A method for preparing bismuth vanadate with sodium dodecyl sulfate as an auxiliary and the bismuth vanadate and applications thereof

Abstract

The application provides a kind of bismuth vanadate prepared by using sodium dodecyl sulfate auxiliary and method and application, according to (1-6) :(3-8) Mole ratio, bismuth nitrate pentahydrate and ammonium metavanadate are dissolved in ultrapure water, to obtain mixed solution a, then sodium dodecyl sulfate is added and uniformly mixed, to obtain mixed solution b;The pH of mixed solution b is adjusted to 2-10, to obtain precursor solution, the precursor solution is hydrothermally treated at 60-100 DEG C, to obtain reaction liquid;The product is washed and dried after cooling to room temperature, to obtain bismuth vanadate.The BiVO4 photocatalytic material prepared by low-temperature water bath method has controllable structure and shows good visible light photocatalytic degradation performance.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, and relates to a method and application of bismuth vanadate prepared with the assistance of sodium dodecyl sulfate. Background Technology

[0002] Since the beginning of the 21st century, global industrial development has been rapid, but this has been accompanied by massive energy consumption and environmental pollution, particularly the increasingly prominent issues of water resources and the greenhouse effect. In 1972, Fujishima et al. first proposed the use of titanium dioxide (TiO2) for photocatalytic water splitting to produce hydrogen, a novel and environmentally friendly approach with significant implications for wastewater treatment and energy regeneration. As a type of advanced oxidation method, photocatalytic oxidation offers advantages such as low cost, high efficiency, and zero pollution, demonstrating promising application prospects in water pollution treatment.

[0003] Bismuth vanadate (BiVO4) is a visible-light-responsive semiconductor photocatalyst capable of degrading recalcitrant organic matter in wastewater, thereby purifying the water. The photocatalytic activity of BiVO4 is primarily influenced by its band structure, crystal phase, size, specific surface area, and morphology. BiVO4 is a novel n-type semiconductor, widely used due to its broad spectral response range, strong catalytic activity, high stability, and low cost. It effectively degrades organic matter and decomposes water under visible light; however, its narrow bandgap results in a high carrier recombination probability, thus affecting its photocatalytic performance.

[0004] It has been reported that surfactants can not only regulate the morphology and particle size of BiVO4, but also adjust the position of its band structure, thereby improving its photocatalytic activity. Zhang et al. prepared BiVO4 photocatalysts assisted by hexadecyltrimethylammonium bromide (HTAB), polyvinyl alcohol (PVA), and polyvinylpyrrolidone (PVP) via a hydrothermal method, but to date, no reports have been made on the precise control of the morphology and structure of BiVO4. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method and application for the preparation of bismuth vanadate using sodium dodecyl sulfate as an aid. The method is highly efficient, and the BiVO4 photocatalytic material prepared by the low-temperature water bath method has a controllable structure and exhibits good visible light photocatalytic degradation performance.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing bismuth vanadate using sodium dodecyl sulfate as an aid includes the following steps:

[0008] S1, according to the molar ratio of (1-6):(3-8), bismuth nitrate pentahydrate and ammonium metavanadate are dissolved in ultrapure water to obtain mixture a, and then sodium dodecyl sulfate is added and mixed evenly to obtain mixture b;

[0009] S2, adjust the pH of the mixture b to 2-10 to obtain the precursor solution, and perform hydrothermal treatment on the precursor solution at 60-100℃ to obtain the reaction solution;

[0010] S3. Cool the reaction solution to room temperature, wash the product and dry it to obtain bismuth vanadate.

[0011] Preferably, in S1, mixture a is obtained according to the following process:

[0012] Dissolve 1-6 mmol of bismuth nitrate pentahydrate in 10-100 mL of ultrapure water to obtain a bismuth nitrate pentahydrate solution;

[0013] Dissolve 3-8 mmol of ammonium metavanadate in 50-100 mL of ultrapure water to obtain an ammonium metavanadate solution.

[0014] The bismuth nitrate pentahydrate solution and ammonium metavanadate solution were mixed evenly to obtain mixture a.

[0015] Furthermore, the volume ratio of the bismuth nitrate pentahydrate solution to the ammonium metavanadate solution is (10-100):(50-100).

[0016] Preferably, the molar ratio of sodium dodecyl sulfate and bismuth nitrate pentahydrate in S1 is (0.15-0.6):(1-6).

[0017] Preferably, in S2, ammonia water with a mass percentage of 25% is used to adjust the pH of the mixture b to 2-10, and then the mixture is stirred for 20-40 minutes to obtain the precursor solution.

