared in Example 1 and Comparative Example 2 was added to 100 mL of the bisphenol A aqueous solution, respectively, and magnetic stirring was performed for 30 min to reach adsorption / desorption equilibrium. Then 1.0 mL of the solution was taken out and marked as 0 o'clock. After the timing started, 300 μM PMS was added to the bisphenol A aqueous solution for reaction, and stirring was continued. 1.0 mL of the sample was taken at 5, 10, 15, 30, 60, 90, and 120 min, and 0.5 mL of 0.2 mol / L sodium sulfite solution was added to stop the reaction, and then filtered with a 0.45 μm aqueous phase filter membrane, and the concentration of the target pollutant bisphenol A in the sample was determined by high performance liquid chromatography (HPLC).

[0056] Figure 5 The effect diagram of catalytic degradation of BPA by the original carbon nitride prepared in comparative example 1, the iron-oxygen co-doped carbon nitride prepared in comparative example 2, and the three oxygen-doped iron single-atom carbon nitrides prepared in example 1. Figure 5 It can be seen that 1:4SAFe-OgC 3 N 4 The catalytic degradation efficiency of BPA was the highest, reaching 75.4%. This is because within a certain range, the Fe 2+ The concentration of Fe increases, which increases the concentration of ·OH in the solution. ·OH participates in the reaction with BPA, so Fe 2+ The catalyst with a high ratio was better than other catalysts in degrading BPA, and the 1:2 SAFe-OgC 3 N 4 The reason for the low degradation rate is that Fe 2+ The concentration of Fe is too high so that some Fe 2+ Oxidized to Fe 3+ , Fe 3+ Instead, it robs ·OH and forms a precipitate, which leads to a decrease in reaction efficiency.

[0057] In order to determine the effect of catalyst dosage on catalyst performance, the degradation experiment was conducted with other reaction conditions unchanged, and only the catalyst concentration was changed. The corresponding catalyst concentrations were 0.1 g / L, 0.9 g / L, 2.0 g / L, and 4.0 g / L, respectively, using 1:4 SAFe-OgC with a mass of 0.01 g, 0.09 g, 0.2 g, and 0.4 g. 3 N 4 , the adsorption-degradation experiment was carried out in the form of catalyst performance experiment, and then the BPA concentration was tested.

[0058] Figure 6 1:4SAFe-OgC 3 N 4 The effect diagram of catalytic degradation of BPA under different catalyst dosages. As the dosage increases from 0.1g / L to 0.9g / L, the degradation rate of BPA gradually increases. When it further increases to 4.0g / L, the degradation of BPA reaches equilibrium, indicating that the excess catalyst provides sufficient or even saturated active centers for PMS. Under the conditions of catalyst dosages of 0.9g / L and 4.0g / L, the final degradation rates are similar. Considering the effective utilization rate of the catalyst, the study concludes that the optimal catalyst dosage is 0.9g / L.

[0059] In order to determine the effect of oxidant (PMS) concentration on catalyst performance and to obtain the optimal PMS concentration, the catalyst was 1:4SAFe-OgC3 N 4 In the degradation experiment, other reaction conditions remained unchanged, only the PMS concentration was changed to 160μM, 300μM, 800μM, and 1600μM, respectively. The adsorption-degradation experiment was carried out in the manner of a catalyst performance experiment, and then the BPA concentration was tested.

[0060] Figure 7 1:4SAFe-OgC 3 N 4 The effect of catalytic degradation of BPA under different PMS concentrations. Figure 7 It can be seen that the degradation effect of 300 μM PMS concentration reached 75.4%, but with the increase of PMS concentration, the degradation effect decreased. On the one hand, it was due to the ·OH generated during the adsorption degradation process. - Plasma inhibits the degradation efficiency of oxygen-doped iron single-atom catalysts, and on the other hand, it is due to the fact that SAFe-OgC 3 N 4 The number of PMS molecules adsorbed on the surface has reached saturation, and the excess PMS does not participate in the degradation reaction, limiting the degradation rate. Considering the economic benefits, the optimal PMS concentration is 300μM.

[0061] In order to determine the effect of pollutant concentration on catalyst performance and to obtain the optimal pollutant concentration, the catalyst is 1:4SAFe-OgC 3 N 4 In the degradation experiment, other reaction conditions remained unchanged, only the concentration of BPA aqueous solution was changed (80 mg / L, 40 mg / L, 20 mg / L, and 10 mg / L, respectively). The adsorption-degradation experiment was carried out in the manner of a catalyst performance experiment, and then the BPA concentration was tested.

