A BiVO4 / MIL-68(In) heterojunction composite material, its preparation method and application

Abstract

The present invention provides a BiVO₄ / MIL-68(In) heterojunction composite material, a preparation method thereof and an application thereof, belonging to the technical fields of photocatalysis-persulfate materials, water treatment and environmental governance. In the composite material, BiVO₄ is loaded on MIL-68(In); the heterojunction is a heterojunction structure formed by peanut-shaped granular BiVO₄ embedded in hexagonal rod-shaped MIL-68(In); the diameter of the peanut-shaped granular BiVO₄ is 1-3 μm; the length of the hexagonal rod-shaped MIL-68(In) is 5-10 μm. The present invention combines the heterojunction composite material with photocatalysis-persulfate to realize the coupling of photocatalytic degradation and persulfate degradation, enhances the degradation efficiency of the catalyst through the enhancement of electron transfer of the heterojunction material, and simultaneously enhances the degradation efficiency by utilizing the synergistic effect of photocatalysis-persulfate in degrading pollutants.

Description

Technical Field

[0001] The present invention relates to the technical fields of photocatalytic materials, water treatment, and environmental governance, and particularly relates to a photocatalytic-persulfate composite material for degrading antibiotics and its application. Background Art

[0002] Ofloxacin (OFL) belongs to fluoroquinolone drugs and is widely used in medical treatment of diseases. After being ingested by humans or livestock, most of the OFL cannot be completely absorbed in the body and is excreted through urination and other means, resulting in frequent detection in the water environment. Residual OFL in the environment may induce large-scale bacterial resistance and antibiotic resistance, posing a serious risk to public and animal health. In addition, the chemical structure of OFL is stable, and it is difficult to effectively remove it by traditional water pollution treatment methods. It has become a top priority to urgently find an effective method to remove antibiotic pollution in water.

[0003] Photocatalysis, as one of the advanced oxidation processes, can effectively degrade organic pollutants by generating free radicals (such as OH· and O2 - ·, etc.). The disadvantages of photocatalysis are also obvious, manifested as insufficient visible light absorption, high recombination rate of photoexcited electron-hole pairs resulting in low quantum yield of reactive substances, and weak pollutant adsorption ability. Persulfate activation mainly activates persulfate to generate effective sulfate radicals (SO4 - ·) and effectively degrades pollutants in water. However, the activation process of metal ions usually requires an acidic reaction environment, and a large amount of metal sludge will be generated after the reaction, bringing secondary pollution. Many studies have found that photocatalysis and persulfate activation have a positive synergistic effect on the removal of antibiotics. Persulfate can generate sulfate radicals by self-activating and capturing photogenerated electrons. At the same time, it promotes the separation of photogenerated electron-hole pairs, enhances the photocatalytic activity, and further improves the persulfate activation.

[0004] Bi-based and In-based semiconductor materials have always been widely concerned in the field of photocatalysis-persulfate. They have great potential in removing antibiotics due to their simple composition, low toxicity, photocatalytic stability, and excellent photocatalytic activity. The stable structure formed by the connection of metal oxide clusters and organic ligands in MOF materials can cause atomic structure changes and have certain catalytic properties. Among them, MIL-68(In) has been widely studied due to its high temperature resistance, acid and alkali resistance, and strong physicochemical stability. However, the actual application effect of MIL-68(In) needs to be improved at present, and the catalytic degradation efficiency of the combination process of photocatalysis and persulfate needs to be further studied. In the present invention, a composite material is successfully prepared by using MOF and single materials and is used for photocatalysis-persulfate to remove antibiotics, which can form a complementary and synergistic effect. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a BiVO4 / MIL-68(In) heterojunction composite material, a preparation method thereof and an application thereof. The present invention can realize the coupling of photocatalytic degradation and persulfate degradation, enhance the degradation efficiency of the catalyst through the enhancement of electron transfer of the heterojunction material, and simultaneously enhance the degradation efficiency by using the synergistic effect of photocatalytic-persulfate degradation of pollutants.

