Preparation method and application of a bismuth vanadate photocatalyst with oxygen vacancies

Abstract

The application relates to a preparation method and application of a bismuth vanadate photocatalyst with oxygen vacancies, and relates to a preparation method and application of a photocatalyst. The application aims to solve the problems of low efficiency of existing bismuth vanadate photocatalytic degradation of sulfamethoxazole and low utilization efficiency of titanium dioxide on sunlight. The application comprises the following steps: I. preparing a mixed solution of NaVO3 and CTAB; II. preparing a bismuth nitrate solution; III. adjusting the pH value to 6.0; IV. hydrothermal reaction; V. washing and drying. The bismuth vanadate photocatalyst with oxygen vacancies is used for degrading antibiotics. The bismuth vanadate photocatalyst with oxygen vacancies prepared by the application is synthesized by a hydrothermal method, the preparation conditions of the catalyst are effectively controlled, a long rod-shaped bismuth vanadate photocatalyst with suitable concentration oxygen vacancies and controllable morphology is obtained, the catalyst is green and environment-friendly, the response to visible light is good, the utilization rate of sunlight is high, the degradation rate of SMX is high, and the best degradation rate can reach 93% within 120 min.

Description

Technical Field

[0001] This invention relates to a method for preparing a photocatalyst and its application. Background Technology

[0002] Antibiotics have been detected in surface water, groundwater, sewage, and drinking water in various regions of the world. Antibiotic pollution has become one of the water pollution problems facing all of humanity, and how to effectively treat antibiotic wastewater has attracted widespread attention from experts and scholars both at home and abroad.

[0003] Sulfamethoxazole (SMX) is one of the most widely used sulfonamide antibiotics in the world, extensively used to treat bacterial infections. However, the widespread use of SMX has led to increasingly serious environmental residue problems. Not only are its detection rates and concentrations among the highest in the environment, but its cumulative levels are also rising. Reports indicate that SMX residues are high in rivers and surface water and can persist in the aquatic environment for extended periods, posing a serious threat to aquatic life. SMX residues have even been detected in drinking water sources, significantly increasing the risk of the spread of drug-resistant bacteria and resistance genes in the environment. According to the International Agency for Research on Cancer (IARC) of the World Health Organization, SMX is listed as a Group 3 carcinogen. The residues of SMX in the aquatic environment pose a significant threat to the health of humans and other animals and plants; therefore, the removal of sulfamethoxazole has become a focal point of concern.

[0004] Currently, titanium dioxide (TiO2) has been well-appointed for treating various organic pollutants in the field of photocatalytic oxidation degradation of antibiotics. However, the wide bandgap of TiO2 (3.2 eV) limits its activation only under ultraviolet (approximately 5% of sunlight) irradiation, thus restricting its solar energy utilization efficiency. Bismuth monoclinic vanadate (m-BiVO4)-based photocatalysts are visible-light-responsive semiconductors with low toxicity and good stability in the visible light range, and their potential in environmental remediation remains to be explored. However, the high recombination and low charge transport characteristics of m-BiVO4 electron-hole pairs reduce its photocatalytic performance. Therefore, improving the photogenerated charge separation efficiency and photocatalytic degradation performance of m-BiVO4 is a research direction and goal. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of low efficiency in the photocatalytic degradation of sulfamethoxazole by bismuth vanadate and low utilization efficiency of sunlight by titanium dioxide, and to provide a method for preparing and applying a bismuth vanadate photocatalyst with oxygen vacancies.

[0006] A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies is specifically carried out according to the following steps:

[0007] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0008] Sodium metavanadate and hexadecyltrimethylammonium bromide were added to water and heated and stirred for a period of time to obtain a mixed solution of NaVO3 and CTAB.

[0009] II. Preparation of bismuth nitrate solution:

[0010] Bi(NO3)3·5H2O was added to nitric acid and stirred for a period of time to obtain a bismuth nitrate solution.

[0011] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for a period of time, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0012] IV. Hydrothermal reaction:

[0013] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0014] V. Washing and drying:

[0015] The reaction product was centrifuged and washed several times, and then dried in a vacuum drying oven to obtain a bismuth vanadate photocatalyst with oxygen vacancies.

[0016] A bismuth vanadate photocatalyst with oxygen vacancies is used to degrade antibiotics.