[0062] Figure 8 1:4SAFe-OgC 3 N 4 The effect of catalytic degradation of BPA at different BPA concentrations. Figure 8 It can be seen that as the pollutant concentration increases from 10 mg / L to 20 mg / L, the degradation effect becomes better. After further increasing to 40 mg / L, the degradation of BPA reaches equilibrium. When the BPA concentration is 80 mg / L, the degradation is inhibited, indicating that high concentrations of BPA are not conducive to catalytic degradation reactions. This is attributed on the one hand to the adsorption of intermediates produced by the reaction on the catalyst surface, and on the other hand to the increase in the initial concentration of BPA occupying active sites that can be used for degradation. Both of these reasons hinder the progress of the reaction and make the reaction saturated. Compared with 40 mg / L, BPA reaches degradation equilibrium first within 60 minutes under the condition of 20 mg / L, and the degradation rate is slightly ahead. Therefore, the optimal pollutant concentration is 20 mg / L.

[0063] The stability of catalysts over a wide pH range is crucial for their potential practical applications. Fig. 9 1:4SAFe-OgC 3 N 4 The degradation curve of BPA under different pH conditions shows that BPA can be effectively removed in the pH range of 3-11 with no significant difference. 3 N 4 The active sites have strong acid-base tolerance.

[0064] According to the optimal single factor reaction conditions determined above, the factor levels were set, and the response surface experiment was designed and analyzed using Design-Expert8.0.6 software. In the response surface interaction analysis, when analyzing the effects of two of the influencing factors on the degradation rate, the value of the remaining factor was fixed at its middle level.

[0065] Fig.10 This is a 3D response surface diagram designed using Design-Expert 8.0.6 software. Fig.10 The a region in the middle describes the three-dimensional response surface diagram and contour diagram of the effect of catalyst dosage and oxidant concentration on the degradation rate of BPA when the pH is maintained at 7. As the oxidant concentration increases, the degradation rate increases with the increase of catalyst dosage when the catalyst dosage is in the range of 0 to 1.04 g / L; but when the catalyst dosage is in the range of 1.04 g / L to 1.86 g / L, the degradation rate increases with the decrease of catalyst dosage. Fig.10 The b area in the middle describes the three-dimensional response surface diagram and contour diagram of the effect of catalyst dosage and pH on BPA degradation rate when the oxidant concentration is maintained at 300 μM. As the pH value decreases, the degradation rate increases with the increase of catalyst dosage in the range of 0 to 1.04 g / L; the degradation rate decreases with the increase of catalyst dosage in the range of 1.04 g / L to 1.86 g / L. Fig.10 The c area in the middle describes the three-dimensional response surface diagram and contour diagram of the effect of oxidant concentration and pH on BPA degradation rate when the catalyst dosage is kept at 0.9 g / L. When the oxidant concentration increases from 26.85 μM to 626.85 μM, the degradation rate increases as the pH decreases.

[0066] Finally, three groups of optimal reaction conditions were obtained. The first group: catalyst dosage was 1.17 g / L, PMS concentration was 334.32 μM, pH = 5.71; the second group: catalyst dosage was 1.04 g / L, PMS concentration was 445.72 μM, pH = 7.07; the third group: catalyst dosage was 1.4 g / L, PMS concentration was 150 μM, pH = 5.00.

[0067] Fig.11 1:4SAFe-OgC 3 N 4 The degradation rate curve of catalytic degradation of BPA under the final optimized conditions is shown in the figure. The first-order reaction kinetic model is fitted for the catalytic degradation of BPA under the three conditions. Fig.11 It can be seen from the middle b area that the first-order reaction rates of the three groups of reactions are 0.11798, 0.2051 and 0.12785 respectively, among which the first-order reaction rate of the second group is 1.7 times and 1.9 times of that of the other two optimized reaction conditions respectively. Therefore, the final optimized conditions are: catalyst dosage of 1.04g / L, PMS concentration of 445.72μM, pH = 7.07. Under these conditions, SAFe-OgC 3 N 4 The degradation rate of BPA reaches 100% in 30 minutes, and the first-order reaction rate reaches 0.2051.

[0068] Evaluation of various inorganic anions (Cl - 、NO 3 - , CO 3 2- ) on the effect of catalyst on the degradation of BPA, the catalyst is 1:4SAFe-OgC 3 N 4 , the other reaction conditions of the degradation reaction remain unchanged, only Cl is added during the reaction - 、NO 3 - , CO 3 2- These three inorganic anions.

[0069] Fig.12 For three anion pairs 1:4SAFe-OgC 3 N 4 The effect diagram of catalytic degradation of BPA shows that NO 3 - , CO 3 2- The degradation caused by the Cl - Can significantly promote the degradation process, mainly because Cl -Can react with PMS to generate HClO, which can promote 1 O 2 The above shows that Cl - 、NO 3 - , CO 3 2- These three types of inorganic anions have a great influence on SAFe-OgC 3 N 4 The catalytic degradation of BPA has little effect or plays a promoting role.

