Manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies as well as preparation method and application of manganese-modified bismuth oxide composite photocatalyst

Abstract

The invention relates to a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies as well as a preparation method and application thereof, and belongs to the technical field of photocatalytic material preparation and water treatment. The manganese modified bismuth oxide composite catalyst rich in oxygen vacancies is prepared by adopting a simple one-step in-situ loading method, and efficient regulation and control on the oxygen vacancies and the photocatalytic capacity are realized by adjusting the variety and the loading capacity of manganese salts. The photocatalyst can form a synergistic system with ultra-low power LED white light / Fe < 3 + >, realizes rapid and efficient degradation of various organic pollutants such as antibiotics and phenols in water, and has excellent anti-interference capability and stability. The preparation method is simple to operate, green and environment-friendly, and the prepared photocatalytic material can fully utilize the full-wavelength LED spectrum to achieve the purpose of efficiently purifying organic pollutants in the environment.

Description

Technical Field

[0001] The invention relates to a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, a preparation method and application thereof, and belongs to the technical field of photocatalytic material preparation and water treatment. Background Art

[0002] With the acceleration of industrialization, water pollution is becoming increasingly serious. Traditional water treatment methods such as flocculation and sedimentation, physical adsorption, and microbial degradation have limited treatment efficiency and are prone to secondary pollution. Photocatalytic oxidation technology, as a new type of advanced oxidation technology, has the advantages of high efficiency, environmental protection, and no secondary pollution, and has broad application prospects in the field of water treatment. Bismuth oxide is an important semiconductor photocatalytic material, but single bismuth oxide has the disadvantages of low visible light utilization, high recombination rate of photogenerated carriers, and unstable photocatalytic performance. Its photocatalytic performance can be effectively improved by introducing foreign element modification and constructing oxygen vacancies. Among them, foreign element modification can introduce impurity elements into the forbidden band gap of the photocatalyst, reduce the energy required for electron jumping, and adjust the built-in electric field of the material, thereby improving the visible light absorption of the photocatalyst and prolonging the life of the photogenerated charge; oxygen vacancies play a vital role in electron-hole separation, mediating oxygen activation, and providing adsorption and reaction active sites. Therefore, it is of great significance to develop element-modified bismuth oxide composite photocatalysts rich in oxygen vacancies.

[0003] The modifying elements currently used in the research mainly include transition metals, rare earth elements and non-metallic elements, and the methods for preparing element-modified bismuth oxide composite materials mainly include liquid phase method and solid phase method. For example, the invention patent (ZL201810303987.2) uses a solid phase method to prepare a metal element doped bismuth oxide composite material, that is, using bismuth acid salt, doping source, reducing agent, and auxiliary agent as raw materials, through high-energy ball milling, heat treatment (200-600℃, 0.5-10h), washing and impurity removal, solid-liquid separation, drying and other steps, to prepare a metal element doped bismuth oxide photocatalytic material; the invention patent (ZL202010408312.1) uses a liquid phase method to prepare a nanosilver doped bismuth oxide composite material, that is, a mixed aqueous solution system of sodium bismuth acid and silver nitrate is reacted under natural light for 0.5-2h, and then separated, washed, dried and other steps to prepare a catalyst with dark photocatalytic activity; the invention patent (ZL202211465711.7) uses a liquid phase method to prepare a loaded Fe 3+ The photocatalytic bismuth-based material is a mixed solution of sodium bismuthate and ferric chloride, which is subjected to simple ultrasound, stirring and other steps to prepare Fe-based photocatalytic bismuth-based photocatalytic material that can be used to degrade antibiotics in aquaculture wastewater. 3+Loaded photocatalytic bismuth-based materials; Invention patent (ZL202110860500.2) uses liquid phase alkali co-precipitation method to prepare manganese-doped soft bismuth ore photocatalyst, that is, the Bi raw material is dissolved in acid and mixed with Mn-containing solution, excess alkali solution is added for precipitation, and then hydrothermally reacted at 110-130℃ for 5-7h to obtain a sheet-like structure of Bi. 12 MnO 20 Photocatalyst. At present, the methods for constructing oxygen vacancies mainly include water or solvent thermal method, high temperature annealing method, reduction method, ion doping method, etc. For example, the invention patent (ZL202410929098.2) discloses a Bi rich in oxygen vacancies. 2 O 2 CO 3 / Cu 9 S 5 A method for preparing heterojunction photocatalytic materials, by introducing oxygen vacancies by adding glyoxal solvent into the reaction solution; an invention patent (CN202410865716.1) discloses a method for preparing a semiconductor photocatalyst for efficient ethylene degradation, by introducing oxygen vacancies through hydrothermal synthesis, reducing atmosphere annealing treatment and other steps; a literature (ACS Appl. Mater. Interfaces 2018, 10, 14, 11715–11721) discloses a method for preparing a semiconductor photocatalyst for efficient ethylene degradation, by introducing oxygen vacancies through hydrothermal synthesis, reducing atmosphere annealing treatment and other steps; a method for preparing a heterojunction photocatalytic material, by introducing oxygen vacancies by adding glyoxal solvent into the reaction solution; a method for preparing a semiconductor photocatalyst for efficient ethylene degradation, by introducing oxygen vacancies through hydrothermal synthesis, reducing atmosphere annealing treatment and other steps; a method for preparing a semiconductor photocataly 3 The incorporation of Sr, an element with a lower oxidation state, increases the oxygen vacancies in metal oxides.