[0017] This invention successfully prepared an m-BiVO4 photocatalyst with high photogenerated charge separation efficiency and high degradation performance, possessing oxygen vacancies. It can efficiently degrade and mineralize SMX. This photocatalyst can be prepared via a simple hydrothermal method. By controlling the concentration of added hexadecyltrimethylammonium bromide (CTAB), the oxygen vacancy concentration and microstructure of the catalyst can be controlled, thereby optimizing the SMX degradation effect. Calculations show that this catalyst achieves a high SMX degradation rate (93%). This method is simple, time-efficient, yields high output, and is highly reproducible, making it suitable for mass production. It is of great significance for advancing the practical application research of photocatalytic degradation of antibiotics.

[0018] Compared with existing technologies, the advantages of this invention are:

[0019] (1) The bismuth vanadate photocatalyst with oxygen vacancies prepared by the present invention is synthesized by hydrothermal method. By effectively controlling the preparation conditions of the catalyst, a long rod-shaped bismuth vanadate photocatalyst with a suitable concentration of oxygen vacancies and controllable morphology is obtained. The catalyst is green and environmentally friendly, has good response to visible light, and has high utilization rate of sunlight.

[0020] (2) The bismuth vanadate photocatalyst with oxygen vacancies prepared by the present invention can achieve a high degradation rate of SMX, with the best degradation rate reaching 93% within 120 min.

[0021] (3) The preparation method of the present invention is simple, the process is controllable, the cost is low, and it is easy to mass-produce. Attached Figure Description

[0022] Figure 1 Images of the BiVO4 catalysts in Examples 1-6 under XRD characterization;

[0023] Figure 2 The images show the O1s values ​​of the BiVO4 catalysts in Examples 1-6 under XPS characterization.

[0024] Figure 3 The degradation efficiency of BiVO4 catalysts in Examples 1-6 on SMX after 2 hours of light irradiation is shown in the graphs.

[0025] Figure 4 This is a scanning electron microscope image of the BiVO4 catalyst in Example 5;

[0026] Figure 5 This is a scanning electron microscope image of the BiVO4 catalyst in Example 1;

[0027] Figure 6 This is a scanning electron microscope image of the BiVO4 catalyst in Example 2;

[0028] Figure 7 This is a scanning electron microscope image of the BiVO4 catalyst in Example 3;

[0029] Figure 8 This is a scanning electron microscope image of the BiVO4 catalyst in Example 4;

[0030] Figure 9 This is a scanning electron microscope image of the BiVO4 catalyst in Example 6. Detailed Implementation

[0031] Specific Implementation Method 1: This implementation method describes a method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0032] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0033] Sodium metavanadate and hexadecyltrimethylammonium bromide were added to water and heated and stirred for a period of time to obtain a mixed solution of NaVO3 and CTAB.

[0034] II. Preparation of bismuth nitrate solution:

[0035] Bi(NO3)3·5H2O was added to nitric acid and stirred for a period of time to obtain a bismuth nitrate solution.

[0036] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for a period of time, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0037] IV. Hydrothermal reaction:

[0038] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0039] V. Washing and drying:

[0040] The reaction product was centrifuged and washed several times, and then dried in a vacuum drying oven to obtain a bismuth vanadate photocatalyst with oxygen vacancies.

[0041] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the molar ratio of sodium metavanadate to hexadecyltrimethylammonium bromide in step one is (1 mmol–1.5 mmol):(0.2 mmol–1 mmol); the molar ratio of sodium metavanadate to water in step one is (1 mmol–1.5 mmol):(30 mL–50 mL); the heating and stirring temperature in step one is 40°C–50°C, and the heating and stirring time is 20 min–40 min. Other steps are the same as in Specific Implementation Method One.

[0042] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in the following ways: the concentration of nitric acid in step two is 17 mmol / L to 18 mmol / L; the stirring time in step two is 20 min to 40 min; and the concentration of bismuth nitrate solution in step two is 1 mmol to 1.5 mmol. Other steps are the same as in Specific Implementation Method One or Two.

[0043] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the concentration of the sodium hydroxide solution in step three is 10 mol / L; the molar ratio of hexadecyltrimethylammonium bromide in the mixed solution of bismuth nitrate, NaVO3, and CTAB in step three is 1 mmol:(0.2 mmol to 1 mmol); and the stirring time in step three is 20 min to 40 min. Other steps are the same as in Specific Implementation Methods One to Three.

