Preparation method of bismuth oxychloride photocatalyst
By adding tetracycline and sodium hydroxide in the preparation process of bismuth oxychloride photocatalyst and using photoelution technology, the low light absorption efficiency and electron-hole recombination of bismuth oxychloride photocatalyst under visible light are solved, achieving more efficient photocatalytic performance and stability, while reducing production costs.
Patent Information
- Application Number
- CN202411869001.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-03-25
AI Technical Summary
The existing bismuth oxychloride photocatalysts have limited light absorption efficiency under visible light, serious problems with electron-hole recombination, chemical and physical stability need to be further verified, and there are challenges in durability and low-cost production in complex industrial environments.
By reacting bismuth chloride with substances such as tetracycline and sodium hydroxide, a bismuth oxychloride photocatalyst was formed, and anhydrous ethanol and polyvinylpyrrolidone were used as dispersion media to perform photoeluting to improve the surface area and photocatalytic properties of the catalyst.
The photocatalytic performance of bismuth oxychloride photocatalyst under visible light is improved, the lifetime of electron-holes is extended, the catalytic activity is enhanced, and the production cost is reduced, and the chemical and physical stability of the catalyst is improved.
Smart Images
Figure CN119680589A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of photocatalysis, and in particular relates to a method for preparing a bismuth oxychloride photocatalyst. Background Art
[0002] As a new type of photocatalytic material, bismuth oxychloride (BiOCl) has attracted extensive attention due to its unique layered structure and excellent light absorption properties. The crystal structure of BiOCl gives it good electron transfer ability and stability, making it have excellent photocatalytic performance under visible light. Through methods such as doping and surface modification, the separation efficiency of photogenerated electrons and holes can be further improved, and the catalytic activity can be enhanced.
[0003] At present, bismuth oxychloride has been successfully applied to a variety of chemical reactions in industrial catalysis, especially in organic synthesis and oxidation reactions. For example, in industrial organic synthesis, BiOCl can catalyze the hydroxylation reaction of phenolic compounds. Its unique photocatalytic properties can efficiently convert phenol into hydroquinone under mild conditions, significantly improving the reaction efficiency. In addition, BiOCl also shows superior performance in selective oxidation reactions. For example, it can catalyze the oxidation of alcohol compounds, selectively converting primary alcohols into aldehydes without further oxidation to acids. This selectivity is crucial for many chemical synthesis processes because it reduces the formation of by-products and improves the purity and yield of the target product. These applications not only demonstrate the ability of BiOCl in improving reaction efficiency and selectivity, but also excel in reducing energy consumption and reducing the formation of by-products. These characteristics give it broad application prospects in industrial catalysis, especially in the future production of acetic acid, which is expected to provide a more economical and sustainable solution through photocatalytic processes.
[0004] BiOCl has great potential for industrial catalytic production of acetic acid. Through the photocatalytic process, it can achieve efficient reaction at room temperature and pressure, which not only improves the selectivity and yield of the target product, but also reduces the dependence on traditional high temperature and high pressure equipment, providing a more economical and sustainable solution for acetic acid production.
[0005] Although BiOCl has shown great potential as a photocatalyst in industrial applications, it still faces many challenges. First, its light absorption range is mainly concentrated in the ultraviolet region, and its utilization rate of visible light is limited. It is urgent to improve its light absorption efficiency through doping or structural modification. In addition, the recombination problem of photogenerated electrons and holes significantly reduces the catalytic efficiency. How to effectively promote electron-hole separation has become a key research direction. At the same time, its chemical and physical stability in long-term reactions needs to be verified, especially its durability in complex industrial environments. In addition, it is still challenging to achieve low-cost large-scale production of efficient BiOCl catalysts, and its applicability and efficiency in diversified chemical reactions also need to be further explored. Therefore, in-depth research and technological innovation on these issues are crucial to promoting the application of BiOCl in industrial catalysis. Summary of the invention
[0006] The purpose of the present invention is to provide a method for preparing a bismuth oxychloride photocatalyst in view of the above-mentioned problems existing in the existing bismuth oxychloride photocatalyst. The method has low cost and the prepared bismuth oxychloride photocatalyst has excellent photocatalytic performance under visible light.
