A g-C3N4-based nanocomposite material for removing tetracycline and preparation method thereof

Abstract

The present invention provides a g-C3N4-based nanocomposite material for removing tetracycline, and its preparation method and application. The composite material is prepared by the following method: a sulfur source, a copper source and g-C3N4 are reacted in a solvent at 60-70°C for 1-6h, and then a g-C3N4-based precursor is separated; after drying, the precursor is calcined at a constant temperature of 350-500°C under an air atmosphere to obtain the product. The material of the present invention can utilize green molecular oxygen as an oxidant, and has excellent catalytic performance and adsorption efficiency, high selectivity and stability through the combination of advanced oxidation process and adsorption. Using the composite material, wastewater can be directly used to remove tetracycline without dilution treatment. The present invention is simple to prepare, convenient and fast, and is synthesized using relatively cheap and easily available raw materials. The cost is low, the reproducibility of the sample is relatively good, and it is suitable for large-scale production. It has certain development potential and application prospects in the field of water environment treatment.

Description

Technical Field

[0001] The invention belongs to the field of water pollution control, and particularly relates to a g-C3N4-based nanocomposite material for green removal of tetracycline and a preparation method thereof. Background Art

[0002] With the development of industry, water pollution has attracted increasing attention. Environmental pollutants in water mainly include toxic heavy metal ions and organic pollutants. These environmental pollutants generally have good chemical and biological stability and are difficult to degrade naturally. Take antibiotics as an example. Antibiotics are commonly used as additives in animal medicines and feeds to promote plant growth, control disease outbreaks, and thus improve production efficiency. However, with the overuse of antibiotics, residual antibiotics are accompanied by certain environmental pollution and cause harm to human health. Degradation methods using advanced oxidation processes usually require peroxysulfate (PMS) or hydrogen peroxide as oxidants to achieve the purpose of effectively removing pollutants. However, the ratio of oxidant to pollutant is high or it is more sensitive to environmental conditions. Therefore, finding a suitable catalyst under the condition that oxygen is used as the oxidant is of paramount importance.

[0003] Graphitic carbon nitride (g-C3N4), a metal-free polymer semiconductor prepared by thermal polycondensation, is an ideal medium for studying the properties of different active sites. In recent years, g-C3N4 has demonstrated promising performance in environmental pollutant removal and photocatalytic hydrogen production due to its excellent physicochemical stability, low cost, unique electronic structure, and narrow band gap (2.7 eV). However, due to its stable structure, g-C3N4 is inactive in PMS activation. Therefore, modifying g-C3N4 is particularly important. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a g-C3N4-based nanocomposite material for green removal of tetracycline and a preparation method thereof, which are used to solve the problem of water environmental pollution.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a tetracycline-removed g-C3N4-based nanocomposite material comprises the following steps:

[0007] (1) reacting a sulfur source, a copper source, and g-C3N4 in a solvent at 60-70°C for 1-6 hours, and then separating to obtain a g-C3N4-based precursor;

[0008] (2) After the g-C3N4-based precursor is dried, it is calcined at a constant temperature of 350-500°C in an air atmosphere, preferably at 400°C, to obtain the g-C3N4-based nanocomposite material, which is denoted as CSG.

[0009] Preferably, the g-C3N4 in step (1) is prepared by the following method:

[0010] (0) The nitrogen source is calcined at 500-600° C., preferably 550° C., in an air atmosphere and then cooled to obtain the product.

[0011] Preferably, the nitrogen source in step (0) is thiourea, melamine or urea; most preferably urea.

[0012] Preferably, the sulfur source in step (1) is thiourea or thioacetamide; most preferably, thiourea.

[0013] Preferably, the copper source in step (1) is copper acetate, copper chloride or copper nitrate, most preferably copper acetate.

[0014] Preferably, the solvent in step (1) is methanol, ethanol or water, most preferably ethanol.

