Preparation of porous nano-zinc oxide photocatalyst and application of porous nano-zinc oxide photocatalyst in antibiotic degradation

Abstract

The invention relates to the technical field of photocatalysts, in particular to preparation of a porous nano-zinc oxide photocatalyst and application of the porous nano-zinc oxide photocatalyst in antibiotic degradation, which comprises the following steps: S1, selecting and preparing a template, selecting and preparing a proper template material which is an ordered porous material; s2, preparing a precursor solution; s3, filling a precursor; s4, material deposition; s5, removing the template; s6, post-treatment, wherein the obtained material is washed, dried and subjected to heat treatment; and S7, performance testing. The porous nano zinc oxide photocatalyst is prepared by a template synthesis method, a nano structure with a specific shape and size can be prepared, the porous structure provides a relatively high specific surface area and is beneficial to improvement of catalytic efficiency, a nano material with uniform size distribution can be prepared by the template synthesis method, and the method has good repeatability and is suitable for industrial production. The method is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the technical field of photocatalysts, specifically to the preparation of porous nano zinc oxide photocatalysts and their application in antibiotic degradation. Background Technology

[0002] Porous nano-zinc oxide (ZnO), as a highly efficient photocatalyst, shows broad application prospects in environmental remediation, particularly in antibiotic degradation. Antibiotics, as important drugs for treating human and animal diseases, are used extensively in medicine, animal husbandry, and aquaculture, leading to their residues in the environment. Degrading antibiotic residues has become a crucial issue in environmental protection. However, existing methods for preparing zinc oxide photocatalysts suffer from difficulties in controlling their shape and size, and their specific surface area is relatively low, resulting in low catalytic efficiency. Therefore, improvements are needed. Summary of the Invention

[0003] The purpose of this invention is to provide the preparation of porous nano zinc oxide photocatalysts and their application in antibiotic degradation, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: preparation of porous nano-zinc oxide photocatalysts, comprising the following steps: S1: Select and prepare templates. Select and prepare suitable template materials. Template materials are ordered porous materials, such as polystyrene (PS) colloidal crystals, anodic aluminum oxide (AAO) membranes, or other porous polymers. S2: Preparation of precursor solution. Select a precursor, use zinc salt (such as zinc acetate, zinc nitrate, etc.) as the precursor of ZnO, and then prepare a solution by dissolving the zinc salt in an appropriate solvent, such as ethanol, water or a mixed solvent, to prepare a precursor solution of a certain concentration. S3: Precursor filling, the template material is immersed in the precursor solution, and the precursor solution is drawn into the pores of the template through capillary action; S4: Material deposition, utilizing chemical deposition, by changing the pH value and temperature of the solution or adding a precipitant, to induce a chemical reaction of the precursor in the template pores to form ZnO precipitate; S5: Template removal. After the reaction is complete, remove the template, rinse it with deionized water, and immerse the template in a dissolving solution to remove it. For PS colloidal crystal templates, organic solvents (such as benzene, tetrahydrofuran, etc.) can be used to dissolve them to remove the template. For AAO templates, phosphoric acid or sodium hydroxide solution can be used for etching to remove the template. S6: Post-processing: The obtained materials are washed, dried and heat-treated. Washing: Use deionized water or other solvents to wash away residual template materials and unreacted precursors. Drying: Dry the sample under mild conditions to avoid structural collapse caused by high temperature. Heat treatment: In order to improve the crystallinity and photocatalytic activity of ZnO, the sample can be annealed. S7: Performance testing, the obtained photocatalysts were characterized and photocatalytically tested respectively.

[0005] Preferably, in step S1, a suitable template material is selected and fabricated as a PS colloidal crystal template. PS colloidal crystals are prepared by solution self-assembly. PS microspheres are suspended in a solvent, and through evaporation-induced self-assembly or other self-assembly techniques, the microspheres form an ordered three-dimensional array on the substrate.

[0006] Preferably, in step S3, for cases with low solution concentration, vacuum filtration is used to accelerate the filling of the precursor.

[0007] Preferably, in step S4, the template filled with the precursor is first placed in a sealed reactor for preliminary synthesis or pretreatment, such as the dissolution, mixing, and preliminary reaction of the precursor. The precursor is dissolved in the sealed reactor, where the zinc source (such as zinc nitrate or zinc acetate) can be dissolved in a suitable solvent. The template filling uses a solid template, which can be filled with the precursor solution in the sealed reactor to ensure that the template pores are uniformly filled. The preliminary reaction is carried out at a lower temperature to form a precursor precipitate or gel. After the sealing reactor step is completed, the reaction system is transferred to a high-pressure reactor for hydrothermal or solvothermal reaction under high temperature and high pressure conditions to promote the crystallization and growth of the material. The reaction is carried out for 5-24 hours under high temperature and high pressure conditions (100-200℃, 1-5MPa) to promote the conversion of precursors and the crystallization of nano zinc oxide, forming a porous structure.