[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:
[0008] A method for preparing a bismuth oxychloride photocatalyst comprises the following steps:
[0009] (1) adding bismuth chloride to anhydrous ethanol to dissolve, then sequentially adding polyvinyl pyrrolidone and tetracycline, and mixing well to obtain a precursor solution;
[0010] (2) adding a sodium hydroxide solution dropwise to the precursor solution, stirring for reaction, washing and drying to obtain a photocatalyst precursor;
[0011] (3) Adding the photocatalyst precursor into a quartz glass sealed reactor for photoelution, washing the obtained solid and drying it to obtain a bismuth oxychloride photocatalyst.
[0012] Furthermore, in step (1), the mass ratio of the bismuth chloride to polyvinyl pyrrolidone is (10-11):1, and the amount of the tetracycline used accounts for 1.5%-1.7% of the mass of the bismuth chloride.
[0013] Furthermore, in step (2), the molar ratio of sodium hydroxide to bismuth chloride is 2:1.
[0014] Furthermore, in step (2), the reaction temperature is 20-60° C., and the reaction time is 120-240 min.
[0015] Furthermore, in step (2), the drying temperature is 60° C. and the drying time is 12 h.
[0016] Furthermore, in steps (2) and (3), the washing refers to centrifugal washing with deionized water and anhydrous ethanol alternately at a speed of 8000 r / min.
[0017] Furthermore, in step (3), the photoelution is carried out using a photochemical reactor under the irradiation of a 250W xenon lamp; the photoelution is performed 5 times, each time for 1 hour.
[0018] A bismuth oxychloride photocatalyst is prepared by the method.
[0019] Application of the bismuth oxychloride photocatalyst prepared by the above method in photocatalytic degradation of organic pollutants; the organic pollutant is one of tetracycline, methyl orange, ciprofloxacin, levofloxacin, phenol, p-chlorophenol, rhodamine B or methylene blue; preferably tetracycline, ciprofloxacin or levofloxacin.
[0020] Beneficial effects of the present invention:
[0021] 1) The present invention provides a method for preparing a bismuth oxychloride photocatalyst. According to the property of tetracycline to chelate with metal ions, tetracycline is first combined with bismuth chloride to form a metal chelate, and then sodium hydroxide solution is added to react with bismuth chloride to generate bismuth oxychloride. The dispersion medium used in the preparation process of this method is water, without other solvents, which can greatly reduce the technical requirements for the reaction equipment and save the raw material cost and separation cost of the production process. Moreover, due to the chelation of tetracycline with bismuth ions, it has a limiting effect on the spatial growth of the material, promotes the bismuth oxychloride to form a thinner sheet, presents a flower-like structure, and has a larger surface area than the typical bismuth oxychloride.
[0022] 2) The photocatalyst prepared by the present invention has a more ideal surface distribution and can more effectively inhibit the recombination of photogenerated electrons and holes, so that more photogenerated electrons can reach the catalyst surface and combine with oxygen molecules to form superoxide radicals, thereby bringing better photocatalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 The SEM images of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0024] Figure 2 TEM images of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0025] Figure 3 Element distribution diagram of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0026] Figure 4 The infrared spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0027] Figure 5 The UV spectra and Tauc plots of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0028] Figure 6 XRD spectra of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0029] Figure 7 The fluorescence spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0030] Figure 8 Photocurrent diagrams of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0031] Fig. 9 The electrochemical impedance diagrams of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0032] Fig.10 Specific surface area diagram of bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1;
[0033] Fig.11 The photoelectron spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1;
[0034] Fig.12 The test results of the catalytic rate of tetracycline by the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 under light irradiation;
[0035] Fig.13 The test results of the catalytic rate of levofloxacin by the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 under light irradiation;
[0036] Fig.14 The catalytic efficiency test results of ciprofloxacin under light for the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1. DETAILED DESCRIPTION
[0037] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the implementation manner of the present invention is not limited thereto.
