Preparation method and application of polydopamine modified Cu2O catalyst

Abstract

The application provides a preparation method of a polydopamine modified Cu2O catalyst and application thereof, and belongs to the technical field of environmental pollution treatment. The preparation method comprises the following steps: S1. mixing a copper salt, a dispersing agent and pure water, adding an alkali solution and a reducing agent under water bath stirring in sequence, centrifuging, washing and drying after reaction to obtain Cu2O powder; S2. dissolving dopamine hydrochloride in a buffer solution, adding the Cu2O powder prepared in step S1, stirring and reacting at room temperature, collecting the precipitate and washing and drying to obtain a polydopamine modified Cu2O catalyst. The activity, stability and cycle performance of the Cu2O catalyst are significantly improved through polydopamine modification, and the mild and simple liquid phase preparation method has the advantages of efficient degradation and industrial application.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution control technology, and more specifically, to a method for preparing polydopamine-modified Cu2O catalysts and their applications. Background Technology

[0002] As public demands for health and ecological environment quality continue to rise, standards and regulations in the field of water environment management are becoming increasingly stringent. Residual antibiotic pollutants in wastewater, due to their persistent degradation, ecotoxicity, and potential risk of inducing bacterial resistance, have become a pressing global environmental problem. Tetracycline (TC), a broad-spectrum antibiotic widely used in medicine, animal husbandry, and aquaculture, generates large amounts of tetracycline-containing wastewater during its production and use, primarily originating from the pharmaceutical and aquaculture industries, posing multiple threats to the environment and public health.

[0003] The residual antibiotic components in this type of wastewater are chemically stable and difficult to degrade effectively through natural processes. Once discharged into water bodies, they not only severely disrupt the balance of aquatic ecosystems, inhibit the activity of beneficial microorganisms, and interfere with the self-purification function of water bodies, but also strongly induce antibiotic resistance in bacteria due to long-term exposure to low concentrations, promoting the rapid spread of resistance genes in water and soil. These resistance genes may eventually be transmitted to human pathogens through the food chain or direct environmental contact, posing a significant challenge to the treatment of clinical infectious diseases and seriously threatening public health and safety. Furthermore, the wastewater may further pollute soil and groundwater, affecting crop safety and constituting a systemic risk from the environment to health. Therefore, the efficient and thorough removal of tetracycline pollutants is not only a technical requirement for environmental protection but also a crucial link in breaking the chain of antibiotic resistance transmission and ensuring public health and safety.

[0004] Among numerous water treatment technologies, advanced oxidation technologies have attracted significant attention due to their ability to efficiently generate highly oxidizing free radicals. Among these, the photo-mediated peracetic acid (PAA) activation system demonstrates significant advantages in degrading tetracycline wastewater. This system utilizes light energy (such as ultraviolet or visible light) to excite peracetic acid, efficiently generating various highly reactive species such as hydroxyl radicals (•OH) and organic oxygen radicals (CH3CO(O)O•, CH3COO•, etc.), achieving rapid attack, structural destruction, and deep mineralization of tetracycline molecules. Compared to traditional Fenton (Fe... 2+Photo-mediated peracetic acid activation systems utilize either H2O2 (hydrogen ions) or ozone oxidation (O3) technology, offering milder reaction conditions and avoiding secondary pollution issues such as iron sludge. Crucially, this system effectively attacks the core pharmacodynamic structure of tetracycline (such as the bisphenol ring) and simultaneously degrades its highly toxic intermediates, significantly inhibiting the generation and spread of resistance genes. Furthermore, peracetic acid and its decomposition products are water, oxygen, and carbon dioxide, making it environmentally friendly and eliminating the risk of secondary pollution. Therefore, this technology provides a promising solution for the efficient and green treatment of tetracycline wastewater and the control of antibiotic resistance spread.