[0008] Porous nano-zinc oxide photocatalysts are used for the degradation of antibiotics.

[0009] Compared with the prior art, the beneficial effects of the present invention are: This invention prepares porous zinc oxide nano-photocatalysts via template synthesis, which can produce nanostructures with specific shapes and sizes. The porous structure provides a high specific surface area, which is beneficial to improving catalytic efficiency. The template synthesis method can prepare nanomaterials with uniform size distribution. This method has good reproducibility and is suitable for large-scale production. Detailed Implementation

[0010] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0011] This invention provides a technical solution: the preparation of porous nano-zinc oxide photocatalysts, comprising the following steps: S1: Select and prepare templates. Select and prepare suitable template materials. Template materials are ordered porous materials, such as polystyrene (PS) colloidal crystals, anodic aluminum oxide (AAO) membranes, or other porous polymers. S2: Preparation of precursor solution. Select a precursor, use zinc salt (such as zinc acetate, zinc nitrate, etc.) as the precursor of ZnO, and then prepare a solution by dissolving the zinc salt in an appropriate solvent, such as ethanol, water or a mixed solvent, to prepare a precursor solution of a certain concentration. S3: Precursor filling, the template material is immersed in the precursor solution, and the precursor solution is drawn into the pores of the template through capillary action; S4: Material deposition, utilizing chemical deposition, by changing the pH value and temperature of the solution or adding a precipitant, to induce a chemical reaction of the precursor in the template pores to form ZnO precipitate; S5: Template removal. After the reaction is complete, remove the template, rinse it with deionized water, and immerse the template in a dissolving solution to remove it. For PS colloidal crystal templates, organic solvents (such as benzene, tetrahydrofuran, etc.) can be used to dissolve them to remove the template. For AAO templates, phosphoric acid or sodium hydroxide solution can be used for etching to remove the template. S6: Post-processing: The obtained materials are washed, dried and heat-treated. Washing: Use deionized water or other solvents to wash away residual template materials and unreacted precursors. Drying: Dry the sample under mild conditions to avoid structural collapse caused by high temperature. Heat treatment: In order to improve the crystallinity and photocatalytic activity of ZnO, the sample can be annealed. S7: Performance testing. The obtained photocatalyst was characterized and tested. Characterization: The porous nano-ZnO was characterized in structure and performance using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption and other methods. Photocatalytic testing: The activity of the photocatalyst was evaluated by degrading model pollutants (such as dyes, antibiotics, etc.).

[0012] In S1, a suitable template material is selected and fabricated as a PS colloidal crystal template. PS colloidal crystals are prepared by solution self-assembly. PS microspheres are suspended in a solvent and formed into an ordered three-dimensional array on the substrate by evaporation-induced self-assembly (EISA) or other self-assembly techniques.

[0013] In S3, for cases with low solution concentration, vacuum filtration is used to accelerate the loading of the precursor.

[0014] In S4, the template filled with the precursor is first placed in a sealed reactor for preliminary synthesis or pretreatment, such as the dissolution, mixing, and preliminary reaction of the precursor. The precursor is dissolved in the sealed reactor, where the zinc source (such as zinc nitrate or zinc acetate) can be dissolved in a suitable solvent. The template filling uses a solid template, which can be filled with the precursor solution in the sealed reactor to ensure that the template pores are uniformly filled. The preliminary reaction is carried out at a lower temperature to form a precursor precipitate or gel. After the sealing reactor step is completed, the reaction system is transferred to a high-pressure reactor for hydrothermal or solvothermal reaction under high temperature and high pressure conditions to promote the crystallization and growth of the material. The reaction is carried out for 5-24 hours under high temperature and high pressure conditions (100-200℃, 1-5MPa) to promote the conversion of precursors and the crystallization of nano zinc oxide, forming a porous structure.

[0015] Specific Implementation: A PS colloidal crystal template was prepared on a glass slide using PS microspheres via a self-assembly method. 2.0 g of zinc acetate was dissolved in 20 mL of ethanol and stirred until completely dissolved. The PS template was immersed in the zinc acetate solution for 10 minutes, allowing the solution to fill the template pores through capillary action. The template was then removed, and excess solution was absorbed with filter paper. The template filled with the precursor was placed in a high-pressure reactor, and deionized water was added to 1 / 3 of the reactor volume. The reaction system was then transferred to a sealed reactor and heated to 120°C for 24 hours. After the reaction was complete, the template was removed, rinsed with deionized water, and then immersed in benzene for 24 hours to dissolve the PS microspheres and remove the template. The sample after template removal was dried at 60°C for 12 hours. Annealing was then performed in air at a heating rate of 2°C / min to 300°C for 2 hours. The structure and properties of the prepared porous nano-ZnO were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption.

