Preparation method of in2o3 / mn2o3 photocatalytic composite material and application thereof in degradation of tetracycline wastewater in cooperation with pms

Abstract

The application belongs to the technical field of photocatalytic materials, and provides a preparation method of In2O3 / Mn2O3 photocatalytic composite material, a precursor MIL-68(In) is prepared through a hydrothermal method; the precursor MIL-68(In) is combined with manganese acetate to generate a heterojunction to obtain the In2O3 / Mn2O3 photocatalytic composite material; finally, PMS is added to activate the In2O3 / Mn2O3-PMS photocatalytic system to degrade tetracycline. The preparation method is simple, environment-friendly, and easy to control. The prepared In2O3 / Mn2O3 photocatalytic composite material has a large specific surface area, is not prone to agglomeration, is easy to disperse, improves photocatalytic degradation performance, saves cost, reduces reaction time, can be repeatedly used, and is environment-friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a preparation method of an In2O3 / Mn2O3 photocatalytic composite material and application thereof in degrading tetracycline wastewater in cooperation with PMS. BACKGROUND

[0002] Antibiotics in organisms cannot be completely metabolized, and part of them is excreted through feces and urine, and widely exists in urban wastewater, surface water and groundwater. The existence of antibiotics in the environment can destroy biodiversity and ecological balance, and induce diseases in human bodies. Aquatic organisms are affected by antibiotics, which endanger human health through the food chain, leading to the risk of acute and chronic poisoning of humans. Antibiotics are mainly used in the pharmaceutical, livestock, veterinary and agricultural industries, and people have developed various technologies to degrade the antibiotics generated in life. Various methods such as electrochemistry (electro-oxidation, electro-coagulation and electro-degradation), advanced oxidation technology (photocatalysis, ultraviolet oxidation, photo-Fenton reagent oxidation, photolysis and acoustic wave dissolution), coagulation, air flotation, adsorption, use of various types of membrane separation, chemical oxidation, ozone, oxygen, anaerobic and biological enhancement technology. Among them, the advanced oxidation technology has the advantages of environmental protection and economy, and is widely used in the degradation of antibiotics. Many dyes or organic pollutants existing in wastewater can be degraded by advanced oxidation technology. It mainly uses chemical methods to generate free radicals and other active oxidizing substances with strong oxidation in the system to achieve degradation, and then mineralizes small molecular organic matter, until mineralizes into water and carbon dioxide and corresponding inorganic ions, so as to achieve the removal of pollutants.

[0003] Photocatalytic degradation of antibiotics is a technique that utilizes photocatalysts to accelerate the decomposition of antibiotics under light conditions. Common photocatalysts include titanium dioxide, ZnO, and others. While this photocatalytic technology has shown great potential in treating antibiotic pollution in water bodies, there are still some technical defects and challenges in its practical application. These problems mainly include: (1) Catalyst stability: Some photocatalysts gradually lose their activity over time or under strong light conditions, affecting their long-term use efficiency, stability, and sustainability. Some photocatalysts are prone to aggregation during the reaction, leading to a decrease in their activity and difficulty in recycling from the reaction system, affecting their reusability. (2) Selectivity issues: Photocatalysts may also act on other non-target substances in water while degrading target antibiotics, leading to the generation of side reactions. This can produce new pollutants or reduce the degradation efficiency of target pollutants, creating new environmental pollution problems. (3) Phototoxicity and secondary pollution: Photocatalytic processes may generate some toxic intermediates that can pose new threats to the environment and living organisms. To overcome these technical defects, researchers are developing new photocatalyst materials such as modified In2O3, doped semiconductors, etc., to improve light utilization efficiency and catalyst stability; exploring new catalyst recovery techniques to facilitate catalyst reuse; and researching more selective photocatalytic systems to reduce non-target reactions and secondary pollution. In addition, evaluating and optimizing operating conditions such as pH, light intensity, and reaction time during photocatalysis is also one of the current research focuses.

[0004] Despite these technical challenges, through the progress of material science and innovation of catalytic technology, photocatalytic technology has made significant progress in improving light utilization efficiency, catalyst stability, and selectivity, as well as reducing costs. Wang et al. prepared a photocatalyst, self-assembled oxygen vacancy modified layered hollow tube Bi2WO6 / In2O3, which can be easily prepared by interface adjustment strategy to form Z-type heterojunction with built-in electric field. The construction of Z-type heterojunction shows that a strong built-in electric field is generated, which provides a strong driving force for the transfer of photo-generated electrons from In2O3 CB to BWO VB. This heterojunction shortens the charge transfer distance and accelerates the charge transfer rate, thereby promoting the interface charge separation. In addition, the self-assembled high dispersion BWO is beneficial to enhance the exposure of active sites, and the introduced oxygen vacancies can act as trapping centers to stimulate the spatial separation of photo-induced electron-hole pairs (Journal of Environmental Chemical Engineering 12 (2024) 112010).