[0015] Preferably, the mass ratio of the copper element in the copper source to the g-C3N4 in step (1) is 0.076 to 2.76:1. The most preferred mass ratio is 1.03:1.

[0016] Preferably, the reaction temperature in step (1) is 65° C. and the reaction time is 4 h.

[0017] Preferably, the drying in step (2) is performed at 60-80°C.

[0018] Preferably, the burning time in step (2) is 2 to 4 hours, preferably 4 hours.

[0019] The present invention also provides a g-C3N4-based nanocomposite material prepared by the above preparation method.

[0020] The present invention also provides the use of the g-C3N4-based nanocomposite material prepared by the above preparation method in the oxidative degradation of tetracycline in water.

[0021] Preferably, the molar concentration of tetracycline is 20 mg / L.

[0022] The beneficial effects of the present invention are:

[0023] (1) Compared with other g-C3N4-based nanocomposite nanomaterials, the structure of CSG shortens the electron transmission path, increases the contact area with the degradation substrate, provides more active sites, and is more conducive to the catalytic oxidation reaction of tetracycline.

[0024] (2) Using relatively cheap and abundant raw materials to synthesize CSG nanocomposites has the advantages of simple preparation, low cost, high yield and stability, low requirements for reaction equipment and environmental friendliness, and is suitable for large-scale synthesis.

[0025] (3) The CSG nanocomposite material prepared by the present invention has a simple modification method and does not require other conductive carriers. It can achieve efficient degradation of tetracycline aqueous solution and has the advantages of wide adaptability to environmental pH, no need for external light source, high selectivity, and good reproducibility. Various environmental factors screened in the experiment show that the CSG nanocomposite material can be directly used for degradation without the need for dilution treatment of the wastewater.

[0026] (4) By optimizing the molar ratio of copper acetate to thiourea, a more multi-layered and rough surface nanocomposite material was synthesized. And by screening the calcination conditions, a hollow CuS x Good composite with g-C3N4. When too much or too little, it is impossible to obtain a uniformly distributed hollow structure under this condition, and its collapsed structure causes the material's oxidation catalytic performance to be poor.

[0027] (5) The present invention further calcined the g-C3N4-based Cu, S complex obtained by the hydrothermal reaction. Appropriate calcination temperature and holding time have a positive effect on the carbonization degree of the material. A certain degree of carbonization first affects the pore size distribution and pore structure of the material surface, then affects the surface morphology of the material, and also affects the distribution and number of active sites. Excessively high calcination temperature and excessively long holding time will lead to excessive carbonization, resulting in a decrease in performance, while too low a temperature will not achieve the carbonization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image (SEM) of the material obtained in Example 1, wherein A is g-C3N4 and B is a CSG (4:1) nanocomposite material.

[0029] Figure 2 1 is a transmission electron microscope (TEM) image and element distribution map (mapping) of the CSG (4:1) nanocomposite material prepared in Example 1, wherein A and B are TEM images, and C to G are element distribution maps (mapping).

[0030] Figure 3It is the X-ray photoelectron spectroscopy analysis chart (XPS) of the CSG (4:1) nanocomposite material prepared in Example 1, wherein A is the full XPS spectrum of the CSG (4:1) nanocomposite material; B is the carbon 1s orbital energy spectrum of the CSG (4:1) nanocomposite material; C is the nitrogen 1s orbital energy spectrum of the CSG (4:1) nanocomposite material; D is the copper 2p orbital energy spectrum of the CSG (4:1) nanocomposite material; and E is the sulfur 2p orbital energy spectrum of the CSG (4:1) nanocomposite material.

[0031] Figure 4 This is the X-ray powder diffraction pattern (XRD) of the CSG (4:1) nanocomposite material prepared in Example 1.

[0032] Figure 5 This is a comparison chart of the performance of nanocomposites made with different mass ratios of copper acetate and g-C3N4 and pure g-C3N4 on the oxidative degradation of tetracycline.