[0006] The technical solution of the present invention is as follows:

[0007] A BiVO4 / MIL-68(In) heterojunction composite material, wherein the heterojunction composite material is a heterojunction structure formed by peanut-shaped granular BiVO4 embedded on hexagonal rod-shaped MIL-68(In);

[0008] The peanut-shaped granular BiVO4 has a diameter of 1-3 μm; the hexagonal rod-shaped MIL-68(In) has a diameter of 5-10 μm.

[0009] The preparation method of the BiVO4 / MIL-68(In) heterojunction composite material comprises the following steps:

[0010] (1) Preparation of MIL-68(In):

[0011] Dissolve In(NO3)3·4H2O in DMF, stir evenly, add the organic ligand 1,4-benzenedicarboxylic acid, continue to stir evenly, and transfer it to a polytetrafluoroethylene lining; seal the polytetrafluoroethylene lining in a stainless steel autoclave and keep it at 100-120 °C for 40-48 hours. After cooling, wash and dry the obtained solid to obtain MIL-68(In);

[0012] (2) Preparation of BiVO4 / MIL-68(In) heterojunction composite material:

[0013] First, dissolve the vanadium source NH4VO3 in deionized water and stir to form solution A. Then, dissolve MIL-68(In) in ethylene glycol, add the bismuth source Bi(NO3)3·5H2O and stir to form solution B. Then, slowly add solution A to solution B to form a mixed solution, continue to stir evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, and carry out a hydrothermal reaction at 100-150 °C for 15-18 h; after cooling, wash and dry to obtain the BiVO4 / MIL-68(In) heterojunction composite material.

[0014] Preferably, in step (1), by molar ratio, In(NO3)3·4H2O:1,4-benzenedicarboxylic acid = 1-1.2:1-1.5.

[0015] Preferably, in step (1), the mass-volume ratio of In(NO3)3·4H2O to DMF is 23-26: 1-1.2 mg / mL.

[0016] Preferably, in step (2), by mass ratio, the ratio of NH4VO3, MIL-68(In), and Bi(NO3)3·5H2O is 3-4.5: 1-1.5: 12-15.

[0017] Preferably, in step (2), in solution A, the ratio of NH4VO3 to deionized water is 11-13: 1-1.3 mg / mL; in solution B, the ratio of MIL-68(In) to ethylene glycol is 4-11: 1-1.2 mg / mL.

[0018] The present invention also provides the application of the BiVO4 / MIL-68(In) heterojunction composite material, that is, using the BiVO4 / MIL-68(In) heterojunction composite material to degrade antibiotics.

[0019] Preferably, the antibiotic is ofloxacin.

[0020] Preferably, the antibiotic exists in the flowing-phase water body.

[0021] Furthermore, in the photocatalysis-persulfate system of the BiVO4 / MIL-68(In) heterojunction composite material, persulfate is activated under visible light conditions to generate h + , ·O2 - and 1 O2-dominated free radicals, as well as SO4 - · and ·OH secondary radical active substances, thereby degrading antibiotics.

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

[0023] 1. The present invention combines BiVO4 / MIL-68(In) for the first time for photocatalysis-persulfate degradation. BiVO4 and MIL-68(In) have excellent matching in electric potential energy and band gap, and the formed heterojunction material can effectively solve problems such as low visible light response, low electron conductivity, and photo-generated carrier annihilation.

[0024] 2. In the present invention, BiVO4 / MIL-68(In) is synthesized using a stable organic ligand as a precursor. Its morphological characteristics are such that MIL-68(In) serves as the main body, with BiVO4 embedded therein. The overall particle size of BiVO4 is in the micron range, with a peanut-shaped core. The overall peanut-shaped particles exist in clusters or individually. The overall particle size of MIL-68(In) is approximately 5 - 10 μm, and its morphology is a hexagonal rod-like structure. BiVO4 is embedded in the gaps or on the surface of MIL-68(In), forming an overall structure with a relatively large specific surface area, which can enhance the adhesion of pollutants for effective degradation.

[0025] 3. The BiVO4 / MIL-68(In) material prepared in the present invention belongs to a Z-type heterojunction structure. Composite materials of this heterojunction type have higher electrical potential energy, higher electron conductivity, and more effective electron-hole separation performance.

