Preparation method and application of bismuth oxybromide / indium oxide heterojunction photocatalytic material

Abstract

The invention belongs to the field of catalytic materials, and particularly relates to a preparation method and application of a bismuth oxybromide / indium oxide heterojunction photocatalytic material. The method specifically comprises the following steps: dispersing indium nitrate pentahydrate and p-dibenzoic acid in dimethylformamide, then carrying out hydrothermal reaction on the obtained mixed solution, collecting the product, washing and drying to obtain an indium oxide precursor; dispersing bismuth nitrate pentahydrate, sodium bromide and indium oxide precursors into deionized water, stirring, drying and collecting a white product; and calcining the obtained white product to obtain the bismuth oxybromide / indium oxide photocatalytic material. The obtained composite photocatalytic material is controllable in morphology, and rapid light degradation of tetracycline can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of catalytic materials, and in particular relates to a preparation method and application of a bismuth oxybromide / indium oxide heterojunction photocatalytic material. Background Art

[0002] Due to the complex composition, biological toxicity, low concentration, chemical stability and environmental persistence of antibiotics, it is difficult to completely remove and mineralize them, resulting in unprecedented difficulties for traditional water treatment technologies including adsorption, flocculation, centrifugation, coagulation, gravity separation and biodegradation. Traditional sewage treatment plant processes have limited effects on the removal of antibiotics, and 30-90% of antibiotics are discharged into the environment in their original form or as metabolites. Therefore, it is imperative to develop technologies that can effectively remove antibiotic pollutants in aquatic environments.

[0003] As an effective wastewater treatment method using solar energy, photocatalytic technology has the advantages of low cost, recyclability, less toxic byproducts, and the use of abundant and renewable solar energy resources, and has broad application prospects. The development of new photocatalyst systems with high activity and high oxidation capacity in response to visible light has become the research direction of environmental photocatalysis.

[0004] Bismuth oxybromide is an indirect bandgap semiconductor with a suitable visible light response bandgap, excellent performance and unique structure. Therefore, it is widely used in many fields, such as supercapacitor electrode materials, sensors and photocatalysis. However, the high recombination rate of photogenerated carriers in the original bismuth oxybromide is still an obstacle to the performance and application of photocatalysts. Further modification is usually required to accelerate the transfer and separation efficiency of photoexcited charges. Heterostructure construction, doping, defect engineering and precious metal deposition are typical modification strategies.

[0005] Indium oxide is a typical n-type semiconductor photocatalyst that has attracted extensive attention due to its unique optical properties, excellent chemical stability, and controllable morphology modification. It is worth noting that compared with two-dimensional nanosheets, nanoflowers, and nanorods, metal-organic framework-derived indium oxide can improve solar energy collection efficiency, reduce photogenerated carrier recombination, and increase specific surface area and reaction sites. Summary of the invention

[0006] The invention provides a method for preparing a bismuth oxybromide / indium oxide heterojunction photocatalytic material, evaluates the performance of the bismuth oxybromide / indium oxide heterojunction photocatalytic material in degrading tetracycline, and applies the material to actual organic wastewater treatment.

[0007] The present invention realizes the efficient preparation of bismuth oxybromide / indium oxide heterojunction photocatalytic materials through key process parameters such as hydrothermal method, calcination method and ultrasonic wave. The obtained bismuth oxybromide / indium oxide heterojunction photocatalytic materials show excellent tetracycline degradation performance, providing a new and efficient solution for related fields.

[0008] In order to achieve the purpose of the present invention, the technical solutions adopted are as follows: A method for preparing a bismuth oxybromide / indium oxide heterojunction photocatalytic material comprises the following steps: (1) Indium nitrate pentahydrate and p-dibenzoic acid are dispersed in a dimethylformamide solvent; the mass ratio of the indium nitrate pentahydrate to p-dibenzoic acid is 1:0.4; as a preferred embodiment, indium nitrate pentahydrate and p-dibenzoic acid are dispersed in dimethylformamide with the assistance of ultrasound, and the ultrasound time is based on the clarification of the solution.

[0009] (2) subjecting the mixed solution obtained in (1) to a hydrothermal reaction, collecting the product, washing and drying it, and obtaining an indium oxide precursor; the temperature of the hydrothermal reaction is 150° C., and the time is 12 h; the temperature of the drying is 80° C., and the time is 12 h.

[0010] (3) dispersing bismuth nitrate pentahydrate, sodium bromide and indium oxide precursor in deionized water, stirring, drying and collecting a white product; the mass ratio of bismuth nitrate pentahydrate, sodium bromide and indium oxide precursor is 1:0.25:1.1; as a preferred embodiment, dispersing bismuth nitrate pentahydrate, sodium bromide and indium oxide precursor in deionized water with the assistance of ultrasound, and the ultrasound time is based on the clarification of the solution.

