Application of FAP-CN photocatalytic material

Abstract

The invention provides application of an FAP-CN photocatalytic material, and belongs to the technical field of wastewater treatment and advanced treatment of antibiotics. The FAP (at) CN photocatalytic material is a Fe < 3 + >-doped Ag3PO4 (at) g-C3N4 composite material. The preparation method comprises the following steps: S1, carrying out heat preservation on melamine at 500-600 DEG C for 4-6 hours to obtain g-C3N4; s2, a 10-60 mM AgNO3 solution is prepared, 0.01-10 mol% of Fe (NO3) 3.9 H2O is added, ultrasonic dispersion is conducted to be uniform, and the solution is marked as a solution A; preparing 20 to 60 mM of Na2HPO4, and recording the Na2HPO4 as a solution B; s3, on the basis of the mass of Ag3PO4 which can be generated theoretically, adding 10-400 wt% of g-C3N4 into the solution A, and performing uniform ultrasonic dispersion to obtain a solution C; s4, slowly adding the solution B into the solution C, wherein the volume ratio of the solution B to the solution C is 1: (1-6); s5, continuously stirring after mixing, and then filtering, washing and drying the precipitate to obtain a solid product, namely FAP (at) CN; the steps from S1 to S5 are all operated in a dark place. The FAP-CN composite material prepared by the invention has the advantages of strong photocatalytic activity and good stability, and has a wide application prospect in the field of removal of antibiotics in wastewater.

Description

Technical Field

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

[0002] Against the backdrop of increasingly severe environmental pollution, water pollution has become a major global concern. Antibiotics, such as sulfamethoxazole (SMX), one of the most common antibiotics found in water, are particularly difficult to remove completely using traditional wastewater treatment processes. Sulfamethoxazole is highly stable in water, posing a threat not only to aquatic ecosystems but also potentially accumulating through the food chain and impacting human health. Therefore, developing efficient water treatment technologies, especially photocatalytic materials capable of removing antibiotic pollutants from wastewater, has become a current research hotspot.

[0003] Compared to traditional wastewater treatment technologies, photocatalysis has attracted widespread attention due to its utilization of solar energy, an inexhaustible energy source. Photocatalytic degradation of organic pollutants using solar energy is considered one of the most promising methods. Therefore, the selection of photocatalysts is a crucial step in photocatalysis technology. Metal-free semiconductor graphitic carbon nitride (g-C3N4) has garnered significant attention in the field of photocatalysis due to its suitable band gap (2.7 eV), low cost, and good thermal and chemical stability.

[0004] However, the development of g-C3N4 in practical photocatalytic applications is still somewhat limited due to its rapid charge recombination rate, poor conductivity, and weak visible light absorption (<460 nm). Silver phosphate (Ag3PO4) exhibits excellent performance in the degradation of organic pollutants and has been shown to have extremely high quantum yields (approximately 80%) under illumination with wavelengths less than 480 nm. It has been reported that when g-C3N4 is combined with Ag3PO4, the resulting g-C3N4 / Ag3PO4 photocatalyst exhibits significantly enhanced photocatalytic activity. However, during the photocatalytic process, photoexcitation of Ag3PO4 leads to the reduction of silver ions to metallic silver, thereby initiating photocorrosion and severely reducing its stability. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides an application of FAP@CN photocatalytic materials. The Fe prepared by this invention... 3+ The doped Ag3PO4@g-C3N4 composite material has the advantages of strong photocatalytic activity and good stability, and has broad application prospects in the field of removing antibiotics from wastewater.

[0006] The technical solution of the present invention is as follows: An application of a FAP@CN photocatalytic material for the photocatalytic degradation of sulfamethoxazole in wastewater, wherein the photocatalytic material can be reused 5-100 times in 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. The reaction equation for silver phosphate is: 3Ag + + PO4 3- = Ag3PO4 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.

[0007] Preferably, in step S2, the ultrasonic dispersion time is 30-60 min.

[0008] Preferably, in step S3, the ultrasonic dispersion time is 1-2 hours.

[0009] Preferably, in step S4, the stirring speed is 200-400 rpm.