[0004] The existing composite photocatalysts, preparation methods and their applications generally have the following problems: (1) The visible light absorption and utilization capacity of photocatalysts is limited, making it difficult to efficiently utilize the full wavelength spectrum, and photogenerated electrons and holes are easily recombined on the catalyst surface; (2) The preparation method is complex and the reaction conditions are harsh, often involving precious metals or scarce metals, and the element doping amount is generally large, resulting in a high preparation cost of the composite photocatalyst; (3) When composite photocatalysts are used in water treatment, there are shortcomings such as the need for high-power light sources, difficulty in fully utilizing the full wavelength spectrum, susceptibility to interference from multiple coexisting substances in the water environment, and a harsh application pH range.

[0005] Therefore, a solution is currently needed to solve the technical problems existing in the prior art. The present invention rationally designs a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies and uses it for ultra-low power LED white light / Fe 3+ Efficient degradation of organic pollutants such as antibiotics and phenols in a synergistic system. Summary of the invention

[0006] The purpose of the present invention is to provide a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, which is rich in oxygen vacancies and has excellent photocatalytic performance and can be used for ultra-low power LED white light / Fe 3+In the synergistic system, efficient degradation of various organic pollutants in water, such as antibiotics and phenols, is achieved.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, which method has simple process, low cost and is easy to industrialize.

[0008] Another object of the present invention is to provide the use of the above-mentioned manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies in the efficient degradation of organic pollutants.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] On the one hand, the present invention provides a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, wherein: the composite photocatalyst is prepared by a one-step in-situ loading method using sodium bismuthate as a raw material and manganese salt as a modifier, and the composite photocatalyst is BiO 2-x 、Bi 2 O 3 、NaBiO 3 mixture.

[0011] According to a preferred embodiment of the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the composite photocatalyst is rich in oxygen vacancies, and the oxygen vacancies can be regulated by adjusting the type and loading amount of the manganese salt.

[0012] On the other hand, the present invention provides a method for preparing the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, comprising the following steps:

[0013] (1) after uniformly dispersing a certain amount of sodium bismuthate in water by ultrasonication, adding a certain amount of manganese salt under continuous stirring at room temperature to form a uniform dispersion;

[0014] (2) adding an alkaline solution to adjust the pH value of the dispersion, reacting at room temperature for 10-30 minutes, centrifuging the resulting mixture, washing with water, and drying at 50-110° C. to obtain a dark brown composite photocatalyst product.

[0015] According to a preferred embodiment of the method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the manganese salt described in step (1) is a divalent manganese salt, and the molar ratio of the manganese salt to sodium bismuthate is 0.0001-0.3:1.

