A bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material, a preparation method thereof and application thereof to removal of organic pollutants from wastewater

Abstract

The application discloses a preparation method of a bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material. The method adopts a hydrothermal method, first prepares a bismuth sulfide precursor, and then grows the bismuth sulfide nanorod / bismuth oxybromide composite material through hydrothermal growth after the bismuth sulfide precursor is uniformly stirred with bismuth nitrate pentahydrate and sodium bromide. The composite material has a unique nano structure and good photocatalytic performance by adjusting the mass of the bismuth sulfide precursor in the composite material. When 2 mmol of bismuth oxybromide and 0.05 g of the bismuth sulfide precursor are used to hydrothermally synthesize the bismuth sulfide nanorod / bismuth oxybromide composite material, the composite material has the optimal rhodamine B removal performance, and the removal rate can reach 99.2% after 30 min of dark adsorption and 15 min of photocatalytic reaction; meanwhile, the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material also has good removal effects on tetracycline, methyl orange and other organic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of composite photocatalytic material preparation technology, specifically relating to a bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material, its preparation method, and its application in the photocatalytic removal of organic pollutants (such as Rhodamine B, tetracycline, methyl orange, etc.) from wastewater. Background Technology

[0002] The rapid development of modern industry has led to a continuous increase in the discharge of organic pollutant wastewater, posing a significant challenge to modern water environment management. To meet the enormous demand for organic wastewater treatment, there is an urgent need to develop a green, efficient, and economical treatment method. Currently, organic pollutant wastewater treatment mainly employs methods such as adsorption, membrane treatment, microbial treatment, chemical oxidation, photo / electric and photoelectrocatalytic oxidation technologies, and catalytic oxidation technologies. Among these, photocatalytic oxidation technology is a highly promising wastewater treatment method. It utilizes abundant solar energy to completely decompose organic pollutants into small molecule products such as carbon dioxide and water, offering a green and clean advantage in energy utilization compared to other methods. Therefore, research progress in photocatalytic oxidation technology has broad application value in wastewater treatment, and the development of high-performance photocatalysts is particularly crucial in this process.

[0003] Bismuth oxybromide (BiOBr) is an easily synthesized photocatalyst that exhibits visible light responsiveness, stable physicochemical properties, and a unique layered structure. The [Bi₂O₂] in its layered structure... 2+ With [Br] -The internal electric field between the plates can promote and accelerate the transfer of photogenerated carriers to the BiOBr surface. However, BiOBr still faces some unresolved issues in practical photocatalytic applications, such as small specific surface area, low visible light absorption efficiency, rapid recombination of photogenerated carriers, and insufficient performance in removing organic pollutants from water. Research has found that by combining other semiconductor photocatalytic materials to form heterojunctions with matched band structures, the separation efficiency of photogenerated carriers can be significantly improved, thereby effectively enhancing the photocatalytic activity of the composite photocatalyst. Existing research shows that semiconductor materials such as bismuth vanadate, bismuth sulfide, titanium dioxide, bismuth tungstate, graphitic carbon nitride, bismuth oxychloride, and molybdenum sulfide can all form effective heterostructures with BiOBr and improve its photocatalytic performance. Among these semiconductor materials, bismuth sulfide (Bi2S3) has attracted widespread attention due to its wide visible light response range, abundant raw materials, high biocompatibility, and low toxicity. Due to the band structure matching of Bi2S3 / BiOBr and the fact that Bi2S3 can absorb approximately 45% of the solar spectrum, Bi2S3 / BiOBr photocatalysts exhibit better light collection and carrier transfer efficiencies. Researchers have also reported that Bi2S3 / BiOBr-based photocatalysts show significantly improved photocatalytic activity in the decomposition of phenols and other substances. However, current synthetic routes for Bi2S3 / BiOBr-based composite photocatalysts are constrained by the complex preparation process of Bi2S3. Generally, high-performance Bi2S3 / BiOBr composite photocatalysts require multi-step reaction procedures, such as secondary hydrothermal reactions, prolonged high-temperature reactions, water baths, and reflux treatments. Furthermore, certain Bi2S3 nanomaterials with specific morphologies and sizes require the synthesis and preparation of complex precursors, often involving organic solvents such as toluene, acetone, oleic acid, and octadecene, as well as a vacuum or nitrogen atmosphere.