[0016] This photocatalyst is used for the degradation of antibiotics, and the application effect of the photocatalyst is tested by degrading oxytetracycline.

[0017] The experimental conditions are as follows: Photocatalyst dosage: 10 mg; Initial concentration of oxytetracycline: 20 mg / L; Light exposure time: 120 minutes; UV lamp power: 8 W; Reactor volume: 50 mL; Temperature: Room temperature (approximately 25°C). 10 mg of porous ZnO nano-photocatalyst was added to 50 mL of 20 mg / L OTC solution. The solution was stirred in the dark for 30 minutes to reach adsorption-desorption equilibrium. A UV lamp was then turned on, and a timer was started. Samples were taken at regular intervals (e.g., every 20 minutes), and the absorbance of the samples was measured at the maximum absorption wavelength of OTC (approximately 360 nm) using a UV-Vis spectrophotometer. The degradation rate of OTC was calculated based on the change in absorbance. Degradation rate = [(A0 - At) / A0] × 100%, where A0 is the initial absorbance and At is the absorbance after time t.

[0018] Samples were taken every 20 minutes from the start of the experiment to measure and calculate absorbance and degradation rate. The experimental data for absorbance and degradation rate obtained are as follows: Absorbance (A): 1.20, 1.05, 0.85, 0.65, 0.45, 0.30, 0.15; Degradation rate (%): 0, 12.5, 29.2, 46.7, 62.5, 75.0, 87.5. The experimental results show that the absorbance of OTC gradually decreases with increasing illumination time, indicating that the concentration of OTC is decreasing and the photocatalyst is functioning. Within a 120-minute illumination period, the degradation rate of OTC reached 87.5%, demonstrating that the prepared porous nano-ZnO photocatalyst has good photocatalytic activity. These results prove the effectiveness of the porous nano-ZnO photocatalyst prepared by the template synthesis method in the photocatalytic degradation of antibiotics. By optimizing the catalyst structure and reaction conditions, the degradation efficiency can be improved, allowing for further application in practical environmental purification processes.

[0019] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Preparation of porous nano-zinc oxide photocatalysts, characterized in that: It includes the following steps: S1: Select and prepare templates, select and prepare suitable template materials, the template materials are ordered porous materials; S2: Preparation of precursor solution. Select a precursor, use zinc salt as the precursor of ZnO, and then prepare a solution by dissolving the zinc salt in an appropriate solvent to prepare a precursor solution of a certain concentration. S3: Precursor filling, the template material is immersed in the precursor solution, and the precursor solution is drawn into the pores of the template through capillary action; S4: Material deposition, utilizing chemical deposition, by changing the pH value and temperature of the solution or adding a precipitant, to induce a chemical reaction of the precursor in the template pores to form ZnO precipitate; S5: Template removal. After the reaction is complete, remove the template, rinse it with deionized water, and immerse the template in the dissolving solution to remove the template. S6: Post-processing, the above-obtained materials are washed, dried and heat-treated; S7: Performance testing, the obtained photocatalysts were characterized and photocatalytically tested respectively.

2. The preparation of the porous nano-zinc oxide photocatalyst according to claim 1, characterized in that: In step S1, a suitable template material is selected and fabricated as a PS colloidal crystal template. PS colloidal crystals are prepared by solution self-assembly. PS microspheres are suspended in a solvent and evaporation-induced self-assembly or other self-assembly techniques are used to form an ordered three-dimensional array of microspheres on the substrate.

3. The preparation of the porous nano-zinc oxide photocatalyst according to claim 1, characterized in that: In step S3, for cases with low solution concentration, vacuum filtration is used to accelerate the filling of the precursor.

4. The preparation of the porous nano-zinc oxide photocatalyst according to claim 1, characterized in that: In step S4, the template filled with the precursor is first placed in a sealed reactor for preliminary synthesis or pretreatment. After the sealing reactor step is completed, the reaction system is transferred to a high-pressure reactor for hydrothermal or solvothermal reaction under high temperature and high pressure conditions to promote the crystallization and growth of the material. The reaction is carried out for 5-24 hours under high temperature and high pressure conditions (100-200℃, 1-5MPa) to promote the conversion of precursors and the crystallization of nano zinc oxide, forming a porous structure.

5. The porous nano-zinc oxide photocatalyst according to any one of claims 1-4, characterized in that: This photocatalyst is used for the degradation of antibiotics.