[0016] According to a preferred embodiment of the method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the manganese salt is selected from one or more of manganese chloride, manganese sulfate, and manganese oxalate.

[0017] According to a preferred embodiment of the method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the molar ratio of the manganese salt to sodium bismuthate is 0.001-0.01:1.

[0018] According to a preferred embodiment of the method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the pH value in step (2) is in the range of 8-11.

[0019] According to a preferred embodiment of the method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the pH value range is 9-10.

[0020] In a third aspect, the present invention also provides an application of the above-mentioned manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, wherein: the composite photocatalyst is used for ultra-low power LED white light / Fe 3+ In the synergistic system, rapid and efficient degradation of organic pollutants in water is achieved. The power of ultra-low power LED white light is as low as 5W, and the wavelength range is 360nm-760nm.

[0021] According to a preferred embodiment of the application of the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the degraded organic pollutants are antibiotics and / or phenols.

[0022] According to a preferred embodiment of the application of a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies described in the present invention, the antibiotics are selected from one or more of sulfamethoxazole SMT, tetracycline TC, and ciprofloxacin CIP, and the phenols are selected from one or more of phenol Phe and bisphenol ABPA.

[0023] In specific applications, manganese-modified bismuth oxide composite photocatalysts rich in oxygen vacancies were added to simulated wastewater containing organic pollutants. 3+ The photocatalytic reaction was carried out in a synergistic system, the dosage of the composite photocatalyst was 0.05-0.5 g / L, the light source was an ultra-low power LED lamp (5W, 380-760nm), Fe 3+ The concentration is 0.1-20mmol / L, and the reaction time is 0.5-6 hours. The synergistic system has strong anti-interference ability, and the common coexisting substances in water (including cations, anions, and humus) have little effect on the photocatalytic performance; it is applicable in a wide pH range (3-9) and has excellent reusability and stability; when using actual water bodies (such as lake water and sewage treatment plant effluent) as the background, the removal efficiency of typical pollutants is close to 100%.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The composite photocatalyst prepared by the present invention contains trace manganese elements and abundant oxygen vacancy defects, has the remarkable characteristics of wide light absorption range, easy separation of photogenerated carriers, providing adsorption and reaction active sites and activating molecular oxygen and water molecules, and thus has excellent photocatalytic ability.

[0026] (2) The preparation of the composite photocatalyst disclosed in the present invention can be carried out in an aqueous solution at room temperature. By simply adjusting the type and loading amount of the manganese salt, the crystal form of bismuth oxide can be adjusted and abundant oxygen vacancy defects can be constructed on the catalyst surface. The preparation method is simple, easy to operate, low-cost, and easy to industrialize.

[0027] (3) The composite photocatalyst prepared by the present invention can be used with ultra-low power LED / Fe 3+ A synergistic system is formed to achieve efficient degradation of various antibiotics and phenols and other organic pollutants in polluted water. The system has strong anti-interference ability and has high catalytic activity in a wide range of pH 3-9. In particular, it is almost unaffected by various coexisting anions and cations and humic acid, and the removal rate of various antibiotics and phenols organic pollutants is still as high as 100% with actual water bodies (such as lake water, sewage treatment plant effluent) as the background, and has excellent reusability and stability. It has broad application prospects in the field of water organic pollutant treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0029] Figure 1 The composite photocatalyst prepared in Example 2 of the present invention and the NaBiO prepared in Comparative Example 1 3 SEM images and EDS scans of the photocatalyst;

[0030] Figure 2 The XRD spectrum of the composite photocatalyst prepared in Example 2 of the present invention;

[0031] Figure 3 The composite photocatalyst prepared in Example 2 of the present invention and the NaBiO prepared in Comparative Example 1 3 EPR spectra, light absorption properties and XPS spectra of photocatalysts (Bi4f and Mn2p);

[0032] Figure 4 The composite photocatalysts prepared in Examples 1-5 of the present invention and the NaBiO prepared in Comparative Example 13 Photocatalyst degradation curve of sulfadimethoxine in ultra-low power LED system;

[0033] Figure 5 The composite photocatalyst prepared in Example 2 of the present invention and the NaBiO prepared in Comparative Example 1 3 Photocatalyst in ultra-low power LED / Fe 3+ and ultra low power LED / Fe 3+ -OA (oxalic acid) synergistic system degradation curve of sulfamethazine.