[0005] In the photo-mediated peracetic acid activation system, developing efficient catalysts is key to improving its performance. Cu₂O, as a typical p-type semiconductor photocatalyst, exhibits unique advantages and obvious shortcomings. Its core advantage lies in its suitable bandgap, demonstrating good visible light response and the ability to synergistically catalyze peracetic acid. Under illumination, the photogenerated electrons produced by Cu₂O can efficiently activate peracetic acid, generating various reactive oxygen species; simultaneously, its own Cu… + / Cu 2+ The valence state cycle of Cu2O can also heterogeneously catalyze the decomposition of peracetic acid, thereby achieving efficient degradation and mineralization of tetracycline and significantly improving light energy utilization efficiency and oxidation capacity. However, its shortcomings are also quite prominent: on the one hand, Cu2O is prone to photocorrosion during the reaction process, leading to the dissolution of copper ions, which not only reduces the activity of the catalyst but may also bring potential risks of secondary metal pollution; on the other hand, its high recombination rate of photogenerated electron-hole pairs limits further improvement of its catalytic activity, and the material has poor structural stability and recycling performance in water, making it difficult to meet the needs of practical applications.

[0006] In summary, there is an urgent need to develop a Cu2O-based catalyst that is simple to prepare, has high catalytic activity, stable structure, and is recyclable, in order to overcome the technical bottlenecks of existing Cu2O catalysts in the photo-mediated degradation of tetracycline by peracetic acid, such as insufficient activity, severe copper ion dissolution, and poor recycling performance. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing polydopamine-modified Cu2O catalysts and their applications, aiming to solve the problems mentioned in the background art.

[0008] This invention is achieved through a method for preparing a polydopamine-modified Cu2O catalyst, comprising the following steps: S1. Mix copper salt, dispersant and pure water, add alkali solution and reducing agent in sequence under water bath stirring, centrifuge, wash and dry after reaction to obtain Cu2O powder; S2. Dissolve dopamine hydrochloride in buffer solution, add the Cu2O powder prepared in step S1, stir the reaction at room temperature, collect the precipitate and wash and dry it to obtain polydopamine-modified Cu2O catalyst.

[0009] Optionally, in step S1, the copper salt is CuCl2·2H2O; the dispersant is polyvinylpyrrolidone with an average molecular weight of 24,000; the alkaline solution is NaOH solution; and the reducing agent is ascorbic acid solution.

[0010] Optionally, in step S1, the concentration of the copper salt is 10 mM, the amount of the dispersant added is 6.0 g, the concentration of the alkaline solution is 2 M, and the concentration of the reducing agent is 0.6 M.

[0011] Optionally, in step S1, the temperature of the water bath stirring is 55°C and the reaction time is 3 hours; in step S2, the buffer solution is Tris-hydrochloric acid buffer with a concentration of 50 mM.

[0012] Optionally, in step S2, the amount of dopamine hydrochloride added is 50 mg, the amount of Cu2O powder added is 0.03 g, and the stirring reaction time is 8 h.

[0013] Optionally, in steps S1 and S2, the drying is performed under vacuum at a temperature of 60°C, the drying time for preparing Cu2O powder is 12 h, and the drying time for preparing polydopamine-modified Cu2O catalyst is 6 h.

[0014] Another objective of this invention is to provide an application of the polydopamine-modified Cu2O catalyst prepared by the aforementioned method in the degradation of tetracycline wastewater. The polydopamine-modified Cu2O catalyst is applied to a photo-mediated peracetic acid activation system, and through the synergistic effect of photogenerated electrons and peracetic acid, reactive oxygen species are generated to degrade tetracycline in the water.

[0015] Optionally, the process includes the following steps: mixing and dispersing polydopamine-modified Cu2O catalyst powder with tetracycline solution, irradiating with a light source, and simultaneously injecting peracetic acid solution into the reaction system to initiate the degradation reaction.

[0016] Optionally, the light source is a 300W xenon lamp equipped with an AM 1.5 filter; the initial concentration of the tetracycline solution is 20 mg / L; and the concentration of the peracetic acid solution is 10 mM.

[0017] Optionally, the dosage of the polydopamine-modified Cu2O catalyst is 5-20 mg / 100 mL tetracycline solution; the dosage of the peracetic acid solution is 0.5-1 mL / 100 mL tetracycline solution.

