Application of FAP@CN photocatalytic material

Abstract

The application provides application of FAP@CN photocatalytic material and belongs to the technical field of wastewater treatment and antibiotic deep treatment. 3+ The preparation method of the doped Ag3PO4@g-C3N4 composite material is as follows: S1, melamine is kept at 500-600 DEG C for 4-6 hours to obtain g-C3N4; S2, 10-60 mM of AgNO3 solution is prepared, 0-10 mol% of Fe(NO3)3.9H2O is added, and ultrasonic dispersion is uniform, which is recorded as A liquid; 20-60 mM of Na2HPO4 is prepared, which is recorded as B liquid; S3, based on the mass of Ag3PO4 that can be generated in theory, 10-400 wt% of g-C3N4 is added to the A liquid, ultrasonic dispersion is uniform, and the C liquid is recorded; S4, the B liquid is slowly added into the C liquid, and the volume ratio of the B liquid to the C liquid is 1:1-6; S5, after mixing, stirring is continued, then the precipitate is filtered, washed and dried, and the obtained solid product is the FAP@CN; the steps S1-S5 are all operated in the dark. The FAP@CN composite material prepared by the application has the advantages of strong photocatalytic activity and good stability, and has a wide application prospect in the field of removing antibiotics in wastewater.

Description

TECHNICAL FIELD

[0001] The application relates to the fields of wastewater treatment and antibiotic advanced treatment, and in particular to application of a FAP@CN photocatalytic material. BACKGROUND

[0002] Under the background of increasingly serious environmental pollution, water pollution has become one of the global focus problems. Especially antibiotics, such as sulfamethoxazole (SMX), as one of the most common antibiotics in water, are difficult to be completely removed in the traditional wastewater treatment process. Sulfamethoxazole has strong stability in water, which not only threatens the water ecosystem, but also may accumulate through the food chain, thereby affecting human health. Therefore, developing efficient water treatment technology, especially photocatalytic materials capable of removing antibiotic pollutants in wastewater, has become a research hotspot.

[0003] Compared with traditional wastewater treatment technology, photocatalytic technology has attracted much attention due to its use of solar energy, an inexhaustible energy source. Using solar energy for photocatalytic degradation of organic pollutants is considered to be one of the most promising methods. Therefore, the selection of photocatalysts is a key link in photocatalytic technology. Metal-free semiconductor graphite carbon nitride (g-C3N4) has attracted widespread attention in the field of photocatalysis due to its suitable band gap (2.7 eV), low cost, and good thermal stability and chemical stability.

[0004] However, due to the fast charge recombination rate, poor electrical conductivity and weak visible light absorption ability (<460 nm), the development of g-C3N4 in practical photocatalytic applications is still limited to a certain extent. Silver phosphate (Ag3PO4) has excellent performance in the degradation of organic pollutants, and it has been proved to have a very high quantum yield of about 80% under light with a wavelength of less than 480 nm. It has been reported that when g-C3N4 is combined with Ag3PO4, the generated g-C3N4 / Ag3PO4 photocatalyst exhibits significantly enhanced photocatalytic activity. However, during the photocatalytic process, Ag3PO4 is excited by light, which leads to the reduction of silver ions to metallic silver, thereby causing photocorrosion phenomenon, which seriously reduces its stability. SUMMARY

[0005] In view of the above problems existing in the prior art, the application provides application of a FAP@CN photocatalytic material. 3+ The doped Ag3PO4@g-C3N4 composite material has the advantages of strong photocatalytic activity and good stability, and has a broad application prospect in the field of removing antibiotics in wastewater.