[0034] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The present invention adopts a simple one-step in-situ loading method to prepare a manganese-modified bismuth oxide composite catalyst rich in oxygen vacancies. By adjusting the type and loading amount of manganese salt, efficient regulation of oxygen vacancies and photocatalytic ability is achieved. The photocatalyst can be combined with ultra-low power LED white light / Fe 3+ A synergistic system is formed to achieve rapid and efficient degradation of various organic pollutants in water, such as antibiotics and phenols, and has excellent anti-interference ability and stability. The invention is simple to operate, green and environmentally friendly, and the prepared photocatalytic material can make full use of the full wavelength LED spectrum to achieve the purpose of efficient purification of organic pollutants in the environment.

[0037] The present invention discloses a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, wherein: the composite photocatalyst is prepared by a one-step in-situ loading method using sodium bismuthate as a raw material and manganese salt as a modifier, and the composite photocatalyst is BiO 2-x 、Bi 2 O 3 、NaBiO 3 mixture.

[0038] Preferably, the composite photocatalyst is rich in oxygen vacancies, and the oxygen vacancies can be regulated by adjusting the type and loading amount of the manganese salt.

[0039] A method for preparing the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies comprises the following steps:

[0040] (1) after uniformly dispersing a certain amount of sodium bismuthate in water by ultrasonication, adding a certain amount of manganese salt under continuous stirring at room temperature to form a uniform dispersion;

[0041] (2) adding an alkaline solution to adjust the pH value of the dispersion, reacting at room temperature for 10-30 minutes, centrifuging the resulting mixture, washing with water, and drying at 50-110° C. to obtain a dark brown composite photocatalyst product.

[0042] Preferably, the manganese salt described in step (1) is a divalent manganese salt, and the molar ratio of the manganese salt to sodium bismuthate is 0.0001-0.3:1.

[0043] Preferably, the manganese salt is selected from one or more of manganese chloride, manganese sulfate and manganese oxalate.

[0044] Preferably, the molar ratio of the manganese salt to sodium bismuthate is 0.001-0.01:1.

[0045] Preferably, the pH value in step (2) is in the range of 8-11.

[0046] Preferably, the pH value range is 9-10.

[0047] An application of the above-mentioned manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies of the present invention, wherein: the composite photocatalyst is used for ultra-low power LED white light / Fe 3+ In the synergistic system, rapid and efficient degradation of organic pollutants in water is achieved. The power of ultra-low power LED white light is as low as 5W, and the wavelength range is 360nm-760nm.

[0048] Preferably, the degraded organic pollutants are antibiotics and / or phenols.

[0049] Preferably, the antibiotic is selected from one or more of sulfamethazine SMT, tetracycline TC, and ciprofloxacin CIP, and the phenol is selected from one or more of phenol Phe and bisphenol ABPA.

[0050] The present invention is further described below with reference to specific examples, but the present invention is not limited to these embodiments.

[0051] Example 1

[0052] 1 mmol of sodium bismuthate was dispersed in 30 mL of water and ultrasonically dispersed to form a suspension. Under continuous stirring at room temperature, 0.0001 mmol of manganese chloride was added to form a uniform dispersion. Alkaline solution was added to adjust the pH value of the solution to 9. After reacting for 30 minutes, the resulting mixture was centrifuged, washed with water, and dried at 90°C to obtain a dark brown composite photocatalyst product, which was recorded as BiMn 0.0001 .

[0053] Example 2

[0054] The process of this embodiment is the same as that of embodiment 1, except that the divalent manganese salt is adjusted to manganese sulfate, the amount of manganese salt added is adjusted to 0.001 mmol, and the obtained composite photocatalyst product is recorded as BiMn 0.001 .

