A bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material of a complex bismuth type, a preparation method thereof and application thereof in removing tetracycline in a water body

Abstract

The application discloses a complex bismuth type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material and a preparation method and application thereof in removing tetracycline in water bodies. 12 O 17 Cl2) is in a nanosheet structure, and the complex bismuth type bismuth oxychloride is attached on bismuth tungstate (Bi2WO6). The heterojunction material composed of bismuth tungstate and the complex bismuth type bismuth oxychloride has good stability, and the recovery mode is simple and the reusability is high. Through mixing the complex bismuth type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material with water bodies containing tetracycline and performing a photocatalytic reaction under visible light irradiation, efficient degradation of tetracycline in the water bodies can be realized.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation treatment of environmental pollutants, specifically relating to a bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material, its preparation method, and its application in removing tetracycline from water. Background Technology

[0002] Tetracycline (TC) is an environmental pollutant frequently detected in various water sources, even drinking water. This is caused by the overuse of pharmaceuticals and personal care products, as well as the abuse of antibiotics. Due to the proliferation of antibiotics, the rapid increase in antibiotic-resistant bacteria and antibiotic resistance genes has become another major environmental pollution problem affecting human health. Among the many available antibiotics, TC is the second most commonly used antibiotic in the world, widely used for the prevention and control of various human and animal diseases. Furthermore, due to TC's high stability and poor biodegradability, some conventional treatment processes cannot eliminate it. Therefore, there is an urgent need to find an effective method to remove TC from aqueous solutions before it is discharged into the environment.

[0003] Photocatalysis, electrocatalysis, and thermocatalysis have been widely used to address environmental pollution problems. However, it is well known that electrocatalysis has issues with energy consumption and the safety of thermocatalysis. Given these factors, photocatalysis technology is more energy-efficient, highly effective, and safe. In recent years, photocatalysis technology has seen increasingly widespread application. Currently, significant progress has been made in the development of highly efficient photocatalysts. They are being applied to the degradation of environmental pollutants, the artificial synthesis of clean energy, and photoelectrochemical conversion. Among the various photocatalysts used to remove recalcitrant pollutants from the environment, semiconductor photocatalysis features high oxidation intensity, complete mineralization of pollutants, and direct utilization of sunlight.

[0004] Bi₂WO₆ is a simple and novel n-type narrow bandgap semiconductor photocatalyst material with a calcite-like layered structure. Its crystal structure consists of [WO₄] 2- and [Bi2O2] 2+ The structure consists of an orthorhombic crystal phase. Furthermore, Bi₂WO₆ possesses high visible light utilization efficiency, a stable crystal structure, and high quantum and electron transport efficiency, making it a research hotspot in the field of semiconductor photocatalyst materials. Unfortunately, despite these inherent properties, it still suffers from drawbacks such as low photogenerated electron-hole pair separation efficiency and small specific surface area. Therefore, it is urgent to investigate how to improve the photocatalytic performance of Bi₂WO₆. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material with high processing efficiency, wide application range, strong reusability, simple operation and no secondary pollution, and a method for removing tetracycline from water using the same material.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing a bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material includes the following steps:

[0008] (1) Preparation of bismuth oxychloride complex:

[0009] A mixed aqueous solution of ammonium chloride and sodium hydroxide was prepared and added dropwise to an ethylene glycol solution of bismuth nitrate pentahydrate. A hydrothermal reaction was then carried out. After the reaction was completed, the solution was cooled, washed, and dried to obtain bismuth oxychloride.

[0010] (2) Preparation of bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst:

[0011] Bismuth oxychloride was added to a bismuth nitrate solution and stirred. Then, sodium tungstate solution was added dropwise and stirred to obtain a suspension. A hydrothermal reaction was then carried out. After the reaction was completed, the mixture was cooled, washed, and dried to obtain a bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material.