[0006] The technical scheme of the application is as follows:

[0007] The application of FAP@CN photocatalytic material for photocatalytic degradation of sulfamethoxazole in wastewater, wherein the photocatalytic material can be reused for 5-100 times when photocatalytically degrading sulfamethoxazole in wastewater;

[0008] The FAP@CN photocatalytic material is Fe 3+ The preparation method of the doped Ag3PO4@g-C3N4 composite material comprises the following steps:

[0009] S1, grinding the melamine to 500-600℃ at a temperature increasing rate of 2-4℃ per minute under a nitrogen atmosphere and maintaining for 4-6 hours, and finely grinding the obtained product into powder to obtain g-C3N4;

[0010] S2, preparing an AgNO3 solution with a molar concentration of 10-60 mM, adding Fe(NO3)3·9H2O with a molar concentration of 0.01-10 mol% of AgNO3 to the solution, and uniformly ultrasonic dispersing to obtain A liquid; and then preparing Na2HPO4 with a molar concentration of 20-60 mM to obtain B liquid;

[0011] S3, adding 10-400 wt% of g-C3N4 to the A liquid based on the mass of Ag3PO4 that can be generated in theory, and uniformly ultrasonic dispersing to obtain C liquid;

[0012] The reaction equation of silver phosphate is: 3Ag + + PO4 3- = Ag3PO4

[0013] S4, slowly adding the B liquid drop by drop to the C liquid at a speed of 1-2 drops per second, and stirring during the mixing process, wherein the volume ratio of the B liquid to the C liquid is 1:1-6;

[0014] S5, continuing to stir after mixing, and then filtering, washing, and drying the precipitate, and the obtained solid product is Fe 3+ doped Ag3PO4@g-C3N4;

[0015] Steps S1-S5 are operated in the dark.

[0016] Preferably, in step S2, the ultrasonic dispersion time is 30-60 min.

[0017] Preferably, in step S3, the ultrasonic dispersion time is 1-2 hours.

[0018] Preferably, in step S4, the stirring speed is 200-400 rpm.

[0019] Preferably, in step S5, the stirring time after mixing is 2-4 hours, and the drying temperature is 60-80℃.

[0020] Preferably, during the photocatalytic degradation, the light source wavelength is 400-780 nm and the light intensity is 80-100 mW / cm²; the concentration of sulfamethoxazole in the wastewater is 0.1-200 mg / L, and the dosage of the photocatalytic material is 0.1-10 g / L.

[0021] The beneficial technical effects of this invention are as follows:

[0022] 1. The Fe provided by this invention 3+ In the doped Ag3PO4@g-C3N4 composite material, Fe 3+ It can interact with photogenerated electrons through redox reactions, reducing the interaction between photogenerated electrons and silver ions (Ag) in Ag3PO4. + The probability of photocorrosion occurring. Fe 3+ Fe is generated after combining with photogenerated electrons. 2+ It can be oxidized into Fe in the air. 3+ Fe 3+ / Fe 2+ Continuous cyclical transformation achieves the effect of continuously inhibiting photocorrosion and further enhances the stability of the photocatalyst.

[0023] 2. The Fe provided by this invention 3+ In the doped Ag3PO4@g-C3N4 composite material, Fe 3+ It can combine with photogenerated electrons, reduce recombination of photogenerated charge carriers, and enhance the separation efficiency of charge carriers, thereby improving the performance of photocatalytic oxidation in removing sulfamethoxazole.

[0024] 3. The Fe provided by this invention 3+ In the doped Ag3PO4@g-C3N4 composite material, Fe is doped... 3+ Improving the adsorption capacity of photocatalytic materials can enhance the removal performance of sulfamethoxazole. Attached Figure Description

[0025] Figure 1 TEM images of different photocatalytic materials;

[0026] Figure 2 XRD scan results for different photocatalytic materials;

[0027] Figure 3 for Figure 2 A magnified view of the shaded area;

[0028] Figure 4 XPS test results for different photocatalytic materials;

[0029] Figure 5 The removal effect of different photocatalytic materials on sulfamethoxazole;

[0030] Figure 6 The removal effect of FAP@CN on sulfamethoxazole in the cycle experiment. DETAILED DESCRIPTION

[0031] The application will be described in greater detail with reference to the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0032] Example 1: Preparation of FAP@CN photocatalytic material

[0033] S1, weigh 6 g of ground melamine into a porcelain boat and transfer it to a tube furnace, and heat it to 550℃ at a rate of 4℃ per minute under a nitrogen atmosphere and keep it for 4 hours. The obtained product, graphite phase carbon nitride (g-C3N4), is finely ground into powder and marked as CN.