[0033] Figure 6 This is a comparison chart of the performance of CSG (4:1) nanocomposites prepared at different calcination temperatures on the oxidative degradation of tetracycline.

[0034] Figure 7 Pseudo-first-order kinetics of tetracycline removal from nanocomposites prepared at different calcination temperatures.

[0035] Figure 8 is a graph of tetracycline removal rate constants of nanocomposites prepared at different calcination temperatures.

[0036] Figure 9 This is a performance diagram of the uncalcined CSG nanocomposite precursor prepared in Comparative Example 2 on the oxidative degradation of tetracycline.

[0037] Figure 10 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 for the oxidative degradation of tetracycline under different pH conditions.

[0038] Figure 11 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 for the oxidative degradation of tetracycline at different catalyst dosages.

[0039] Figure 12 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 on the oxidative degradation of tetracycline at different tetracycline concentrations.

[0040] Figure 13 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 on the oxidative degradation of tetracycline under different temperature conditions.

[0041] Figure 14This is a diagram of a free radical capture experiment of the CSG (4:1) nanocomposite material prepared in Example 1.

[0042] Figure 15 This is the electron paramagnetic resonance spectrum (EPR) of the CSG (4:1) nanocomposite material prepared in Example 1.

[0043] Figure 16 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 for the oxidative degradation of tetracycline under different light sources.

[0044] Figure 17 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 for the oxidative degradation of tetracycline when different oxidants are added.

[0045] Figure 18 This is a performance diagram of the CSG (4:1) nanocomposite material prepared in Example 1 for tetracycline degradation under different water sources. DETAILED DESCRIPTION

[0046] Example 1

[0047] (1) Preparation of g-C3N4:

[0048] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0049] (2) Preparation of CSG nanocomposites:

[0050] 1.62 mmol of copper acetate, 6.48 mmol of thiourea, and 100 mg of g-C3N4 powder were sequentially added to 30 mL of ethanol and allowed to solvothermally react at 65°C for 4 hours. After the reaction, the precursor was washed by centrifugation with ethanol and dried at 60°C. The resulting precursor was calcined at 400°C in air for 4 hours to obtain a yellow-gray sample, which is the CSG (4:1) nanocomposite.

[0051] Example 2

[0052] (1) Preparation of g-C3N4:

[0053] Place 10 g of thiourea in a crucible, and place the crucible in a muffle furnace and calcine at 500 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0054] (2) Preparation of CSG nanocomposites:

[0055] 1.62 mmol of copper chloride, 6.48 mmol of thioacetamide, and 100 mg of g-C3N4 powder were sequentially added to 30 mL of ethanol and allowed to solvothermally react at 60°C for 6 hours. After the reaction, the precursor was washed by centrifugation with ethanol and dried at 70°C to obtain the precursor. The resulting precursor was calcined at 400°C in air for 3 hours to obtain a yellow-gray sample, which is the CSG nanocomposite.

[0056] Example 3

[0057] (1) Preparation of g-C3N4:

[0058] 10 g of melamine was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 600 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0059] (2) Preparation of CSG nanocomposites:

[0060] 1.62 mmol of copper nitrate, 6.48 mmol of thiourea, and 100 mg of g-C3N4 powder were sequentially added to 30 mL of ethanol and allowed to solvothermally react at 70°C for 1 hour. After the reaction, the precursor was washed with ethanol by centrifugation and dried at 80°C. The resulting precursor was calcined at 400°C in air for 2 hours to obtain a yellow-gray sample, the CSG nanocomposite.

[0061] Example 4

[0062] (1) Preparation of g-C3N4:

[0063] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0064] (2) Preparation of CSG nanocomposites:

[0065] 1.62 mmol of copper acetate, 6.48 mmol of thiourea, and 100 mg of g-C3N4 powder were sequentially added to 30 mL of ethanol and allowed to solvothermally react at 65°C for 4 hours. After the reaction, the precursor was washed with ethanol by centrifugation and dried at 60°C to obtain the precursor. The resulting precursor was calcined at 350°C in air for 4 hours to obtain a yellow-gray sample, which is the CSG nanocomposite.