[0044] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the hydrothermal reaction temperature in step four is 105°C, and the hydrothermal reaction time is 20-24 hours. The other steps are the same as in Specific Implementation Methods One to Four.

[0045] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in the following ways: In step five, the centrifugal washing speed is 100 rpm for 10 to 15 minutes each time; in step five, the reaction product is first centrifuged and washed 3 to 5 times with anhydrous ethanol, and then centrifuged and washed 3 to 5 times with deionized water; the vacuum drying temperature in step five is 60°C to 70°C, and the vacuum drying time is 10 to 12 hours. Other steps are the same as in Specific Implementation Methods One to Five.

[0046] Specific Implementation Method Seven: This implementation method is a bismuth vanadate photocatalyst with oxygen vacancies used for the degradation of antibiotics.

[0047] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the antibiotic used is sulfamethoxazole. The other steps are the same as in Specific Implementation Methods One to Seven.

[0048] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that: a method for using a bismuth vanadate photocatalyst with oxygen vacancies to degrade antibiotics is carried out according to the following steps:

[0049] 1. Add the bismuth vanadate photocatalyst with oxygen vacancies to the antibiotic solution and stir for a period of time in the dark;

[0050] 2. The solution is degraded for a period of time under the conditions of irradiation with a 150W xenon lamp, a distance of 10cm from the light source, and a light intensity of 132.5kLux, to obtain a solution after antibiotic removal. Other steps are the same as in specific implementation methods one through eight.

[0051] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in the following ways: the mass ratio of the bismuth vanadate photocatalyst with oxygen vacancies to the volume ratio of the antibiotic solution in step one is 5 mg:100 mL; the stirring time in the dark in step one is 0.5 h to 1 h; the concentration of the antibiotic solution in step one is 5 mg / L; and the degradation time in step two is 100 min to 120 min. The other steps are the same as in Specific Implementation Methods One to Nine.

[0052] The beneficial effects of the present invention are verified using the following embodiments:

[0053] Example 1: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies is carried out according to the following steps:

[0054] I. Preparation of NaVO3 solution:

[0055] Add 0.192 g of sodium metavanadate to 30 mL of water and stir at 45 °C for 30 min to obtain a NaVO3 solution.

[0056] II. Preparation of bismuth nitrate solution:

[0057] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0058] The concentration of nitric acid mentioned in step two is 17.8 mmol;

[0059] 3. Add bismuth nitrate solution to NaVO3 solution, stir for 30 min, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0060] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0061] IV. Hydrothermal reaction:

[0062] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0063] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0064] V. Washing and drying:

[0065] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0066] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0067] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0068] Example 2: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0069] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0070] 0.192 g sodium metavanadate and 0.116 g cetyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB.

[0071] II. Preparation of bismuth nitrate solution:

[0072] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0073] The concentration of nitric acid mentioned in step two is 17.8 mmol / L;

[0074] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0075] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0076] IV. Hydrothermal reaction:

[0077] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0078] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0079] V. Washing and drying:

[0080] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0081] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0082] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0083] Example 3: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0084] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0085] 0.192 g sodium metavanadate and 0.154 g cetyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB.

[0086] II. Preparation of bismuth nitrate solution:

[0087] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0088] The concentration of nitric acid mentioned in step two is 17.8 mmol / L;

[0089] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0090] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0091] IV. Hydrothermal reaction:

[0092] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0093] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0094] V. Washing and drying:

[0095] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0096] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0097] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0098] Example 4: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0099] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0100] 0.192 g sodium metavanadate and 0.193 g hexadecyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB.

[0101] II. Preparation of bismuth nitrate solution:

[0102] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0103] The concentration of nitric acid mentioned in step two is 17.8 mmol / L;

[0104] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0105] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0106] IV. Hydrothermal reaction:

[0107] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0108] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0109] V. Washing and drying:

[0110] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0111] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0112] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0113] Example 5: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0114] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0115] 0.192 g sodium metavanadate and 0.232 g cetyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB.