[0055] Example 3

[0056] The process of this embodiment is the same as that of embodiment 1, except that the divalent manganese salt is adjusted to manganese oxalate, the amount of manganese salt added is adjusted to 0.01 mmol, and the obtained composite photocatalyst product is recorded as BiMn 0.01 .

[0057] Example 4

[0058] The process of this example is the same as that of Example 1, except that the amount of manganese salt added is adjusted to 0.1 mmol, and the obtained composite photocatalyst product is recorded as BiMn 0.1 .

[0059] Example 5

[0060] The process of this example is the same as that of Example 1, except that the amount of manganese salt added is adjusted to 0.3 mmol, and the obtained composite photocatalyst product is recorded as BiMn 0.3 .

[0061] Comparative Example 1

[0062] The process of this example is the same as that of Example 1, except that no manganese salt is added, and the obtained photocatalyst product control is recorded as NaBiO 3 .

[0063] The BiMn prepared in Example 2 of the present invention was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), electron paramagnetic resonance (EPR), ultraviolet visible absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). 0.001 Composite photocatalyst and NaBiO prepared in Comparative Example 1 3 The morphology, surface element distribution, oxygen vacancies, light absorption properties and element form of the photocatalyst are characterized.

[0064] The results are as follows Figure 1-3 Compared with NaBiO 3 Photocatalyst, manganese-modified BiMn 0.001 The composite photocatalyst has a more regular morphology (cubic), with trace amounts of Mn elements evenly distributed on the surface, and mainly Mn 4+ The existence of Mn 4+The incorporation of ions promotes the NaBiO 3 The release of lattice oxygen in the lattice forms oxygen vacancies and promotes Bi 5+ Xiang Bi 3+ The morphological transformation of BiMn 0.001 The composite photocatalyst is BiO 2-x 、Bi 2 O 3 、NaBiO 3 Both photocatalysts have good light absorption properties in a wide spectral range.

[0065] Application Example 1

[0066] Evaluation of the pollutant degradation performance of manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies in LED system: the target pollutant is sulfadimethoxine (SMT), and the experimental conditions are: SMT 0.05mmol / L, photocatalyst 0.2g / L. First, a dark environment adsorption experiment was carried out, and then the LED light source was turned on. At several preset time intervals, sampling and filtration were performed to monitor the changes in pollutant concentration. The concentration of SMT was analyzed by high-performance liquid chromatography, and the detection wavelength was 264nm.

[0067] The results are as follows Figure 4 SMT is almost not photolyzed in a single LED white light system; adding photocatalyst can significantly improve the degradation efficiency of SMT, and the degradation efficiency is closely related to the Mn doping amount. The optimal Mn doping amount is 0.001-0.01 mol, indicating that trace Mn doping can significantly improve the photocatalytic performance, and further increasing the Mn doping amount is not conducive to photocatalysis; the optimal BiMn 0.01 Almost 100% of SMT can be removed within 6 hours; LED wavelength affects the photocatalytic effect, the optimal wavelength is 365nm, and the photocatalytic efficiency decreases with the increase of wavelength, but even at a wavelength as low as 630nm, the degradation efficiency of SMT is still as high as 70% after 6 hours. This shows that the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies disclosed in the present invention can make full use of the full wavelength spectrum and has excellent photocatalytic performance in the LED system, but the Mn doping amount should be carefully controlled to ensure the best photocatalytic performance.

[0068] Application Example 2

[0069] Evaluation of oxygen vacancy-rich manganese-modified bismuth oxide composite photocatalysts in LED / Fe 3+ Synergistic system and LED / Fe 3 + -O-OA synergistic system pollutant degradation performance: The target pollutant is sulfadimethoxine (SMT), and the experimental conditions and detection conditions are the same as those in Application Example 1.