[0066] Example 5

[0067] (1) Preparation of g-C3N4:

[0068] 15 g of thiourea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0069] (2) Preparation of CSG nanocomposites:

[0070] 1.62 mmol of copper acetate, 6.48 mmol of thiourea, and 100 mg of g-C3N4 powder were sequentially added to 30 mL of ethanol and allowed to solvothermally react at 65°C for 4 hours. After the reaction, the precursor was washed with ethanol by centrifugation and dried at 60°C. The resulting precursor was calcined at 500°C in air for 4 hours to obtain a yellow-red sample, the CSG nanocomposite.

[0071] Comparative Example 1

[0072] (1) Preparation of g-C3N4:

[0073] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0074] (2) Preparation of CSG nanocomposites

[0075] 1.62 mmol of copper acetate, 6.48 mmol of thiourea, and 100 mg of the product from step 1 were sequentially added to 30 mL of ethanol solution and allowed to solvothermally react at 65°C for 4 h. After the reaction, the precursor was washed with ethanol by centrifugation and dried at 60°C to obtain a precursor for later use. The resulting precursor was calcined at 600°C in air for 4 h to obtain a red sample.

[0076] Comparative Example 2

[0077] (1) Preparation of g-C3N4:

[0078] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0079] (2) Preparation of CSG nanocomposite precursor

[0080] 1.62mmol copper acetate, 6.48mmol thiourea and 100mg g-C3N4 powder were added to 30mL ethanol solution in sequence, and the solvent thermal reaction was carried out at 65℃ for 4h. After the reaction, the mixture was centrifuged and washed with ethanol, and dried at 60℃ to obtain the CSG nanocomposite precursor for use.

[0081] Example 6

[0082] (1) Preparation of g-C3N4:

[0083] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0084] (2) Preparation of CSG nanocomposites

[0085] 0.12mmol copper acetate, 0.48mmol thiourea, and 100mg g-C3N4 powder were sequentially added to 30mL of ethanol solution and subjected to solvothermal reaction at 65°C for 4h. After the reaction, the precursor was centrifuged and washed with ethanol and then dried at 60°C to obtain a CSG nanocomposite precursor. The resulting precursor was calcined at 400°C in air for 4h to obtain a yellow sample, which is the CSG (1:4) nanocomposite.

[0086] Example 7

[0087] (1) Preparation of g-C3N4:

[0088] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0089] (2) Preparation of CSG nanocomposites

[0090] 0.466mmol of copper acetate, 1.864mmol of thiourea, and 100mg of g-C3N4 powder were sequentially added to 30mL of ethanol solution and allowed to solvothermally react at 65°C for 4h. After the reaction, the mixture was centrifuged and washed with ethanol and then dried at 60°C to obtain a CSG nanocomposite precursor. The resulting precursor was calcined at 400°C in air for 4h to obtain a yellow-gray sample, which was the CSG (1:1) nanocomposite.

[0091] Example 8

[0092] (1) Preparation of g-C3N4:

[0093] 10 g of urea was placed in a crucible, and the crucible was placed in a muffle furnace and calcined at 550 °C for 3 h at a heating rate of 10 °C / min to obtain a light yellow solid, which was then ground to obtain g-C3N4 powder.

[0094] (2) Preparation of CSG nanocomposites

[0095] 4.32mmol of copper acetate, 17.28mmol of thiourea, and 100mg of g-C3N4 powder were sequentially added to 30mL of ethanol solution and subjected to a solvothermal reaction at 65°C for 4h. After the reaction, the solution was centrifuged and washed with ethanol and then dried at 60°C to obtain a CSG nanocomposite precursor. The resulting precursor was calcined at 400°C in air for 4h to obtain a silver sample, the CSG (9:1) nanocomposite.