[0005] Although considerable efforts have been made to develop advanced visible light-driven photocatalysts, how to form a close-structured composite material of two components through a simplified method and how to significantly improve the degradation performance of the composite material on organic pollutants remain to be solved. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of In2O3 / Mn2O3 photocatalytic composite material and its application in degrading tetracycline wastewater in cooperation with PMS.

[0007] The In2O3 / Mn2O3 photocatalytic composite material prepared by the present application has a large specific surface area, is not prone to agglomeration and easy to disperse, improves the photocatalytic degradation performance, saves cost, reduces reaction time, can be repeatedly used and is environmentally friendly.

[0008] The technical solution adopted by the present application to solve the technical problems is as follows:

[0009] The present application provides a preparation method of In2O3 / Mn2O3 photocatalytic composite material, which specifically comprises the following steps:

[0010] (1) Preparation of precursor MIL-68(In)

[0011] Indium nitrate is added to N,N-dimethylformamide by ultrasonic for 3-5 min until it is uniformly dispersed, and stirring is performed until it is completely dissolved. Then, terephthalic acid is added to the mixture by ultrasonic for 3-5 min, and stirring is continuously performed for 15-20 min. The obtained mixture is transferred into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heated at 110-130℃ for 2-4 h. After natural cooling to room temperature, the obtained solid product is centrifuged, and washed with N,N-dimethylformamide and ethanol for multiple times. The product is dried at 50-70℃ overnight to obtain a white powder, which is the precursor MIL-68(In).

[0012] (2) Preparation of In2O3 / Mn2O3 photocatalytic material

[0013] Manganese acetate is weighed and added to a mixed solution composed of methanol and water, and ultrasonic is performed until it is uniformly dispersed to form a suspension. The precursor MIL-68(In) is added to the suspension, and ultrasonic is performed for 4-6 min until it is uniformly dispersed. Magnetic stirring is performed for 5-7 h, and after centrifugation, the product is transferred to an oven and dried at 55-65℃ overnight. Then, the product is transferred to a muffle furnace and calcined at 450-550℃ for 1.5-2.5 h to obtain the In2O3 / Mn2O3 photocatalytic material.

[0014] As a preferred embodiment, in step (1), the amount of indium nitrate and N,N-dimethylformamide is 0.32g:30mL.

[0015] As a preferred embodiment, in step (1), the mass ratio of indium nitrate to terephthalic acid is 0.32:0.2.

[0016] As a preferred embodiment, in step (2), the volume ratio of methanol to water is 1:1.

[0017] As a preferred embodiment, in step (2), the ratio of the amount of manganese acetate to the mixed solution composed of methanol and water is (0.1-0.25) g:30 mL.

[0018] As a preferred embodiment, in step (2), the mass ratio of manganese acetate to the precursor MIL-68(In) is (0.1-0.25):1.

[0019] As a preferred embodiment, in step (2), the calcination is performed under air at a heating rate of 2℃ / min to 450-550℃ for 1.5-2.5h.

[0020] An In2O3 / Mn2O3 photocatalytic composite material prepared by the preparation method of the In2O3 / Mn2O3 photocatalytic composite material provided by the application.

[0021] The application of the In2O3 / Mn2O3 photocatalytic composite material prepared by the preparation method of the In2O3 / Mn2O3 photocatalytic composite material provided by the application in the preparation of an In2O3 / Mn2O3-PMS photocatalytic system for degrading tetracycline wastewater.

[0022] As a preferred embodiment, the In2O3 / Mn2O3-PMS photocatalytic system is composed of the In2O3 / Mn2O3 photocatalytic composite material and PMS, and the mass ratio of the In2O3 / Mn2O3 photocatalytic composite material to PMS is (20-80) mg:(0.1-1.5) mmol.

[0023] As a preferred embodiment, the pH of the PMS is 2-8.

