Silver vanadate / zinc oxide composite photocatalytic material and preparation method and application thereof

Abstract

This invention discloses a silver vanadate / zinc oxide composite photocatalytic material, its preparation method, and its application. Synthesized ZnO is used as the composite matrix, and AgVO3 is generated in situ on its surface through a chemical reaction. Specific steps include: ultrasonically dissolving sodium citrate dihydrate and zinc acetate in distilled water, adjusting the pH, performing a hydrothermal reaction, and then calcining at high temperature to obtain ZnO; adding the obtained ZnO to a soluble silver salt aqueous solution and a metavanadate aqueous solution, stirring, centrifuging, collecting the precipitate, washing, and vacuum drying to obtain the silver vanadate / zinc oxide composite photocatalytic material. This invention has the advantages of simple operation, wide applicability, and easily controllable reaction conditions, making it suitable for constructing highly efficient and stable composite photocatalytic materials. The specific microstructure of this composite material determines its excellent photocatalytic performance, with 20% wt AgVO3... 3 / Under light irradiation, the ZnO composite photocatalytic material achieved a 100% degradation rate of the organic pollutant RhB within 13 minutes.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic material preparation technology, and more specifically, relates to a silver vanadate / zinc oxide composite photocatalytic material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of an increasingly urgent need to improve environmental quality, photocatalytic materials are considered a promising purification solution due to their ability to completely degrade organic pollutants into harmless substances at room temperature and pressure. Among numerous photocatalytic materials, zinc oxide (ZnO) has attracted widespread attention due to its strong redox capabilities, safety, non-toxicity, and low cost. However, pure ZnO faces two major technical bottlenecks in practical applications: its wide bandgap limits its light absorption range to ultraviolet light, resulting in extremely low utilization of sunlight; and the rapid recombination rate of photogenerated electron-hole pairs in ZnO limits its photocatalytic activity, making it difficult to meet the demand for efficient purification in daily life. To overcome these bottlenecks, researchers often employ modification strategies to ZnO. Silver vanadate, as a narrow bandgap semiconductor, not only effectively absorbs visible light but also possesses excellent electron transport properties. Theoretical analysis and previous studies have shown that combining silver vanadate with ZnO is expected to form a matched band structure at their interface, constructing an efficient charge transfer channel, thereby significantly suppressing the recombination of photogenerated carriers and broadening the response range of the composite material to visible light.

[0003] Patent CN 113926453 A discloses a method for preparing and applying a photocatalytic material of silver vanadate / ZnO composite supported on hemp stalk activated carbon. This method primarily addresses the problems of poor photoresponse of ZnO in the visible light region and secondary pollution and incomplete degradation of levofloxacin in existing methods. The method involves preparing hemp stalk activated carbon via a hydrothermal process, then loading ZnO onto the activated carbon. Finally, silver nitrate and sodium vanadate are added under ultrasonic conditions and mixed uniformly in the dark. The mixture is then subjected to irradiation in a microwave digester to obtain the hemp stalk activated carbon-supported Ag3VO4 / ZnO composite photocatalytic material. The degradation effect on levofloxacin was evaluated, showing a degradation rate of 85.3% within 120 minutes. The above methods combine hydrothermal and microwave synthesis, which involve complicated steps, high equipment investment, and high costs. Moreover, the prepared composite photocatalytic material has a sheet-like structure, with Ag3VO4 and ZnO particles uniformly grown on the surface of hemp stalk activated carbon. Although this can improve the photocatalytic performance of ZnO alone, the interfacial bonding between AgVO3 and ZnO is weak, resulting in poor photocatalytic degradation effect. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a method for preparing silver vanadate / zinc oxide composite photocatalytic materials. This preparation method does not require complex equipment or harsh conditions such as high temperature and high pressure. The process is simple and the parameters are easy to control. It has the advantages of low cost, simple process and easy control of conditions.

[0005] The problem to be solved by the present invention is to provide a silver vanadate / zinc oxide composite photocatalytic material that has excellent visible light photocatalytic performance for Rhodamine B (RhB).

[0006] The problem to be solved by this invention is to provide an application of a silver vanadate / zinc oxide composite photocatalyst material in wastewater treatment, which is particularly suitable for wastewater systems with Rhodamine B (RhB) as the main organic pollutant.