[0116] II. Preparation of bismuth nitrate solution:

[0117] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0118] The concentration of nitric acid mentioned in step two is 17.8 mmol / L;

[0119] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0120] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0121] IV. Hydrothermal reaction:

[0122] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0123] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0124] V. Washing and drying:

[0125] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0126] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0127] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0128] Example 6: A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, specifically carried out according to the following steps:

[0129] I. Preparation of a mixed solution of NaVO3 and CTAB:

[0130] 0.192 g sodium metavanadate and 0.27 g cetyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB.

[0131] II. Preparation of bismuth nitrate solution:

[0132] Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution.

[0133] The concentration of nitric acid mentioned in step two is 17.8 mmol / L;

[0134] 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0;

[0135] The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L;

[0136] IV. Hydrothermal reaction:

[0137] A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product.

[0138] The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours.

[0139] V. Washing and drying:

[0140] The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies (BiVO4 catalyst).

[0141] In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes.

[0142] The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

[0143] Figure 1 Images of the BiVO4 catalysts in Examples 1-6 under XRD characterization;

[0144] The XRD pattern shows that the synthesized catalyst exhibits diffraction peaks at 2θ of 18.67°, 28.82°, 30.55°, 34.49°, 35.22°, 39.78°, 42.46°, 45.43°, 46.71°, 49.96°, 53.31°, 55.27°, and 59.26°. The diffraction peaks correspond well with the standard card PDF#14-0688, conforming to the crystal structure of BiVO4 monoclinic scheelite. Furthermore, no diffraction peaks are present for other substances or other crystal phases of bismuth vanadate, indicating that the synthesized catalyst contains only bismuth vanadate.

[0145] Figure 2 The images show the O1s values ​​of the BiVO4 catalysts in Examples 1-6 under XPS characterization.

[0146] Figure 2The chemical bond energy and surface chemical state of the BiVO4 photocatalyst are shown. XPS spectra reveal that the asymmetric O1s XPS spectrum can be fitted with three peaks, centered at 532.7, 531.3, and 529.1 eV, corresponding to chemisorbed oxygen (OC), oxygen vacancies (OV), and lattice oxygen (OL), respectively. The intensity of the oxygen vacancy (OV) peak in Examples 1–6 differs significantly, indicating the presence of varying numbers of oxygen vacancies in the samples.

[0147] Application Example 1: A method for using a bismuth vanadate photocatalyst with oxygen vacancies to degrade antibiotics is carried out according to the following steps:

[0148] 1. Take 5 mg of the catalyst prepared in Examples 1 to 6 and add it to six reaction flasks containing 100 mL of 5 mg / L sulfamethoxazole solution (SMX solution). Stir and adsorb for half an hour in the dark.

[0149] 2. Irradiation under a 150W xenon lamp, with the solution surface 10cm away from the light source, the light intensity is 132.5kLux, and the solution is kept stirred during the degradation process;

[0150] 3. Take 2 mL of sample every 20 min into a small syringe, filter through a 0.22 μm filter membrane, and inject into a liquid chromatography vial. Take a total of 7 samples at (0, 20, 40, 60, 80, 100, and 120 min).

[0151] Fourth, using an ultra-high performance liquid chromatograph, a calibration curve was plotted to calculate the antibiotic content.

[0152] Figure 3 The degradation efficiency of BiVO4 catalysts in Examples 1-6 on SMX after 2 hours of light irradiation is shown in the graphs.

[0153] from Figure 3 It can be seen that: after 2 hours of light irradiation, Example 5 showed the best photocatalytic effect on SMX, removing 93% of SMX, while the degradation rates of SMX by Examples 2, 3, 4, 6 and 1 were 63%, 73%, 78%, 14.5% and 51%, respectively.

[0154] Figure 4 This is a scanning electron microscope image of the BiVO4 catalyst in Example 5;

[0155] SEM results showed that with increasing CTAB addition, the morphology of Examples 1-6 changed from aggregated particles to long rod-shaped structures and then to stacked short rod-shaped structures. Example 5, with the best catalytic activity, exhibited a regular long rod-shaped structure.