[0026] 4. The photocatalysis - persulfate process of the present invention can significantly improve the degradation efficiency of the BiVO4 / MIL-68(In) composite material. Experimental results show that after adding persulfate during the photocatalysis process of the BiVO4 / MIL-68(In) composite material catalyst at the same dosage, the degradation effect is significantly improved. This indicates that the composite material of the present invention can well couple the photocatalysis process and persulfate, and also solves the defects of the composite material in the photocatalysis process and the activation of persulfate.

[0027] 5. When the heterojunction composite material prepared in the present invention is excited by visible light, due to the strong electrostatic attraction between the holes on the valence band of BiVO4 and the electrons on the conduction band of MIL-68(In) in the single material due to the relatively low band gap energy, the photo-generated electrons in the conduction band and the photo-generated holes in the valence band quickly annihilate. Compared with the single-component material, the heterojunction material in the BiVO4 / MIL-68(In) composite material generates more active substances, effectively improving the photocatalysis - persulfate degradation performance of the material for ofloxacin.

[0028] 6. Experimental results show that in a flowing water body, after irradiating the BiVO4 / MIL-68(In) composite material with visible light (300W xenon lamp) for 25 minutes, 100% degradation of ofloxacin in water can be achieved. After four cycles, the photocatalytic degradation efficiency of tetracycline is still as high as over 85%, indicating that the composite material has good stability and recyclability and can effectively degrade antibiotics in water.

[0029] 7. The present invention has the characteristics of simple preparation method. In the synthesis process of BiVO4, deionized water is used as the solvent. Compared with the synthesis processes of most BiVO4 that require dilute nitric acid or sodium hydroxide as solvents, the cost is reduced and the economic benefits are improved. The synthesis process has characteristics such as low energy efficiency and stable operation, and has potential application prospects in the field of photocatalysis - persulfate, and has great potential in practical applications and large-scale production. Description of the Drawings

[0030] Figure 1 SEM images of the materials obtained in Example 1, where (a) is BiVO4, (b) is MIL-68(In), and (c) and (d) are BiVO4 / MIL-68(In);

[0031] Figure 2 XRD patterns of BiVO4, MIL-68(In), and BiVO4 / MIL-68(In) of the materials obtained in Example 1;

[0032] Figure 3 Transient photocurrent diagram of BiVO4 / MIL-68(In) (BVM-75) obtained in Example 1;

[0033] Figure 4 EIS impedance diagram of BiVO4 / MIL-68(In) (BVM-75) obtained in Example 1;

[0034] Figure 5 Photocatalysis - persulfate degradation diagrams of BiVO4, MIL-68(In), and BiVO4 / MIL-68(In) for ofloxacin in Test Example 1;

[0035] Figure 6 Photocatalysis - persulfate removal rate diagrams of BiVO4 / MIL-68(In) with different precursor dosages for ofloxacin solution in Test Example 2;

[0036] Figure 7 Photocatalysis - persulfate removal rate diagrams of BiVO4 / MIL-68(In) (BVM-75) for ofloxacin solutions with different concentrations in Test Example 3;

[0037] Figure 8 Photocatalysis - persulfate removal rate diagrams of BiVO4 / MIL-68(In) (BVM-75) for ofloxacin solutions with different pH values in Test Example 4;

[0038] Figure 9 Cycle number - degradation efficiency diagrams corresponding to the cyclic degradation of ofloxacin solution by BiVO4 / MIL-68(In) (BVM-75) in Test Example 5. Detailed Embodiments

[0039] The present invention will be specifically described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Embodiment 1:

[0041] This embodiment provides a BiVO4 / MIL-68(In) heterojunction composite material and a preparation method thereof. The specific steps are as follows:

[0042] S1. Dissolve 2 mmol (601 mg) of In(NO3)3·4H2O in 25 mL of DMF, stir evenly, add 2.4 mmol (398.7 mg) of the organic ligand 1,4-benzenedicarboxylic acid, continue to stir evenly, and then transfer it to a polytetrafluoroethylene liner; seal the polytetrafluoroethylene liner in a stainless steel autoclave and maintain it at 120 °C for 40 hours. After cooling, wash and dry the obtained solid to obtain MIL-68(In);