[0007] To solve the above problems, the present invention is achieved through the following technical solution: A method for preparing a silver vanadate / zinc oxide composite photocatalytic material includes the following specific steps: (1) Weigh out sodium citrate dihydrate and add it to distilled water, then dissolve it by sonication to obtain solution A; (2) Weigh zinc acetate and add it to distilled water, then sonicate to dissolve it to obtain solution B; (3) The A solution is slowly added to the B solution under continuous stirring. After mixing evenly at room temperature, an alkaline reagent is added to adjust the pH value to the preset value. Then, the solution is transferred to a high-pressure reactor for constant temperature hydrothermal reaction to obtain the C solution. (4) The C liquid is subjected to solid-liquid separation, washing, vacuum drying, and high-temperature calcination to obtain ZnO; (5) Add the ZnO to an aqueous solution of metavanadate and an aqueous solution of soluble silver salt to obtain solution D; (6) The D liquid is stirred, centrifuged, the precipitate is collected, washed and vacuum dried to obtain silver vanadate / zinc oxide composite photocatalytic material.

[0008] Preferably, solution A is an aqueous solution of sodium citrate with a concentration of 1.0~2.0 mol / L, and solution B is an aqueous solution of zinc acetate with a concentration of 0.25~1.0 mol / L.

[0009] Preferably, the molar ratio of zinc acetate in solution B to sodium citrate dihydrate in solution A is 1:4 to 1:6.

[0010] Preferably, in step (3), liquid A is slowly added dropwise to liquid B under continuous stirring, the stirring speed is 350~400 r / min, and the stirring time at room temperature is 1~4h; The alkaline reagent is either sodium hydroxide or sodium bicarbonate, and the preset pH value is 9.5~10.5; The constant-temperature hydrothermal reaction is carried out at a temperature of 140~160℃ for 6~10 h.

[0011] Preferably, in step (4), the atmosphere for high-temperature calcination is air, the calcination temperature is 550~650℃, the heating rate is 5~8℃ / min, and the calcination time is 2~3h.

[0012] Preferably, in step (5), the concentration of the metavanadate aqueous solution is 0.025~0.160 mol / L, and the concentration of the soluble silver salt aqueous solution is 0.025~0.160 mol / L; The metavanadate aqueous solution is any one of ammonium metavanadate aqueous solution and sodium metavanadate aqueous solution; the soluble silver salt aqueous solution is any one of silver nitrate aqueous solution, silver fluoride aqueous solution, silver acetate aqueous solution, and silver perchlorate aqueous solution. The soluble silver salt aqueous solution is composed of a mixture of soluble silver salt and an aqueous solution, wherein the molar ratio of ZnO to soluble silver salt is 7~50:1.

[0013] Preferably, step (5) includes: Weigh the ZnO, first add a soluble silver salt aqueous solution, stir well, then add a metavanadate aqueous solution; or Weigh out the ZnO, first add it to a metavanadate aqueous solution, stir until homogeneous, and then add a soluble silver salt aqueous solution.

[0014] Preferably, in step (6), the washing refers to washing with distilled water and ethanol 3 to 4 times respectively, the vacuum drying temperature is 50 to 70°C, and the vacuum drying time is 2 to 8 hours; the AgVO3 loading ratio of the silver vanadate / zinc oxide composite photocatalyst is 5 to 30%.

[0015] Accordingly, the present invention also provides a silver vanadate / zinc oxide composite photocatalytic material, and the application of the composite material in the treatment of gaseous organic pollutants, volatile organic pollutants and wastewater.