[0096] Example 9

[0097] (1) Characterization of the structure and morphology of CSG (4:1) nanocomposites:

[0098] Figure 1 and Figure 2 These are the SEM and TEM images of the g-C3N4 and CSG (4:1) nanocomposite material prepared in Example 1. It can be seen that the morphology of the CSG (4:1) nanocomposite material is a multi-layered nanosheet with a rough surface.

[0099] Depend on Figure 2 The mapping diagram shows the distribution of Cu, S, C, and N elements.

[0100] Depend on Figure 3 The XPS graph shows that the valence changes of different elements in the CSG (4:1) nanocomposite material are caused by energy changes.

[0101] Figure 4 This is the XRD pattern of the final product obtained in Example 1, which confirms that the yellow-gray product obtained is CSG (4:1).

[0102] This rough and multi-layered nanosheet shortens the electron transmission path, increases the contact area with pollutants, provides more active sites, and is more conducive to the oxidative degradation reaction of tetracycline.

[0103] (2) Experimental scheme for green removal of tetracycline using CSG (4:1) nanocomposite materials:

[0104] The CSG (4:1) nanocomposite material prepared in Example 1 was added into tetracycline simulated wastewater made from pure water, and then the corresponding oxidative degradation performance of the constructed material was tested:

[0105] The test used a UV spectrophotometer to measure the absorbance of the supernatant extracted every half hour to calculate the residual tetracycline concentration, thereby demonstrating the degradation performance of the CSG (4:1) nanocomposite. After one and a half hours, the degradation efficiency reached 98.4%.

[0106] Figure 5The performance graphs of CSG nanocomposites with different g-C3N4 to copper ratios prepared in Examples 1 and Examples 6 to 8 and pure g-C3N4 on the oxidative degradation of tetracycline are shown. The performance of CSG (1:4) prepared in Example 6 is close to that shown in Example 1, but is ultimately slightly inferior to CSG (4:1) prepared in Example 1. Figure 6 The performance of materials calcined at different temperatures obtained in Examples 1, 4, 5 and Comparative Example 1 is shown. The performance of Example 5 calcined at 500°C is close to that of Example 1 calcined at 400°C, but both the morphology and performance are slightly inferior to those calcined at 400°C. Figure 7 、 Figure 8 The two figures are kinetic analyses of materials obtained at different calcination temperatures, indicating that Example 1 at 400°C also performs best in kinetics and has the highest reaction rate constant.

[0107] Figure 9 The degradation performance of the uncalcined CSG nanocomposite precursor for tetracycline prepared in Comparative Example 2 is compared. Under the same reaction conditions, the degradation rate is 65% within 90 minutes, which is lower than that of the calcined CSG (4:1). Therefore, appropriate calcination temperature and holding time have a positive effect on the carbonization degree of the material. A certain degree of carbonization first affects the pore size distribution and pore structure of the material surface, and secondly affects the surface morphology of the material. It also affects the distribution and number of active sites, thereby improving the catalytic performance of the material.

[0108] Figures 10-13 The performance of Example 1 under environmental factors is constructed. Figure 10 The pH factor shows that the material is not suitable for strong acid environments, but can be effective in environments ranging from weak acid to strong alkaline. Figure 11 is the amount of material added. The figure shows that the performance will increase with the increase of the amount added, but too much material will cause certain active centers to be covered, resulting in a decrease in catalytic performance. Figure 12 This figure shows the effect of tetracycline concentration on the material. It shows that a certain concentration of tetracycline will stimulate the generation of active centers, but too high a concentration will lead to excessive competition among active centers and a decrease in performance. Figure 13 The material is not affected by the ambient water temperature and can play a catalytic degradation role.