[0018] The method for preparing polydopamine-modified Cu2O catalyst and its application provided by this invention have the following beneficial effects: This invention achieves a simple synthesis of catalysts under mild conditions via a liquid-phase reduction-polymerization method, effectively overcoming the shortcomings of existing Cu2O catalysts, such as insufficient activity, severe copper ion dissolution, and poor cycling performance. This method is simple to operate, requires no special equipment, and is conducive to industrial scale-up. The prepared catalyst not only significantly improves the catalytic activity and stability of photo-mediated peracetic acid-activated degradation of tetracycline, but also effectively inhibits metal ion dissolution through a polydopamine modification layer, greatly enhancing the structural stability and recyclability of the material, thus combining high catalytic efficiency with good environmental safety.

[0019] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0021] Figure 1 The images show the XRD patterns of Cu2O surfaces before and after modification with polydopamine.

[0022] Figure 2 The image shows a comparison of FT-IR images of Cu2O surfaces before and after modification with polydopamine.

[0023] Figure 3 Comparison of the performance of Cu2O and polydopamine-modified Cu2O in the photo-mediated peracetic acid activation system for degrading tetracycline.

[0024] Figure 4 A bar chart showing the leaching of Cu ions during the degradation of tetracycline using Cu2O and polydopamine-modified Cu2O in a photo-mediated peracetic acid activation system.

[0025] Figure 5 Bar chart showing the cyclic degradation performance of Cu2O and polydopamine-modified Cu2O in a photo-mediated peracetic acid-activated system for the degradation of tetracycline. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] Example 1 This embodiment provides a method for preparing a polydopamine-modified Cu2O catalyst, the specific steps of which are as follows: First, the Cu2O precursor was synthesized: 10 mM CuCl2·2H2O and 6.0 g polyvinylpyrrolidone (PVP, average molecular weight 24000) were dissolved in 100 mL of deionized water under stirring in a 55 °C water bath. Then, 10 mL of 2 M NaOH solution was added dropwise to the above solution. After stirring for 30 min, 10 mL of 0.6 M ascorbic acid solution was added dropwise as a reducing agent. The reaction was continued under the above conditions for 3 h. After the reaction was completed, the brick-red precipitate at the bottom was collected by centrifugation, washed three times successively with deionized water and anhydrous ethanol, and then placed in a vacuum drying oven and dried at 60 °C for 12 h to obtain Cu2O powder.

[0028] Next, polydopamine surface modification was performed: 50 mg of dopamine hydrochloride was dissolved in 10 mL of Tris-hydrochloric acid (50 mM) buffer solution. Subsequently, 0.03 g of the Cu2O powder prepared above was dispersed in the solution, and the reaction was continuously stirred at room temperature for 8 h. After the reaction was completed, the precipitate was collected, washed four times alternately with anhydrous ethanol and deionized water, and finally dried at 60 °C under vacuum for 6 h to obtain the polydopamine-modified Cu2O catalyst.

[0029] The application and degradation performance tests of the catalyst are as follows: 10 mg of the polydopamine-modified Cu2O catalyst powder prepared above was added to 100 mL of tetracycline (TC) solution with an initial concentration of 20 mg / L, and placed in a quartz jacketed reactor with a circulating water cooling device, and ultrasonically dispersed evenly.

[0030] Irradiate the system with a light source (a 300W xenon lamp equipped with an AM 1.5 filter) and simultaneously inject 1 mL of 10 mM peracetic acid (PAA) solution into the reaction system to initiate the photo-mediated peracetic acid activation and degradation of tetracycline.

[0031] At reaction times of 1, 5, 10, and 20 min, 3 mL samples were taken from the reaction system. After centrifugation to remove the catalyst, the supernatant was taken and the characteristic absorbance of the residual tetracycline was measured using a UV-Vis spectrophotometer (UV-2550, Shimadzu, Japan) in the wavelength range of 300-450 nm to calculate its concentration.

[0032] The experimental results are as follows: The determination showed that the degradation rate of tetracycline reached 99.77% after 20 minutes of reaction.

[0033] Example 2 This embodiment aims to investigate the effect of catalyst dosage on degradation efficiency. The photo-mediated peracetic acid-activated degradation of tetracycline was carried out using the polydopamine-modified Cu2O catalyst prepared in Example 1.

[0034] The experimental steps are as follows: Five mg of polydopamine-modified Cu2O catalyst powder was added to 100 mL of a 20 mg / L tetracycline solution and placed in a quartz jacketed reactor equipped with a circulating water cooling system for mixing and dispersion. Subsequently, a light source (a 300 W xenon lamp equipped with an AM 1.5 filter) was turned on for irradiation, and 1 mL of a 10 mM peracetic acid solution was simultaneously injected into the reaction system to initiate the photocatalytic degradation reaction.