[0016] This invention constructs an in-situ grown silver vanadate / zinc oxide composite photocatalyst material. Synthesized ZnO is used as the composite matrix, and AgVO3 is generated in situ on its surface through a chemical reaction. By employing specific preparation steps and process parameters, and controlling the conditions (temperature, time, pH) of hydrothermal ZnO synthesis, as well as the concentration, molar ratio, reaction temperature, and time of the reactants in the subsequent in-situ composite process, the ZnO and silver vanadate / zinc oxide composite photocatalyst material obtained by this invention possesses a specific microstructure through precise control of its structure and preparation process. Due to its advantages of simple operation, wide applicability, and easily controllable reaction conditions, it is suitable for constructing highly efficient and stable composite photocatalyst materials. The deposition of AgVO3 on the ZnO surface creates a tight interfacial contact, which is beneficial for charge transport. The specific microstructure of this composite material determines its excellent photocatalytic performance. Comparative experiments showed that the AgVO3 / ZnO composite photocatalyst material with an AgVO3 loading ratio of 20%wt exhibited the best photocatalytic performance, achieving a 100% degradation rate of the organic pollutant RhB within 13 minutes under illumination. This is of great significance for its application in photocatalytic degradation of organic pollutants, especially dye wastewater containing RhB, as well as in other environmental purification fields such as photocatalytic sterilization and VOCs decomposition. Therefore, its application in the treatment of gaseous organic pollutants, volatile organic pollutants, and wastewater can not only meet the environmental protection demand for high-efficiency purification materials, but also expand the functional applications of composite materials, fill existing technological gaps, and has significant technological value and market prospects.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. An in-situ grown silver vanadate / zinc oxide composite photocatalyst was constructed, effectively promoting the separation of photogenerated electron-hole pairs and broadening the response range to visible light. Under xenon lamp irradiation and with the established reaction system conditions, the composite material exhibited superior degradation performance of RhB solution, achieving complete degradation in just 13 minutes. Compared with single-component silver vanadate and zinc oxide, its photocatalytic degradation rate was increased by 56% and 96%, respectively, demonstrating a significant synergistic enhancement effect.

[0018] 2. By in-situ composite of micron-sized rod-shaped zinc oxide with silver vanadate precursor solution, this method does not require complex equipment or harsh conditions such as high temperature and high pressure. The process is simple and the parameters are easy to control. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope image of ZnO.

[0020] Figure 2 This is a scanning electron microscope image of AgVO3.

[0021] Figure 3This is a scanning electron microscope image of the AgVO3 / ZnO composite material.

[0022] Figure 4 This is a transmission electron microscope (TEM) image of ZnO.

[0023] Figure 5 This is a transmission electron microscope image of AgVO3.

[0024] Figure 6 This is a transmission electron microscope (TEM) image of the AgVO3 / ZnO composite material.

[0025] Figure 7 X-ray diffraction patterns of ZnO, AgVO3, and AgVO3 / ZnO composite materials.

[0026] Figure 8 Fourier transform infrared spectra of ZnO, AgVO3, and AgVO3 / ZnO composite materials.

[0027] Figure 9 The image shows the EDS energy spectrum of the AgVO3 / ZnO composite material.

[0028] Figure 10 The UV-Vis diffuse reflectance spectra of ZnO, AgVO3, and AgVO3 / ZnO composites are shown.

[0029] Figure 11 Degradation curves of RhB catalytic degradation by ZnO, AgVO3, and AgVO3 / ZnO composite materials.

[0030] Figure 12 Degradation effect of 15wt% AgVO3 / ZnO on RhB.

[0031] Figure 13 Degradation effect of 20wt% AgVO3 / ZnO on RhB.

[0032] Figure 14 Degradation effect of 25wt% AgVO3 / ZnO on RhB. Detailed Implementation

[0033] The technical solution of this invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments. To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0034] Example 1 1. Preparation To verify the effect of AgVO3 loading on the photocatalytic performance of the composite material and to determine the optimal composite ratio.

[0035] Example 1-1 In Example 1 of this invention, composite photocatalytic materials of 15wt% AgVO3 / ZnO, 20wt% AgVO3 / ZnO, and 25wt% AgVO3 / ZnO were prepared by changing the amounts of ammonium metavanadate and silver nitrate, respectively.

[0036] The specific preparation steps of the 15wt% AgVO3 / ZnO composite photocatalytic material are as follows: (1) Weigh 7.35g (25.0 mmol) sodium citrate dihydrate and dissolve it in 20mL of distilled water by sonication to obtain solution A; (2) Weigh 1.10 g (5.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 350 r / min, stir at room temperature for 2 h to mix evenly, adjust the pH of the solution to 10 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 8 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 70°C for 8 hours. Finally, heat it to 600°C in air at a heating rate of 7°C / min and keep it at a constant temperature for 2 hours to obtain powdered solid ZnO. (5) Weigh 0.0177g of ammonium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 75.7mmol / L. Weigh 0.0255g of silver nitrate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 75mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the ammonium metavanadate solution. Stir for 30min to mix evenly. Then add the silver nitrate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70°C for 6 hours to obtain 15wt% AgVO3 / ZnO composite photocatalytic material.