[0109] Figure 14 、 15 This is the mechanism verification diagram of Example 1, Figure 14 In the free radical capture experiment, EDTA, TBA and BQ captured holes, hydroxyl radicals and superoxide radicals respectively. The experimental results showed that hydroxyl radicals played the main role. Figure 15These are the results of ESR / EPR tests. The left picture shows that the hydroxyl radicals present in the reaction are captured, the middle picture shows that singlet oxygen is captured, and the right picture shows that S vacancies are formed by calcining the material. The S vacancies mainly serve as active centers.

[0110] Figure 16 、 17 It is the environmental impact factor diagram of Example 1 and the comparison diagram with real materials. Figure 16 This is the light source effect diagram. The degradation ability is slightly affected in a dark environment. The performance of other natural light, incandescent lamps, and xenon lamps are almost the same. The performance of natural light and incandescent lamps will be more stable, reflecting the mild environmental conditions required by the material and the energy-saving characteristics. Figure 17 Comparisons of hydrogen peroxide and nitrogen atmospheres with air. Compared to other existing technologies, this material achieves equivalent or even better performance in an air environment without the addition of hydrogen peroxide. Nitrogen purge experiments demonstrate the crucial role of oxygen in the experiment.

[0111] Figure 18 This is the effect of different water sources on the catalytic performance of the material in Example 1. The figure shows that the material is less affected by the water source, has good adaptability to the environment, and has low requirements for the purity of the water itself.

[0112] The CSG nanocomposite material of this application demonstrates excellent environmental adaptability (pH, temperature, etc.), easily degrading antibiotics (tetracyclines) in wastewater without the need for dilution. Furthermore, this nanomaterial is simple to prepare, with low-cost, abundant raw materials, and can be synthesized in large quantities. It does not require additional carriers or energy sources (such as light sources or purified water sources), and exhibits high catalytic oxidation performance.

Claims

1. A method for preparing a g-C3N4-based nanocomposite material for removing tetracycline, characterized in that: The following steps are involved: (1) reacting a sulfur source, a copper source, and g-C3N4 in a solvent at 60-70°C for 1-6 h, and then separating to obtain a g-C3N4-based precursor; the sulfur source is thiourea or thioacetamide; (2) After drying the g-C3N4-based precursor, calcining it at a constant temperature of 350-500°C in an air atmosphere to obtain the g-C3N4-based nanocomposite material.

2. The preparation method according to claim 1, wherein The reaction temperature in step (1) is 65°C.

3. The preparation method according to claim 1, wherein The constant temperature burning temperature in step (2) is 400°C.

4. The preparation method according to claim 1, characterized in that The g-C3N4 described in step (1) is prepared by the following method: (0) The nitrogen source is calcined at 500-600°C in an air atmosphere and then cooled to obtain the product.

5. The preparation method according to claim 4, characterized in that The calcination temperature in step (0) is 550°C.

6. The preparation method according to claim 4, characterized in that The nitrogen source in step (0) is thiourea, melamine or urea.

7. The preparation method according to claim 1, characterized in that The copper source in step (1) is copper acetate, copper chloride or copper nitrate; and the solvent is methanol, ethanol or water.

8. The preparation method according to claim 1, characterized in that The molar ratio of the copper element in the copper source in step (1) to the nitrogen element in the g-C3N4 is 1:10~16.

9. The preparation method according to claim 1, characterized in that The reaction time in step (1) is 4 hours.

10. The preparation method according to claim 1, characterized in that The drying in step (2) is performed at 60-80°C.

11. The preparation method according to claim 1, characterized in that The burning time in step (2) is 2 to 4 hours.

12. The preparation method according to claim 11, characterized in that The burning time in step (2) is 4 hours.

13. The g-C3N4-based nanocomposite material prepared by the preparation method according to any one of claims 1 to 12.

14. Use of the g-C3N4-based nanocomposite material prepared by the preparation method according to any one of claims 1 to 12 in the oxidative degradation of tetracycline in water.

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