[0004] To date, Bi₂S₃ nanomaterials have shown great promise for applications in various fields such as photocatalysis, electrochemical hydrogen storage, hydrogen sensing, and biomolecular detection due to their unique properties. Therefore, the synthesis of bismuth sulfide nanocrystals with controllable size, shape, and hierarchical structure has attracted widespread research interest. Meanwhile, the preparation of Bi₂S₃ nanorods remains a crucial research area in materials science. Methods for synthesizing Bi₂S₃ nanorods with lengths in the 100 nm range are still relatively few. Most existing methods involve complex preparation procedures and extreme experimental conditions, and heavily rely on the use of organic solvents, leading to environmental pollution and other environmental problems.

[0005] This invention provides a simple preparation technique for synthesizing bismuth sulfide nanorods, and a one-step hydrothermal reaction can synthesize bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst. This technique has advantages such as high yield, no need for large amounts of organic solvents in the synthesis route, simple synthesis equipment, and convenient preparation process. In the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst developed by this invention, the bismuth sulfide nanorods and bismuth oxybromide possess suitable nanoscale sizes and good interfacial structures, while the composite photocatalyst exhibits excellent photocatalytic activity. Therefore, it demonstrates excellent performance in removing organic pollutants from wastewater, which is of great significance for improving the practical application of wastewater organic pollutant treatment efficiency. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a bismuth sulfide nanorod and a bismuth sulfide nanorod / bismuth oxybromine composite photocatalytic material, which solves the problems of complex preparation process of existing bismuth sulfide nanorods, heavy reliance on the use of organic solvents, and insufficient performance of single-phase bismuth oxybromine in photocatalytic removal of organic pollutants in wastewater.

[0007] The present invention also provides a method for preparing the above-mentioned bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material, and its application in the photocatalytic removal of organic pollutants in wastewater (such as rhodamine B, tetracycline, methyl orange, etc.).

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material includes the following steps: First, a bismuth sulfide precursor is synthesized. Then, the raw material for synthesizing bismuth oxybromide is mixed with the bismuth sulfide precursor and subjected to hydrothermal treatment. Finally, the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material is prepared in one step.

[0010] a) Preparation of bismuth sulfide precursor

[0011] Disperse trithiocyanic acid and sodium hydroxide in deionized water to prepare a sodium trithiocyanate solution; dissolve bismuth nitrate pentahydrate and mannitol in deionized water (dissolution can be promoted by stirring for 0.5-2 h) to prepare a bismuth salt solution; then add the sodium trithiocyanate solution to the bismuth salt solution, stir for 4-24 h, separate the solid and liquid, wash and dry to obtain the bismuth sulfide precursor;

[0012] b) Preparation of bismuth sulfide nanorods / bismuth oxybromide composite photocatalysts

[0013] Bismuth nitrate pentahydrate and mannitol were dissolved in deionized water to prepare a bismuth salt solution (dissolution can be promoted by stirring for 10-30 min); then a certain amount of bismuth sulfide precursor was added and mixed (stirred for 5-10 min), followed by the addition of sodium bromide and mixing (stirred for 10-30 min). After hydrothermal reaction at 150-200℃ for 5-12 h, the solid and liquid were separated, washed, and dried to obtain a low aspect ratio bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material, denoted as XBSB (X=0.01, 0.05, 0.15, 0.3, where X represents the mass of bismuth sulfide precursor added to the composite material).

[0014] Specifically, in step a), the molar ratio of trithiocyanate to bismuth nitrate pentahydrate is 1-3:1. Further, in step a), the molar ratio of trithiocyanate to sodium hydroxide is 1:3-4.

[0015] More preferably, in step a), when trithiocyanate and sodium hydroxide are dispersed in deionized water, the process can be carried out in a water bath at a temperature of 60-100°C for 1-3 hours.

[0016] Furthermore, in steps a) and b), the molar ratio of bismuth nitrate pentahydrate to mannitol is 1:2-6.

[0017] Specifically, in step b), the mass of bismuth sulfide precursor added per 2 mmol of bismuth nitrate pentahydrate is 0.01-0.5 g. Further, in step b), the molar ratio of bismuth nitrate pentahydrate to sodium bromide is 1:1-1.2.

