Method for photocatalytic degradation of tetracycline and application

Abstract

The invention discloses a method for photocatalytic degradation of tetracycline and application. The tetracycline is rapidly degraded under visible light by adopting a copper-doped carbon quantum dot (Cu-CDs) catalyst. The preparation method of the copper-doped carbon quantum dot catalyst comprises the following steps: calcining an analysis-grade solid precursor containing carbon and copper in an inert atmosphere; grinding the calcined product into powder, dissolving the powder in an organic solvent, then carrying out ultrasonic treatment, and centrifuging to obtain a uniform clear solution; and filtering the uniform solution, and directly drying the filtrate to obtain the copper-doped carbon quantum dot catalyst. According to the invention, a one-step low-temperature pyrolysis method is adopted, and the Cu-CDs are synthesized by taking the copper disodium ethylene diamine tetraacetate which is low in price and easy to obtain as a precursor. Under the irradiation of visible light, the Cu-CDs show excellent photocatalytic degradation performance on tetracycline. Experiments prove that when the dosage of the catalyst is 0.5 mg / mL, 72% of tetracycline is degraded within 5 minutes, and 100% of tetracycline is completely degraded within 40 minutes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalysis, in particular to a method for photocatalytic degradation of tetracycline and application. BACKGROUND

[0002] Tetracycline is widely used in agriculture, veterinary and human medical fields, and has been detected in various environmental media, posing a serious threat to aquatic ecosystems, soil fertility and human health through biological enrichment in the food chain. Traditional methods for treating tetracycline pollution in water or soil, such as ultraviolet irradiation, microbial degradation and chlorination, have been widely studied and applied, but due to their high energy consumption, toxic byproduct generation, high operating cost and complex operation, their practical application is still limited.

[0003] In recent years, photocatalytic technology has attracted widespread attention in the removal of organic pollutants due to its advantages such as no harmful byproducts, strong catalytic activity, high efficiency and good environmental compatibility. To meet the urgent need for green and efficient pollution control, researchers have begun to explore nanomaterials, especially CDs. CDs have excellent physical and chemical properties, such as high surface reactivity, excellent stability and controllable surface chemical properties, making them a highly potential material for catalytic degradation of organic pollutants. In the photocatalytic process, CDs can act as both a photosensitizer and an electron mediator, extending the photon absorption band and inhibiting electron-hole (e - / h + ) recombination. Despite its many advantages, research on building CDs composite materials to enhance photocatalytic performance is still limited. For example, Wang et al. developed S-CDs loaded on hollow tubular g-C3N4 for tetracycline degradation; in other studies, TiO2 nanosheets decorated with CQDs were also used for tetracycline removal. However, the practical application of these materials is still limited by the complex synthesis process and high preparation cost. SUMMARY

[0004] The present application provides a method for photocatalytic degradation of tetracycline and application, aiming to solve the problems of complex synthesis process and high preparation cost in existing photocatalytic technology.

[0005] The technical solution provided by the present application is as follows: A method for photocatalytic degradation of tetracycline, using copper-doped carbon quantum dot catalyst to degrade tetracycline under visible light; The preparation method of the copper-doped carbon quantum dot catalyst comprises: calcining an analytical grade solid precursor containing carbon and copper in an inert atmosphere; grinding the calcined product into a powder and dissolving it in an organic solvent, then performing ultrasonic treatment and centrifugation to obtain a brown upper layer solution; The upper brown solution is filtered, and the filtrate is dried to obtain the copper-doped carbon quantum dot catalyst.

[0006] Further, the copper-doped carbon quantum dot catalyst is mixed with a tetracycline sample solution at room temperature, stirred in the dark until adsorption equilibrium is reached, and then subjected to a catalytic reaction under visible light. The concentration of tetracycline in the tetracycline sample solution is 10-30 mg / L, and the amount of the copper-doped carbon quantum dot catalyst added is 0.1-0.5 g per liter of the tetracycline sample solution.

[0007] Further, the solid precursor is Na2[Cu(EDTA)] or K2[Cu(EDTA)].

[0008] Further, during the calcination process of the analytical grade solid precursor, the furnace temperature is raised from room temperature to 150-450 °C at a rate of 2-15 °C / min, and the calcination time is 30-150 min.

[0009] Further, the organic solvent is methanol, ethanol or acetylacetone. The inert atmosphere includes argon and nitrogen.

[0010] Further, the grinding of the calcined product into a powder is specifically grinding the calcined product into a superfine powder by a ball mill, and the grinding time is 30-60 min.

[0011] Further, the pore size of the filter membrane used when filtering the upper brown solution is 0.1-0.45 µm.