[0024] The application has the following beneficial effects:

[0025] The preparation method of the In2O3 / Mn2O3 photocatalytic composite material provided by the application first prepares a precursor MIL-68(In) through a hydrothermal method, further combines it with manganese acetate to generate a heterojunction, and finally obtains the In2O3 / Mn2O3 photocatalytic material after calcination.

[0026] The application provides a preparation method of an In2O3 / Mn2O3 photocatalytic composite material, a precursor MIL-68(In) is prepared through a hydrothermal method, then the precursor MIL-68(In) is combined with manganese acetate to generate a heterojunction, and finally, PMS (Na2S2O8, sodium persulfate) is added to construct an In2O3 / Mn2O3-PMS photocatalytic composite system.

[0027] Compared with pure In2O3 material, the prepared In2O3 / Mn2O3 photocatalytic composite material has higher photocatalytic degradation performance, mainly utilizes In2O3 and Mn2O3 to activate PMS for photocatalytic degradation of tetracycline wastewater, the reaction process uses a xenon lamp as a light source and the In2O3 / Mn2O3 photocatalytic composite material as a catalyst to decompose organic matters into carbon dioxide and water. Through activation of PMS, the photocatalytic degradation performance is improved by about 30%, and the catalyst dosage in the reaction process is also less. Therefore, the prepared In2O3 / Mn2O3-PMS photocatalytic system has the advantages of energy saving and low cost, and the photocatalytic degradation process takes a short time, and can be widely applied to photocatalytic degradation treatment of various organic wastewater.

[0028] In addition, the prepared In2O3 / Mn2O3 photocatalytic composite material has excellent dispersibility, a large specific surface area and is not prone to agglomeration, can effectively avoid light loss, can maximize photocatalytic degradation treatment of tetracycline wastewater, improves photocatalytic degradation performance and has good recyclability and can be used for multiple times.

[0029] The application combines MIL-68(In) and manganese acetate to generate a heterojunction, through construction of the heterojunction structure, the photocatalytic performance of In2O3 can be further enhanced, the recombination of carriers is inhibited to a certain extent, has considerable cost advantage and is of great significance to reduce the economic cost, time cost and energy consumption of wastewater treatment.

[0030] The method for realizing photocatalytic degradation treatment of tetracycline wastewater by using the prepared In2O3 / Mn2O3 photocatalytic composite material as a catalyst and cooperating with PMS has the advantages of green environmental protection, repeated use of photocatalytic materials and low cost, is a new type of wastewater treatment scheme with huge market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 XRD diagrams of In2O3, In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, In2O3 / MnO-4 and In2O3.

[0032] Figure 2 The full spectrum of In2O3 / MnO-3 and Mn2p, In3d, O1s spectra. In the figure, (a) full spectrum; (b) Mn2p spectrum; (c) In3d spectrum; (d) O1s spectrum.

[0033] Figure 3 The UV-visible diffuse reflectance spectrum of In2O3, In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, In2O3 / MnO-4 and In2O3.

[0034] Figure 4 The effect of In2O3, In2O3 / MnO-1-PMS, In2O3 / MnO-2-PMS, In2O3 / MnO-3-PMS, In2O3 / MnO-4-PMS and In2O3 on the photocatalytic degradation of tetracycline.

[0035] Figure 5 The effect of the photocatalytic system In2O3 / MnO-3-PMS prepared according to different dosages of the photocatalytic composite material In2O3 / MnO-3 on the photocatalytic degradation of tetracycline.

[0036] Figure 6 The effect of the photocatalytic system In2O3 / MnO-3-PMS prepared according to different dosages of PMS on the photocatalytic degradation of tetracycline.

[0037] Figure 7 The effect of the photocatalytic system In2O3 / MnO-3-PMS prepared according to different initial pH of PMS on the photocatalytic degradation of tetracycline.

[0038] Figure 8 The test results of the photocatalytic cyclic degradation ability of the photocatalytic system In2O3 / MnO-3-PMS on tetracycline. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] Example 1 Preparation of In2O3 / Mn2O3-1 photocatalytic composite material

[0041] (1) 0.32 g of indium nitrate (In(NO3)3) was added into N,N-dimethylformamide by ultrasonic for 4 min to disperse uniformly, and was stirred vigorously for 15 min until completely dissolved. 0.2 g of terephthalic acid was added into the obtained solution by ultrasonic for 3 min, and was continuously stirred for 15 min. The obtained mixture was transferred into a high-pressure reactor with polytetrafluoroethylene as the inner liner, and was heated at 120 °C for 3 h. After naturally decreasing to room temperature, the obtained solid product was treated by centrifugation at 4500 r / min for 3 min, and was washed with N,N-dimethylformamide and ethanol for more than three times, respectively. Then, the obtained product was dried at 60 °C overnight to obtain a white powder, which was the precursor MIL-68(In).

