Preparation method and application of BiOBr flower ball catalyst
By controlling the pH of the solution and preparing BiOBr flower-shaped catalysts via a hydrothermal method, the problem of poor morphology and size uniformity was solved, achieving the effect of large specific surface area and efficient photocatalytic degradation of organic dye wastewater.
Patent Information
- Application Number
- CN202311094118.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-29
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2043-08-29
AI Technical Summary
Existing BiOBr flower-like catalysts have poor morphology and size uniformity, resulting in small specific surface area and limiting their application effects.
By controlling the pH of the solution, a clear solution was formed using hexadecylmethylammonium bromide, glycerol, and hexamethylenetetramine, which was then reacted with a bismuth salt solution. The temperature and time were controlled using a hydrothermal method to prepare a BiOBr flower-shaped catalyst with uniform size.
The prepared BiOBr flower-shaped catalyst exhibits good morphology and size uniformity, and a large specific surface area, making it suitable for photocatalytic degradation of organic dye wastewater, with a significantly improved degradation effect.
Smart Images
Figure CN117101685B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a preparation method and application of BiOBr flower ball catalyst. BACKGROUND
[0002] In recent years, with the increasing progress of industrial development, the problems of energy shortage and environmental pollution are increasingly prominent, and researchers actively study the problems of photoelectric materials in artificial photoelectric reaction and photocatalytic environmental governance. Photocatalytic materials are favored by researchers due to their many characteristics in optics, mechanics, electromagnetism and biology, and have advantages such as good stability, green and less pollution, and high catalytic efficiency.
[0003] Bismuth oxybromide has the advantages of good environmental stability and high visible light catalytic efficiency, and its conduction band potential is positive, has strong oxidizing property, has good degradation effect on pollutants such as dyes, ammonia nitrogen compounds and organic matters in the air and water, and has good application in energy conversion, lithium battery electrode materials, biological pharmaceuticals, environmental treatment and the like. In recent years, researchers have actively explored the synthesis of BiOBr catalyst materials with different morphologies in order to further improve the catalytic degradation of BiOBr. At present, flaky, spherical and flower-like BiOBr has been successfully prepared. Among them, the flower-like BiOBr has a high specific surface area, multiple active sites, low bulk density and other characteristics, and is widely used in environmental catalysis, so the synthesis of flower-like BiOBr has attracted much attention.
[0004] In the prior art, the synthesis method of flower-like BiOBr mainly includes the following: one is to use ethylene glycol, isopropyl alcohol and cetyltrimethylammonium bromide for synthesis; the other is to use anhydrous ethanol and ethylene glycol as solvents, or anhydrous ethanol and water as solvents, and to synthesize by solvothermal or hydrothermal method. The BiOBr flower ball catalyst prepared by these existing methods has the problems of poor uniformity of morphology and size, and small specific surface area, which limits its application. SUMMARY
[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a preparation method of BiOBr flower ball catalyst, which has good uniformity of morphology and size, and large specific surface area.
[0006] The present application first controls the pH value of the solution to form a bismuth salt solution in water, then heats and dissolves cetyltrimethylammonium bromide, glycerol and hexamethylenetetramine into a clear solution, and then interacts with Bi in the solution under certain conditions to form BiOBr precipitate with a certain structure. Then, by using the hydrothermal method, the temperature, pressure and time are controlled to further grow the precipitate, so as to form BiOBr flower ball catalyst with uniform size. The specific scheme is as follows:
[0007] A preparation method of a BiOBr flower ball catalyst, comprising the following steps:
[0008] (1) nitric acid and bismuth salt are added into water, ultrasonic and heated to completely dissolve, to obtain a bismuth salt solution;
[0009] (2) hexadecyl trimethyl ammonium bromide, hexamethylenetetramine and glycerol are added into water, ultrasonic and heated to obtain a clear solution;
[0010] (3) the bismuth salt solution of step (1) and the clear solution of step (2) are mixed uniformly, and then transferred to a reaction kettle for hydrothermal reaction, after the reaction is completed, cooled to room temperature, then centrifuged to remove supernatant, the precipitate is washed and vacuum dried to obtain a solid product;
[0011] (4) the solid product is calcined in a muffle furnace to obtain a BiOBr flower ball catalyst.
[0012] In step (1), the concentration of the bismuth salt solution is 0.08-0.12 mol / L.
[0013] In step (2), the molar ratio of hexadecyl trimethyl ammonium bromide, hexamethylenetetramine and bismuth salt is 0.2-0.8:0.2-0.8:1.
[0014] Further, in step (1), the heating temperature is 65-70 DEG C.
[0015] Further, in step (1), the bismuth salt is any one of bismuth nitrate pentahydrate, bismuth chloride or bismuth acetate.
[0016] Further, in step (2), the volume ratio of glycerol and water is 1:20.
[0017] Further, in step (3), the temperature of the hydrothermal reaction is 120-150 DEG C, and the reaction time is 18-24 h.
[0018] Further, in step (3), the centrifugal speed is 4000 r / min, and the time is 5-8 min.