[0012] Further, the ultrasonic treatment time is 10-40 min.

[0013] Further, the centrifugal speed is 9000-15000 r / min, the centrifugal time is 10-30 min, and the centrifugation is repeated multiple times.

[0014] The application also provides a use of the above-mentioned copper-doped carbon quantum dot catalyst in treating water body or soil pollution caused by tetracycline.

[0015] Compared with the prior art, the application has the following beneficial effects: The application adopts one-step low-temperature pyrolysis method to synthesize Cu-CDs by using cheap and easily available copper sodium ethylenediaminetetraacetate as a precursor. Under visible light irradiation, Cu-CDs exhibits excellent tetracycline photocatalytic degradation performance. When the catalyst dosage is 0.5 mg / mL, 72% of tetracycline is degraded within 5 minutes, and 100% complete degradation is achieved within 40 minutes. The results show that Cu-CDs provides a fast, selective and simple tetracycline pollution water and soil remediation strategy. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Reaction mechanism diagram of Cu-CDs prepared in the embodiments of the application; Figure 2 Transmission electron microscope (TEM) image of Cu-CDs prepared in the embodiments of the application; Figure 3 Amplified Fourier transform infrared spectrometer (FTIR) spectrum of CDs and Cu-CDs in the embodiments of the application; Figure 4 Figure of the influence of Cu-CDs and sunlight on the photocatalytic effect in Example 1 and the comparative example; Figure 5 Figure of the influence of different initial tetracycline concentrations on the degradation efficiency in Example 1 (Cu-CDs = 0.25 mg / mL; TC = 10, 20, 30 mg / L); Figure 6 Figure of the influence of different initial tetracycline concentrations on the degradation effect under the same Cu-CDs concentration in Example 1 (Cu-CDs = 0.5 mg / mL; TC = 10, 20, 30 mg / L); Figure 7 Table of the performance comparison of Cu-CDs prepared in the application and other photocatalysts in TC degradation; Figure 8 Figure of the stability performance of Cu-CDs prepared in the application after three consecutive degradation cycles. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the embodiments described below are part of the embodiments of the present application, rather than all the embodiments of the present application.

[0018] As Figure 1As shown, the present application provides a method for photocatalytic degradation of tetracycline, which uses copper-doped carbon quantum dot catalyst to degrade tetracycline under visible light. Specifically, the copper-doped carbon quantum dot catalyst is mixed with a tetracycline sample solution at room temperature, then stirred in the dark until adsorption equilibrium is reached, and then placed under visible light for catalytic reaction. The concentration of tetracycline in the tetracycline sample solution is 10-30 mg / L, and the addition amount of the copper-doped carbon quantum dot catalyst is 0.1-0.5 g per liter of tetracycline sample solution.

[0019] The preparation method of the copper-doped carbon quantum dot catalyst comprises: Step 1. Calcining carbon and copper-containing analytical grade solid precursors in an inert atmosphere.

[0020] The solid precursor here is Na2[Cu(EDTA)] or K2[Cu(EDTA)], and the inert atmosphere is argon or nitrogen. During calcination, the furnace temperature is raised from room temperature to 150-450 °C at a rate of 2-15 °C / min, and the calcination time is 30-150 min.

[0021] Step 2. Grinding the calcined product into a powder and dissolving it in an organic solvent, then performing ultrasonic treatment and centrifugation to obtain the upper brown solution.

[0022] Specifically, the calcined product is ground into a superfine powder by a ball mill, the grinding time is 30-60 min, the organic solvent is methanol, ethanol or acetylacetone, etc., the ultrasonic treatment time is 10-40 min, the centrifugal speed is 9000-15000 r / min, the centrifugal time is 10-30 min, and the upper brown solution is obtained by repeating centrifugation 2-3 times.

[0023] Step 3. Filtering the upper brown solution and drying the filtrate to obtain the copper-doped carbon quantum dot catalyst.

[0024] The filter membrane used when filtering the upper brown solution has a pore size of 0.1-0.45 μm, and the filtrate is dried in a vacuum drying oven at 70 °C. The obtained powder is ground and weighed to prepare the copper-doped carbon quantum dot catalyst, which is named Cu-CDs.

[0025] Example 1 A method for photocatalytic degradation of tetracycline, comprising the following steps: 1. Preparation of copper-doped carbon quantum dot catalyst (1) Place 3 g of analytical grade pure Na2[Cu(EDTA)] in a quartz boat, and place it in the center of a quartz tube, and calcine it at 300 °C for 90 min under a nitrogen atmosphere at a heating rate of 5 °C / min.