[0018] This invention provides a bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material prepared by the above preparation method.

[0019] This invention also provides the application of the above-mentioned bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material in the removal of organic pollutants in wastewater, especially in the photocatalytic removal of Rhodamine B, tetracycline, or methyl orange.

[0020] This invention employs a hydrothermal method to first prepare a bismuth sulfide precursor, which is then hydrothermally grown with bismuth nitrate pentahydrate and sodium bromide to form a bismuth sulfide nanorod / bismuth oxybromide composite material. By controlling the mass of the bismuth sulfide precursor in the composite material, a composite material with a unique nanostructure and excellent photocatalytic performance was obtained. When 2 mmol of bismuth oxybromide and 0.05 g of bismuth sulfide precursor were hydrothermally synthesized together to form the bismuth sulfide nanorod / bismuth oxybromide composite material, the composite material exhibited optimal Rhodamine B removal performance, achieving a removal rate of 99.2% after 30 minutes of dark adsorption followed by 15 minutes of photocatalytic reaction. Simultaneously, this bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material also showed good removal effects on organic pollutants such as tetracycline and methyl orange.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Using the preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material described in this invention, based on scanning electron microscope images ( Figure 1 As can be seen from the results, the length of the prepared bismuth sulfide nanorods is around 100 nanometers, and the preparation process uses simple and readily available materials as raw materials, with a simple synthesis route that does not require the use of organic solvents, making it easy to achieve large-scale production. This invention provides a new method and new ideas for constructing novel bismuth sulfide nanorods with optimized structures, as well as composite photocatalytic materials for the efficient photocatalytic removal of organic pollutants (such as Rhodamine B, tetracycline, or methyl orange) from wastewater.

[0023] The method for removing Rhodamine B and tetracycline using the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material of the present invention can be referred to the following steps.

[0024] Performance testing of photocatalytic removal of Rhodamine B: The degradation system used a 300 W xenon lamp as the light source, with 50 mg of bismuth sulfide nanorods / bismuth oxybromide composite photocatalyst, a Rhodamine B solution concentration of 20 mg / L, and a solution volume of 100 mL in a 100 mL beaker. First, a dark reaction was carried out for 30 min, followed by a 5 mL sample. Then, under light irradiation, a 5 mL sample was taken every 5 min. The samples were centrifuged at 13000 rpm for 5 min to remove residual photocatalyst. The absorbance was measured using a UV-Vis spectrophotometer to determine the residual concentration of the Rhodamine B solution. Based on the initial concentration of the Rhodamine B solution, the concentration change was calculated, and the removal rate was then determined. The experimental results showed that after 15 min of photocatalytic reaction, a maximum removal rate of 99.2% could be achieved.

[0025] Photocatalytic removal performance test of tetracycline: The degradation system used a 300 W xenon lamp as the light source, with 50 mg of bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst, a tetracycline solution concentration of 20 mg / L, and a solution volume of 100 mL in a 100 mL beaker. After illumination, 5 mL samples were taken every 5 min. The samples were centrifuged at 13000 rpm for 5 min to remove residual photocatalyst. The absorbance was then measured using a UV-Vis spectrophotometer to determine the concentration change of the tetracycline solution, and the removal rate was calculated. The experimental results showed that after 60 min of photocatalytic reaction, the maximum removal rate reached 89.2%.

[0026] Performance test of photocatalytic removal of methyl orange: A 300 W xenon lamp was used as the light source in the degradation system. The amount of bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst was 50 mg, the concentration of methyl orange solution was 20 mg / L, and the solution volume was 100 mL. A 100 mL beaker was used. After the light was turned on, a 5 mL sample was taken every 30 min. The samples were centrifuged at 13000 rpm for 5 min to remove residual photocatalyst. The absorbance was then measured using a UV-Vis spectrophotometer to obtain the concentration change of the methyl orange solution, and the removal rate was calculated. Attached Figure Description

[0027] Figure 1 The image shown is a scanning electron microscope image of the bismuth sulfide nanorods obtained in Comparative Example 1, with the upper right inset image being a magnified view of the nanorods.

[0028] Figure 2 The image shown is a scanning electron microscope image of bismuth oxybromide obtained in Comparative Example 2, with the upper right inset image being a magnified view of it.