[0038] Example 1
[0039] A method for preparing a bismuth oxychloride photocatalyst comprises the following steps:
[0040] (1) adding 1.57 g of bismuth chloride to 10.0 mL of anhydrous ethanol and dissolving by ultrasonication, then adding 0.15 g of polyvinyl pyrrolidone and 25 mg of tetracycline, and mixing by ultrasonication to obtain a precursor solution;
[0041] (2) 5 mL of 2.0 mol / L sodium hydroxide solution was added dropwise to the precursor solution, and the mixture was stirred at room temperature for 2 h, and then washed alternately with deionized water and anhydrous ethanol for 3 times, and the solid was dried in an oven at 60° C. for 12 h to obtain a precursor photocatalyst;
[0042] (3) 0.4 g of the photocatalyst precursor was added to a quartz glass sealed reactor filled with 100 mL of deionized water for photoelution (using a GHX-3 photochemical reactor, irradiated for 1 h under a 250 W xenon lamp, and continuously introducing air), the solution was filtered, and the obtained solid was added back to a quartz glass sealed reactor filled with 100 mL of deionized water. After repeating the photoelution five times, the solid was filtered, and the obtained solid was dried at 60° C. for 12 h to obtain a bismuth oxychloride photocatalyst.
[0043] Example 2
[0044] A method for preparing a bismuth oxychloride photocatalyst comprises the following steps:
[0045] (1) adding 3.14 g of bismuth chloride to 15.0 mL of anhydrous ethanol and dissolving by ultrasonication, then adding 0.3 g of polyvinyl pyrrolidone and 50 mg of tetracycline, and mixing by ultrasonication to obtain a precursor solution;
[0046] (2) 10 mL of 2.0 mol / L sodium hydroxide solution was added dropwise to the precursor solution, and the mixture was stirred at room temperature for 4 h, and then washed alternately with deionized water and anhydrous ethanol for 3 times, and the solid was dried in an oven at 60° C. for 12 h to obtain a precursor photocatalyst;
[0047] (3) 0.4 g of the photocatalyst precursor was added to a quartz glass sealed reactor filled with 100 mL of deionized water for photoelution (using a GHX-3 photochemical reactor, irradiated for 1 h under a 250 W xenon lamp, and continuously introducing air), the solution was filtered, and the obtained solid was added back to a quartz glass sealed reactor filled with 100 mL of deionized water. After repeating the photoelution five times, the solid was filtered, and the obtained solid was dried at 60° C. for 12 h to obtain a bismuth oxychloride photocatalyst.
[0048] Example 3
[0049] A method for preparing a bismuth oxychloride photocatalyst comprises the following steps:
[0050] (1) adding 4.71 g of bismuth chloride to 20.0 mL of anhydrous ethanol and dissolving by ultrasonication, then adding 0.45 g of polyvinyl pyrrolidone and 75 mg of tetracycline, and mixing by ultrasonication to obtain a precursor solution;
[0051] (2) 15 mL of 2.0 mol / L sodium hydroxide solution was added dropwise to the precursor solution, and the mixture was stirred at room temperature for 4 h, and then washed alternately with deionized water and anhydrous ethanol for 3 times, and the solid was dried in an oven at 60° C. for 12 h to obtain a precursor photocatalyst;
[0052] (3) 0.4 g of the photocatalyst precursor was added to a quartz glass sealed reactor filled with 100 mL of deionized water for photoelution (using a GHX-3 photochemical reactor, irradiated for 1 h under a 250 W xenon lamp, and continuously introducing air), the solution was filtered, and the obtained solid was added back to a quartz glass sealed reactor filled with 100 mL of deionized water. After repeating the photoelution five times, the solid was filtered, and the obtained solid was dried at 60° C. for 12 h to obtain a bismuth oxychloride photocatalyst.
[0053] Comparative Example 1
[0054] A method for preparing a bismuth oxychloride photocatalyst comprises the following steps:
[0055] (1) adding 3.14 g of bismuth chloride to 15.0 mL of anhydrous ethanol and dissolving by ultrasonication, then adding 0.3 g of polyvinyl pyrrolidone and mixing by ultrasonication to obtain a precursor solution;
[0056] (2) 10 mL of 2.0 mol / L sodium hydroxide solution was added dropwise to the precursor solution, and the mixture was stirred at room temperature for 4 h, and then washed alternately with deionized water and anhydrous ethanol for 3 times, and the solid was dried in an oven at 60° C. for 12 h to obtain a precursor photocatalyst;
[0057] (3) 0.4 g of the photocatalyst precursor was added to a quartz glass sealed reactor filled with 100 mL of deionized water, and light eluted (using a GHX-3 photochemical reactor, irradiated for 1 h under a 250 W xenon lamp, and continuously introduced with air), the solution was filtered, and the obtained solid was added back to a quartz glass sealed reactor filled with 100 mL of deionized water. After repeating the light elution five times, the solid was filtered, and the obtained solid was dried at 60° C. for 12 h to obtain a bismuth oxychloride photocatalyst.