[0070] Using 1:4SAFe-OgC 3 N 4 Catalytic degradation of various pollutants (such as triclosan (TCS), indole (Indole), rhodamine B (RhB), tetracycline (TC)), except that BPA was replaced by other pollutants, the other reaction conditions of the degradation experiment remained unchanged.

[0071] Fig.13 1:4SAFe-OgC 3 N 4 From the degradation curves of different pollutants, it can be seen that the degradation rates of TCS and RhB both reached 100% within 60 minutes, and there was also a good degradation effect on Indole and TC, with the final degradation rates being 96.3% and 82.9% respectively.

[0072] Studying the degradation effect of catalysts in different water bodies has certain reference significance for the practical application of catalysts. The catalyst is 1:4SAFe-OgC 3 N 4 , the experimental water body was changed, and other reaction conditions of the degradation experiment remained unchanged.

[0073] Fig.14 1:4SAFe-OgC 3 N 4 The degradation curves of BPA in tap water and actual water show that the degradation rates of BPA in ultrapure water, tap water and actual water can reach 100%, indicating that SAFe-OgC 3 N 4 It has great potential for practical application.

[0074] The reusability and stability of the catalyst are important indicators for evaluating its potential practical application prospects. Therefore, four cycle tests were carried out under the same conditions, and the catalysts were 1:4SAFe-OgC prepared in Example 1: 3 N 4 and Fe-OgC prepared in Comparative Example 2 3 N4 , the other reaction conditions of the degradation experiment remained unchanged.

[0075] Fig.15 1:4SAFe-OgC prepared in Example 1 3 N 4 The degradation curve of BPA after four cycles of catalytic degradation shows that the BPA removal rates from the first to the fourth cycles are 99%, 98%, 91% and 77%, respectively. 3 N 4 It has good reusability and stability. Fig.16 The degradation curve of the catalyst prepared in Example 2 after four cycles of catalytic degradation of BPA shows that the degradation efficiency of the catalyst after four cycles is 55.22% lower than that of the first cycle. 3 N 4 Compared with the Fe-OgC prepared in Comparative Example 2 3 N 4 Compared with other materials, it has higher stability.

[0076] The above is only a preferred implementation of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A method for preparing an oxygen-doped iron single-atom carbon nitride composite catalyst, characterized in that: The method comprises the following steps: mixing an iron source, oxalic acid hydrate, polyvinylpyrrolidone, 2-methylimidazole, Pluronic F127 and an alcohol solution, and then ball-milling the mixture, filtering, washing, drying and grinding the mixture to obtain a precursor; then mixing the precursor with melamine, calcining the mixture without oxygen, and grinding and sieving the mixture after cooling.

2. The method for preparing the oxygen-doped iron single-atom carbon nitride composite catalyst according to claim 1, characterized in that: The iron source is FeSO4·7H2O, and the oxalic acid hydrate is: C2H2O4·2H2O; and the molar ratio of FeSO4·7H2O to C2H2O4·2H2O is 1:(1-10); The mass ratio of the total mass of the iron source and oxalic acid hydrate to the mass ratio of polyvinylpyrrolidone, 2-methylimidazole, and Pluronic F127 is (2-4):(3-5):(4-6):(2-4).

3. The method for preparing the oxygen-doped iron single-atom carbon nitride composite catalyst according to claim 1, characterized in that: The drying conditions are: under vacuum conditions, 60-100°C, 10-15h.

4. The method for preparing the oxygen-doped iron single-atom carbon nitride composite catalyst according to claim 1, characterized in that: The mass ratio of the precursor to melamine is 1:(3-8).

5. The method for preparing the oxygen-doped iron single-atom carbon nitride composite catalyst according to claim 1, characterized in that: The conditions for oxygen-free calcination are: in a nitrogen atmosphere, 500-800°C for 2-5h, and a heating rate of 1-5°C / min.

6. An oxygen-doped iron single-atom carbon nitride composite catalyst, characterized in that: The method is prepared by any one of claims 1 to 5.

7. Application of the oxygen-doped iron single-atom carbon nitride composite catalyst prepared by the method according to any one of claims 1 to 5 in activating PMS to degrade phenol pollutants in water, characterized in that: The method is to add the catalyst into the water body containing phenol pollutants, and then add PMS for degradation after reaching the adsorption-desorption equilibrium.

8. The use according to claim 7, characterized in that: The phenolic pollutant is bisphenol A.

9. The use according to claim 8, characterized in that: The dosage of the catalyst is 0.1-4 g / L, the dosage of PMS is 160-1600 μM, the concentration of bisphenol A in the water body is 10-80 mg / L, and the pH value of the water body is 3-11.

10. The use according to claim 9, characterized in that: The adsorption-desorption equilibrium time is 20-30min; the degradation reaction time is 30-120min.

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