[0029] Figure 3 This is a scanning electron microscope image of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material obtained in Example 1.

[0030] Figure 4 The XRD patterns are of the bismuth sulfide nanorods obtained in Comparative Example 1, the bismuth oxybromine obtained in Comparative Example 2, and the bismuth sulfide nanorod / bismuth oxybromine composite photocatalysts obtained in Example 3. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] In the following examples, all raw materials used are common commercially available products that can be purchased directly or can be prepared using conventional methods in the art.

[0033] Example 1

[0034] The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material in this embodiment includes the following steps:

[0035] 1) Preparation of bismuth sulfide precursor

[0036] A sodium trithiocyanate solution was prepared by dispersing 10 mmol of trithiocyanate and 30 mmol of sodium hydroxide in 50 mL of deionized water under a water bath at 80 °C for 2 h of stirring. A bismuth salt solution was prepared by dissolving 10 mmol of bismuth nitrate pentahydrate and 50 mmol of mannitol in deionized water under a stirring for 2 h of stirring. The sodium trithiocyanate solution was then added dropwise to the bismuth salt solution, and the mixture was stirred for 24 h. Solid particles were obtained by vacuum filtration and washed three times alternately with deionized water and ethanol. The particles were then dried in an oven at 60 °C for 24 h to obtain the bismuth sulfide precursor.

[0037] 2) Preparation of bismuth sulfide nanorods / bismuth oxybromide composite materials

[0038] A bismuth salt solution was prepared by dissolving 2 mmol of bismuth nitrate pentahydrate and 5 mmol of mannitol in 50 mL of deionized water after stirring for 30 min. Then, 0.01 g of bismuth sulfide precursor was added, and the mixture was stirred for 10 min. Next, 2 mmol of sodium bromide was added, and the mixture was stirred for another 30 min. The solution was poured into a 100 mL reactor and subjected to hydrothermal reaction at 160 °C for 12 h. The resulting solid particles were obtained by vacuum filtration and washed three times alternately with deionized water and ethanol. The particles were then dried in an oven at 60 °C for 24 h to obtain the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material, denoted as 0.01 BSB.

[0039] Figure 3 Scanning electron microscope (SEM) images of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material obtained in Example 1 are provided. The images show that the bismuth sulfide nanorods and bismuth oxybromide are stacked together to form the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material, and the two phases exhibit good interfacial bonding.

[0040] Photocatalytic degradation test: The 0.01 BSB sample prepared in this example was used as a photocatalyst to test the Rhodamine B removal performance. Specifically:

[0041] The degradation system used a 300W xenon lamp as the light source, with 50 mg of photocatalyst and 100 mL of Rhodamine B solution at a concentration of 20 mg / L. The beaker used had a capacity of 100 mL. First, after a 30-minute dark reaction, 5 mL of the suspension sample was uniformly extracted. Then, the xenon lamp was turned on to initiate the photocatalytic reaction, with 5 mL of the suspension sample taken every 5 minutes. The samples were centrifuged at 13000 rpm for 5 minutes to remove the 0.01 BSB composite photocatalyst particles from the suspension. The absorbance of the resulting liquid was then measured using a UV-Vis spectrophotometer to determine the residual concentration of the Rhodamine B solution. The removal rate was then calculated based on the initial concentration of the Rhodamine B solution.

[0042] The 0.01 BSB sample prepared in this embodiment was used as a photocatalyst to test its tetracycline removal performance. Specifically:

[0043] Photocatalytic removal performance test of tetracycline: The degradation system used a 300 W xenon lamp as the light source, with a photocatalyst dosage of 50 mg, a tetracycline solution concentration of 20 mg / L, and a solution volume of 100 mL. The beaker used had a capacity of 100 mL. After the light was turned on, a 5 mL sample was taken every 5 minutes. The samples were centrifuged at 13000 rpm for 5 minutes to remove residual photocatalyst. The absorbance was then measured using a UV-Vis spectrophotometer to obtain the concentration change of the tetracycline solution, and the removal rate was calculated.

[0044] The removal performance of the 0.01 g BSA sample prepared in Example 1 for Rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, the sample (0.01 g BSA) with 0.01 g of bismuth sulfide precursor in the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material achieved a Rhodamine B removal rate of 87.6% after 30 min of dark adsorption and 15 min of photocatalytic reaction, and an oxybromide tetracycline removal rate of 88.0% after 60 min of photocatalytic reaction.