[0012] Preferably, in step (1), the ratio of ammonium chloride, sodium hydroxide, and water is 3 mmol: 10 mmol: 30 ml;

[0013] Preferably, the ratio of bismuth nitrate pentahydrate to ethylene glycol is 1 mmol: 5 ml;

[0014] Preferably, the molar ratio of bismuth nitrate pentahydrate to ammonium chloride is 1:3.

[0015] Preferably, in step (1), the hydrothermal reaction conditions are: reaction at 150-170℃ for 11-13 hours;

[0016] Preferably, the washing process involves alternating between deionized water and anhydrous ethanol for 3 to 4 washes.

[0017] Preferably, the drying temperature is 80-90℃ and the drying time is 12-18h.

[0018] Preferably, in step (2), the ratio of bismuth oxychloride to bismuth nitrate is (0.031–0.156 g): 2 mmol;

[0019] Preferably, the ratio of bismuth nitrate to glacial acetic acid is 2 mmol: 10 mL;

[0020] Preferably, the ratio of sodium tungstate to water is 1 mmol: 50 mL;

[0021] Preferably, the molar ratio of bismuth nitrate to sodium tungstate is 2:1.

[0022] Preferably, in step (2), the hydrothermal reaction conditions are 170–190°C for 23–24 hours:

[0023] Preferably, the stirring time is 30-50 minutes;

[0024] Preferably, the drying temperature is 60–80°C and the drying time is 12–18 hours.

[0025] Preferably, the hydrothermal reaction further includes the following treatment: washing and drying the product obtained after the hydrothermal reaction; washing is performed by alternating washing with deionized water and anhydrous ethanol 3 to 4 times; the amount of bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material added is 0.2 g per liter of water containing tetracycline; the concentration of tetracycline in the water containing tetracycline is 20 to 25 mg / L.

[0026] The present invention also provides a bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material prepared by the above preparation method, wherein the mass ratio of bismuth-type bismuth oxychloride to bismuth tungstate is (1-5):20.

[0027] Preferably, bismuth oxychloride with a nanosheet structure is attached to bismuth tungstate.

[0028] This invention also provides the application of the above-mentioned bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst in the removal of tetracycline from water, characterized by comprising the following steps:

[0029] Bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst was added to water containing tetracycline. After stirring in the dark until adsorption-desorption equilibrium was reached, the photocatalytic reaction was carried out under visible light while stirring (stirring in the dark was to distinguish the photocatalytic effect; in practical applications, adsorption and photocatalytic reactions can also be carried out simultaneously).

[0030] Preferably, the mass concentration ratio of the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst to tetracycline is 10:(1-1.25);

[0031] Preferably, the photocatalytic reaction is carried out with stirring at 880 r / min, and the photocatalytic reaction time is 0 to 80 min.

[0032] Preferably, the photocatalytic reaction is carried out under visible light with a wavelength of 380–780 nm.

[0033] The principle of the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material prepared in this invention for removing tetracycline from water is shown in formulas (1) to (7). Specifically, the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material generates photogenerated holes and photogenerated electrons under visible light excitation. Then, through the oxidizing properties of the photogenerated holes and the reducing properties of the photogenerated electrons, they react with oxygen and water to generate superoxide radicals and hydroxyl radicals with stronger oxidizing and reducing properties. These active substances are then used to attack tetracycline in the water, promoting tetracycline mineralization and generating carbon dioxide and water, thereby achieving efficient removal of tetracycline from water by photocatalytic technology.