[0034] S2, prepare a 30 mM AgNO3 solution, and add 0.33 mol% Fe(NO3)3·9H2O based on the molar concentration of AgNO3, ultrasonic dispersion for 30 min, marked as A liquid; prepare a 40 mM Na2HPO4 solution, marked as B liquid.

[0035] S3, based on the mass of Ag3PO4 that can be generated in theory, add 20 wt% CN to A liquid, ultrasonic dispersion for 1 hour, marked as C liquid.

[0036] S4, slowly add B liquid drop by drop to C liquid at a speed of 1-2 drops per second, the volume ratio of B:C = 1:4, and keep stirring during the mixing process, the stirring speed is 300 rpm.

[0037] S5, continue stirring for 2 hours after mixing, then filter, wash and dry at 60℃ the precipitate, the precipitate is Fe 3+ doped Ag3PO4@g-C3N4 composite material, marked as FAP@CN.

[0038] All the above operations are carried out in the dark, and all the containers are wrapped with aluminum foil.

[0039] Comparative Example 1: Preparation of Ag3PO4 (AP)

[0040] The preparation of AP and the above steps S2-S5 are similar, and in the preparation of AP, Fe(NO3)3·9H2O is not added in A liquid, and C liquid is not prepared, and A liquid and B liquid are directly mixed.

[0041] Preparation of Ag3PO4@g-C3N4 (AP@CN)

[0042] The preparation of AP@CN and the above steps are similar, and in the preparation of AP@CN, Fe(NO3)3·9H2O is not added in A liquid.

[0043] Test Example 1: TEM image of the photocatalytic material

[0044] The scanning results of TEM of the photocatalytic materials prepared in the above Example 1 and Comparative Examples 1 and 2 are shown in FIG. 1. Figure 1 As can be seen from the figure, AP is in the form of particles with a size of 100-300 nm; CN is in the form of nanosheet structure; in the TEM spectrum of AP@CN, dark AP particles are observed to be attached to CN nanosheets, and in FAP@CN, AP is distributed on CN nanosheets in the form of smaller particles.

[0045] Test Example 2: XRD and XPS test of the photocatalytic material

[0046] The scanning results of XRD of the photocatalytic materials prepared in the above Example 1 and Comparative Examples 1 and 2 are shown in FIG. 2. Figure 2 , 3 As can be seen from the figure, after doping Fe, the XRD diffraction peak representing Ag3PO4 will be shifted to the right, which means that Fe may enter the Ag3PO4 lattice to replace Ag. Since the ionic radius of Fe 3+ is smaller than that of Ag + , Fe 3+ replacement of Ag + is easy to cause the lattice volume to decrease. The decrease of the lattice volume of Ag3PO4 means that the crystal structure will shrink, thereby causing the lattice spacing to decrease. According to Bragg's law, when the lattice spacing decreases, the diffraction angle increases, thereby causing the peak to shift to the right.

[0047] The scanning results of XPS of the photocatalytic materials prepared in the above Example 1 and Comparative Examples 1 and 2 are shown in FIG. 3. Figure 4 As can be seen from the figure, in the XPS spectrum of FAP@CN material, Fe 2p and Ag 3s can be observed in the interval of 700 eV-730 eV. Specifically, the characteristic peaks at about 712.1 eV (Fe 2p 3 / 2 ) and 725.2 eV (Fe 2p 1 / 2 ) and their accompanying satellite peaks in the Fe 2p region clearly indicate that Fe exists in the form of trivalent. The signal appearing at about 718.6 eV belongs to Fe3+ Satellite peaks of Ag3s orbitals.

[0048] Test Example 3: Specific surface area test

[0049] The above prepared photocatalytic materials of Example 1 and Comparative Examples 1 and 2 were subjected to BET test, and the results showed that the specific surface area of AP was very small, only 1.37 m 2 / g, the specific surface area of AP@CN was increased by 159%, and the specific surface area of FAP@CN was increased by 231%.

[0050] Example 2: Preparation of FAP@CN photocatalytic material

[0051] S1, 6 g of ground melamine was weighed and placed in a porcelain boat and transferred to a tube furnace, and heated to 500℃ at a rate of 2℃ per minute under nitrogen atmosphere and kept for 6 hours, and the obtained product graphite phase carbon nitride (g-C3N4) was finely ground into powder and marked as CN.