[0019] Further, in step (3), the temperature of the vacuum drying is 60-65 DEG C, and the time is 6-10 h.
[0020] Further, in step (4), the calcination temperature is 200-500 DEG C, and the time is 4-6 h.
[0021] The BiOBr flower ball catalyst prepared by the above method is applied to photocatalytic degradation of organic dye wastewater.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] (1) This invention provides a method for preparing BiOBr flower-shaped catalysts, which has low raw material costs, simple and easy production process, and is easy to achieve large-scale production. Furthermore, the prepared BiOBr flower-shaped catalysts have good morphology and size uniformity.
[0024] (2) The present invention uses a system of hexadecylmethylammonium bromide, glycerol and hexamethylenetetramine to achieve the synthesis of BiOBr flower ball catalyst with uniform morphology, which has a larger specific surface area compared with BiOBr catalyst synthesized by traditional methods. Attached Figure Description
[0025] Figure 1 SEM images of the BiOBr flower-shaped catalysts prepared in Examples 1-5 and the BiOBr catalyst prepared in Comparative Example 1;
[0026] Figure 2 XRD patterns of the BiOBr flower-shaped catalysts prepared in Examples 1-5;
[0027] Figure 3 The results are experimental findings on the photocatalytic degradation of Rhodamine B solution by the BiOBr flower-shaped catalyst prepared in Examples 1-5. Detailed Implementation
[0028] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.
[0029] Example 1
[0030] A method for preparing a BiOBr flower-shaped catalyst includes the following steps:
[0031] (1) Add 0.05 mL of concentrated nitric acid and 0.49 g of bismuth nitrate pentahydrate to 9 mL of water and sonicate at 65 °C for 1 h to completely dissolve, to obtain a bismuth salt solution;
[0032] (2) Add 0.18g cetyltrimethylammonium bromide, 0.07g hexamethylenetetramine and 0.5mL glycerol to 10mL of water, and sonicate at 65℃ for 1h to obtain a clear solution;
[0033] (3) The bismuth salt solution of step (1) and the clear solution of step (2) are mixed uniformly, and then transferred to a reaction kettle, and hydrothermally reacted at 120℃ for 18h. After the reaction is completed, it is cooled to room temperature, and then centrifuged at a speed of 4000r / min for 5min. The obtained precipitate is washed with deionized water and anhydrous ethanol, and finally placed in a vacuum drying box at a temperature of 60-65℃ for 10h to obtain a solid product;
[0034] (4) The solid product is transferred to a muffle furnace, calcined at 200℃ for 4h to obtain a BiOBr flower ball catalyst.
[0035] The specific surface area of the BiOBr flower ball catalyst prepared in Example 1 is measured by a Germany Beckman SA3100 specific surface area tester, and is 177.39m 2 / g, the correlation coefficient is 0.99982, the Langmuir area is 161.01m 2 / g, and the correlation coefficient is 0.9992.
[0036] Example 2
[0037] The calcination temperature in step (4) is changed to 280℃, and the rest is the same as Example 1.
[0038] Example 3
[0039] The calcination temperature in step (4) is changed to 300℃, and the rest is the same as Example 1.
[0040] Example 4
[0041] The calcination temperature in step (4) is changed to 320℃, and the rest is the same as Example 1.
[0042] Example 5
[0043] The calcination temperature in step (4) is changed to 400℃, and the rest is the same as Example 1.
[0044] Comparative Example 1
[0045] A preparation method of a BiOBr catalyst, comprising the following steps:
[0046] (1) 0.05mL of concentrated nitric acid and 0.20g of bismuth nitrate pentahydrate are added to 9mL of water, and ultrasonic is performed at 65℃ for 1h to obtain a turbid solution;
[0047] (2) 0.18g of cetyltrimethylammonium bromide, 0.07g of hexamethylenetetramine and 0.5mL of glycerol are added to 10mL of water, and ultrasonic is performed at 65℃ for 1h to obtain a clear solution;
[0048] (3) The turbid solution of step (1) and the clear solution of step (2) are mixed uniformly and then transferred to a reaction kettle, and hydrothermal reaction is carried out at 120℃ for 18h. After the reaction is completed, the reaction kettle is cooled to room temperature, and then centrifuged at a speed of 4000r / min for 5min. The obtained precipitate is washed with deionized water and anhydrous ethanol, and finally placed in a vacuum drying oven at a temperature of 60-65℃ for 10h to obtain a solid product;
[0049] (4) The solid product is transferred to a muffle furnace and calcined at 200℃ for 4h to obtain a BiOBr catalyst.
[0050] The specific surface area of the BiOBr catalyst prepared in Comparative Example 1 is 1.785m 2 / g, and the correlation coefficient is 0.93359. The Langmuir area is 0.673m 2 / g, and the correlation coefficient is 0.9964.