[0034] (1)Bi 12 O 17 Cl2 + hv → e - CB (Bi 12 O 17 Cl2)+h + VB (Bi 12 O 17 Cl2)

[0035] (2)Bi2WO6+hv→e - CB (Bi2WO6)+h + VB (Bi2WO6)

[0036] (3)e - CB (Bi2WO6)+h + VB (Bi 12 O 17 Cl2) → Complex

[0037] (4)e - CB (Bi 12 O 17 Cl2) + O2 → O2 - (Bi 12 O 17 Cl2)

[0038] (5)h + VB (Bi₂WO₆) + H₂O → ·OH(Bi₂WO₆) + H₂O +

[0039] (6)h + VB (Bi₂WO₆) + OH⁻ → ·OH(Bi₂WO₆)

[0040] (7)h + +·O2- (Bi 12 O 17 Cl2) + ·OH(Bi2WO6) + TC → Degradation products

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] 1. This invention achieves highly efficient degradation of tetracycline in water by mixing a bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material with water containing tetracycline under visible light irradiation. This is a novel advanced oxidation technology. Compared with traditional technologies, the photocatalytic degradation technology used in this invention is green and environmentally friendly. It utilizes solar energy as a reaction condition, is simple to operate, has a wide range of applications, and the photocatalytic products do not cause secondary pollution to the environment. The catalytic process has low energy consumption, and the photocatalytic material is non-toxic, stable, and can be reused repeatedly, improving the efficiency of resource reuse. It has high application and commercial value.

[0043] 2. The heterojunction photocatalytic material used in this invention includes bismuth-containing bismuth oxychloride (Bi). 12 O 17 Cl2 and bismuth tungstate (Bi2WO6), a bibismuth-type bismuth oxychloride, are attached to bismuth tungstate. Using bismuth tungstate as the main material, due to its relatively positive valence band position, the resulting photogenerated holes possess strong oxidizing capabilities. Some can directly oxidize and degrade organic pollutants, while others can react with water to generate hydroxyl radicals with even stronger oxidizing power. These hydroxyl radicals, along with the photogenerated holes, also degrade organic pollutants in the water. (The last sentence appears to be incomplete and possibly refers to a different topic.) 12 O 17 Cl2 is used as a modifying material because of its narrow band gap, resulting in a wide visible light absorption range. Due to its negative conduction band position, the photogenerated electrons have strong reducing power. Some of these photogenerated electrons participate in the degradation of organic pollutants in water, while others react with oxygen in the water to generate superoxide radicals, which also participate in the degradation of tetracycline in the water. The combination of these two forms a Z-shaped heterojunction. Compared with traditional heterojunctions, in the photocatalytic process of the Z-shaped heterojunction, under photoexcitation, Bi... 12 O 17 Electron-hole pairs at the valence band positions of Cl2 and Bi2WO6 separate, and the resulting photogenerated electrons transfer to Bi2WO6, respectively. 12 O 17 Electrons from the conduction band of Cl2 and Bi2WO6 are transferred to Bi2WO6 under the influence of an electric potential. 12 O 17 At the valence band of Cl2, photogenerated electrons recombine with photogenerated holes in the valence band, thereby reducing the amount of Bi. 12 O17 The recombination of electrons and holes on Cl2 and Bi2WO6 enhances the photocatalytic performance of the composite material; superoxide radicals generated on the conduction band and hydroxyl radicals generated on the valence band react with pollutants in the water, thereby achieving the purpose of degrading pollutants from the water; through Bi 12 O 17 The interaction between Cl2 and Bi2WO6 can significantly improve the visible light absorption range of bismuth tungstate, thereby enhancing the utilization rate of sunlight by bismuth tungstate. Therefore, the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material of this invention is a semiconductor photocatalyst material with a wide visible light absorption range, simple operation, excellent photocatalytic performance, and no secondary pollution. It can achieve efficient degradation of tetracycline under visible light and has good application prospects.

[0044] 3. In this invention, the practical value is evaluated by assessing the reusability of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst. By continuously treating tetracycline-contaminated water five times under visible light irradiation, the catalytic activity of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst remained essentially unchanged and at a high level, improving the material's reusability. The material recovery method is also quite convenient; most of the material can be recovered simply by centrifugation, and the material loss is negligible. Therefore, it can be seen that the heterojunction material composed of bismuth tungstate and bismuth-containing bismuth oxychloride in this invention has excellent stability, a simple recovery method, and a high reusability rate, making it a semiconductor photocatalyst material with high commercial value.