[0011] (4) calcining the white product obtained in (3) to obtain: Specifically, the calcination is performed by increasing the temperature to 500° C. at 5° C. / min and keeping the temperature at 500° C. for 3 h.

[0012] The invention also provides a bismuth oxybromide / indium oxide heterojunction photocatalytic material prepared by the method.

[0013] The present invention further provides application of the bismuth oxybromide / indium oxide heterojunction photocatalytic material for degrading organic pollution in water.

[0014] In a further embodiment, the bismuth oxybromide / indium oxide heterojunction photocatalytic material is added to water containing organic pollutants, stirred, and reacted under light, wherein the pH of the water is 7±0.2.

[0015] Furthermore, the organic pollutant is tetracycline (TC), the concentration of tetracycline in water is 5 mg / L, and the amount of bismuth oxybromide / indium oxide heterojunction photocatalytic material added to water is 20-40 mg / L.

[0016] The beneficial effects of the present invention are: The indium oxide spinel provided by the present invention is derived from a metal organic framework, has good solar energy collection efficiency, reduces photogenerated carrier recombination, and increases specific surface area and reaction sites; the bismuth oxybromide / indium oxide heterojunction photocatalytic material method provided by the present invention has a simple process and low production cost, is suitable for large-scale production, and has broad economic benefits and application prospects in the field of restoration of water bodies contaminated by difficult-to-degrade antibiotics. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the SEM image of bismuth oxybromide / indium oxide heterojunction photocatalyst.

[0018] a: Scanning electron microscope (SEM) image of bismuth oxybromide / indium oxide heterojunction photocatalyst, resolution 5 μm; b: Scanning electron microscope (SEM) image of bismuth oxybromide / indium oxide heterojunction photocatalyst, resolution 2 μm; c: Scanning electron microscope (SEM) image of bismuth oxybromide / indium oxide heterojunction photocatalyst, resolution 1 μm; d: Scanning electron microscope (SEM) image of bismuth oxybromide / indium oxide heterojunction photocatalyst, resolution 0.5 μm.

[0019] Figure 2 XRD patterns of bismuth oxybromide (BiOBr), indium oxide (In2O3) and bismuth oxybromide / indium oxide heterojunction (In-BOB) photocatalysts.

[0020] Figure 3 The adsorption and degradation curves of tetracycline on bismuth oxybromide (BiOBr), indium oxide (In2O3) and bismuth oxybromide / indium oxide heterojunction (In-BOB) photocatalysts.

[0021] Figure 4 This is the adsorption and degradation curve of bismuth oxybromide / indium oxide heterojunction photocatalyst for different concentrations of tetracycline.

[0022] Figure 5 The adsorption and degradation curves of tetracycline on bismuth oxybromide / indium oxide heterojunction photocatalysts with different dosages.

[0023] Figure 6 This is the adsorption and degradation curve of tetracycline on bismuth oxybromide / indium oxide heterojunction photocatalyst under different coexisting anions.

[0024] Figure 7 This is the adsorption and degradation curve of tetracycline on bismuth oxybromide / indium oxide heterojunction photocatalyst under different water qualities. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all 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.

[0026] Example 1 Preparation of Bismuth Oxybromide / Indium Oxide Heterojunction Photocatalyst (1) 1.2 g of indium nitrate pentahydrate and 0.468 g of p-dibenzoic acid were dispersed in 40 mL of dimethylformamide with the assistance of ultrasound.

[0027] (2) transferring the mixed solution obtained in (1) to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at a temperature of 150° C. for 12 h, collecting the product for washing and drying to obtain an indium oxide precursor; the drying temperature is 80° C. for 12 h; (3) 0.485 g of bismuth nitrate pentahydrate, 0.123 g of sodium bromide and 0.534 g of indium oxide precursor were dispersed in 60 mL of deionized water with the aid of ultrasonic wave, stirred, dried and the white product was collected; (4) The white product obtained in (3) was transferred to a muffle furnace, heated to 500°C at a rate of 5°C / min, and kept at this temperature for 3 h.

[0028] The SEM image of the bismuth oxybromide / indium oxide heterojunction photocatalyst prepared in this example is shown in FIG. Figure 1 As shown, bismuth oxybromide is in the form of irregular flakes, while indium oxide is in the form of tiny spherical particles. The surface of bismuth oxybromide is covered with a large amount of indium oxide, making the composite material porous and fluffy, indicating the successful preparation of bismuth oxybromide / indium oxide heterojunction photocatalyst.