[0051] The SEM images of the BiOBr flower ball catalysts prepared in Examples 1-5 and the BiOBr catalyst prepared in Comparative Example 1 are shown in Figure 1 , which are obtained on a U.S. Thermal NovaNanoSEM450 field emission scanning electron microscope, wherein, Figure 1 A is the BiOBr flower ball catalyst prepared in Example 1, Figure 1 B is the BiOBr flower ball catalyst prepared in Example 2, Figure 1 C is the BiOBr flower ball catalyst prepared in Example 3, Figure 1 D is the BiOBr flower ball catalyst prepared in Example 4, Figure 1 E is the BiOBr flower ball catalyst prepared in Example 5, Figure 1 F is the BiOBr catalyst prepared in Comparative Example 1. It can be seen that the BiOBr flower ball catalysts prepared in Examples 1-5 have uniform size and are all flower-shaped microspheres. The BiOBr catalyst material prepared in Comparative Example 1 is not a flower-shaped structure.
[0052] The XRD patterns of the BiOBr flower ball catalysts prepared in Examples 1-5 are shown in Figure 2The XRD spectrum shows that the strongest peak 2theta is located at 31.6878°, corresponding to (102) crystal face, the second strongest peak 2theta is located at 32.2289°, corresponding to (110) crystal face, and the rest of the peaks 2theta are located at 11.1047°, 25.1944°, 46.2195°, 57.1268°, etc., corresponding to (001), (101), (200), (212) crystal faces, etc., respectively, which is consistent with the standard card 085-0862 of BiOBr, and the crystal structure is tetragonal.
[0053] The BiOBr flower ball catalyst prepared in Examples 1-5 was subjected to photocatalysis experiment:
[0054] The photocatalysis instrument produced by Beijing Zhongjiao Jin Yuan Technology Co., Ltd. was used for photocatalysis reaction, 5 mg of BiOBr flower ball catalyst was weighed, 50 mg / L rhodamine B solution was moved into the quartz reactor, the circulating water was opened for cooling, and the stirring was carried out in the dark for 1.5 h to adsorb the equilibrium, the visible light was opened, the liquid was taken every 5 min, after centrifugal precipitation, the absorbance of the supernatant was determined by ultraviolet visible spectrophotometer, and the degradation rate was calculated.
[0055] Figure 3 For the experimental results of BiOBr flower ball catalyst prepared in Examples 1-5 for photocatalytic degradation of rhodamine B solution, it can be seen that the BiOBr flower ball catalyst prepared in Examples 1-5 of the present application has good degradation effect on rhodamine B solution under visible light irradiation, especially the rhodamine B can be completely degraded in 20 min after calcination at 280℃, which further indicates that the BiOBr flower ball catalyst synthesized in the present application is a good photocatalyst and has good application in the field of photocatalysis.
[0056] The above describes the embodiments of the present application in combination with examples, but the present application is not limited to the above embodiments, and for those skilled in the art, after knowing the contents described in the present application, some equivalent transformations and substitutions can be made without departing from the principles of the present application, and these equivalent transformations and substitutions should also be regarded as belonging to the protection scope of the present application.
Claims
1. A method for preparing a BiOBr flower-shaped catalyst, characterized in that, Includes the following steps: (1) Add nitric acid and bismuth salt to water, sonicate and heat to completely dissolve, to obtain a bismuth salt solution; (2) Add hexadecyltrimethylammonium bromide, hexamethylenetetramine and glycerol to water, sonicate and heat to obtain a clear solution; (3) Mix the bismuth salt solution from step (1) and the clear solution from step (2) evenly, then transfer them to a reaction vessel for hydrothermal reaction. After the reaction is completed, cool to room temperature, then centrifuge to remove the supernatant, wash the precipitate and vacuum dry it to obtain a solid product. (4) The solid product was calcined in a muffle furnace to obtain BiOBr flower ball catalyst; In step (1), the concentration of the bismuth salt solution is 0.08-0.12 mol / L; In step (2), the molar ratio of hexadecyltrimethylammonium bromide, hexamethylenetetramine, and bismuth salt is 0.2~0.8:0.2~0.8:1; In step (3), the temperature of the hydrothermal reaction is 120~150℃ and the reaction time is 18~24h; In step (4), the calcination temperature is 200~500℃ and the time is 4~6 h.
2. The preparation method of the BiOBr flower-shaped catalyst as described in claim 1, characterized in that, In step (1), the heating temperature is 65~70℃.
3. The preparation method of the BiOBr flower-shaped catalyst as described in claim 1, characterized in that, In step (1), the bismuth salt is any one of bismuth nitrate pentahydrate, bismuth chloride, or bismuth acetate.
4. The preparation method of the BiOBr flower-shaped catalyst as described in claim 1, characterized in that, In step (2), the volume ratio of glycerol to water is 1:
20.
5. The method for preparing the BiOBr flower-shaped catalyst as described in claim 1, characterized in that, In step (3), the centrifugation speed is 4000 r / min and the time is 5~8 min.
6. The method for preparing the BiOBr flower-shaped catalyst as described in claim 1, characterized in that, In step (3), the vacuum drying temperature is 60~65℃ and the time is 6~10 h.