[0045] Example 2

[0046] The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material in this embodiment includes the following steps:

[0047] 1) Same steps as in Example 1;

[0048] 2) Dissolve 2 mmol of bismuth nitrate pentahydrate and 5 mmol of mannitol in 50 mL of deionized water to prepare a bismuth salt solution. Then add 0.05 g of bismuth sulfide precursor, stir for 10 min, then add 2 mmol of sodium bromide, stir for 30 min, pour into a 100 mL reactor, and react hydrothermally at 160 °C for 12 h. After filtration under reduced pressure, obtain solid particles, which are washed three times alternately with deionized water and ethanol. Dry in an oven at 60 °C for 24 h to obtain the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material, denoted as 0.05 BSB.

[0049] The 0.05 BSB sample prepared in this embodiment was subjected to tests for the removal performance of rhodamine B and tetracycline, following the same steps as in Example 1.

[0050] The removal performance of the 0.05 BSB sample obtained in Example 2 for Rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, the sample (0.05 BSB) with an added mass of 0.05 g of bismuth sulfide precursor in the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material achieved a 99.2% removal rate for Rhodamine B after 30 min of dark adsorption and 15 min of photocatalytic reaction, and an 89.2% removal rate for tetracycline after 60 min of photocatalytic reaction.

[0051] The methyl orange removal performance of the 0.05 BSB sample prepared in this embodiment was tested. Photocatalytic removal performance of methyl orange: A 300 W xenon lamp was used as the light source for the degradation system. The amount of photocatalyst was 50 mg, the concentration of the methyl orange solution was 20 mg / L, and the solution volume was 100 mL. The beaker used had a capacity of 100 mL. After the light was turned on, 5 mL samples were taken every 30 min. The samples were centrifuged at 13000 rpm for 5 min to remove residual photocatalyst from the solution. The absorbance was then measured using a UV-Vis spectrophotometer to obtain the concentration change of the methyl orange solution, and the removal rate was calculated.

[0052] The removal performance of methyl orange by the 0.05 BSB sample prepared in Example 2 is shown in Table 1. As can be seen from Table 1, the sample (0.05 BSB) with an added mass of 0.05 g of bismuth sulfide precursor in the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material achieved a methyl orange removal rate of 24.9% after 150 min of photocatalytic reaction.

[0053] Example 3

[0054] The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material in this embodiment includes the following steps:

[0055] 1) Same steps as in Example 1;

[0056] 2) Dissolve 2 mmol of bismuth nitrate pentahydrate and 5 mmol of mannitol in 50 mL of deionized water to prepare a bismuth salt solution. Then add 0.15 g of bismuth sulfide precursor, stir for 10 min, then add 2 mmol of sodium bromide, stir for 30 min, pour into a 100 mL reactor, and react hydrothermally at 160 °C for 12 h. After filtration under reduced pressure, obtain solid particles, which are washed three times alternately with deionized water and ethanol. Dry in an oven at 60 °C for 24 h to obtain the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material, denoted as 0.15BSB.

[0057] The 0.15 BSB sample prepared in this embodiment was subjected to tests for the removal performance of rhodamine B and tetracycline, following the same steps as in Example 1.

[0058] The removal performance of the 0.15 BSB sample obtained in Example 3 for Rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, the sample (0.15 BSB) with an added mass of 0.15 g of bismuth sulfide precursor in the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material achieved a Rhodamine B removal rate of 87.4% after 30 min of dark adsorption and 15 min of photocatalytic reaction, and an oxybromide tetracycline removal rate of 86.8% after 60 min of photocatalytic reaction.

[0059] Example 4

[0060] The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material in this embodiment includes the following steps:

[0061] 1) Same steps as in Example 1;

[0062] 2) Dissolve 2 mmol of bismuth nitrate pentahydrate and 5 mmol of mannitol in 50 mL of deionized water to prepare a bismuth salt solution. Then add 0.3 g of bismuth sulfide precursor, stir for 10 min, then add 2 mmol of sodium bromide, stir for 30 min, pour into a 100 mL reactor, and react hydrothermally at 160 °C for 12 h. After filtration under reduced pressure, solid particles are obtained, and washed three times alternately with deionized water and ethanol. Dry in an oven at 60 °C for 24 h to obtain the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material, denoted as 0.3BSB.