[0037] Examples 1-2 The specific preparation steps of the 20wt% AgVO3 / ZnO composite photocatalytic material are as follows: (1) Weigh 7.35g (25.0 mmol) sodium citrate dihydrate and dissolve it in 20mL of distilled water by sonication to obtain solution A; (2) Weigh 1.10 g (5.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 350 r / min, stir at room temperature for 2 h to mix evenly, adjust the pH of the solution to 10 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 8 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 70°C for 8 hours. Finally, heat it to 600°C in air at a heating rate of 7°C / min and keep it at a constant temperature for 2 hours to obtain powdered solid ZnO. (5) Weigh 0.0251g of ammonium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 107 mmol / L. Weigh 0.0364g of silver nitrate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 107 mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the ammonium metavanadate solution. Stir for 30min to mix evenly. Then add the silver nitrate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70℃ for 6h to obtain 20wt% AgVO3 / ZnO composite photocatalytic material.

[0038] Examples 1-3 The specific preparation steps of the 25wt% AgVO3 / ZnO composite photocatalytic material are as follows: (1) Weigh 7.35g (25.0 mmol) sodium citrate dihydrate and dissolve it in 20mL of distilled water by sonication to obtain solution A; (2) Weigh 1.10 g (5.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 350 r / min, stir at room temperature for 2 h to mix evenly, adjust the pH of the solution to 10 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 8 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 70°C for 8 hours. Finally, heat it to 600°C in air at a heating rate of 7°C / min and keep it at a constant temperature for 2 hours to obtain powdered solid ZnO.

[0039] (5) Weigh 0.0334g of ammonium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 142mmol / L. Weigh 0.0480g of silver nitrate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 141mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the ammonium metavanadate solution. Stir for 30min to mix evenly. Then add the silver nitrate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70°C for 6 hours to obtain 25wt% AgVO3 / ZnO composite photocatalytic material.

[0040] 2. Performance Analysis Example 1 of this invention evaluated the degradation effect of composite materials with different AgVO3 loadings on RhB. Comparative experiments revealed that the AgVO3 loading significantly affected the RhB degradation performance. The test method was as follows: 15wt% AgVO3 / ZnO, 20wt% AgVO3 / ZnO, and 25wt% AgVO3 / ZnO composite photocatalyst materials prepared using the method in Example 1 were added to 50 mL of a 1×10⁻⁶ solution. -5 In a mol / L Rhodamine B (RhB) aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a temperature-controlled magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0041] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0042] Figure 12 The graph shows the degradation effect of RhB by 15wt% AgVO3 / ZnO. Figure 13 The graph shows the degradation effect of RhB by 20wt% AgVO3 / ZnO. Figure 14The degradation effect of 25wt% AgVO3 / ZnO on RhB is shown in the figure. Table 1 shows the degradation effect of composite materials with different AgVO3 loadings on RhB. The comparison shows that 20wt% AgVO3 / ZnO has the best catalytic activity and can achieve complete degradation of RhB in only 13min. The samples with lower (15wt%) or higher (25wt%) loadings require 21min and 24min respectively. This shows that both excessive and insufficient loading will cause an inhibitory effect. Therefore, 20wt% is the optimal loading ratio.

[0043] Table 1 shows the degradation effect of composite materials with different AgVO3 loadings on RhB.