[0070] The results are as follows Figure 5 As shown.3+ It has a certain synergistic effect with LED white light, and Fe 3+ The introduction of LED system can significantly accelerate the photocatalytic removal efficiency of SMT. 3+ The function of Fe is to form a bridge between pollutants and photocatalysts, promoting the preferential adsorption of pollutants and improving the degradation efficiency; further introduction of oxalic acid (OA) 3+ -OA complexation leads to a decrease in adsorption performance, but significantly increases the photocatalytic efficiency. 3+ The molar ratio of -OA is 1:1.5-2, and the pollutants can be completely removed in just 1 hour under the optimal conditions. 3+ Synergistic system and LED / Fe 3+ -OA synergistic system has excellent photocatalytic performance, single Fe 3+ or Fe 3+ -OA introduction can effectively improve BiMn x Activity of composite photocatalysts.

[0071] Application Example 3

[0072] Evaluation of oxygen vacancy-rich manganese-modified bismuth oxide composite photocatalysts in LED / Fe 3+ Synergistic system and LED / Fe 3 + -OA synergistic system degradation performance of pollutants: The target pollutants are tetracycline (TC), ciprofloxacin (CIP), phenol (Phe), bisphenol A (BPA), and the photocatalyst used is BiMn prepared in Example 2 0.001 , the experimental conditions are the same as those in Application Example 1.

[0073] The results show that the best composite photocatalyst BiMn 0.001 With LED white light / Fe 3+ -OA composite system can remove almost 100% of TC, CIP, Phe and BPA within 6 hours. This shows that the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies disclosed in the present invention is effective in LED / Fe 3+ -OA has excellent photocatalytic performance in the synergistic system and can be used for the efficient removal of various organic pollutants.

[0074] It can be seen from the above application examples that the catalyst of the present invention has good application prospects when applied to actual wastewater treatment.

[0075] The above descriptions are only preferred embodiments and application examples of the present invention, and do not limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies, characterized in that: The composite photocatalyst is prepared by a one-step in-situ loading method using sodium bismuthate as a raw material and manganese salt as a modifier. The composite photocatalyst is BiO 2-x , Bi2O3, and NaBiO3.

2. The manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 1, characterized in that: The composite photocatalyst is rich in oxygen vacancies, and the oxygen vacancies can be regulated by adjusting the type and loading amount of the manganese salt.

3. A method for preparing the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to any one of claims 1 to 2, characterized in that: The steps include: (1) after uniformly dispersing a certain amount of sodium bismuthate in water by ultrasonication, adding a certain amount of manganese salt under continuous stirring at room temperature to form a uniform dispersion; (2) adding an alkaline solution to adjust the pH value of the dispersion, reacting at room temperature for 10-30 minutes, centrifuging the resulting mixture, washing with water, and drying at 50-110° C. to obtain a dark brown composite photocatalyst product.

4. The method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 3, characterized in that: The manganese salt described in step (1) is a divalent manganese salt, and the molar ratio of the manganese salt to sodium bismuthate is 0.0001-0.3:

1.

5. The method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 4, characterized in that: The manganese salt is selected from one or more of manganese chloride, manganese sulfate and manganese oxalate.

6. The method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 5, characterized in that: The molar ratio of the manganese salt to sodium bismuthate is 0.001-0.01:

1.

7. The method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 3, characterized in that: The pH value range described in step (2) is 8-11.

8. The method for preparing a manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to claim 7, characterized in that: The pH value range is 9-10.

9. Use of a composite photocatalyst prepared by the preparation method of the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to any one of claims 1 to 2 or the manganese-modified bismuth oxide composite photocatalyst rich in oxygen vacancies according to any one of claims 3 to 8, characterized in that: The composite photocatalyst is used for ultra-low power LED white light / Fe 3+ In the synergistic system, rapid and efficient degradation of organic pollutants in water is achieved. The power of ultra-low power LED white light is as low as 5W, and the wavelength range is 360nm-760nm.

10. The use of the composite photocatalyst according to claim 9, characterized in that: The degraded organic pollutants are antibiotics and / or phenols, the antibiotics are selected from one or more of sulfamethazine SMT, tetracycline TC, and ciprofloxacin CIP, and the phenols are selected from one or more of phenol Phe and bisphenol ABPA.

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