[0018] Preferably, the precursor solution described in S2 is subjected to hydrothermal treatment at 60-100°C for 4-16 hours to obtain the reaction solution.

[0019] Preferably, after cooling the reaction solution to room temperature in step S3, it is washed 3-5 times sequentially with ultrapure water and anhydrous ethanol while being filtered, and then dried.

[0020] Preferably, the drying described in S3 is vacuum drying, carried out at 30-60°C for 5-12 hours to obtain bismuth vanadate.

[0021] Preferably, in step S3, the washed product is dried and then ground into powder to obtain bismuth vanadate.

[0022] A bismuth vanadate obtained by the method described in any one of the above-mentioned methods for preparing bismuth vanadate using sodium dodecyl sulfate.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] This invention discloses a method for preparing bismuth vanadate using sodium dodecyl sulfate (SDS) with the assistance of a low-temperature water bath method. The reaction conditions are mild, easy to implement, and the process is easily controlled. By controlling the reaction temperature, reaction time, and pH of the precursor solution, the structure can be controlled, yielding plate-like BiVO4 that exhibits good visible light photocatalytic degradation performance. The surfactant SDS effectively controls the problem of excessively large BiVO4 powder particle size and small specific surface area, which leads to excessively rapid photogenerated electron-hole recombination and low carrier transport efficiency. In the absence of a surfactant, BiVO4… 3+ and VO3 - BiVO4 can diffuse and nucleate in solution, indicating that it can be rapidly formed under water bath heating. The particles are relatively large and irregular in shape. SDS is an anionic surfactant that selectively adsorbs on the core plane and can be used to prepare nanoparticles of specific shapes. SDS can be adsorbed on the (010) crystal plane of the BiVO4 core and affect its growth. Therefore, due to the inhibition of SDS, the formed nanomaterials will grow along the (121) crystal plane, resulting in crystal plane compression and the formation of a sheet-like stacked structure of BiVO4, which greatly improves the photocatalytic degradation performance. Attached Figure Description

[0025] Figure 1 The image shows the XRD pattern of BiVO4 (SDS / BiVO4) prepared with SDS assistance obtained in Example 1 of this invention.

[0026] Figure 2 This is a SEM image of the pure phase BiVO4 without the addition of SDS and directly subjected to a water bath in Example 1 of the present invention.

[0027] Figure 3 The image shows the BiVO4 SDS / BiVO4 SEM spectrum obtained in Example 1 of this invention.

[0028] Figure 4 for Figure 3 A magnified view of a portion of the image.

[0029] Figure 5 A comparison of the degradation rates of 10 mg / L Rhodamine B by BiVO4 and SDS / BiVO4 obtained in Example 1 of this invention within 60 min. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0031] This invention discloses a method for preparing bismuth vanadate using sodium dodecyl sulfate as an aid, comprising the following steps:

[0032] 1. Dissolve 1-6 mmol of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 10-100 mL of ultrapure water. Stir slowly to ensure that Bi(NO3)3·5H2O is fully dissolved. Stir for a total of 1 h with a magnetic stirrer to obtain precursor solution A.

[0033] 2. Dissolve 3-8 mmol of ammonium metavanadate (NH4VO3) in 50-100 mL of ultrapure water. Stir slowly to ensure that NH4VO3 is fully dissolved. Stir for a total of 1 hour using a magnetic stirrer to obtain precursor solution B.

[0034] 3. With the help of a magnetic stirrer, slowly add precursor solution A to precursor solution B and stir until homogeneous to obtain precursor solution C.

[0035] 4. Add different amounts of the surfactant sodium dodecyl sulfate (SDS) to precursor solution C and stir thoroughly with a magnetic stirrer. Since the molar amount of SDS needs to account for 3-30% of the final BiVO4, 0.15mmol-0.6mmol of SDS needs to be added. Then, adjust the pH of precursor solution C to 2-10 using 25% ammonia water (NH3H2O) and continue stirring for 30 minutes to obtain precursor solution D.

[0036] 5. Adjust the temperature of the magnetically stirred water bath to 60-100℃, transfer the precursor solution D into a three-necked flask, seal it with plastic wrap, and place the three-necked flask in the magnetically stirred water bath. Let the precursor solution D bathe in the water bath for 4-16 hours.

[0037] 6. After the three-necked flask has cooled to room temperature, wash it three times each with ultrapure water and anhydrous ethanol, and then vacuum dry it in an electric heating drying oven at 30-60℃ for 5-12 hours. Grind the dried powder thoroughly in a mortar and pestle. This powder is a BiVO4 photocatalytic material prepared with SDS assistance.