[0063] The 0.3 BSB sample prepared in this embodiment was subjected to tests for the removal performance of rhodamine B and tetracycline, following the same steps as in Example 1.

[0064] The removal performance of the 0.3 BSB sample obtained in Example 4 for rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, the sample (0.3 BSB) with an added mass of 0.3 g of bismuth sulfide precursor in the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material achieved a rhodamine B removal rate of 57.0% after 30 min of dark adsorption and 15 min of photocatalytic reaction, and a tetracycline removal rate of 63.7% after 60 min of photocatalytic reaction.

[0065] Comparative Example 1

[0066] For comparison, single-phase bismuth sulfide nanorods were prepared, including the following steps:

[0067] 1) Preparation of bismuth sulfide precursor

[0068] A sodium trithiocyanate solution was prepared by dispersing 10 mmol of trithiocyanate and 30 mmol of sodium hydroxide in 50 mL of deionized water under a water bath at 80 °C for 2 h of stirring. A bismuth salt solution was prepared by dissolving 10 mmol of bismuth nitrate pentahydrate and 50 mmol of mannitol in 50 mL of deionized water under a stirring for 2 h of stirring. The sodium trithiocyanate solution was then added dropwise to the bismuth salt solution, and the mixture was stirred for 24 h. Solid particles were obtained by vacuum filtration and washed three times alternately with deionized water and ethanol. The particles were then dried in an oven at 60 °C for 24 h to obtain the bismuth sulfide precursor.

[0069] 2) The bismuth sulfide precursor obtained in step 1) was dispersed in 50 mL of deionized water, stirred for 10 min, and then poured into a 100 mL reactor. After hydrothermal reaction at 160 °C for 12 h, the solid particles were obtained by vacuum filtration and washed three times alternately with deionized water and ethanol. After drying in an oven at 60 °C for 24 h, bismuth sulfide nanorods were obtained, denoted as Bi2S3.

[0070] Figure 1 Scanning electron microscope (SEM) images of the bismuth sulfide nanorods obtained in Comparative Example 1 are shown, with a magnified view of the image in the upper right corner. The images show that the synthesized bismuth sulfide nanorods have a nanorod-like microstructure and a length of approximately 100 nm.

[0071] The Bi2S3 sample prepared in Comparative Example 1 was subjected to performance tests for removing Rhodamine B and tetracycline, using the same testing method as in Example 1.

[0072] The removal performance of Bi₂S₃ samples obtained in Comparative Example 1 for Rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, after 30 min of dark adsorption and 15 min of visible light irradiation, bismuth sulfide nanorods (Bi₂S₃) showed almost no photocatalytic reaction, with a removal rate of only 10.0% for Rhodamine B through adsorption alone. After 60 min of visible light irradiation, the removal rate for tetracycline was 26.2%.

[0073] Comparative Example 2

[0074] For comparison, single-phase bismuth oxybromide without composite bismuth sulfide nanorods was prepared, including the following steps:

[0075] 2 mmol of bismuth nitrate pentahydrate and 5 mmol of mannitol were dissolved in 50 mL of deionized water to prepare a bismuth salt solution. Then, 2 mmol of sodium bromide was added, and the solution was stirred for 30 min. The mixture was then poured into a 100 mL reactor and subjected to hydrothermal reaction at 160 °C for 12 h. The resulting solid particles were obtained by vacuum filtration and washed three times alternately with deionized water and ethanol. After drying in an oven at 60 °C for 24 h, single-phase bismuth oxybromide, denoted as BiOBr, was obtained.

[0076] Figure 2 Scanning electron microscope (SEM) images of bismuth oxybromide obtained in Comparative Example 2 are shown, with a magnified view of the image in the upper right corner. The images show that the synthesized bismuth oxybromide has a nanosheet structure, with the nanosheet width approximately 100 nm.