[0042] (2) 100 mg of manganese acetate was weighed and added into 30 mL of a mixed solution composed of methanol and water (methanol: water = 1:1 (v / v)), and was ultrasonically dispersed for 5 min to form a suspension, which was marked as A solution.

[0043] (3) Then, 0.1 g of the precursor MIL-68(In) was added into the A solution, and was ultrasonically dispersed for 5 min and magnetically stirred for 6 h. The mixture was centrifuged at 4000 r / min for 1 min, and was transferred into an oven to be dried at 60 °C overnight. Then, it was transferred into a muffle furnace to be calcined, and was heated at an air flow rate of 2 °C / min to 500 °C and calcined for 2 h to obtain an In2O3 / Mn2O3 photocatalytic material, which was named as In2O3 / MnO-1 according to the addition amount of manganese acetate.

[0044] Example 2 Preparation of an In2O3 / Mn2O3-2 photocatalytic composite material

[0045] (1) 0.32 g of indium nitrate (In(NO3)3) was added into N,N-dimethylformamide by ultrasonic for 4 min to disperse uniformly, and was stirred vigorously for 15 min until completely dissolved. 0.2 g of terephthalic acid was added into the obtained solution by ultrasonic for 3 min, and was continuously stirred for 15 min. The obtained mixture was transferred into a high-pressure reactor with polytetrafluoroethylene as the inner liner, and was heated at 120 °C for 3 h. After naturally decreasing to room temperature, the obtained solid product was treated by centrifugation at 4500 r / min for 3 min, and was washed with N,N-dimethylformamide and ethanol for more than three times, respectively. Then, the obtained product was dried at 60 °C overnight to obtain a white powder, which was the precursor MIL-68(In).

[0046] (2) 150 mg of manganese acetate was weighed and added into 30 mL of a mixed solution composed of methanol and water (methanol: water = 1:1 (v / v)), and was ultrasonically dispersed for 5 min to form a suspension, which was marked as A solution.

[0047] (3) Then 0.1 g of the precursor MIL-68(In) was added to the A liquid, ultrasonic dispersion for 5 min, and magnetic stirring for 6 h. The mixture was centrifuged at 4000 r / min for 1 min, and then transferred to an oven for drying at 60°C overnight. Then it was transferred to a muffle furnace for calcination, and heated to 500°C at a heating rate of 2°C / min in air, and calcined for 2 h to obtain the In2O3 / Mn2O3 photocatalytic material, which was named In2O3 / MnO-2 according to the amount of manganese acetate added.

[0048] Example 3 Preparation of In2O3 / Mn2O3-3 photocatalytic composite material

[0049] (1) 0.32 g of indium nitrate (In(NO3)3) was added to N,N-dimethylformamide and ultrasonic dispersion for 4 min, and then stirred vigorously for 15 min until completely dissolved. 0.2 g of terephthalic acid was added to the obtained solution and ultrasonic dispersion for 3 min, and then stirred for 15 min. The obtained mixture was transferred to a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heated at 120°C for 3 h. After natural cooling to room temperature, the obtained solid product was treated by centrifugation at 4500 r / min for 3 min, and then washed with N,N-dimethylformamide and ethanol for more than three times, respectively. Then it was dried at 60°C overnight to obtain a white powder, which was the precursor MIL-68(In).

[0050] (2) 200 mg of manganese acetate was weighed and added to 30 mL of a mixed solution composed of methanol and water (methanol: water = 1:1 (v / v)), and ultrasonic dispersion for 5 min to form a suspension, which was labeled as A liquid.

[0051] (3) Then 0.1 g of the precursor MIL-68(In) was added to the A liquid, ultrasonic dispersion for 5 min, and magnetic stirring for 6 h. The mixture was centrifuged at 4000 r / min for 1 min, and then transferred to an oven for drying at 60°C overnight. Then it was transferred to a muffle furnace for calcination, and heated to 500°C at a heating rate of 2°C / min in air, and calcined for 2 h to obtain the In2O3 / Mn2O3 photocatalytic material, which was named In2O3 / MnO-3 according to the amount of manganese acetate added.