[0038] Example 1:

[0039] This invention discloses a method for preparing bismuth vanadate using sodium dodecyl sulfate as an aid, comprising the following steps:

[0040] 1. Dissolve 3 mmol of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 10 mL of ultrapure water. Stir slowly to ensure that Bi(NO3)3·5H2O is fully dissolved. Stir for 1 h with a magnetic stirrer to obtain precursor solution A.

[0041] 2. Dissolve 3 mmol of ammonium metavanadate (NH4VO3) in 50 mL of ultrapure water. Stir slowly to ensure that NH4VO3 is fully dissolved, and stir for 1 h with a magnetic stirrer to obtain precursor solution B.

[0042] 3. With the help of a magnetic stirrer, slowly add precursor solution A to precursor solution B and stir until homogeneous to obtain precursor solution C.

[0043] 4. Add different amounts of sodium dodecyl sulfate (SDS) to precursor solution C and stir thoroughly with a magnetic stirrer. The surfactant SDS (0.6 mmol) accounts for 3% of the total BiVO4. Then, adjust the pH of precursor solution C to 2 with 25% ammonia water (NH3H2O), and continue stirring for 30 min to obtain precursor solution D.

[0044] 5. Adjust the temperature of the magnetically stirred water bath to 60℃, transfer the precursor solution D into a three-necked flask, seal it with plastic wrap, and place the three-necked flask in the magnetically stirred water bath. Let the precursor solution D bathe in the water bath for 10 hours.

[0045] 6. After the three-necked flask has cooled to room temperature, wash it three times each with ultrapure water and anhydrous ethanol, and then vacuum dry it in an electric heating drying oven at 30°C for 5 hours. Grind the dried powder thoroughly in a mortar and pestle. This powder is a BiVO4 photocatalytic material prepared with SDS assistance.

[0046] Example 2

[0047] This invention discloses a method for preparing bismuth vanadate using sodium dodecyl sulfate as an aid, comprising the following steps:

[0048] 1. Dissolve 4 mmol of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 50 mL of ultrapure water. Stir slowly to ensure that Bi(NO3)3·5H2O is fully dissolved. Stir for 1 h with a magnetic stirrer to obtain precursor solution A.

[0049] 2. Dissolve 8 mmol of ammonium metavanadate (NH4VO3) in 100 mL of ultrapure water. Stir slowly to ensure that NH4VO3 is fully dissolved, and stir for 1 h with a magnetic stirrer to obtain precursor solution B.

[0050] 3. With the help of a magnetic stirrer, slowly add precursor solution A to precursor solution B and stir until homogeneous to obtain precursor solution C.

[0051] 4. Add different amounts of sodium dodecyl sulfate (SDS) to precursor solution C and stir thoroughly with a magnetic stirrer. The surfactant SDS (0.15 mmol) accounts for 15% of the total BiVO4. Then, adjust the pH of precursor solution C to 5 with 25% ammonia water (NH3 H2O), and continue stirring for 30 min to obtain precursor solution D.

[0052] 5. Adjust the temperature of the magnetically stirred water bath to 80℃, transfer the precursor solution D into a three-necked flask, seal it with plastic wrap, and place the three-necked flask in the magnetically stirred water bath. Let the precursor solution D bathe in the water bath for 8 hours.

[0053] 6. After the three-necked flask has cooled to room temperature, wash it three times each with ultrapure water and anhydrous ethanol, and then vacuum dry it in an electric heating drying oven at 60°C for 10 hours. Grind the dried powder thoroughly in a mortar and pestle. This powder is a BiVO4 photocatalytic material prepared with SDS assistance.

[0054] Example 3:

[0055] This invention discloses a method for preparing bismuth vanadate using sodium dodecyl sulfate as an aid, comprising the following steps:

[0056] 1. Dissolve 6 mmol of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 80 mL of ultrapure water. Stir slowly to ensure that Bi(NO3)3·5H2O is fully dissolved. Stir for 1 h with a magnetic stirrer to obtain precursor solution A.

[0057] 2. Dissolve 4 mmol of ammonium metavanadate (NH4VO3) in 50 mL of ultrapure water. Stir slowly to ensure that NH4VO3 is fully dissolved, and stir for 1 h with a magnetic stirrer to obtain precursor solution B.

[0058] 3. With the help of a magnetic stirrer, slowly add precursor solution A to precursor solution B and stir until homogeneous to obtain precursor solution C.