[0045] 4. In the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst used in this invention, both bismuth tungstate and bismuth-containing bismuth oxychloride are bismuth-based semiconductors. Bismuth is known as a "green element," and my country has the world's largest reserves, accounting for 70% of the world's total reserves. Compared to traditional photocatalysts, the precursors used in this invention are widely available and inexpensive, making rational use of my country's existing resources to address the pollution problems my country faces. Therefore, the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst of this invention will not pollute the environment, and the raw materials are inexpensive and widely available, making it a green and environmentally friendly semiconductor photocatalyst.

[0046] 5. This invention uses bismuth tungstate as the main material and bismuth oxychloride as the support material. A simple hydrothermal method can be used to prepare a bismuth oxychloride / bismuth tungstate heterojunction photocatalyst with high catalytic performance and stability. Compared with other preparation methods, this invention has advantages such as simple operation, high crystallinity, controllable morphology, controllable conditions, low raw material cost, and simple operation, making it suitable for large-scale production and use, and possessing high application value. Attached Figure Description

[0047] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention, wherein:

[0048] Figure 1 The bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalysts (A1, A2, A3) and bismuth-type bismuth oxychloride (Bi) prepared in Examples 1-3 of this invention are examples of bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalysts. 12 O 17 XRD patterns of Cl2 and bismuth tungstate (Bi2WO6).

[0049] Figure 2 The bismuth tungstate (Bi2WO6) prepared in this invention ( Figure 2 a) Bismuth oxychloride (Bi) 12 O 17 Cl2)( Figure 2 b) and the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 ( Figure 2 c) SEM image.

[0050] Figure 3 The bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalysts in Examples 1-3 of this invention (A1, A2, A3) and the bismuth-containing bismuth oxychloride (Bi 12 O 17 Degradation effects of Cl2 and bismuth tungstate (Bi2WO6) on tetracycline under different photocatalytic treatment time conditions.

[0051] Figure 4 The image shows the degradation effect of tetracycline on the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) in Example 2 of this invention under different ion coexistence conditions.

[0052] Figure 5 The graph shows the degradation effect of tetracycline on the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) in different water source environments in Example 2 of this invention. Detailed Implementation

[0053] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0054] All materials and instruments used in the following examples are commercially available, and the raw materials are of analytical grade. Unless otherwise specified, the data obtained in the following examples are the average values ​​of three or more repeated experiments.

[0055] Example 1

[0056] In this embodiment, the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst (A1) is prepared by the following method, including the following steps:

[0057] (1) Dissolve 2 mmol of bismuth nitrate pentahydrate in 10 mL of ethylene glycol solution and stir magnetically for 30 minutes to obtain a bismuth nitrate solution; then dissolve 6 mmol of ammonium chloride and 20 mmol of sodium hydroxide in 60 mL of deionized water and stir magnetically for 30 minutes to obtain a mixed solution of ammonium chloride and sodium hydroxide. Add 60 mL of the mixed solution of ammonium chloride and sodium hydroxide dropwise to the bismuth nitrate solution to obtain a mixed suspension. Transfer the mixed suspension to a 100 mL stainless steel reactor and place it in an oven to react at 160 °C for 12 h. After the reaction, allow the stainless steel reactor to cool naturally to room temperature, remove the reactants from the polytetrafluoroethylene liner, wash them three times alternately with deionized water and anhydrous ethanol, and place the resulting solid in an oven to dry at 80 °C for 12 h to obtain bismuth oxychloride (Bi). 12 O 17 Cl2).