[0052] Example 4 Preparation of In2O3 / Mn2O3-4 photocatalytic composite material

[0053] (1) 0.32 g of indium nitrate (In(NO3)3) was added into N,N-dimethylformamide and ultrasonically dispersed for 4 min, and then stirred vigorously for 15 min until completely dissolved. 0.2 g of terephthalic acid was added into the obtained solution and ultrasonically dispersed for 3 min, and then stirred for 15 min. The obtained mixture was transferred into a high-pressure reactor with a polytetrafluoroethylene inner liner, and heated at 120℃ for 3 h. After naturally cooling to room temperature, the obtained solid product was treated by centrifugation at 4500 r / min for 3 min, and then washed with N,N-dimethylformamide and ethanol for more than three times, respectively. Then, the product was dried at 60℃ overnight to obtain a white powder, which was the precursor MIL-68(In).

[0054] (2) 250 mg of manganese acetate was weighed and added into 30 mL of a mixed solution composed of methanol and water (methanol: water = 1:1 (v / v)), and ultrasonically dispersed for 5 min to form a suspension, which was marked as solution A.

[0055] (3) Then, 0.1 g of the precursor MIL-68(In) was added into solution A, and ultrasonically dispersed for 5 min until uniformly dispersed, and then magnetically stirred for 6 h. The mixture was centrifuged at 4000 r / min for 1 min, and then transferred into an oven and dried at 60℃ overnight. Then, the product was transferred into a muffle furnace and calcined, and heated at a rate of 2℃ / min to 500℃ under air, and then calcined for 2 h to obtain an In2O3 / Mn2O3 photocatalytic material, which was named as In2O3 / MnO-4 according to the amount of manganese acetate added.

[0056] Test Example 1

[0057] The XRD patterns of the photocatalytic composite materials In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, In2O3 / MnO-4 prepared in Examples 1-4 of the present application and the existing photocatalytic material In2O3 are shown in Fig. 1. Figure 1As shown in the diagram, the main diffraction peaks of the pure In₂O₃ nanocatalyst are at 2θ values ​​of 21.39°, 30.6°, 35.56°, 37.63°, 41.87°, 45.67°, 51.0°, 55.91°, and 60.64°, exhibiting crystal planes of (211), (222), (400), (411), (332), (431), (440), and (622). The strong characteristic peaks of In₂O₃ indicate good crystallinity. The diffraction peaks of In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, and In2O3 / MnO-4 are similar to those of pure In2O3, with the main diffraction peaks at 2θ values ​​of 23°, 33°, 38°, 49°, 54°, and 64°, exhibiting crystal planes of (221), (222), (221), (400), (440), and (622). Among these, the strongest peak of Mn2O3 typically appears at a 2θ value of approximately 33°. The similarity between the In2O3 / Mn2O3 samples and pure In2O3 demonstrates that the addition of Mn2O3 did not alter the original structure of In2O3. The peak intensities decreased slightly, while the characteristic peaks of Mn2O3 increased with increasing addition amount, indicating its high crystallinity. Therefore, the In2O3 / Mn2O3 photocatalytic composite material was successfully prepared.

[0058] Experimental Example 2

[0059] The full spectrum and Mn2p, In3d, and O1s spectra of the photocatalytic composite material In2O3 / MnO-3 prepared in Example 3 of this invention are shown below. Figure 2 As shown. (Through) Figure 2 (a) shows that the full spectrum of In2O3 / Mn2O3-3 exhibits In, O, and Mn peaks, confirming the successful synthesis of In2O3 / Mn2O3-3. Figure 2 (b) It can be seen that Mn2p has a peak at 630–660 eV, among which there are two relatively strong peaks at 641.4 and 653.2 eV, which correspond to Mn2p respectively. 1 / 2 Mn 2p 3 / 2 This means that in the synthesis of heterojunctions, the Mn element is mainly composed of Mn. 3+ The valence exists in In₂O₃. Through... Figure 2 (c) It can be seen that the fitted XPS spectrum of In 3d shows two peaks at 444.5 and 451.1 eV, corresponding to In 3d respectively. 5 / 2 In3d 3 / 2 This indicates the presence of In in In2O3 / Mn2O3-3. 3+ State. Through Figure 2(d) It can be seen that the O1s spectrum in In2O3 / Mn2O3-3 is divided into two fitting characteristic peaks with binding energies of 529.7 and 531.9 eV, which are attributed to lattice oxygen In-O and In-OH, respectively. The above XPS confirms the coexistence of In2O3 and Mn2O3 in the In2O3 / Mn2O3-3 heterostructure and the good performance of the photocatalytic composite material.