[0156] Comparative example: Existing methods for preparing bismuth vanadate nanosheets:

[0157] 2.21 g of BiCl3 and 1.05 g of hexadecyltrimethylammonium bromide (CTAB) were dissolved in 60 mL of ethylene glycol and stirred vigorously. Then, 2.80 g of NaVO3 was added to the above system and stirred continuously for 30 min. The mixture was then transferred to a 50 mL polytetrafluoroethylene-lined autoclave, sealed, and heated at 120 °C for 12 h. After the system cooled to room temperature, the resulting product was washed repeatedly with ethanol and deionized water, and then dried in a vacuum oven at 60 °C. Finally, the obtained sample was rapidly calcined at 400 °C for 8 min to obtain bismuth vanadate nanosheets.

[0158] Degradation effect:

[0159] 1. Take 5 mg of bismuth vanadate nanosheets prepared in the control example and add them into a reaction flask containing 100 mL of 5 mg / L sulfamethoxazole solution (SMX solution). Stir and adsorb for half an hour in the dark.

[0160] 2. Irradiation under a 150W xenon lamp, with the solution surface 10cm away from the light source, the light intensity is 132.5kLux, and the solution is kept stirred during the degradation process;

[0161] 3. Take 2 mL of sample every 20 min into a small syringe, filter through a 0.22 μm filter membrane, and inject into a liquid chromatography vial. Take a total of 7 samples at (0, 20, 40, 60, 80, 100, and 120 min).

[0162] Fourth, using an ultra-high performance liquid chromatograph, a calibration curve was plotted to calculate the antibiotic content.

[0163] The results showed that the degradation rate of SMX by the bismuth vanadate nanosheets prepared in the control example was 6.68%.

Claims

1. A method for preparing a bismuth vanadate photocatalyst with oxygen vacancies, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of a mixed solution of NaVO3 and CTAB: 0.192 g sodium metavanadate and 0.232 g cetyltrimethylammonium bromide were added to 30 mL of water and stirred at 45 °C for 30 min to obtain a mixed solution of NaVO3 and CTAB. II. Preparation of bismuth nitrate solution: Add 0.52 g Bi(NO3)3·5H2O to 15 mL of nitric acid and stir for 30 min to obtain a bismuth nitrate solution. The concentration of nitric acid mentioned in step two is 17.8 mmol / L; 3. Add bismuth nitrate solution to the mixed solution of NaVO3 and CTAB, stir for 30 minutes, and then adjust the pH value to 6.0 with sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0; The concentration of the sodium hydroxide solution mentioned in step three is 10 mol / L; IV. Hydrothermal reaction: A mixed solution with a pH of 6.0 was placed in a stainless steel reactor and then placed in an oven for hydrothermal reaction to obtain the reaction product. The hydrothermal reaction in step four is carried out at a temperature of 105°C for 24 hours. V. Washing and drying: The reaction product was washed five times by centrifugation with anhydrous ethanol, then washed five times by centrifugation with deionized water, and then dried in a vacuum drying oven to obtain a yellow bismuth vanadate photocatalyst with oxygen vacancies. In step five, each centrifugal wash is performed at a speed of 100 rpm for 10 minutes. The vacuum drying temperature in step five is 60°C, and the vacuum drying time is 12 hours.

2. The application of a bismuth vanadate photocatalyst with oxygen vacancies prepared by the preparation method according to claim 1, characterized in that... A bismuth vanadate photocatalyst with oxygen vacancies is used to degrade antibiotics.

3. The application of the bismuth vanadate photocatalyst with oxygen vacancies according to claim 2, characterized in that... The antibiotic in question is sulfamethoxazole.

4. The application of the bismuth vanadate photocatalyst with oxygen vacancies according to claim 2, characterized in that... A method for using a bismuth vanadate photocatalyst with oxygen vacancies to degrade antibiotics is carried out according to the following steps:

1. Add the bismuth vanadate photocatalyst with oxygen vacancies to the antibiotic solution and stir for a period of time in the dark; 2. The solution was degraded for a period of time under the conditions of irradiation with a 150W xenon lamp, a distance of 10cm from the light source, and a light intensity of 132.5 kLux, to obtain a solution after the antibiotics were removed.

5. The application of the bismuth vanadate photocatalyst with oxygen vacancies according to claim 4, characterized in that... The mass ratio of the bismuth vanadate photocatalyst with oxygen vacancies to the volume ratio of the antibiotic solution in step one is 5 mg: 100 mL; the stirring time in the dark in step one is 0.5 h to 1 h; the concentration of the antibiotic solution in step one is 5 mg / L; and the degradation time in step two is 100 min to 120 min.

Images