[0052] S2, 60 mM of AgNO3 solution was prepared, 0.033 mol% of Fe(NO3)3·9H2O was added based on the molar concentration of AgNO3, and ultrasonic dispersion was performed for 40 min, marked as A liquid; 20 mM of Na2HPO4 was prepared, marked as B liquid.

[0053] S3, 20 wt% of CN was added to A liquid based on the mass of Ag3PO4 that could be generated in theory, and ultrasonic dispersion was performed for 1.2 hours, marked as C liquid.

[0054] S4, B liquid was slowly added dropwise to C liquid at a speed of 1-2 drops per second, and the volume ratio of B:C was 1:1, and the mixing process was kept stirring, and the stirring speed was 200 rpm.

[0055] S5, after mixing, continue to stir for 3 hours, then filter, wash and dry at 70℃ the precipitate, the precipitate is Fe 3+ doped Ag3PO4@g-C3N4 composite material, marked as FAP@CN.

[0056] All the above operations were carried out in the dark, and all the containers were wrapped with aluminum foil.

[0057] Example 3: Preparation of FAP@CN photocatalytic material

[0058] S1, 6 g of ground melamine was weighed and placed in a porcelain boat and transferred to a tube furnace, and heated to 600℃ at a rate of 4℃ per minute under nitrogen atmosphere and kept for 4 hours, and the obtained product graphite phase carbon nitride (g-C3N4) was finely ground into powder and marked as CN.

[0059] S2, 15 mM AgN03 solution was configured, 3.3 mol% Fe(N03)3-9H20 was added based on the molar concentration of AgN03, and ultrasonic dispersion was performed for 50 min, which was recorded as A liquid; 25 mM Na2HP04 was configured, which was recorded as B liquid.

[0060] S3, 20 wt% CN was added to the A liquid based on the mass of Ag3P04 that could be theoretically generated, and ultrasonic dispersion was performed for 1.5 hours, which was recorded as C liquid.

[0061] S4, the B liquid was slowly added dropwise to the C liquid at a speed of 1-2 drops per second, the volume ratio of B:C = 1:5, and the mixing process was kept stirring, and the stirring speed was 400 rpm.

[0062] S5, after mixing, stirring was continued for 4 hours, then the precipitate was filtered, washed, and dried at 60°C, and the precipitate was Fe 3+ doped Ag3P04@g-C3N4 composite material, recorded as FAP@CN.

[0063] All the above operations were carried out in the dark, and all the containers were wrapped with aluminum foil.

[0064] Application Example 1: Removal effect of sulfamethoxazole by photocatalytic material

[0065] The photocatalytic degradation experiment of sulfamethoxazole was carried out on the photocatalytic materials prepared in the above embodiment 1 and comparative examples 1 and 2. The experiment was carried out in a glass reactor, which used a 300 W xenon lamp as a light source, the spectral range covered 400-780 nm, and a filter was configured to simulate the visible spectrum of the sun. The light intensity was controlled at 80-100 mW / cm 2 , and a circulating water system ensured that the entire device was operated at a constant temperature of 25 ± 2°C.

[0066] Under standard experimental conditions, the volume of the reaction system was 200 mL, the initial pollutant concentration was set to sulfamethoxazole (SMX) 30 mg / L, and the photocatalyst dosage was 0.3 g / L. The experiment was divided into 30 min of dark experiment and 30 min of light experiment.

[0067] The results are shown in Figure 5 , in the 30 min dark experiment, the adsorption rate of each material to sulfamethoxazole was FAP@CN (37.7%) > AP@CN (16.7%) > AP (9.0%) > CN (1.2%). In the subsequent photocatalytic experiment, the removal rate of each material to sulfamethoxazole conforms to the pseudo-first-order kinetics, and the pseudo-first-order rate constant FAP@CN (0.2459 min -1 ) > AP@CN (0.1696 min -1AP (0.1066 min -1 CN (0.0020 min -1 ).

[0068] The FAP@CN composite materials prepared in Examples 2 and 3 were tested under the same experimental conditions, and the results showed that Example 1 was better than Example 2, which was better than Example 3. With the increase of Fe doping amount, the SMX removal time first increased and then decreased.