[0060] Experimental Example 3

[0061] The ultraviolet-visible diffuse reflectance spectra of the photocatalytic composite materials In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, and In2O3 / MnO-4 prepared in Examples 1-4 of this invention, as well as the existing photocatalytic material In2O3, are shown below. Figure 3 As shown. (Through) Figure 3 It can be seen that, compared with pure In2O3 nanocatalysts, the In2O3 / Mn2O3 photocatalytic composite material exhibits stronger absorption in both the ultraviolet and visible light regions, which may be attributed to the interaction between In2O3 and Mn2O3 nanocatalysts. With increasing Mn2O3 content, the In2O3 / Mn2O3 photocatalytic composite material shows a significant redshift, further confirming that under visible light catalytic conditions, the In2O3 / Mn2O3 photocatalytic composite material is more beneficial than In2O3 alone in improving the response of the photocatalytic composite material to visible light, thereby enhancing photocatalytic activity.

[0062] Experimental Example 4: In2O3 / Mn2O3-PMS Photocatalytic System and Its Application in the Degradation of Tetracycline Wastewater

[0063] 1. Preparation of In2O3 / Mn2O3-PMS photocatalytic system

[0064] Photocatalytic composite materials In2O3 / MnO-1, In2O3 / MnO-2, In2O3 / MnO-3, and In2O3 / MnO-4 were prepared according to Examples 1-4, respectively. Then, PMS (Na2S2O8, Sodium persulfate) was added to these photocatalytic composite materials to obtain In2O3 / Mn2O3-PMS photocatalytic systems, which were named In2O3 / MnO-1-PMS, In2O3 / MnO-2-PMS, In2O3 / MnO-3-PMS, and In2O3 / MnO-4-PMS, respectively.

[0065] 2. Photodegradation test of tetracycline aqueous solution

[0066] The photocatalytic degradation performance of the prepared photocatalytic systems In₂O₃ / MnO₁-PMS, In₂O₃ / MnO₂-PMS, In₂O₃ / MnO₃-PMS, and In₂O₃ / MnO₄-PMS was studied by testing the photocatalytic degradation of tetracycline in aqueous solution. The specific experimental procedure is as follows:

[0067] Using a xenon lamp as the external light source, a pre-prepared 40 mg / L tetracycline aqueous solution was used as the pollutant for degradation. The photocatalytic system prepared in this invention was added to the tetracycline aqueous solution, and the mixture was ultrasonically treated to ensure homogeneity. The mixture was then stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium between the photocatalytic system and the pollutant through a dark reaction. After transferring the mixture to xenon lamp illumination, a certain volume of tetracycline wastewater was collected at 30-minute intervals. The sample was filtered through a 0.25 μm organic phase filter membrane, and the absorbance was measured using a UV-Vis spectrophotometer to calculate the photodegradation efficiency. During the reaction, the optimal experimental conditions were obtained by varying the amounts of the In₂O₃ / Mn₂O₃ photocatalytic composite material and PMS, as well as the pH value of the PMS. The aim was to achieve the best photocatalytic degradation effect while minimizing costs to protect the environment.

[0068] The test results are as follows:

[0069] 1. The photocatalytic degradation effects of the photocatalytic systems In2O3 / MnO-1-PMS, In2O3 / MnO-2-PMS, In2O3 / MnO-3-PMS, and In2O3 / MnO-4-PMS prepared in this invention, as well as the existing photocatalytic material In2O3, on tetracycline photocatalytic degradation are as follows: Figure 4 As shown.

[0070] The initial experimental conditions were: tetracycline concentration 40 mg / L, 1 mmol PMS, PMS pH = 4, In₂O₃ / Mn₂O₃ photocatalytic composite material dosage 60 mg. All systems were first reacted in the dark for 30 min to reach adsorption saturation. Then, PMS was added, and the light was turned on. Small samples were taken every 30 min, and the absorbance of tetracycline was measured using a UV-Vis spectrophotometer. Figure 4 It can be seen that the photocatalytic performance of the In2O3 / Mn2O3-PMS photocatalytic system is higher than that of In2O3. The degradation efficiency of In2O3 / MnO-1-PMS, In2O3 / MnO-2-PMS, In2O3 / MnO-3-PMS, and In2O3 / MnO-4-PMS increased from 84.1% to 91.5% in 120 min, indicating enhanced photocatalytic activity of the In2O3 / Mn2O3-PMS system. Among them, In2O3 / MnO-3-PMS exhibits the optimal degradation rate, but its recombination efficiency of photogenerated carriers is the lowest.