[0035] At 1, 5, 10 and 20 min of reaction, 3 mL of reaction solution was collected. After centrifugation to remove the solid catalyst, the supernatant was taken and the concentration of residual tetracycline was determined by full wavelength scanning in the wavelength range of 300-450 nm using a UV-Vis spectrophotometer (UV-2550, Shimadzu, Japan).

[0036] The experimental results are as follows: The results showed that, with a catalyst dosage of 5 mg, the degradation rate of tetracycline was 79.41% after 20 minutes of reaction.

[0037] Example 3 This embodiment aims to further investigate the effect of catalyst dosage on degradation efficiency. The photo-mediated peracetic acid-activated degradation of tetracycline was carried out using the polydopamine-modified Cu2O catalyst prepared in Example 1.

[0038] The experimental steps are as follows: 15 mg of polydopamine-modified Cu2O catalyst powder was added to 100 mL of a 20 mg / L tetracycline solution and placed in a quartz jacketed reactor equipped with a circulating water cooling system for mixing and dispersion. Subsequently, a light source (a 300 W xenon lamp equipped with an AM1.5 filter) was turned on for irradiation, and 1 mL of a 10 mM peracetic acid solution was simultaneously injected into the reaction system to initiate the photocatalytic degradation reaction.

[0039] At 1, 5, 10 and 20 min of reaction, 3 mL of reaction solution was collected. After centrifugation to remove the solid catalyst, the supernatant was taken and the concentration of residual tetracycline was determined by full wavelength scanning in the wavelength range of 300-450 nm using a UV-Vis spectrophotometer (UV-2550, Shimadzu, Japan).

[0040] The experimental results are as follows: The test results showed that when the catalyst dosage was 15 mg, the degradation rate of tetracycline reached 99.79% after 20 min of reaction.

[0041] Example 4 This embodiment further investigates the effect of different catalyst dosages on the efficiency of photomediated peracetic acid activation and degradation of tetracycline, using the polydopamine-modified Cu2O catalyst prepared in Example 1 for the experiment.

[0042] The experimental steps are as follows: Weigh 20 mg of polydopamine-modified Cu2O catalyst powder and add it to 100 mL of tetracycline solution with an initial concentration of 20 mg / L. Place the solution in a quartz jacketed reactor with a circulating water cooling system and disperse the catalyst evenly by ultrasonication.

[0043] Irradiate the system with a light source (a 300W xenon lamp equipped with an AM 1.5 filter) and simultaneously inject 1 mL of 10 mM peracetic acid (PAA) solution into the reaction system to initiate the photocatalytic degradation reaction.

[0044] At 1, 5, 10 and 20 min of reaction, 3 mL of reaction solution was quantitatively transferred from the reactor, and the solid catalyst was removed by high-speed centrifugation (e.g., centrifugation at 10000 rpm for 5 min), and the supernatant was taken.

[0045] The supernatant was scanned in the wavelength range of 300-450 nm using a UV-Vis spectrophotometer (UV-2550, Shimadzu, Japan), and the absorbance values ​​were recorded. The concentration of residual tetracycline was calculated using a standard curve.

[0046] The experimental results are as follows: With a catalyst dosage of 20 mg, the degradation rate of tetracycline reached 99.87% after 20 min of reaction. The results indicate that the degradation efficiency of tetracycline by the photocatalytic system is significantly improved with increasing catalyst dosage.

[0047] This example, compared with Examples 1-3, shows that when the catalyst dosage increases from 5 mg to 20 mg, the 20-minute degradation rate of tetracycline increases from 79.41% to 99.87%, proving that the catalyst dosage has a significant impact on the degradation efficiency and providing a basis for optimizing process parameters in practical applications.

[0048] Example 5 This example aims to investigate the effect of peracetic acid (PAA) dosage on the efficiency of photomediated degradation of tetracycline, and the polydopamine-modified Cu2O catalyst prepared in Example 1 was used for the experiment.