[0044] Example 1 of this invention further evaluates the optimal loading ratio of 20wt% AgVO3 / ZnO composite photocatalyst. Figure 1 and Figure 4 The images are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of ZnO, by... Figure 1 and Figure 4 It can be seen that ZnO has a rod-like structure. Figure 2 and Figure 5 The images are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of AgVO3, by... Figure 2 and Figure 5 It can be seen that AgVO3 material has a long, thin rod structure. Figure 3 and Figure 6 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the AgVO3 / ZnO composite material obtained by the preparation method of this invention. Figure 3 and Figure 6 It can be seen that AgVO3 grows in situ on the ZnO surface, with tight interfacial contact and uniform distribution. Figure 7 X-ray diffraction patterns of ZnO, AgVO3, and AgVO3 / ZnO composite materials. Figure 8 Fourier transform infrared spectra of ZnO, AgVO3, and AgVO3 / ZnO composite materials. Figure 9 The EDS spectrum of the AgVO3 / ZnO composite material is shown below. Figure 7 , Figure 8 , Figure 9 It can be seen that the composite material contains the same characteristic peaks as the two single components AgVO3 and ZnO, which indicates that the preparation method of the present invention has successfully obtained the AgVO3 / ZnO composite material. Figure 10The images show the UV-Vis diffuse reflectance spectra of ZnO, AgVO3, and AgVO3 / ZnO composites. ZnO exhibits the worst absorption capacity for visible light, while AgVO3 shows the strongest absorption capacity. The AgVO3 / ZnO composite material falls between the two in terms of visible light absorption capacity. This indicates that the composite material prepared by loading AgVO3 onto the ZnO surface can successfully improve the defect of poor visible light response of ZnO.

[0045] To further verify the catalytic degradation effect of the 20%wt AgVO3 / ZnO composite photocatalyst material in Examples 1-2 on RhB aqueous solution, it was compared with single ZnO and single AgVO3, respectively. The specific steps are as follows: Single ZnO, single AgVO3, and 20%wt AgVO3 / ZnO composite photocatalyst material were added to 50 mL of a solution with a concentration of 1×10⁻⁶. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0046] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0047] Figure 11 Table 1 shows the degradation curves of RhB catalyzed by ZnO, AgVO3, and AgVO3 / ZnO composite materials. Table 2 shows the specific data records of the degradation effects of ZnO, AgVO3, and AgVO3 / ZnO composite materials on RhB. Figure 11 As shown in Table 2, under visible light irradiation, using the AgVO3 / ZnO composite material as a photocatalyst, the RhB aqueous solution completely decolorized within 13 minutes, achieving a degradation rate of 100%, and its UV-Vis absorption characteristic peak completely disappeared, indicating that RhB was completely degraded. In contrast, under the same conditions, the degradation rate of RhB by an equal mass of AgVO3 was only 44%, and the degradation rate of RhB by an equal mass of ZnO was only 4%. This result fully demonstrates that the preparation method of the AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0048] Table 2 shows the degradation effect of RhB on Examples 1-2.

[0049] Example 2 1. Preparation (1) Weigh 5.88 g (20.0 mmol) sodium citrate dihydrate and dissolve it in 20 mL of distilled water by sonication to obtain solution A; (2) Weigh 1.10 g (5.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 400 r / min, stir at room temperature for 1 h to mix evenly, adjust the pH of the solution to 9.5 with sodium bicarbonate, and then transfer it to a high-pressure reactor and react at a constant temperature of 140℃ for 10 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 70°C for 8 hours. Finally, heat it to 650°C in air at a heating rate of 5°C / min and keep it at a constant temperature for calcination for 2 hours to obtain powdered solid ZnO. (5) Weigh 0.00115g of sodium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 47.9mmol / L. Weigh 0.0119g of silver fluoride and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 47 mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the sodium metavanadate solution. Stir for 30min to mix evenly. Then add the silver fluoride aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 50°C for 8 hours to obtain 10wt% AgVO3 / ZnO composite photocatalytic material.

[0050] 2. Performance Analysis Table 3 shows the specific data on the degradation effects of ZnO, AgVO3, and 10wt% AgVO3 / ZnO composite materials on RhB. The specific steps are as follows: Single ZnO, single AgVO3, and 10wt% AgVO3 / ZnO composite photocatalyst materials were added to 50 mL of a 1×10⁻⁶ solution, respectively. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0051] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0052] As shown in Table 3, under visible light irradiation, using the 10%wt AgVO3 / ZnO composite material as a photocatalyst, the degradation rate of RhB aqueous solution was 74% within 13 minutes. In contrast, under the same conditions, the degradation rate of RhB by the same mass of AgVO3 was only 46%, and the degradation rate of RhB by the same mass of ZnO was only 4.5%. This result fully demonstrates that the preparation method of the 10%wt AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0053] Table 3 shows the degradation effect of RhB in Example 2.