[0071] 2. The photocatalytic degradation effect of tetracycline on the In2O3 / MnO-3-PMS photocatalytic system prepared by different dosages of the photocatalytic composite material In2O3 / MnO-3 is as follows: Figure 5 As shown.

[0072] The initial experimental conditions were: tetracycline concentration 40 mg / L, 1 mmol PMS, PMS pH = 4, and In₂O₃ / MnO₃ dosages of 20 mg, 40 mg, 60 mg, and 80 mg, respectively. (The text abruptly ends here.) Figure 5 It was found that the degradation efficiency significantly improved when the In₂O₃ / MnO₃ dosage increased from 20 mg to 80 mg. Higher In₂O₃ / MnO₃ dosage increased the number of active sites, leading to the interaction between In₂O₃ / MnO₃ and PMS, generating more active chemical substances. However, when the In₂O₃ / MnO₃ dosage increased from 60 mg to 80 mg, the improvement in degradation efficiency became insignificant, and even had the opposite effect. This may be because excessive In₂O₃ / MnO₃ accumulation reduced light utilization, affecting its photocatalytic degradation efficiency for tetracycline. Therefore, the optimal dosage of the photocatalytic composite In₂O₃ / MnO₃ in this reaction system was determined to be 60 mg.

[0073] 3. The photocatalytic degradation effects of the In2O3 / MnO-3-PMS photocatalytic system prepared with different dosages of PMS on tetracycline are as follows: Figure 6 As shown.

[0074] The initial experimental conditions were: tetracycline concentration 40 mg / L, In₂O₃ / MnO₃ dosage 60 mg, PMS pH = 4, and PMS dosages of 0.1 mmol, 0.5 mmol, 1 mmol, and 1.5 mmol, respectively. (The text abruptly ends here.) Figure 6 It was found that adding PMS to In2O3 / MnO-3 effectively activated the system at a PMS concentration of 1 mmol. However, when the PMS dosage was 1.5 mmol, the excess PMS reacted with reactive oxygen species, thus reducing the degradation performance of In2O3 / MnO-3 for tetracycline. Considering economic costs, the optimal PMS dosage for this reaction system was determined to be 1 mmol.

[0075] 4. The photocatalytic degradation effect of tetracycline by the In2O3 / MnO-3-PMS photocatalytic system prepared according to different initial pH values ​​is as follows: Figure 7 As shown.

[0076] The initial experimental conditions were: tetracycline concentration 40 mg / L, In₂O₃ / MnO₃ dosage 60 mg, PMS dosage 1 mmol, and PMS pH values ​​of 2, 4, 6, and 8. (The text abruptly ends here.) Figure 7 It can be seen that under the same conditions, the highest removal rates of 92.7% and 93.9% were observed at pH = 2–4. When pH = 6–8, the degradation efficiency decreased, as pH increased the electrostatic repulsion between In₂O₃ / MnO₃ and the tetracycline surface charge, which was observed during PMS activation. + It has an adverse effect, ·OH and ·SO4 - The shortened lifespan leads to a decrease in tetracycline degradation efficiency. Under acidic conditions, In₂O₃ / MnO₃ electrostatic adsorption promotes tetracycline degradation. Conversely, under alkaline conditions, electrostatic repulsion hinders the interaction between the catalyst and tetracycline, reducing the removal efficiency. Therefore, considering the electrostatic adsorption characteristics of the catalyst and the features of the PMS activation process, In₂O₃ / MnO₃ exhibits the optimal tetracycline degradation effect at pH = 4, consistent with experimental expectations. Therefore, the pH of PMS in this reaction system was determined to be 4.

[0077] 5. Test of the photocatalytic degradation ability of tetracycline by the In2O3 / MnO-3-PMS photocatalytic system

[0078] The degradation ability of the optimal photocatalytic system In2O3 / MnO-3-PMS for tetracycline was evaluated through four-cycle experiments. The results are as follows: Figure 8 As shown. (Through) Figure 8 As can be seen, even after four cycles of use, In2O3 / MnO-3-PMS still exhibits excellent performance, with the tetracycline removal rate remaining at a high level of 89.98%. This data demonstrates the high stability and excellent recyclability of the In2O3 / Mn2O3-PMS photocatalytic system prepared in this invention. The maintenance of the performance of the In2O3 / Mn2O3-PMS photocatalytic system proves the stability of its structure during repeated use and also illustrates the persistence of its active sites during the catalytic reaction.