[0058] (2) Dissolve 2 mmol of bismuth nitrate pentahydrate in 10 mL of glacial acetic acid solution to obtain a bismuth nitrate solution. Add 0.03 g of the prepared bismuth oxychloride (Bi2) 12 O 17 Cl2) was added to the bismuth nitrate solution prepared above, and after magnetic stirring for 30 min, bismuth nitrate and bismuth oxychloride (Bi) were obtained. 12 O 17 A mixture of bismuth nitrate and bismuth oxychloride (Cl2) was prepared. 1 mmol of sodium tungstate dihydrate was dissolved in 50 mL of deionized water to obtain a sodium tungstate solution. This sodium tungstate solution was then added dropwise to a mixture of bismuth nitrate and bismuth oxychloride (Bi2). 12 O 17The mixture of Cl2 and bismuth oxychloride was magnetically stirred for 2 hours to obtain a mixed suspension. The mixed suspension was transferred to a 100 mL stainless steel reactor and placed in an oven at 180°C for 24 hours. After the reaction, the stainless steel reactor was naturally cooled to room temperature. The solid material inside the polytetrafluoroethylene liner was removed and washed three times alternately with deionized water and anhydrous ethanol. The resulting solid was then placed in an oven and dried at 80°C for 18 hours to obtain the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst (A1). In this embodiment, the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst (A1) includes bismuth-containing bismuth oxychloride and bismuth tungstate. The bismuth-containing bismuth oxychloride is attached to bismuth tungstate to form a heterojunction material. The bismuth-containing bismuth oxychloride is Bi... 12 O 17 Cl2.

[0059] In this embodiment, the mass ratio of bismuth oxychloride to bismuth tungstate in the bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A1) is 1:20.

[0060] Example 2

[0061] In this embodiment, the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) used is basically the same as the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A1) in Example 1. The only difference is that the amount of bismuth-type bismuth oxychloride in step (2) is 0.094g, and the mass ratio of bismuth-type bismuth oxychloride to bismuth tungstate in the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) is 3:20.

[0062] Example 3

[0063] In this embodiment, the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A3) used is basically the same as the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A1), the only difference being that: the amount of bismuth-type bismuth oxychloride in step (2) is 0.156g, and the mass ratio of bismuth-type bismuth oxychloride to bismuth tungstate in the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A3) is 1:4.

[0064] The preparation method of bismuth tungstate (Bi2WO6) monomer material includes the following steps:

[0065] Simultaneously, 2 mmol of bismuth nitrate pentahydrate and 1 mmol of sodium tungstate dihydrate were dissolved in 10 mL of glacial acetic acid solution and 50 mL of deionized water, respectively. After magnetic stirring for 30 min, bismuth nitrate solution and sodium tungstate solution were obtained. The sodium tungstate solution was then added dropwise to the bismuth nitrate solution, and the mixture was magnetically stirred for 2 h to obtain a mixed suspension. The mixed suspension was transferred to a 100 mL stainless steel reactor and placed in an oven for reaction at 180 °C for 24 h. After the reaction was completed, the stainless steel reactor was allowed to cool naturally to room temperature. The solid material inside the polytetrafluoroethylene liner was removed and washed three times alternately with deionized water and anhydrous ethanol. The resulting solid was then placed in an oven and dried at 80 °C for 5 h to obtain bismuth tungstate (Bi2WO6) monomer material.

[0066] Bismuth oxychloride Bi 12 O 17 The preparation method of Cl2 monomer material includes the following steps:

[0067] 2 mmol of bismuth nitrate pentahydrate was dissolved in 10 mL of ethylene glycol solution and magnetically stirred for 30 min to obtain a mixed solution of bismuth nitrate. Then, 6 mmol of ammonium chloride and 20 mmol of sodium hydroxide were dissolved in 60 mL of deionized water and magnetically stirred for 30 min to obtain a mixed solution of ammonium chloride and sodium hydroxide. 60 mL of the ammonium chloride and sodium hydroxide mixed solution was added dropwise to the bismuth nitrate mixed solution to obtain a mixed suspension. The mixed suspension was then transferred to a 100 mL stainless steel reactor and placed in an oven at 160 °C for 12 h. After the reaction, the stainless steel reactor was allowed to cool naturally to room temperature. The reactants inside the polytetrafluoroethylene liner were removed and washed three times alternately with deionized water and anhydrous ethanol. The resulting solid was then placed in an oven and dried at 80 °C for 12 h to obtain bismuth oxychloride (Bi). 12 O 17 Cl2).