[0043] S2. Weigh 234 mg of NH4VO3 and dissolve it in 20 mL of deionized water, stir for 20 min to form solution A;

[0044] S3. Weigh 25, 75, 125, and 225 mg of MIL-68(In) respectively, disperse them evenly in 20 mL of ethylene glycol, add 970 mg of Bi(NO3)3·5H2O, and stir for 20 min to form solution B;

[0045] S4. Slowly add solution A to solution B to form a mixed solution, continue to stir on a magnetic stirrer at a speed of 900 rpm for 30 min, then transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and carry out a hydrothermal reaction at 110 °C for 15 h. After the autoclave is naturally cooled, wash and dry it to obtain the BiVO4 / MIL-68(In) composite material.

[0046] The successfully compounded composite material is named according to the loading amount as BVM-x (x = 25, 75, 125, 225), where x represents the amount of MIL-68(In) added. The SEM of the material prepared in this embodiment is as Figure 1 shown. As can be seen from Figure 1 (a), BiVO4 is peanut-shaped granular, with a transverse diameter of 1-3 μm and a length of 2-8 μm; as can be seen from Figure 1(b) It can be seen that MIL-68(In) is in the shape of hexagonal rods with a diameter of 3 - 10 μm, preferably 5 - 10 μm, and a length greater than 5 μm, preferably 10 - 200 μm; from Figure 1 (c) and (d), it can be observed that BiVO4 forms clusters or is individually embedded on the surface of MIL-68(In) to form a stable composite material.

[0047] The XRD of the material prepared in this example is as shown in Figure 2 . It can be seen from the figure that the characteristic diffraction peaks of Bi2O2CO3 and MIL-68(In) appear simultaneously in the composite material, indicating that the two single materials have been successfully compounded.

[0048] The composite material was tested by transient photocurrent response and electrochemical impedance to explore the charge carrier separation behavior and interfacial charge transfer resistance in the composite material. In Figure 3 , the transient photocurrent response diagram of the composite material is presented. It can be seen from the figure that under light illumination, the current peaks of different materials all respond rapidly and reach a steady state. Among them, the heterojunction composite material BVM-75 exhibits the highest current intensity, and the current peaks of single Bi2O2CO3 and MIL-68(In) are significantly reduced, and the composite material is better in terms of repeated current stability.

[0049] Figure 4 The corresponding impedance curves of each material are presented in. Among them, the smaller the curve radius, the smaller the resistance suffered by the charge transfer of the corresponding material, and thus more electron-hole pairs can be generated. The curve radius of MIL-68(In) is the largest, followed by Bi2O2CO3, while the curve radius of BVM-75 is the smallest, significantly lower than that of the single material. It is proved that the photogenerated electrons of the heterojunction composite material have the smallest migration resistance and the largest charge separation efficiency.

[0050] Test Example 1:

[0051] The BiVO4 / MIL-68(In) composite material prepared in Example 1 was used to degrade ofloxacin in a photocatalytic reactor to evaluate its photocatalytic - persulfate ability under visible light. At the same time, single BiVO4 with a diameter of 1 - 3 μm and single rod-shaped MIL-68(In) with a length of 5 - 10 μm were used as controls. The specific method is as follows:

[0052] Visible light irradiation was provided using a 300 W xenon lamp and a 420 nm ultraviolet cut-off filter (>420 nm). 20 mg of the composite material was dispersed into a photocatalytic reactor containing 100 mL of ofloxacin solution (the concentration of ofloxacin was 5 mg / L). Adsorption was carried out with stirring for 30 min in the dark to achieve adsorption equilibrium between the catalyst and the pollutants. During illumination, approximately 1.5 mL of the suspension was taken at regular intervals (5 min), and then filtered through a syringe filter membrane (0.22 μm) to remove catalyst particles. The degradation rate of ofloxacin was determined using a high performance liquid chromatograph.