[0049] The experimental steps are as follows: Weigh 10 mg of polydopamine-modified Cu2O catalyst powder and add it to 100 mL of tetracycline solution with an initial concentration of 20 mg / L. Place the solution in a quartz jacketed reactor with a circulating water cooling system and disperse the catalyst evenly by ultrasonication.

[0050] Irradiate the system with a light source (a 300W xenon lamp equipped with an AM 1.5 filter) and simultaneously inject 0.5 mL of 10 mM peracetic acid solution into the reaction system to initiate the photocatalytic degradation reaction.

[0051] At 1, 5, 10 and 20 min of reaction, 3 mL of reaction solution was quantitatively transferred from the reactor, and the solid catalyst was removed by high-speed centrifugation (e.g., centrifugation at 10000 rpm for 5 min), and the supernatant was taken.

[0052] The supernatant was scanned in the wavelength range of 300-450 nm using a UV-Vis spectrophotometer (UV-2550, Shimadzu, Japan), and the absorbance values ​​were recorded. The concentration of residual tetracycline was calculated using a standard curve.

[0053] The experimental results are as follows: When the amount of peracetic acid added was 0.5 mL, the degradation rate of tetracycline reached 78.99% after 20 min of reaction.

[0054] This example, compared with Example 1 (peracetic acid dosage 1 mL, i.e., 10 mmol / L, degradation rate 99.77%), shows that when the peracetic acid dosage is reduced by half, the tetracycline degradation rate decreases significantly. This indicates that peracetic acid plays a crucial role as an oxidant in the photocatalytic system, and its concentration directly affects the free radical generation rate and pollutant degradation efficiency. These results provide important basis for optimizing the oxidant dosage in practical applications.

[0055] To facilitate comparison of the reaction conditions and degradation efficiency in each example, the key parameters in Examples 1-5 are summarized in Table 1 below.

[0056] Table 1 Key parameters and degradation efficiency of each embodiment in addition, Figure 1 The XRD patterns of Cu2O surface before and after modification with polydopamine are shown. The diffraction peaks of the two are similar and both conform to the standard diffraction peaks of Cu2O. Moreover, the modification with polydopamine did not introduce a new crystal structure on the surface of Cu2O.

[0057] Figure 2 This is a comparison of FT-IR images of Cu2O surfaces before and after polydopamine modification. Besides the characteristic absorption bands of Cu2O itself, polydopamine-modified Cu2O exhibits a band at 1291 cm⁻¹. -11583cm -1 And 3358cm -1 New absorption bands appeared at the point, corresponding to the -CH2 shear vibration, phenyl and NH stretching vibration in the polydopamine structure, respectively. This result proves that polydopamine has been successfully modified on the Cu2O surface.

[0058] Figure 3 The graph shows a comparison of the performance of Cu2O and polydopamine-modified Cu2O in the photo-mediated peracetic acid activation system for the degradation of tetracycline. It can be seen that the degradation performance of polydopamine-modified Cu2O for tetracycline is greatly improved compared to Cu2O.

[0059] Figure 4 The bar chart shows the leaching of Cu ions during the degradation of tetracycline by Cu2O and polydopamine-modified Cu2O in a photo-mediated peracetic acid activation system. It can be seen that the Cu ion leaching by polydopamine-modified Cu2O is significantly lower than that by Cu2O during the degradation of tetracycline.

[0060] Figure 5 The bar charts show the cyclic degradation performance of Cu2O and polydopamine-modified Cu2O in a photo-mediated peracetic acid activation system for the degradation of tetracycline. It can be seen that the cyclic degradation performance of polydopamine-modified Cu2O is greatly improved compared to Cu2O.

[0061] The above embodiments of the present invention provide a method for preparing polydopamine-modified Cu2O catalysts and their applications, which have the following significant advantages: 1) Polydopamine surface modification effectively improved the electron transfer performance and interfacial reaction kinetics of Cu2O catalysts in photomediated peracetic acid activation systems, significantly enhancing their degradation activity against organic pollutants such as tetracycline. Experiments showed that this catalyst could achieve extremely high degradation rates in a short time (e.g., degradation rate exceeding 99% within 20 minutes), significantly outperforming unmodified Cu2O materials.