[0010] Preferably, in step S5, the stirring time after mixing is 2-4 hours, and the drying temperature is 60-80℃.

[0011] 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.

[0012] The beneficial technical effects of this invention are as follows: 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.

[0013] 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.

[0014] 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

[0015] Figure 1 TEM images of different photocatalytic materials; Figure 2 XRD scan results for different photocatalytic materials; Figure 3 for Figure 2 A magnified view of the shaded area; Figure 4 XPS test results for different photocatalytic materials; Figure 5 The removal efficiency of different photocatalytic materials for sulfamethoxazole; Figure 6 The effect of FAP@CN on the removal of sulfamethoxazole in a cyclic experiment. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] Example 1: Preparation of FAP@CN photocatalytic material S1. Weigh 6g of ground melamine and place it in a ceramic boat and transfer it to a tube furnace. Under a nitrogen atmosphere, raise the temperature to 550°C at a rate of 4°C per minute and hold for 4 hours. Grind the resulting graphitic carbon nitride (g-C3N4) into powder and label it as CN.

[0018] S2. Prepare a 30 mM AgNO3 solution, add 0.33 mol% Fe(NO3)3·9H2O based on the AgNO3 molar concentration, and sonicate for 30 min. This solution is denoted as solution A. Prepare a 40 mM Na2HPO4 solution, denoted as solution B.

[0019] S3. Based on the mass of Ag3PO4 that can be theoretically generated, add 20 wt% CN to solution A, and sonicate for 1 hour. This solution is called solution C.

[0020] S4. Slowly add solution B to solution C dropwise at a rate of 1-2 drops / second, with a volume ratio of B:C = 1:4. Keep stirring during the mixing process at a speed of 300 rpm.

[0021] S5. After mixing, continue stirring for 2 hours, then filter, wash, and dry the precipitate at 60℃. The precipitate is Fe. 3+ The doped Ag3PO4@g-C3N4 composite material is denoted as FAP@CN.

[0022] All of the above operations were performed in the dark, and all containers were wrapped in aluminum foil.

[0023] Comparative Example 1: Preparation of Ag3PO4 (AP) The preparation of AP is similar to steps S2-S5 above. In the preparation of AP, Fe(NO3)3·9H2O is not added to solution A, and solution C does not need to be prepared. Solution A and solution B are directly mixed.

[0024] Comparative Example 2: Preparation of Ag3PO4@g-C3N4 (AP@CN) The preparation of AP@CN is similar to the steps described above, except that Fe(NO3)3·9H2O is not added to solution A in the preparation of AP@CN.

[0025] Test Example 1: TEM image of photocatalytic materials The TEM scanning results of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2 are as follows: Figure 1 As shown in the figure, AP particles are granular with a size of 100-300 nm, while CN has a nanosheet structure. In the TEM image of AP@CN, dark AP particles are observed attached to the CN nanosheets, while in FAP@CN, AP particles are distributed as smaller particles on the CN nanosheets.

[0026] Test Example 2: XRD and XPS Tests of Photocatalytic Materials The XRD scanning results of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2 are as follows: Figure 2 , 3 As shown in the figure, the XRD diffraction peak representing Ag3PO4 shifts to the right after Fe doping, indicating that Fe may have entered the Ag3PO4 lattice and replaced Ag. This is because Fe... 3+ The ionic radius of Ag is greater than that of Ag + Small, Fe 3+ Replace Ag + This can lead to a decrease in lattice volume. A decrease in the lattice volume of Ag3PO4 means that the crystal structure shrinks, resulting in a decrease in lattice spacing. According to Bragg's law, when the lattice spacing decreases, the diffraction angle increases, leading to a rightward shift of the peak position.

[0027] The XPS scanning results of the photocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2 are as follows: Figure 4 As shown in the figure, the FAP@CN material exhibits the superposition of Fe 2p and Ag 3s in the XPS plot range of 700 eV-730 eV. Specifically, the Fe 2p region is located at approximately 712.1 eV (Fe 2p... 3 / 2 ) and 725.2 eV (Fe 2p 1 / 2 The characteristic peaks and their accompanying satellite peaks clearly indicate that Fe exists in its trivalent form. The signal appearing at approximately 718.6 eV belongs to Fe. 3+ The superposition of the satellite peak and the Ag3s orbit.