[0053] Figure 5 This is a graph showing the photocatalytic - persulfate degradation effect of the composite material prepared in Example 1 of the present invention on ofloxacin under visible light. As can be seen from the graph, after 20 min of illumination, the photocatalytic - persulfate degradation rates of ofloxacin using BiVO4, MIL-68(In), and BiVO4 / MIL-68(In) alone were 86.17%, 31.25%, and 100% respectively. This indicates that compared with single-component materials, the heterojunction material effectively improved the photocatalytic - persulfate degradation of ofloxacin.

[0054] Test Example 2:

[0055] Evaluate the photocatalytic - persulfate degradation of BiVO4 / MIL-68(In) composite material on ofloxacin under visible light at different precursor dosages. The specific method is as follows:

[0056] Visible light irradiation was provided using a 300 W xenon lamp and a 420 nm ultraviolet cut-off filter (>420 nm). The composite materials with different precursor loadings (25 mg, 75 mg, 125 mg, 225 mg) prepared were added to 100 mL of ofloxacin solution (5 mg / L). Adsorption was carried out under dark conditions for 30 min to achieve adsorption equilibrium between the composite material and the antibiotic. Persulfate was added during illumination, and approximately 1.5 mL of ofloxacin solution was taken at regular intervals (5 min). The degradation rate of ofloxacin was determined using a high performance liquid chromatograph.

[0057] Figure 6 This is a graph showing the photocatalytic - persulfate degradation effect of the BiVO4 / MIL-68(In) composite material prepared in Example 1 of the present invention on ofloxacin (5 mg / L) under visible light. It can be seen from the graph that as the dosage of MIL-68(In) increased from 75 mg to 225 mg, the degradation rate of the composite material on ofloxacin decreased from 100% to 61.15%. This is because the increase in the precursor reduced the number of active sites in the reaction, and the excessive precursor produced a "coverage effect", preventing the excitation of some active sites.

[0058] Test Example 3:

[0059] In the photocatalytic reaction device, the effects of different antibiotic concentrations on the photocatalytic degradation of ofloxacin were evaluated. The specific method was as follows:

[0060] Visible light irradiation was provided using a 300 W xenon lamp and a 420 nm ultraviolet cut-off filter (>420 nm). The prepared composite material (BVM-75) was added to 100 mL of ofloxacin solutions with different concentrations (5 mg / L, 10 mg / L, 20 mg / L). Adsorption was carried out for 30 min under dark conditions to achieve adsorption equilibrium between the composite material and the antibiotic. During illumination, approximately 1.5 mL of the ofloxacin solution was taken at regular intervals (5 min). The degradation rate of ofloxacin was determined using a high-performance liquid chromatograph.

[0061] Figure 7 This is a graph showing the photocatalytic - persulfate degradation effect of BiVO4 / MIL-68(In) (BVM-75) prepared in Example 1 of the present invention on ofloxacin solutions with different concentrations under visible light. As can be seen from the graph, as the ofloxacin concentration increased from 5 mg / L to 20 mg / L, the photocatalytic degradation rate decreased from 100% to 70.84%. This is because an excessive number of ofloxacin molecules would compete for the adsorption sites and reaction sites on the surface of the photocatalyst, resulting in a decrease in the photocatalytic - persulfate efficiency. Therefore, the composite material prepared in the present invention has good photocatalytic degradation effect when the ofloxacin concentration is lower than 10 mg / L.

[0062] Test Example 4:

[0063] In the photocatalytic reaction device, the effects of different pH values on the photocatalytic - persulfate degradation of ofloxacin were evaluated. The specific method was as follows:

[0064] Visible light irradiation was provided using a 300 W xenon lamp and a 420 nm ultraviolet cut-off filter (>420 nm). The prepared composite material (BVM-75) was added to 100 mL of ofloxacin solutions with different pH values (3, 5, 7, 9, 11). Adsorption was carried out for 30 min under dark conditions to achieve adsorption equilibrium between the composite material and the antibiotic. During illumination, approximately 1.5 mL of the ofloxacin solution was taken at regular intervals (5 min). The degradation rate of ofloxacin was determined using a high-performance liquid chromatograph.