[0069] Application Example 2: Cycle stability experiment of photocatalytic degradation

[0070] The stability of FAP@CN, AP@CN and AP in the cyclic photodegradation of sulfamethoxazole was tested under the same experimental conditions in Application Example 1, and the photocatalyst used each time was the photocatalytic material recovered in the last experiment. The test results of FAP@CN are shown in Table 2. Figure 6 As can be seen from Table 2, FAP@CN can achieve complete removal of SMX in 5 cycles. While AP cannot achieve complete removal of SMX in the second cycle, and the removal rate of SMX has dropped to 59.3% in the fifth cycle. The performance of AP@CN is between the two, and the removal rate of SMX in the fifth cycle is 85.8%. The cycle performance of FAP@CN composite materials prepared in Examples 2 and 3 is similar to that of Example 1.

[0071] Test Example 4: Light corrosion resistance test

[0072] Photocatalytic materials with silver phosphate as the core usually have to face the problem of light corrosion, which is the main factor affecting their stability. Specifically, under light conditions, part of the photo-generated electrons directly reduces the Ag + in the lattice to metallic silver (Ag 0 ), thereby causing the material to gradually lose activity. The ratio of Ag + and Ag 0 in the photocatalytic material after five cycles in Application Example 2 was detected. The results showed that the Ag 0 ratio of AP increased from 6.4% to 81.2% after the cycle experiment. AP@CN performed slightly better, with the Ag 0 ratio increasing from 8.4% to 71.4%; while the Ag 0 ratio of FAP@CN only increased by 7.5%, confirming that doping Fe 3+ significantly improves the light corrosion resistance of silver phosphate.

[0073] Although embodiments of the present application have been disclosed in connection with the above specification and drawings it will be understood that they are not limited to the specific details of the foregoing description, since various changes, modifications and substitutions can be made therein without departing from the spirit and scope of the present application as defined in the following claims.

Claims

1. An application of a FAP@CN photocatalytic material, characterized in that, The photocatalytic material is used for the photocatalytic degradation of sulfamethoxazole in wastewater and can be reused 5-100 times during the photocatalytic degradation of sulfamethoxazole in wastewater. The FAP@CN photocatalytic material is Fe 3+ The preparation method of the doped Ag3PO4@g-C3N4 composite material includes the following steps: S1. The ground melamine is heated to 500-600℃ at a heating rate of 2-4℃ per minute under a nitrogen atmosphere and held at that temperature for 4-6 hours. The resulting product is then finely ground into powder to obtain g-C3N4. S2. Prepare an AgNO3 solution with a molar concentration of 10-60 mM, add 0.01-10 mol% Fe(NO3)3·9H2O to it, and disperse it evenly by ultrasonication. This solution is denoted as solution A. Then prepare a Na2HPO4 solution with a molar concentration of 20-60 mM. This solution is denoted as solution B. S3. Based on the theoretically generated mass of Ag3PO4, add 10-400 wt% g-C3N4 to solution A, and ultrasonically disperse it evenly. This solution is denoted as solution C. S4. Slowly add solution B to solution C dropwise at a rate of 1-2 drops / second, while stirring during the mixing process. The volume ratio of solution B to solution C is 1:1-6. S5. After mixing, continue stirring, then filter, wash, and dry the precipitate. The resulting solid product is Fe. 3+ Doped Ag3PO4@g-C3N4; All steps S1-S5 should be performed in the dark.

2. The application according to claim 1, characterized in that, In step S2, the ultrasonic dispersion time is 30-60 minutes.

3. The application according to claim 1, characterized in that, In step S3, the ultrasonic dispersion time is 1-2 hours.

4. The application according to claim 1, characterized in that, In step S4, the stirring speed is 200-400 rpm.

5. The application according to claim 1, characterized in that, In step S5, the mixing and stirring time is 2-4 hours, and the drying temperature is 60-80℃.

6. The application according to claim 1, characterized in that, During the photocatalytic degradation, the light source wavelength is 400-780 nm and the light intensity is 80-100 mW / cm². 2 The concentration of sulfamethoxazole in the wastewater is 0.1-200 mg / L, and the dosage of photocatalytic material is 0.1-10 g / L.

Images