[0026] (2) The product obtained after calcination was ground in a ball mill for 30 min to obtain ultrafine powder. The ultrafine powder was dissolved in 50 mL of anhydrous methanol, and after ultrasonic treatment at room temperature for 20 min, it was centrifuged at a high speed of 11000 rpm for 20 min.

[0027] (3) The upper brown solution was taken and filtered using a 0.22 µm quantitative filter membrane to remove the non-fluorescent sodium salt precipitate. The sodium salt precipitate was concentrated and dried in a vacuum drying oven at 70 °C for 30 h to obtain Cu-CDs fluorescent powder.

[0028] 2. Catalytic degradation of tetracycline (TC) under visible light using the copper-doped carbon quantum dot catalyst prepared in step 1 The photocatalytic degradation performance of Cu-CDs on tetracycline was tested using a solar simulator at room temperature. 40 mL of tetracycline reaction solution was stirred with the corresponding amount of copper-doped carbon quantum dot catalyst in a beaker. To make the tetracycline reaction solution and copper-doped carbon quantum dot catalyst adsorption-desorption reach equilibrium, it was first placed in the dark for 30 min, and then irradiated under a xenon lamp (Xe). Every 5 min, 3 mL of sample supernatant was taken and the tetracycline concentration was determined using a UV-Vis spectrophotometer at 370 nm to determine the degree of tetracycline catalytic degradation.

[0029] The corresponding relationship between the tetracycline reaction solution and the copper-doped carbon quantum dot catalyst is as follows: The concentration of tetracycline in the tetracycline reaction solution was 10 mg / L, and 4 mg of copper-doped carbon quantum dot catalyst was added; The concentration of tetracycline in the tetracycline reaction solution was 20 mg / L, and 10 mg of copper-doped carbon quantum dot catalyst was added; The concentration of tetracycline in the tetracycline reaction solution was 30 mg / L, and 20 mg of copper-doped carbon quantum dot catalyst was added.

[0030] Comparative Example 1 The CDs catalyst without Cu doping was directly used to catalytically degrade 40 mL of tetracycline solution under visible light. The reaction conditions, the concentration of tetracycline solution, and the amount of CDs catalyst used were the same as in Example 1. Every 5 min, 3 mL of sample supernatant was taken and detected on a UV-Vis spectrophotometer instrument.

[0031] Comparative Example 2 The copper-doped carbon quantum dot catalyst prepared in step 1 was used to catalytically degrade the tetracycline reaction solution in the dark. The difference from Example 1 was that the catalytic degradation was carried out in the dark, and the other conditions were the same. Every 5 min, 3 mL of sample supernatant was taken and detected on a UV-Vis spectrophotometer instrument.

[0032] Comparative Example 3 The 40 mL tetracycline reaction solution was subjected to catalytic degradation under visible light without adding any catalyst, which was different from Example 1 in that no catalyst was added, and the rest of the conditions were the same. Every 5 min, 3 mL of sample supernatant was taken and detected on a UV-Vis spectrophotometer instrument.

[0033] The Cu-doped carbon quantum dot catalyst prepared in Step 1 was characterized: Figure 2 The transmission electron microscopy (TEM) image of Cu-CDs is shown in FIG. 2. The TEM image shows that its lateral size distribution is between 0.6-2.7 nm, and the lattice spacing is 0.22 nm, which proves that Cu-CDs have been successfully synthesized.

[0034] Figure 3 The amplified FTIR spectra of CDs and Cu-CDs are shown in FIG. 3. The FTIR of Cu-CDs and CDs was amplified in the range of 950-1100 cm -1 Compared with pure CDs, Cu-CDs appeared new absorption peaks at 1040 cm -1 and 1020 cm -1 , which further confirmed the formation of Cu coordination complexes in Cu-CDs.

[0035] Figure 4 The effect of Cu-CDs and sunlight on the photocatalytic effect in Example 1 and the comparative example is shown in FIG. 4. Without CDs and Cu-CDs (red line in the figure) and without sunlight (orange line in the figure), the initial concentration of tetracycline hardly changed. However, in the presence of Cu-CDs and sunlight (blue line in the figure), tetracycline (20 mg / L) could be degraded by 72 % in 5 min and completely removed in 40 min. More importantly, the efficiency of Cu-CDs in catalytic degradation of tetracycline was 4.9 times higher than that of CDs without Cu doping. It can be seen that Cu-CDs have the highest degradation efficiency of tetracycline under visible light irradiation.