[0058] Taking the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 as examples, characterization and performance determination were performed:
[0059] Figure 1 The SEM images of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are shown in FIG. Figure 1 It can be seen that the main body of the catalyst presents a three-dimensional nanoflower structure, which may be formed by the stereo self-assembly of bismuth oxychloride.
[0060] Figure 2 TEM images of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1. Figure 2 It can be seen that bismuth oxychloride presents a flower-like structure composed of many stacked flakes, which may optimize the carrier transmission path, reduce the recombination of photogenerated electron-hole pairs, and increase the lifetime of photogenerated electrons, thereby improving the photocatalytic activity.
[0061] Figure 3 Element distribution diagram of bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1, from Figure 3 It can be seen that Bi, O, Cl and other elements are evenly distributed in the element distribution on the catalyst surface.
[0062] Figure 4 The infrared spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are as follows: Figure 4 It can be seen that compared with Comparative Example 1, the Bi-O in Example 2 increases from 460 cm -1 Red shift to 520 cm -1 , the flower-like structure of the prepared bismuth oxychloride photocatalyst led to electron transfer.
[0063] Figure 5 The UV spectra and Tauc plots of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are shown in FIG. Figure 5 a is the ultraviolet spectrum, Figure 5 b is the Tauc diagram calculated based on the ultraviolet spectrum. It can be seen that the visible light absorption range of the bismuth oxychloride photocatalyst of Example 2 is smaller than that of Comparative Example 1, which results in the band gap of Example 2, 2.95 eV, being larger than 2.08 eV of the Comparative Example. A larger band gap can better suppress the coincidence of electrons and holes and improve the catalytic efficiency.
[0064] Figure 6 The XRD spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are shown in FIG. Figure 6 It can be seen that Example 2 has all the characteristic peaks of BiOCl, and the results show that the addition of TC does not change the crystal structure of the material.
[0065] Figure 7 The fluorescence spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are as shown in the figure. The fluorescence intensity of Comparative Example 1 is higher than that of Example 2, indicating that the carrier efficiency of Example 2 is lower and is more conducive to improving the photocatalytic activity.
[0066] Figure 8 The photocurrent diagram of the bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 is shown in FIG. Fig. 9 The electrochemical impedance diagram of the bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 is shown in FIG. Figure 8 and Fig. 9It can be seen that the photocurrent of Example 2 is 3 times that of Comparative Example 1, and the electrochemical impedance is also lower than that of Comparative Example 1. Figure 7 This is consistent with the results of , which shows that the photoelectric performance of the flower-like BiOCl photocatalyst is greatly improved.
[0067] Fig.10 The specific surface area diagram of the bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 is as follows: Fig.10 As shown, the specific surface area of Example 2 is 53.3762m 2 / g, higher than 35.3203m in comparative example 1 2 / g, which is beneficial to the adsorption of pollutants by photocatalysts.
[0068] Fig.11 The photoelectron energy spectra of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 are as follows: Fig.11 a is the XPS total spectrum, Fig.11 b. Fig.11 c. Fig.11 d are high-resolution XPS spectra of Bi 4f, O 1s, and Cl 2p, respectively. As can be seen from the figure, the peaks of Example 2 are all shifted toward the direction of high binding energy, which is due to the transfer of Bi, O, and Cl electrons around the functional groups, resulting in an increase in binding energy.
[0069] Photocatalytic degradation of organic pollutants test:
[0070] 1. Take 20 mg / L tetracycline aqueous solution as simulated wastewater, take 20 mg of bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 and add them into 100 mL simulated wastewater, and use 250W xenon lamp to illuminate for 1 hour, take 1 mL of solution before and after illumination for 1 hour to measure absorbance, and calculate catalytic rate according to absorbance. Catalytic rate formula:
[0071]
[0072] Wherein, A: initial absorbance of tetracycline solution, A0: absorbance of tetracycline solution after reaction.