[0068] application:

[0069] (1) A method for removing tetracycline from water using a bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material, comprising the following steps:

[0070] Weigh out bismuth tungstate monomer material (Bi2WO6) and bismuth oxychloride monomer material (Bi2WO6). 12 O 17Cl2) and 10 mg each of bismuth oxychloride / bismuth tungstate heterojunction photocatalysts (A1, A2, A3) were added to 50 mL and 20 mg / L tetracycline solutions, respectively. The solutions were magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the photocatalyst surface. The photocatalytic reaction was then carried out under visible light with a wavelength of 380–780 nm for 80 min, with the photocatalytic reaction being carried out at a magnetic stirring speed of 800 r / min to complete the degradation of tetracycline in the water.

[0071] Blank group: Take 50 mL of 20 mg / L tetracycline solution, without adding any catalyst, and treat it under the same conditions as a control.

[0072] Figure 1 The bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalysts (A1, A2, A3) and bismuth-type bismuth oxychloride (Bi) prepared in Examples 1-3 of this invention are examples of bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalysts. 12 O 17 XRD patterns of bismuth tungstate (Bi2WO6) and bismuth tungstate (Cl2). The figures show that in Bi... 12 O 17 After Cl2 recombines onto Bi2WO6, the peak position of Bi2WO6 shifts slightly, and, with the addition of Bi... 12 O 17 As the Cl2 doping ratio increases, the crystallinity of Bi2WO6 also changes, indicating that Bi... 12 O 17 Cl2 and Bi2WO6 combine well together.

[0073] Figure 2 The bismuth tungstate (Bi2WO6) and bismuth oxychloride (Bi2WO6) prepared in this invention 12 O 17 SEM images of the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 (Cl2). In the figures, (a), (b), and (c) show Bi2WO6 microspheres, Bi... 12 O 17 Cl2 nanosheets and a bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst (A2). As can be seen from the figure, Bi2WO6 microspheres, with the addition of Bi... 12 O 17 After Cl2 doping, the particles recombine into a blocky structure of stacked sheets, which makes it easier for electrons to transfer between the two substances.

[0074] Figure 3 The bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalysts (A1, A2, A3) prepared in Examples 1-3, and the bismuth-containing bismuth oxychloride (Bi 12O 17 The efficiency of tetracycline degradation in water by Cl2 and bismuth tungstate (Bi2WO6) was illustrated. During the photocatalytic reaction, a sample was taken every 20 minutes, and the concentration change was measured using a UV-Vis spectrophotometer to obtain the degradation efficiency of different materials for tetracycline. After the reaction, solid-liquid separation was performed to complete the degradation of tetracycline. From... Figure 3 It can be seen that the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material of the present invention has a good degradation effect on tetracycline. When the mass ratio of bismuth-containing bismuth oxychloride to bismuth tungstate in Example 2 reaches 3:20, the degradation effect is the best. If the content of bismuth-containing bismuth oxychloride is further increased, the adsorption effect of the composite material will increase, but the overall photocatalytic degradation effect will decrease.

[0075] (2) Taking Example 2 as an example, the degradation efficiency of tetracycline in water by the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material in the presence of different coexisting ions was investigated, including the following steps:

[0076] Five portions (10 mg each) of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 were weighed and added to 50 mL and 20 mg / L tetracycline solutions, respectively. Simultaneously, coexisting ions Na2CO3, NaNO3, NaCl, and Na2SO4 were added to four of the tetracycline solutions, while no coexisting ions were added to the third solution. The mixture was magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material. Then, a photocatalytic reaction was carried out under visible light (380-780 nm) for 80 min, with the magnetic stirring speed at 880 r / min, to complete the degradation of tetracycline in the water.