[0036] Figure 5 The effect of different initial tetracycline concentrations on the degradation efficiency in Example 1 (Cu-CDs = 0.25 mg / mL; TC = 10, 20, 30 mg / L) is shown in FIG. 5. As shown in FIG. 5, under visible light, the removal rate of tetracycline increased with the increase of the amount of Cu-CDs. Specifically, when the dosage of Cu-CDs increased from 0.1 to 0.5 mg / mL, the degradation efficiency of tetracycline also gradually increased. Figure 5

[0037] Figure 6 ​The effect of different initial tetracycline concentrations on degradation efficiency under the same Cu-CDs concentration in Example 1 (Cu-CDs = 0.5 mg / mL; TC = 10, 20, 30 mg / L).

[0038] The dosage of Cu-CDs plays a crucial role in the degradation of tetracycline, providing more active sites for the reaction. In particular, at a Cu-CDs dosage of 0.5 mg / mL, tetracycline at initial concentrations of 10 mg / L and 20 mg / L can be completely degraded.

[0039] To evaluate the photocatalytic performance of Cu-CDs, their efficiency in degrading tetracycline (TC) was compared with that of advanced visible-light-responsive semiconductor photocatalysts reported in the literature, such as... Figure 7 As shown in the figure. Notably, Cu-CDs exhibit a degradation efficiency far exceeding that of traditional photocatalysts, indicating their potential in the treatment of antibiotic-contaminated wastewater.

[0040] Based on ESR analysis and capture experiments, it was confirmed that •O2 - It is the main reactant species. Recycled Cu-CDs can be reused under the same conditions (e.g., Figure 8 (As shown). After three cycles, its degradation efficiency was almost unaffected, maintaining approximately 80% of its initial performance. These results demonstrate that Cu-CDs exhibit excellent chemical stability and reusability in the degradation of tetracycline into intermediate products, showing great potential for practical applications.

[0041] In summary, this invention employs a one-step low-temperature pyrolysis method, using inexpensive and readily available sodium ethylenediaminetetraacetate (EDTA-CO) as a precursor, to synthesize Cu-CDs. Under visible light irradiation, Cu-CDs exhibit excellent photocatalytic degradation performance of tetracycline. At a catalyst dosage of 0.5 mg / mL, 72% of tetracycline is degraded within 5 minutes, and 100% complete degradation is achieved within 40 minutes. These results demonstrate that Cu-CDs provide a rapid, selective, and simple remediation strategy for tetracycline-contaminated water and soil.

[0042] The above description is merely the preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of photocatalytic degradation of tetracycline, characterized by, The copper-doped carbon quantum dot catalyst is used to degrade tetracycline under visible light. The preparation method of the copper-doped carbon quantum dot catalyst comprises: calcining an analytical grade solid precursor containing carbon and copper in an inert atmosphere; grinding the calcined product into powder and dissolving it in an organic solvent, and then performing ultrasonic treatment and centrifugal removal of bottom impurities to obtain an upper brown solution; filtering the upper brown solution and drying the filtrate to obtain the copper-doped carbon quantum dot catalyst.

2. The method according to claim 1, wherein: the copper-doped carbon quantum dot catalyst is mixed with a tetracycline sample solution at room temperature, stirred in the dark until adsorption equilibrium is reached, and then subjected to catalytic reaction under visible light. The concentration of tetracycline in the tetracycline sample solution is 10-30 mg / L, and the addition amount of the copper-doped carbon quantum dot catalyst is 0.1-0.5 g per liter of the tetracycline sample solution.

3. The method according to claim 1, wherein: the solid precursor is Na2[Cu(EDTA)] or K2[Cu(EDTA)].

4. The method according to claim 1, wherein: during the calcination process of the analytical grade solid precursor, the furnace temperature is raised from room temperature to 150-450 °C at a rate of 2-15 °C / min, and the calcination time is 30-150 min.

5. The method according to claim 1, wherein: the organic solvent is methanol, ethanol or acetylacetone; the inert atmosphere comprises argon and nitrogen.

6. The method according to claim 1, wherein: the grinding of the calcined product into powder is performed by ball milling to obtain ultra-fine powder, and the grinding time is 30-60 min.

7. The method according to any one of claims 1-6, wherein: the pore size of the filter membrane used for filtering the upper brown solution is 0.1-0.45 μm.

8. The method according to claim 7, wherein: the ultrasonic treatment time is 10-40 min.

9. The method according to claim 7, wherein: the centrifugal rotation speed is 9000-15000 r / min, the centrifugal time is 10-30 min, and the centrifugal process is repeated multiple times.

10. Use of the copper-doped carbon quantum dot catalyst according to any one of claims 1-9 in the treatment of water body or soil pollution caused by tetracycline.

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