[0054] Example 3 1. Preparation (1) Weigh 11.76 g (40.0 mmol) sodium citrate dihydrate and dissolve it in 20 mL of distilled water by sonication to obtain solution A; (2) Weigh 2.20 g (10.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 380 r / min, stir at room temperature for 4 h to mix evenly, adjust the pH value of the solution to 10.5 with sodium bicarbonate, and then transfer it to a high-pressure reactor and react at a constant temperature of 160℃ for 6 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 50°C for 8 hours. Finally, heat it to 550°C at a heating rate of 8°C / min in air atmosphere and keep it at a constant temperature for calcination for 3 hours to obtain powdered solid ZnO. (5) Weigh 0.0059g of ammonium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 24.9mmol / L. Weigh 0.0104g of silver perchlorate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 25mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the silver perchlorate aqueous solution. Stir for 30min to mix evenly. Then add the ammonium metavanadate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70℃ for 6h to obtain 5wt% AgVO3 / ZnO composite photocatalytic material.

[0055] 2. Performance Analysis Table 4 shows the specific data on the degradation effects of ZnO, AgVO3, and 5wt% AgVO3 / ZnO composite materials on RhB. The specific steps are as follows: Single ZnO, single AgVO3, and 5wt% AgVO3 / ZnO composite photocatalyst materials were added to 50 mL of a 1×10⁻⁶ solution, respectively. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0056] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0057] As shown in Table 4, under visible light irradiation, using the 5%wt AgVO3 / ZnO composite material as a photocatalyst, the degradation rate of RhB aqueous solution was 67% within 13 min. In contrast, under the same conditions, the degradation rate of RhB by the same mass of AgVO3 was only 43%, and the degradation rate of RhB by the same mass of ZnO was only 3.8%. This result fully demonstrates that the preparation method of the 5%wt AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0058] Table 4 shows the degradation effect of RhB in Example 3.

[0059] Example 4 1. Preparation (1) Weigh 10.584 g (36.0 mmol) sodium citrate dihydrate and dissolve it in 20 mL of distilled water by sonication to obtain solution A; (2) Weigh 1.32 g (6.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 350 r / min, stir at room temperature for 3 h to mix evenly, adjust the pH of the solution to 10 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 7 h to obtain solution C; (4) Cool the C liquid to room temperature, filter it, and wash it three times with distilled water and anhydrous ethanol respectively. Place the product in a vacuum drying oven at 60°C and dry it for 8 hours. Finally, heat it to 600°C in air at a heating rate of 7°C / min and keep it at a constant temperature for calcination for 3 hours to obtain powdered solid ZnO. (5) Weigh 0.0392g of sodium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 160.5mmol / L. Weigh 0.0536g of silver acetate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 160.5mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the ammonium metavanadate solution. Stir for 30min to mix evenly. Then add the silver nitrate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70℃ for 6 hours to obtain 30wt% AgVO3 / ZnO composite photocatalytic material.

[0060] 2. Performance Analysis Table 5 shows the specific data on the degradation effects of ZnO, AgVO3, and 30wt% AgVO3 / ZnO composite materials on RhB. The specific steps are as follows: Single ZnO, single AgVO3, and 30wt% AgVO3 / ZnO composite photocatalyst materials were added to 50 mL of a 1×10⁻⁶ solution, respectively. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0061] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0062] As shown in Table 5, under illumination, using the 30%wt AgVO3 / ZnO composite material as a photocatalyst, the degradation rate of RhB aqueous solution was 71% within 13 minutes. In contrast, under the same conditions, the degradation rate of RhB by the same mass of AgVO3 was only 43%, and the degradation rate of RhB by the same mass of ZnO was only 4.1%. This result fully demonstrates that the preparation method of the 30%wt AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0063] Table 5 shows the degradation effect of RhB in Example 4.