[0028] Test Example 3: Specific Surface Area Test BET tests were performed on the photocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2. The results showed that the AP specific surface area was very small, only 1.37 m². 2 / g, AP@CN has a 159% increase in specific surface area, while FAP@CN has an even greater increase of 231%.

[0029] Example 2: Preparation of FAP@CN photocatalytic material S1. Weigh 6g of ground melamine and place it in a ceramic boat and transfer it to a tube furnace. Under a nitrogen atmosphere, raise the temperature to 500℃ at a rate of 2℃ per minute and hold for 6 hours. Grind the resulting graphitic carbon nitride (g-C3N4) into powder and label it as CN.

[0030] S2. Prepare a 60 mM AgNO3 solution, add 0.033 mol% Fe(NO3)3·9H2O based on the AgNO3 molar concentration, and sonicate for 40 min. This solution is denoted as solution A. Prepare a 20 mM Na2HPO4 solution, denoted as solution B.

[0031] S3. Based on the mass of Ag3PO4 that can be theoretically generated, add 20 wt% CN to solution A, and sonicate for 1.2 hours. This solution is called solution C.

[0032] S4. Slowly add solution B to solution C dropwise at a rate of 1-2 drops / second, with a volume ratio of B:C = 1:1. Keep stirring during the mixing process at a speed of 200 rpm.

[0033] S5. After mixing, continue stirring for 3 hours, then filter, wash, and dry the precipitate at 70℃. The precipitate is Fe. 3+ The doped Ag3PO4@g-C3N4 composite material is denoted as FAP@CN.

[0034] All of the above operations were performed in the dark, and all containers were wrapped in aluminum foil.

[0035] Example 3: Preparation of FAP@CN photocatalytic material S1. Weigh 6g of ground melamine and place it in a ceramic boat and transfer it to a tube furnace. Under a nitrogen atmosphere, raise the temperature to 600℃ at a rate of 4℃ per minute and hold for 4 hours. Grind the resulting graphitic carbon nitride (g-C3N4) into powder and label it as CN.

[0036] S2. Prepare a 15 mM AgNO3 solution, add 3.3 mol% Fe(NO3)3·9H2O based on the AgNO3 molar concentration, and sonicate for 50 min. This solution is denoted as solution A. Prepare a 25 mM Na2HPO4 solution, denoted as solution B.

[0037] S3. Based on the mass of Ag3PO4 that can be theoretically generated, add 20 wt% CN to solution A, and sonicate for 1.5 hours. This solution is called solution C.

[0038] S4. Slowly add solution B to solution C dropwise at a rate of 1-2 drops / second, with a volume ratio of B:C = 1:5. Keep stirring during the mixing process at a speed of 400 rpm.

[0039] S5. After mixing, continue stirring for 4 hours, then filter, wash, and dry the precipitate at 60℃. The precipitate is Fe. 3+ The doped Ag3PO4@g-C3N4 composite material is denoted as FAP@CN.

[0040] All of the above operations were performed in the dark, and all containers were wrapped in aluminum foil.

[0041] Application Example 1: The Removal Effect of Photocatalytic Materials on Sulfamethoxazole The photocatalytic degradation experiments of sulfamethoxazole were conducted on the photocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2. The experiments were carried out in a glass reactor using a 300 W xenon lamp as the light source, covering a spectral range of 400-780 nm, and equipped with filters to simulate the visible solar spectrum. The light intensity was controlled at 80-100 mW / cm². 2 The circulating water system ensures that the entire unit operates at a constant temperature of 25 ± 2 ℃.

[0042] Under standard experimental conditions, the reaction system volume was 200 mL, the initial pollutant concentration was set at 30 mg / L for sulfamethoxazole (SMX), and the photocatalyst dosage was 0.3 g / L. The experiment consisted of a 30-minute dark test and a 30-minute light test.