[0029] Example 2 XRD pattern of bismuth oxybromide / indium oxide heterojunction photocatalyst Figure 2The XRD patterns show the chemical composition and crystal structure of bismuth oxybromide, indium oxide and bismuth oxybromide / indium oxide heterojunction photocatalysts. The diffraction peaks at 10.9°, 25.1°, 31.7°, 32.2°, 46.2° and 57.1° are very consistent with the (001), (101), (102), (110), (200) and (212) crystal planes of bismuth oxybromide, indicating the successful preparation of tetragonal bismuth oxybromide. The diffraction peaks at 30.5°, 35.4° and 51.0° are very consistent with the (222), (400) and (440) crystal planes of indium oxide, indicating the successful preparation of cubic indium oxide. The diffraction peaks of both photocatalysts are shown in the bismuth oxybromide / indium oxide heterojunction photocatalyst, which indicates the successful loading of indium oxide. The XRD pattern shows that the bismuth oxybromide / indium oxide heterostructure with high crystallinity was successfully synthesized.

[0030] Example 3 Application of Bismuth Oxybromide / Indium Oxide Heterojunction Photocatalyst to Degradation of Tetracycline The application of different photocatalysts to the degradation of tetracycline includes the following steps: 30 mg of bismuth oxybromide, 30 mg of indium oxide and 30 mg of bismuth oxybromide / indium oxide heterojunction are dispersed in a tetracycline solution (100 mL, 10 mg / L) respectively. Under dark conditions, the mixed solution is stirred for 40 minutes using a magnetic stirrer. After reaching adsorption-desorption equilibrium, a 300W xenon lamp (equipped with a 420nm<λ<780nm filter) is used as a simulated sunlight light source, and samples are taken at preset time points (-40min, -20min, 0min, 20min, 40min, -40min to 0min represents 40 minutes of magnetic stirring, and 0min to 40min represents the reaction time under the xenon lamp), 1 mL of sample is collected through a 0.45µm filter membrane, and the concentration of tetracycline is measured at 357nm using a UV-visible spectrophotometer (Shimadzu, UV-2600).

[0031] Figure 3 The adsorption and degradation curves of tetracycline by bismuth oxybromide, indium oxide and bismuth oxybromide / indium oxide heterojunction photocatalysts. The adsorption capacity of bismuth oxybromide and indium oxide photocatalysts for tetracycline were 17.3% and 11.52% respectively, while the adsorption capacity of bismuth oxybromide / indium oxide heterojunction photocatalyst for tetracycline was significantly improved, reaching 32.6%. At the same time, the degradation rate of tetracycline by indium oxide photocatalyst was only 39.71%, and the degradation rate of bismuth oxybromide was 79.35%. The catalytic effect of bismuth oxybromide / indium oxide heterojunction photocatalyst on the degradation rate of tetracycline was the best, reaching 85.06%.

[0032] Example 4 Application of Bismuth Oxybromide / Indium Oxide Heterojunction Photocatalyst to Degradation of Different Tetracycline Concentrations This example investigates the degradation efficiency of bismuth oxybromide / indium oxide heterojunction photocatalyst for different tetracycline concentrations, and the specific operation is referred to Example 3. This example analyzes the effect of tetracycline concentrations of 5 mg / L to 20 mg / L (specifically 5 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L) on photocatalytic activity.

[0033] The experimental results are as follows Figure 4 As shown in the figure, with the increase of tetracycline concentration, the adsorption performance of bismuth oxybromide / indium oxide heterojunction photocatalyst for tetracycline in the dark reaction and the photocatalytic degradation performance of tetracycline gradually decreased. When the initial mass concentration of tetracycline solution increased from 5 mg / L to 20 mg / L, the removal rate decreased from 86.84% to 61.39%.

[0034] Example 5 Catalytic degradation of tetracycline by different amounts of bismuth oxybromide / indium oxide heterojunction photocatalyst This example investigates the catalytic degradation of tetracycline by different dosages of bismuth oxybromide / indium oxide heterojunction photocatalysts, and the specific operation is referred to Example 3. This example analyzes the effect of catalyst dosages of 20 mg / L to 50 mg / L (specifically 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L) on photocatalytic activity.

[0035] The experimental results are as follows Figure 5 As shown in the figure, increasing the catalyst dosage from 20 mg / L to 30 mg / L and 40 mg / L, the total degradation efficiency increased from 71.31% to 85.06% and 83.56% respectively. The enhancement of active sites leads to increased adsorption of tetracycline molecules and the production of more active oxidizing substances. When the catalyst dosage is further increased to 50 mg / L, the removal rate of tetracycline no longer increases, which may be caused by the excessive catalyst hindering the scattering of visible light.