[0059] 4. Add different amounts of sodium dodecyl sulfate (SDS) to precursor solution C and stir thoroughly with a magnetic stirrer. The surfactant SDS (0.3 mmol) accounts for 20% of the total BiVO4. Then, adjust the pH of precursor solution C to 7 with 25% ammonia water (NH3 H2O), and continue stirring for 30 min to obtain precursor solution D.

[0060] 5. Adjust the temperature of the magnetically stirred water bath to 100℃, transfer the precursor solution D into a three-necked flask, seal it with plastic wrap, and place the three-necked flask into the magnetically stirred water bath. Let the precursor solution D bathe in the water bath for 6 hours.

[0061] 6. After the three-necked flask has cooled to room temperature, wash it three times each with ultrapure water and anhydrous ethanol, and then vacuum dry it in an electric heating drying oven at 60°C for 5 hours. Grind the dried powder thoroughly in a mortar and pestle. This powder is a BiVO4 photocatalytic material prepared with SDS assistance.

[0062] from Figure 1As can be seen, the main peaks in SDS / BiVO4 are located at 18.7°, 19°, 28.8°, 30.5°, 34.5°, 35.2°, 39.8°, and 40.0°, which are attributed to the (110), (011), (-121), (040), (200), (002), (211), and (-112) crystal planes in standard monoclinic BiVO4 nanoparticles (PDF card number: 14–0688). The results indicate that the surfactant has little effect on the crystal structure of BiVO4.

[0063] from Figure 2 As can be seen, pure BiVO4 consists of aggregated blocks and irregular rod-like structures with smooth surfaces. Pure BiVO4 prepared using a water bath process exhibits the characteristics of a monoclinic scheelite structure.

[0064] Combination Figure 3 , Figure 4 As can be seen, BiVO4 mainly exhibits an irregular, plate-like stacked structure. It is worth noting that surfactants have a significant impact on the morphology and photocatalytic performance of BiVO4.

[0065] The photocatalytic performance of BiVO4 and SDS / BiVO4 obtained in Example 1 was tested in this invention:

[0066] The degradation of RhB by BiVO4 samples was carried out in a quartz reactor (BL-GHX-VX, Xi'an Bilang Biotechnology Co., Ltd.) under visible light irradiation.

[0067] The light source was a 300W xenon lamp, 10cm away from the reactor. A 400nm filter was used to ensure that the light source was visible (>400nm) during the reaction. 50mg BiVO4 sample was dispersed in 50ml of 10mg / L RhB solution (10mg Rhodamine B diluted to 1L ultrapure water). After ultrasonic oscillation for 0.5h, the solution was magnetically stirred in the dark for 3h to reach adsorption equilibrium. The reaction solution temperature was maintained at 15℃ using circulating cooling water. Samples were taken every 10min, centrifuged, and the absorbance of the solution was measured at 554nm using a UV-Vis instrument within 60min after a certain reaction time to obtain the RhB concentration (Ct). The Ct / C0 (C0=1) ratio was used to evaluate the photocatalytic degradation efficiency of the sample.

[0068] from Figure 5 As can be seen, pure BiVO4 can achieve a degradation rate of about 40% for 50 ml of Rhodamine B solution with a concentration of 10 mg / L in 40 min, while the degradation rate of SDS / BiVO4 in 40 min is as high as 99%, which greatly improves the photocatalytic degradation performance.

Claims

1. A method for preparing bismuth vanadate with a sheet-like stacked structure using sodium dodecyl sulfate as an aid, characterized in that, Includes the following steps: S1, dissolve 1-6 mmol of bismuth nitrate pentahydrate in 10-100 mL of ultrapure water to obtain a bismuth nitrate pentahydrate solution, dissolve 3-8 mmol of ammonium metavanadate in 50-100 mL of ultrapure water to obtain an ammonium metavanadate solution, mix the bismuth nitrate pentahydrate solution and the ammonium metavanadate solution evenly, with a volume ratio of (10-100):(50-100) to obtain mixture a, then add sodium dodecyl sulfate and mix evenly, with a molar ratio of sodium dodecyl sulfate to bismuth nitrate pentahydrate of (0.15-0.6):(1-6) to obtain mixture b; S2, use 25% ammonia water to adjust the pH of mixture b to 2-10, then stir for 20-40 min to obtain the precursor solution, and then hydrothermally treat the precursor solution at 60-100℃ for 4-16 h to obtain the reaction solution. S3. After cooling the reaction solution to room temperature, wash it 3-5 times with ultrapure water and anhydrous ethanol while filtration, then vacuum dry it at 30-60℃ for 5-12 hours, and grind it into powder to obtain bismuth vanadate with a sheet-like stacked structure.

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