[0077] During the photocatalytic reaction, a sample was taken every 20 minutes. The samples were centrifuged to achieve solid-liquid separation, and the supernatant was collected. The concentration change was measured using a UV-Vis spectrophotometer to obtain the degradation efficiency of tetracycline by the bismuth oxychloride / bismuth tungstate heterojunction photocatalyst under different coexisting ions. The results are as follows: Figure 4 As shown.

[0078] Figure 4 This image shows the degradation effect of tetracycline on the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) in Example 2 of this invention under different coexisting ions. Figure 4 It can be seen that NaCl and Na2SO4 have a strong inhibitory effect on the photocatalytic effect of the bismuth-containing bismuth oxychloride / bismuth tungstate material. This is because Cl... - and SO4 2-It competes with tetracycline for active sites on the catalyst surface, thus reducing the photocatalytic effect; CO3 2- and NO3 - The addition of [a specific ingredient] enhances the adsorption capacity of the bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material surface, with little impact on the overall treatment effect. Even in the presence of coexisting ions such as NaCl, Na₂CO₃, NaNO₃, and Na₂SO₄, the bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material still exhibits extremely high catalytic efficacy against tetracycline in water, demonstrating the wide applicability of this material.

[0079] (3) Taking Example 2 as an example, the degradation efficiency of tetracycline by the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst in different water bodies was investigated:

[0080] Group 1: 10 mg of the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 was added to 50 mL of 20 mg / L ultrapure water containing tetracycline. The mixture was magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the bismuth-type bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material. Then, a photocatalytic reaction was carried out under visible light with a wavelength of 380-780 nm for 80 min. The photocatalytic reaction was carried out at a magnetic stirring speed of 880 r / min to complete the degradation treatment of tetracycline in the water.

[0081] Group 2: 10 mg of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 was added to 50 mL of lake water containing tetracycline at a concentration of 20 mg / L. The mixture was magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material. Then, a photocatalytic reaction was carried out under visible light with a wavelength of 380-780 nm for 80 min. The photocatalytic reaction was carried out at a magnetic stirring speed of 880 r / min to complete the degradation treatment of tetracycline in the water.

[0082] Group 3: 10 mg of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 was added to 50 mL of tap water containing tetracycline at a concentration of 20 mg / L. The mixture was magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material. Then, a photocatalytic reaction was carried out under visible light with a wavelength of 380-780 nm for 80 min. The photocatalytic reaction was carried out at a magnetic stirring speed of 880 r / min to complete the degradation treatment of tetracycline in the water.

[0083] Group 4: 10 mg of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 was added to 50 mL of rainwater containing tetracycline at a concentration of 20 mg / L. The mixture was magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material. Then, a photocatalytic reaction was carried out under visible light with a wavelength of 380-780 nm for 80 min. The photocatalytic reaction was carried out at a magnetic stirring speed of 880 r / min to complete the degradation treatment of tetracycline in the water.

[0084] Figure 5 This figure shows the degradation effect of the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) in Example 2 of this invention on tetracycline under different water source environments, including ultrapure water, lake water, tap water, and rainwater. In the figure, the vertical axis represents the ratio of the concentration of tetracycline after degradation to its initial concentration at a certain moment. As can be seen from the figure, the removal rates of tetracycline by the bismuth-containing bismuth oxychloride / bismuth tungstate heterojunction photocatalyst material (A2) prepared in Example 2 of this invention for ultrapure water, lake water, tap water, and rainwater are 76.8%, 82.4%, 75.4%, and 64.4%, respectively. The decrease in the degradation rate of the material in rainwater may be due to the presence of Cl in the rainwater. - The overall degradation level resulting from the capture of free radicals indicates that the bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst of this invention exhibits highly efficient photocatalytic performance for tetracycline in different water source environments, and can effectively degrade tetracycline in different water environments. This also shows that the bismuth-based bismuth oxychloride / bismuth tungstate heterojunction photocatalyst of this invention can be widely used to treat tetracycline in different water source environments, and has good application prospects and practical applicability in the field of photocatalysis.