[0065] Figure 8Photocatalytic - persulfate degradation efficiency curve of BiVO4 / MIL - 68(In) (BVM - 75) prepared in Example 1 of the present invention for ofloxacin solutions with different pH values under visible light. As can be seen from the figure, when the pH value increases from 5 to 11, the degradation rate remains above 99%, indicating that the prepared composite material has a wide pH adaptability and strong usability in actual sewage treatment processes. When pH = 3, the adsorption and photocatalytic degradation efficiency decreases. The reason may be that excessive H + can combine with active species (O2 - ). Therefore, the composite material prepared in the present invention has good photocatalytic - persulfate degradation effect at pH 5 - 11.

[0066] Test Example 5:

[0067] The long - term reusability and stability of the catalyst are key factors in actual water treatment processes. In the present invention, the BiVO4 / MIL - 68(In) (BVM - 75) composite material was used for four cycles of photocatalytic - persulfate degradation of ofloxacin, with the concentration of ofloxacin being 5 mg / L. After each cycle was completed, the composite material was taken out, and only simple rinsing with deionized water, filtration, and drying were carried out before being put into the next cycle. The results are as Figure 9 shown. After 4 cycles, the photocatalytic degradation efficiency of ofloxacin is still above 85%, indicating that BVM - 75 has good stability and recyclability. It should be noted that Figure 9 the time on the abscissa in [figure] includes 30 min for reaching adsorption equilibrium under dark conditions.

[0068] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, for ordinary technical personnel in the field, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to specific details.

Claims

1. Application of a BiVO4 / MIL-68(In) heterojunction composite material, characterized in that, The BiVO4 / MIL-68(In) heterojunction composite material is used for degrading antibiotics; the antibiotic is ofloxacin; The BiVO4 / MIL-68(In) heterojunction composite material in the photocatalysis-persulfate system activates persulfate under visible light conditions to generate h + , ·O2 - and 1 O2-dominated free radicals, as well as SO4 - · and ·OH minor free radical active substances, thereby degrading antibiotics; The heterojunction composite material is a heterojunction structure formed by peanut-shaped granular BiVO4 embedded on hexagonal rod-shaped MIL-68(In); The diameter of the peanut-shaped granular BiVO4 is 1-3 μm; the diameter of the hexagonal rod-shaped MIL-68(In) is 5-10 μm; the material belongs to the Z-type heterojunction structure; The preparation method of the BiVO4 / MIL-68(In) heterojunction composite material comprises the following steps: (1) Preparation of MIL-68(In): Dissolve In(NO3)3·4H2O in DMF, stir evenly, add the organic ligand 1,4-benzenedicarboxylic acid, continue to stir evenly, and transfer to a polytetrafluoroethylene liner; seal the polytetrafluoroethylene liner in a stainless steel autoclave and keep it at 100-120 °C for 40-48 hours. After cooling, wash and dry the obtained solid to obtain MIL-68(In); (2) Preparation of the BiVO4 / MIL-68(In) heterojunction composite material: First, dissolve the vanadium source NH4VO3 in deionized water and stir to form solution A. Then dissolve MIL-68(In) in ethylene glycol, add the bismuth source Bi(NO3)3·5H2O and stir to form solution B. Then slowly add solution A to solution B to form a mixed solution, continue to stir evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, and carry out a hydrothermal reaction at 100-150 °C for 15-18 h; after cooling, wash and dry to obtain the BiVO4 / MIL-68(In) heterojunction composite material.

2. The application according to claim 1, wherein In step (1), by molar ratio, In(NO3)3·4H2O:1,4-benzenedicarboxylic acid = 1-1.2:1-1.

5.

3. The application according to claim 1, characterized in that, In step (1), the mass-volume ratio of In(NO3)3·4H2O to DMF is 23-26:1-1.2 mg / mL.

4. The application according to claim 1, wherein In step (2), by mass ratio, the ratio of NH4VO3, MIL-68(In), and Bi(NO3)3·5H2O is 3-4.5:1-1.5:12-15.

5. The application according to claim 1, characterized in that, In step (2), in solution A, the ratio of NH4VO3 to deionized water is 11-13:1-1.3 mg / mL; in solution B, the ratio of MIL-68(In) to ethylene glycol is 4-11:1-1.2 mg / mL.

6. The application according to claim 1, characterized in that, The antibiotic exists in the flowing-phase water body.

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