[0062] 2) The polydopamine coating layer constructs a stable protective interface on the Cu2O surface, effectively inhibiting Cu... + The dissolution and valence state deactivation under light and oxidation environments solve the technical problems of traditional Cu2O catalysts being prone to photocorrosion and having poor cycle performance, and significantly improve the chemical stability and service life of the catalyst.

[0063] 3) Due to the improved structural stability, the catalyst maintains high catalytic activity after multiple reuses, without the need for frequent regeneration or replenishment. It has good recyclability and long-term operational stability, making it suitable for continuous wastewater treatment processes.

[0064] 4) The liquid-phase reduction-polymerization method can be used to complete the reaction at room temperature or under mild heating conditions. It does not require expensive equipment or harsh reaction environment. It is easy to operate, cost controllable, easy to achieve large-scale production, and has good prospects for industrial application.

[0065] In summary, this invention, through material structure design and process optimization, successfully solves the technical bottlenecks of insufficient activity, poor stability, and unsatisfactory cycle performance of Cu2O catalysts in the prior art, providing a novel catalyst system that is efficient, stable, and easy to prepare for photocatalytic peracetic acid advanced oxidation technology.

[0066] Although embodiments of the invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.

Claims

1. A method for preparing a polydopamine-modified Cu2O catalyst, characterized in that, Includes the following steps: S1. Mix copper salt, dispersant and pure water, add alkali solution and reducing agent in sequence under water bath stirring, centrifuge, wash and dry after reaction to obtain Cu2O powder; S2. Dissolve dopamine hydrochloride in buffer solution, add the Cu2O powder prepared in step S1, stir the reaction at room temperature, collect the precipitate and wash and dry it to obtain polydopamine-modified Cu2O catalyst.

2. The method for preparing polydopamine-modified Cu2O catalyst according to claim 1, characterized in that, In step S1, the copper salt is CuCl2·2H2O; The dispersant is polyvinylpyrrolidone, with an average molecular weight of 24,000; The alkaline solution is a NaOH solution; The reducing agent is ascorbic acid solution.

3. The method for preparing polydopamine-modified Cu2O catalyst according to claim 2, characterized in that, In step S1, the concentration of the copper salt is 10 mM, the amount of the dispersant added is 6.0 g, the concentration of the alkaline solution is 2 M, and the concentration of the reducing agent is 0.6 M.

4. The method for preparing polydopamine-modified Cu2O catalyst according to claim 1, characterized in that, In step S1, the temperature of the water bath stirring is 55°C, and the reaction time is 3 hours. In step S2, the buffer solution is Tris-hydrochloric acid buffer with a concentration of 50 mM.

5. The method for preparing polydopamine-modified Cu2O catalyst according to claim 1, characterized in that, In step S2, the amount of dopamine hydrochloride added is 50 mg, the amount of Cu2O powder added is 0.03 g, and the stirring reaction time is 8 h.

6. The method for preparing polydopamine-modified Cu2O catalyst according to claim 1, characterized in that, In steps S1 and S2, the drying is performed under vacuum at a temperature of 60°C. The drying time for preparing Cu2O powder is 12 hours, and the drying time for preparing polydopamine-modified Cu2O catalyst is 6 hours.

7. The application of a polydopamine-modified Cu2O catalyst prepared by the method according to any one of claims 1-6 in the degradation of tetracycline wastewater, characterized in that, The polydopamine-modified Cu2O catalyst was applied to a photo-mediated peracetic acid activation system. Through the synergistic effect of photogenerated electrons and peracetic acid, reactive oxygen species were generated to degrade tetracycline in the water.

8. The application according to claim 7, characterized in that, Specifically, the following steps are included: The polydopamine-modified Cu2O catalyst powder was mixed and dispersed with a tetracycline solution, irradiated with a light source, and peracetic acid solution was simultaneously injected into the reaction system to initiate the degradation reaction.

9. The application according to claim 8, characterized in that, The light source is a 300W xenon lamp equipped with an AM 1.5 filter; The initial concentration of the tetracycline solution was 20 mg / L; The concentration of the peracetic acid solution is 10 mM.

10. The application according to claim 8, characterized in that, The dosage of the polydopamine-modified Cu2O catalyst is 5-20 mg / 100 mL tetracycline solution; The peracetic acid solution was added at a rate of 0.5-1 mL per 100 mL tetracycline solution.

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