[0085] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0086] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for preparing a bismuth-rich bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material, characterized in that, The method comprises the following steps: (1) preparing a bismuth complex type bismuth oxychloride: A mixed aqueous solution of ammonium chloride and sodium hydroxide is prepared, and a bismuth nitrate pentahydrate ethylene glycol solution is added dropwise, followed by a hydrothermal reaction. After the reaction is completed, the product is cooled, washed, and dried to obtain the bismuth complex type bismuth oxychloride; (2) preparing a bismuth complex type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material: The bismuth complex type bismuth oxychloride is added to a bismuth nitrate solution and stirred, and a sodium tungstate solution is added dropwise and stirred to obtain a suspension, followed by a hydrothermal reaction. After the reaction is completed, the product is cooled, washed, and dried to obtain the bismuth complex type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material; The bismuth complex type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material uses bismuth tungstate as a main material and the bismuth complex type bismuth oxychloride as a modification material. The bismuth complex type bismuth oxychloride is attached to the bismuth tungstate and forms a Z-type heterojunction with the bismuth tungstate; In step (2), the ratio of the bismuth complex type bismuth oxychloride to the bismuth nitrate is (0.031-0.156 g): 2 mmol; In step (2), the hydrothermal reaction conditions are 170-190 ℃ for 23-24 h.

2. The preparation method of a bismuthyl bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material according to claim 1, characterized in that, In step (1), the ratio of the ammonium chloride to the sodium hydroxide and water is 3 mmol: 10 mmol: 30 mL; The ratio of the bismuth nitrate pentahydrate to the ethylene glycol is 1 mmol: 5 mL, and the molar ratio of the bismuth nitrate pentahydrate to the ammonium chloride is 1:

3.

3. The method of claim 1, wherein the method is characterized by: In step (1), the hydrothermal reaction conditions are 150-170 ℃ for 11-13 h. The drying temperature is 80-90 ℃, and the drying time is 12-18 h.

4. The method of claim 1, wherein the method is characterized by: In step (2), the ratio of the bismuth nitrate to glacial acetic acid in the bismuth nitrate solution is 2 mmol: 10 mL; The ratio of the sodium tungstate to water in the sodium tungstate solution is 1 mmol: 50 mL; The molar ratio of the bismuth nitrate to the sodium tungstate is 2:

1.

5. The method of claim 1, wherein the method is characterized by: In step (2), the drying temperature is 60-80 ℃, and the drying time is 12-18 h.

6. The bismuthyl-type BiOCl / Bi2WO6 heterojunction photocatalytic material prepared by the preparation method of claim 1, characterized in that, The mass ratio of the bismuth complex type bismuth oxychloride to the bismuth tungstate is (1-5):

20.

7. The Bi2O heterojunction photocatalytic material of claim 6, wherein the Bi2O is BiOCl and the Bi2O is Bi2O3. The bismuth complex type bismuth oxychloride in a nanosheet structure is attached to the bismuth tungstate.

8. The use of a complex bismuth type BiOCl / Bi2WO6 heterojunction photocatalytic material according to claim 6 for removing tetracycline in water bodies, characterized in that, The method comprises the following steps: The bismuth complex type bismuth oxychloride / bismuth tungstate heterojunction photocatalytic material is added to a water body containing tetracycline, and the mixture is stirred in the dark until adsorption-desorption equilibrium is reached. Then, the photocatalytic reaction is carried out under visible light while stirring.

9. Use according to claim 8, characterized in that, The photocatalytic reaction is carried out under stirring at 880 r / min, and the photocatalytic reaction time is 0-80 min and not 0.

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