[0077] Figure 4 The XRD patterns of the bismuth sulfide nanorods obtained in Comparative Example 1, the bismuth oxybromide obtained in Comparative Example 2, and the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst obtained in Example 3 are shown. As can be seen from the figures, the synthesized bismuth sulfide nanorods, bismuth oxybromide, and bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst all possess good crystal structures, and the XRD patterns show their respective typical crystal plane diffraction peaks. Therefore, the successful synthesis of bismuth sulfide nanorods, bismuth oxybromide, and bismuth sulfide nanorod / bismuth oxybromide composite photocatalysts can be demonstrated.

[0078] The BiOBr sample prepared in this comparative example was subjected to performance tests for removing rhodamine B and tetracycline, using the same testing method as in Example 1.

[0079] The removal performance of BiOBr samples obtained in Comparative Example 2 for Rhodamine B and tetracycline is shown in Table 1. As can be seen from Table 1, after 30 min of dark adsorption and 15 min of visible light irradiation photocatalytic reaction, the removal rate of Rhodamine B by BiOBr was only 23.3%, while after 60 min of photocatalytic reaction, the removal rate of tetracycline was 79.3%.

[0080] Table 1 shows the degradation rates of Rhodamine B, tetracycline, and methyl orange by different catalytic materials.

[0081]

[0082] The preparation and removal experiments of Rhodamine B and tetracycline in the above examples and comparative examples demonstrate that the XBSB composite photocatalytic material of this invention exhibits superior removal performance of Rhodamine B compared to pure bismuth sulfide nanorods and single-phase bismuth oxybromide. Furthermore, the mass of the added bismuth sulfide precursor affects the removal efficiency of the XBSB composite photocatalytic material for Rhodamine B and tetracycline. Specifically, when the mass ratio of the added bismuth sulfide precursor is 0.05 g, the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material shows the optimal removal effect of Rhodamine B and tetracycline. After 30 min of dark adsorption and 15 min of photocatalytic reaction, the removal rate of Rhodamine B reaches 99.2%, and after 60 min of photocatalytic reaction, the removal rate of tetracycline is 89.2%.

Claims

1. A method for preparing a bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material, characterized in that, Comprising the following steps: a) preparing a bismuth sulfide precursor Trithiocyanic acid and sodium hydroxide are dispersed in deionized water to prepare a sodium trithiocyanate solution; bismuth nitrate pentahydrate and mannitol are dissolved in deionized water to prepare a bismuth salt solution; then the sodium trithiocyanate solution is added to the bismuth salt solution, stirred for 4-24 h, and then solid-liquid separation, washing and drying are performed to obtain the bismuth sulfide precursor; b) preparing a bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material Bismuth nitrate pentahydrate and mannitol are dissolved in deionized water to prepare a bismuth salt solution; then a certain amount of bismuth sulfide precursor is added, and sodium bromide is added, and then hydrothermal reaction is performed at 150-200℃ for 5-12 h, and then solid-liquid separation, washing and drying are performed to obtain the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material. In step b), the mass of the bismuth sulfide precursor added per 2 mmol of bismuth nitrate pentahydrate is 0.01-0.15 g.

2. The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalyst material according to claim 1, characterized in that, In step a), the molar ratio of trithiocyanic acid to bismuth nitrate pentahydrate is 1-3:

1.

3. The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material according to claim 1, characterized in that, In step a), the molar ratio of trithiocyanic acid to sodium hydroxide is 1:3-4.

4. The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material according to claim 1, characterized in that, In step a), when trithiocyanic acid and sodium hydroxide are dispersed in deionized water, the dispersion is performed in a water bath, and the temperature of the water bath is 60-100℃, and the water bath time is 1-3 h.

5. The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material according to claim 1, characterized in that, In steps a) and b), the molar ratio of bismuth nitrate pentahydrate to mannitol is 1:2-6.

6. The preparation method of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material according to claim 1, characterized in that, In step b), the molar ratio of bismuth nitrate pentahydrate to sodium bromide is 1:1-1.

2.

7. The bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material prepared by the preparation method of any one of claims 1 to 6.

8. The use of the bismuth sulfide nanorod / bismuth oxybromide composite photocatalytic material of claim 7 in removing organic pollutants in wastewater.

9. The use of the Bi2S3 / BiOBr composite photocatalytic material according to claim 8 for removing organic pollutants in wastewater, characterized in that, The organic pollutants are rhodamine B, tetracycline or methyl orange.

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