[0043] The results are as follows Figure 5 As shown, in the 30-min dark experiment, the adsorption rates of sulfamethoxazole for each material were as follows: FAP@CN (37.7%) > AP@CN (16.7%) > AP (9.0%) > CN (1.2%). In the subsequent photocatalytic experiment, the removal rates of sulfamethoxazole for each material followed pseudo-first-order kinetics, with a pseudo-first-order rate constant FAP@CN (0.2459 min). -1 AP@CN (0.1696min) -1 AP (0.1066 min) > AP (0.1066 min) -1 )>CN (0.0020 min) -1 ).

[0044] The FAP@CN composite materials prepared in Examples 2 and 3 were tested using the same experiments. The results showed that Example 1 was better than Example 2, which was better than Example 3. As the Fe doping amount increased, the SMX removal time first increased and then decreased.

[0045] Application Example 2: Cyclic Stability Experiment of Photocatalytic Degradation The stability of FAP@CN, AP@CN, and AP in the cyclic photodegradation of sulfamethoxazole was tested under the same experimental conditions as in Application Example 1. The photocatalyst used each time was the same photocatalyst material recovered from the previous experiment. The test results for FAP@CN are as follows: Figure 6 As shown, FAP@CN achieved complete removal of SMX in all 5 cycles. AP, however, failed to completely remove SMX in the second cycle, and by the fifth cycle, the removal rate had dropped to 59.3%. AP@CN's performance was intermediate, achieving an SMX removal rate of 85.8% in the fifth cycle. The cycling performance of the FAP@CN composites prepared in Examples 2 and 3 was similar to that in Example 1.

[0046] Test Example 4: Photocorrosion Resistance Test Photocatalytic materials based on silver phosphate typically face the problem of photocorrosion, which is the most significant factor affecting their stability. Specifically, under illumination, some photogenerated electrons directly ignite Ag in the crystal lattice. + Reduced to metallic silver (Ag) 0 This leads to the gradual deactivation of the material. The Ag content in the photocatalytic material was detected after five cycles in Application Example 2. + and Ag 0 The proportion of AP was observed. Results showed that after cyclic experiments, the Ag content of AP... 0 The proportion increased significantly from 6.4% to 81.2%. AP@CN performed slightly better, while Ag... 0 The proportion increased from 8.4% to 71.4%; while FAP@CN's Ag 0 The proportion increased only slightly by 7.5%, confirming the presence of Fe doping. 3+ Significantly enhances the anti-photocorrosion effect of silver phosphate.

[0047] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, and for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. Use of a FAP@CN photocatalytic material, characterized in that, The photocatalytic material can be reused for 5-100 times in photocatalytic degradation of sulfamethoxazole in wastewater. The FAP@CN photocatalytic material is Fe 3+ The doped Ag3PO4@g-C3N4 composite material, a preparation method thereof comprises the following steps: S1, the ground melamine is heated to 500-600℃ at a temperature increasing rate of 2-4℃ per minute under nitrogen atmosphere and kept for 4-6 hours, and the obtained product is finely ground into powder to obtain g-C3N4; S2, an AgNO3 solution with a molar concentration of 10-60 mM is prepared, 0.01-10 mol% of Fe(NO3)3·9H2O with respect to AgNO3 is added to the solution, and the solution is uniformly ultrasonically dispersed to obtain A liquid; then a Na2HPO4 solution with a molar concentration of 20-60 mM is prepared to obtain B liquid; S3, based on the theoretical mass of Ag3PO4 that can be generated, 10-400 wt% of g-C3N4 is added to A liquid, and the mixture is uniformly ultrasonically dispersed to obtain C liquid; S4, B liquid is slowly added dropwise to C liquid at a speed of 1-2 drops per second, and stirring is maintained during the mixing process, wherein the volume ratio of B liquid to C liquid is 1:1-6; S5, after mixing, continue to stir, then filter, wash, dry the precipitate, the obtained solid product is Fe 3+ Doped Ag3PO4@g-C3N4; Steps S1-S5 are operated in the dark.

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

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

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

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

6. The use according to claim 1, characterized in that, The wavelength of the light source is 400-780 nm, and the light intensity is 80-100 mW / cm 2 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.

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