[0036] Example 6 Catalytic degradation of tetracycline by bismuth oxybromide / indium oxide heterojunction photocatalyst under different coexisting anions This example investigates the catalytic degradation performance of bismuth oxybromide / indium oxide heterojunction photocatalyst on tetracycline under different coexisting anions. The specific operation refers to Example 3 (adding coexisting anions before stirring the mixed solution with a magnetic stirrer). Specifically, the concentrations of carbonate (provided by sodium carbonate), chloride (provided by sodium chloride) and sulfate (provided by sodium sulfate) are all 5 mmol / L.

[0037] The experimental results are as follows Figure 6As shown. All three anions have a certain effect on the degradation efficiency of tetracycline by bismuth oxybromide / indium oxide heterojunction photocatalyst. The tetracycline removal rate decreased from 85.06% in the control to 80.02% (sulfate), 79.62% (chloride) and 75.86% (carbonate). This is because anions may affect the generation and diffusion rate of free radicals on the photocatalyst by interacting with the catalyst surface, thereby affecting the degradation process of tetracycline.

[0038] Example 7 Catalytic degradation of tetracycline by bismuth oxybromide / indium oxide heterojunction photocatalyst in different water qualities In order to further evaluate the practical application prospects of bismuth oxybromide / indium oxide heterojunction photocatalyst for tetracycline degradation, two actual water samples, urban tap water and surface lake water (the pH values ​​of the two water samples tested in the experiment were 6.8-7.2), were selected to evaluate the water quality impact of bismuth oxybromide / indium oxide heterojunction photocatalyst. Specifically, a tetracycline solution with a concentration of 10 mg / L was prepared using tap water and surface river water as the matrix, and the catalyst addition amount was 30 mg / L.

[0039] like Figure 7 As shown in the figure, when the water sample is tap water, the anions and cations in the water participate in the capture of free radicals and holes, which has a certain effect on the degradation rate, which drops to 67.93%. When the water sample is lake water, the dissolved organic matter (DOM) in the water competes with tetracycline for active sites on the photocatalyst, which to some extent hinders the degradation of tetracycline, which drops to 53.96%. The above shows that the bismuth oxybromide / indium oxide heterojunction photocatalyst has good practicality and provides an option for degrading tetracycline in actual water bodies.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bismuth oxybromide / indium oxide heterojunction photocatalytic material, characterized in that: The steps include: (1) dispersing indium nitrate pentahydrate and p-dibenzoic acid in dimethylformamide; (2) subjecting the mixed solution obtained in (1) to a hydrothermal reaction, collecting the product, washing and drying it, and obtaining an indium oxide precursor; the temperature of the hydrothermal reaction is 150° C.; (3) dispersing bismuth nitrate pentahydrate, sodium bromide and indium oxide precursor in deionized water, stirring, drying and collecting a white product; (4) calcining the obtained white product to obtain; the calcination temperature is 500°C.

2. The method for preparing a bismuth oxybromide / indium oxide heterojunction photocatalytic material according to claim 1, characterized in that: In step (1), the mass ratio of indium nitrate pentahydrate to p-dibenzoic acid is 1:0.

4.

3. The preparation method and application of a bismuth oxybromide / indium oxide heterojunction photocatalytic material according to claim 1, characterized in that: In step (2), the hydrothermal reaction time is 12 h.

4. The preparation method and application of a bismuth oxybromide / indium oxide heterojunction photocatalytic material according to claim 1, characterized in that: In step (3), the mass ratio of bismuth nitrate pentahydrate, sodium bromide and indium oxide precursor is 1:0.25:1.

1.

5. The preparation method and application of a bismuth oxybromide / indium oxide heterojunction photocatalytic material according to claim 1, characterized in that: In step (4), the calcination is carried out by heating the temperature to 500°C at 5°C / min and then keeping the temperature for 3 hours.

6. Bismuth oxybromide / indium oxide heterojunction photocatalytic material prepared by the method according to any one of claims 1 to 5.

7. Use of the bismuth oxybromide / indium oxide heterojunction photocatalytic material according to claim 6 in degrading organic pollutants in water.

8. The use according to claim 7, characterized in that: The pH of the water = 7 ± 0.

2.

9. The use according to claim 7, characterized in that: The organic pollutant is tetracycline, the concentration of tetracycline in water is 5 mg / L, and the addition amount of bismuth oxybromide / indium oxide heterojunction photocatalytic material in water is 20-40 mg / L.

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