[0064] Example 5 1. Preparation (1) Weigh 11.76 g (40.0 mmol) sodium citrate dihydrate and dissolve it in 20 mL of distilled water by sonication to obtain solution A; (2) Weigh 2.2g (10.0 mmol) of zinc acetate and dissolve it in 10mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 400 r / min, stir at room temperature for 2 h to mix evenly, adjust the pH value of the solution to 10.5 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 7 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it and wash it three times with distilled water and anhydrous ethanol respectively. Place the product in a vacuum drying oven at 60°C and dry it for 8 hours. Finally, heat it to 600°C in air at a heating rate of 6°C / min and keep it at a constant temperature for calcination for 3 hours to obtain powdered solid ZnO. (5) Weigh 0.0334g of sodium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 142mmol / L. Weigh 0.0480g of silver fluoride and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 141mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the silver fluoride solution. Stir for 30min to mix evenly. Then add the sodium metavanadate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 50°C for 8 hours to obtain 25wt% AgVO3 / ZnO composite photocatalytic material.

[0065] 3. Performance Analysis Table 6 shows the specific data on the degradation effects of ZnO, AgVO3, and 25wt% AgVO3 / ZnO composite materials on RhB. The specific steps are as follows: Single ZnO, single AgVO3, and 25wt% AgVO3 / ZnO composite photocatalyst materials were added to 50 mL of a 1×10⁻⁶ solution, respectively. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0066] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0067] As shown in Table 6, under illumination, using the 25%wt AgVO3 / ZnO composite material as a photocatalyst, the degradation rate of RhB aqueous solution was 70% within 13 minutes. In contrast, under the same conditions, the degradation rate of RhB by the same mass of AgVO3 was only 43.8%, and the degradation rate of RhB by the same mass of ZnO was only 4.1%. This result fully demonstrates that the preparation method of the 25%wt AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0068] Table 6 shows the degradation effect of RhB in Example 5.

[0069] Example 6 1. Preparation (1) Weigh 8.82 g (30.0 mmol) sodium citrate dihydrate and dissolve it in 20 mL of distilled water by sonication to obtain solution A; (2) Weigh 1.10 g (5.0 mmol) of zinc acetate and dissolve it in 20 mL of distilled water by sonication to obtain solution B; (3) Add solution A slowly to solution B at a stirring speed of 400 r / min, stir at room temperature for 2 h to mix evenly, adjust the pH value of the solution to 10.5 with NaOH, and then transfer it to a high-pressure reactor and react at a constant temperature of 150℃ for 7 h to obtain solution C. (4) Cool the C liquid to room temperature, filter it, wash it three times with distilled water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 60°C for 8 hours. Finally, heat it to 600°C in air at a heating rate of 6°C / min and keep it at a constant temperature for calcination for 3 hours to obtain powdered solid ZnO. (5) Weigh 0.0354g of ammonium metavanadate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 150mmol / L. Weigh 0.0255g of silver perchlorate and dissolve it in 2mL of distilled water to prepare a solution with a concentration of 75mmol / L. Weigh 0.2g of ZnO (2.47mmol) obtained above and add it to the ammonium metavanadate solution. Stir for 30min to mix evenly. Then add the silver perchlorate aqueous solution to obtain solution D. (6) Stir the D liquid evenly, collect the precipitate by centrifugation, wash it 2-3 times with distilled water and anhydrous ethanol, and then dry it under vacuum at 70°C for 6 hours to obtain 15wt% AgVO3 / ZnO composite photocatalytic material.

[0070] 4. Performance Analysis Table 7 shows the specific data on the degradation effects of ZnO, AgVO3, and 15wt% AgVO3 / ZnO composite materials on RhB. The specific steps are as follows: Single ZnO, single AgVO3, and 15wt% AgVO3 / ZnO composite photocatalyst materials were added to 50 mL of a 1×10⁻⁶ solution, respectively. -5 In a mol / L RhB aqueous solution, the mixture was magnetically stirred for 0.5 h in the dark on a constant-temperature magnetic stirrer to reach adsorption saturation. The solution was then irradiated under a 300W xenon lamp (with a UV filter to block all UV light with wavelengths less than 420 nm), with the liquid surface 10 cm above the light source. Samples (5 mL each time) were taken every 3 minutes. The catalyst solids were removed by centrifugation, and the supernatant was collected. The absorption curve was measured using a UV-Vis spectrometer. The maximum absorption wavelength was found around 554 nm; this maximum value was used in the formula for calculation.

[0071] In the formula: η is the degradation rate; C0 is the absorbance value measured after the adsorption equilibrium is reached in the dark for 30 minutes; C t This is the absorbance value measured after illumination for a certain period of time.