[0079] In summary, the prepared In2O3 / Mn2O3 photocatalytic composite material was successfully fabricated through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS).

[0080] The prepared In2O3 / Mn2O3 photocatalytic composite material can effectively improve the degradation time and degradation rate of tetracycline in cooperation with PMS, and compared with pure In2O3 material, the prepared In2O3 / Mn2O3-PMS photocatalytic system has a better inhibiting effect on photo-generated electrons and holes.

[0081] The optimal photocatalytic degradation system for degrading 40mg / L tetracycline is determined by changing the dosage of In2O3 / Mn2O3 photocatalytic composite material, the dosage ratio of manganese acetate, the dosage of PMS and the pH of PMS, and the photocatalytic degradation performance of the prepared In2O3 / Mn2O3-PMS photocatalytic system is not easy to be deactivated through four cycle experiments, which proves that the In2O3 / Mn2O3 activated PMS has good repeatable application performance and has good application potential in wastewater treatment.

[0082] The application discloses a preparation method of an In2O3 / Mn2O3 photocatalytic composite material and application of the In2O3 / Mn2O3 photocatalytic composite material in degrading tetracycline wastewater in cooperation with PMS, and those skilled in the art can refer to the content of the application and appropriately improve process parameters to realize the application. It should be particularly pointed out that all similar replacements and changes are obvious to those skilled in the art, and they are regarded as being included in the application. The product of the application has been described through preferred embodiments, and relevant personnel can obviously change or appropriately change and combine the product described in the application without departing from the content, spirit and scope of the application, so as to realize and apply the application.

Claims

1. A method for preparing In2O3 / Mn2O3 photocatalytic composite material, characterized in that, Includes the following steps: (1) Preparation of precursor MIL-68(In) Indium nitrate was added to N,N-dimethylformamide via hydrothermal method and sonicated for 3-5 minutes until uniformly dispersed. The mixture was then stirred until completely dissolved. Terephthalic acid was added and sonicated for 3-5 minutes, with continuous stirring for 15-20 minutes. The resulting mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene and heated at 110-130℃ for 2-4 hours. After cooling to room temperature, the resulting solid product was centrifuged and washed multiple times with N,N-dimethylformamide and ethanol, respectively. The product was then dried overnight at 50-70℃ to obtain a white powder, which is the precursor MIL-68(In). (2) Preparation of In2O3 / Mn2O3 photocatalytic composite material Weigh manganese acetate and add it to a mixed solution of methanol and water. Sonicate until evenly dispersed to form a suspension. Add the precursor MIL-68(In) to the suspension and sonicate for 4-6 minutes until evenly dispersed. Stir magnetically for 5-7 hours. After centrifugation, transfer to an oven and dry overnight at 55-65℃. Transfer to a muffle furnace and calcine at 450-550℃ for 1.5-2.5 hours to obtain the In2O3 / Mn2O3 photocatalytic composite material.

2. The preparation method of the In2O3 / Mn2O3 photocatalytic composite material according to claim 1, characterized in that, In step (1), the ratio of indium nitrate to N,N-dimethylformamide is 0.32 g: 30 mL.

3. The preparation method of the In2O3 / Mn2O3 photocatalytic composite material according to claim 1, characterized in that, In step (1), the mass ratio of indium nitrate to terephthalic acid is 0.32:0.

2.

4. The method for preparing the In2O3 / Mn2O3 photocatalytic composite material according to claim 1, characterized in that, In step (2), the volume ratio of methanol to water is 1:

1.

5. The method for preparing the In2O3 / Mn2O3 photocatalytic composite material according to claim 1, characterized in that, In step (2), the ratio of manganese acetate to the mixed solution composed of methanol and water is (0.1-0.25) g: 30 mL.

6. The method for preparing the In2O3 / Mn2O3 photocatalytic composite material according to claim 1, characterized in that, In step (2), the temperature is raised to 450-550℃ and calcined for 1.5-2.5h under air at a heating rate of 2℃ / min.

7. The In2O3 / Mn2O3 photocatalytic composite material obtained by the preparation method according to any one of claims 1-6.

8. The application of the In2O3 / Mn2O3 photocatalytic composite material as described in claim 7 in the synergistic degradation of tetracycline wastewater by PMS.

Images