[0073] Fig.12 The catalytic rate test results of the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 for tetracycline under light show that the catalytic rate of the bismuth oxychloride photocatalyst prepared in Example 2 for tetracycline is 92.7%, while that of Comparative Example 1 is 56.1% under the same conditions.
[0074] 2. Using a 20 mg / L levofloxacin aqueous solution as simulated wastewater, 20 mg of each bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 were added into 100 mL of simulated wastewater, and both were illuminated with a 250 W xenon lamp for 1 h. 1 mL of the solution before and after 1 h of illumination was taken to measure the absorbance, and the catalytic rate was calculated based on the absorbance.
[0075] Fig.13 The catalytic rate test results of levofloxacin under light for the bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 show that the catalytic rate of levofloxacin for the bismuth oxychloride photocatalyst prepared in Example 2 is 80.7%, while under the same conditions, the catalytic rate of Comparative Example 1 is 60.6%.
[0076] 3. Using a 20 mg / L ciprofloxacin aqueous solution as simulated wastewater, 20 mg of each bismuth oxychloride photocatalyst prepared in Example 2 and Comparative Example 1 were added into 100 mL of simulated wastewater, and both were illuminated with a 250 W xenon lamp for 1 h. 1 mL of the solution before and after illumination for 1 h was taken to measure the absorbance, and the catalytic rate was calculated based on the absorbance.
[0077] Fig.14 The catalytic rate test results of bismuth oxychloride photocatalysts prepared in Example 2 and Comparative Example 1 for ciprofloxacin under light show that the catalytic rate of bismuth oxychloride photocatalyst prepared in Example 2 for ciprofloxacin is 64.1%, while under the same conditions, the catalytic rate of Comparative Example 1 is 38.8%.
[0078] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; therefore, although the present invention has been described in detail in this specification with reference to the above embodiments, it should be understood by those skilled in the art that the present invention may still be modified or replaced by equivalents; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.
Claims
1. A method for preparing a bismuth oxychloride photocatalyst, characterized in that: The steps include: (1) adding bismuth chloride to anhydrous ethanol to dissolve, then sequentially adding polyvinyl pyrrolidone and tetracycline, and mixing well to obtain a precursor solution; (2) adding a sodium hydroxide solution dropwise to the precursor solution, stirring for reaction, washing and drying to obtain a photocatalyst precursor; (3) Adding the photocatalyst precursor into a quartz glass sealed reactor for photoelution, washing the obtained solid and drying it to obtain a bismuth oxychloride photocatalyst.
2. The method for preparing the bismuth oxychloride photocatalyst according to claim 1, characterized in that: In step (1), the mass ratio of the bismuth chloride to polyvinyl pyrrolidone is (10-11):1, and the amount of the tetracycline accounts for 1.5%-1.7% of the mass of the bismuth chloride.
3. The method for preparing the bismuth oxychloride photocatalyst according to claim 1, characterized in that: In step (2), the molar ratio of sodium hydroxide to bismuth chloride is 2:
1.
4. The method for preparing the bismuth oxychloride photocatalyst according to claim 1, characterized in that: In step (2), the reaction temperature is 20-60° C., and the reaction time is 120-240 min.
5. The method for preparing the bismuth oxychloride photocatalyst according to claim 1, characterized in that: In step (2), the drying temperature is 60° C. and the drying time is 12 h.
6. The method for preparing the bismuth oxychloride photocatalyst according to claim 1, characterized in that: In steps (2) and (3), the washing refers to centrifugal washing with deionized water and anhydrous ethanol alternately at a speed of 8000 r / min.
7. The method for preparing a bismuth oxychloride photocatalyst according to any one of claims 1 to 6, characterized in that: The number of photoelution steps in step (3) is 5, each lasting 1 hour.
8. A bismuth oxychloride photocatalyst prepared by the method according to any one of claims 1 to 7.
9. Use of the bismuth oxychloride photocatalyst prepared by the method according to any one of claims 1 to 7 in the photocatalytic degradation of organic pollutants, wherein the organic pollutant is one of tetracycline, methyl orange, ciprofloxacin, levofloxacin, phenol, p-chlorophenol, rhodamine B or methylene blue.