[0072] As shown in Table 7, under illumination, using the 15%wt AgVO3 / ZnO composite material as a photocatalyst, the degradation rate of RhB aqueous solution was 76% within 13 minutes. In contrast, under the same conditions, the degradation rate of RhB by the same mass of AgVO3 was only 43.8%, and the degradation rate of RhB by the same mass of ZnO was only 4.2%. This result fully demonstrates that the preparation method of the 15%wt AgVO3 / ZnO composite material described in this invention produces a significant synergistic effect, and its catalytic performance is more efficient than that of a single component.

[0073] Table 7 shows the degradation effect of RhB in Example 6.

[0074] The above description is a preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Therefore, any equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a silver vanadate / zinc oxide composite photocatalytic material, comprising the following specific steps: (1) Weigh out sodium citrate dihydrate and add it to distilled water, then dissolve it by sonication to obtain solution A; (2) Weigh zinc acetate and add it to distilled water, then sonicate to dissolve it to obtain solution B; (3) The A solution is slowly added to the B solution under continuous stirring. After mixing evenly at room temperature, an alkaline reagent is added to adjust the pH value to the preset value. Then, the solution is transferred to a high-pressure reactor for constant temperature hydrothermal reaction to obtain the C solution. (4) The C liquid is subjected to solid-liquid separation, washing, vacuum drying, and high-temperature calcination to obtain ZnO; (5) Add the ZnO to an aqueous solution of metavanadate and an aqueous solution of soluble silver salt to obtain solution D; (6) The D liquid is stirred, centrifuged, the precipitate is collected, washed and vacuum dried to obtain silver vanadate / zinc oxide composite photocatalytic material.

2. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, Solution A is an aqueous solution of sodium citrate with a concentration of 1.0~2.0 mol / L, and solution B is an aqueous solution of zinc acetate with a concentration of 0.25~1.0 mol / L.

3. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, The molar ratio of zinc acetate in solution B to sodium citrate dihydrate in solution A is 1:4 to 1:

6.

4. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, In step (3), liquid A is slowly added dropwise to liquid B under continuous stirring. The stirring speed is 350~400 r / min, and the stirring time at room temperature is 1~4 h. The alkaline reagent is either sodium hydroxide or sodium bicarbonate, and the preset pH value is 9.5~10.5; The constant-temperature hydrothermal reaction is carried out at a temperature of 140~160℃ for 6~10 h.

5. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, In step (4), the atmosphere for high-temperature calcination is air, the calcination temperature is 550~650℃, the heating rate is 5~8℃ / min, and the calcination time is 2~3h.

6. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, In step (5), the concentration of the metavanadate aqueous solution is 0.025~0.160 mol / L, and the concentration of the soluble silver salt aqueous solution is 0.025~0.160 mol / L; The metavanadate aqueous solution is any one of ammonium metavanadate aqueous solution and sodium metavanadate aqueous solution; the soluble silver salt aqueous solution is any one of silver nitrate aqueous solution, silver fluoride aqueous solution, silver acetate aqueous solution, and silver perchlorate aqueous solution. The soluble silver salt aqueous solution is composed of a mixture of soluble silver salt and an aqueous solution, wherein the molar ratio of ZnO to soluble silver salt is 7~50:

1.

7. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, Step (5) includes: Weigh the ZnO, first add a soluble silver salt aqueous solution, stir well, then add a metavanadate aqueous solution; or Weigh out the ZnO, first add it to a metavanadate aqueous solution, stir until homogeneous, and then add a soluble silver salt aqueous solution.

8. The method for preparing a silver vanadate / zinc oxide composite photocatalytic material according to claim 1, characterized in that, In step (6), the washing refers to washing with distilled water and ethanol 3 to 4 times respectively, the vacuum drying temperature is 50 to 70°C, and the vacuum drying time is 2 to 8 hours; the AgVO3 loading ratio of the silver vanadate / zinc oxide composite photocatalyst is 5 to 30%.

9. A silver vanadate / zinc oxide composite photocatalytic material, characterized in that, It is prepared by the method of any one of claims 1 to 8 for the preparation of silver vanadate / zinc oxide composite photocatalyst material.

10. The application of the silver vanadate / zinc oxide composite photocatalyst material according to claim 9 in the treatment of gaseous organic pollutants, volatile organic pollutants and wastewater.

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