Bismuth-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a bismuth-based metal organic framework material as well as a preparation method and application thereof, and the bismuth-based metal organic framework material is prepared by taking bismuth salt as metal salt, para aminobenzoic acid as an organic ligand and N, N-dimethyl formyl as a solvent through solvothermal reaction. According to the preparation method disclosed by the invention, the bismuth-based metal organic framework material with large specific surface area, large light absorption range and high photocatalytic activity can be prepared by optimizing the raw material ratio, the organic ligand type, the solvent type and the solvothermal reaction condition; as a novel visible light photocatalyst with excellent photocatalytic performance, the bismuth-based metal organic framework material can be widely used for treating antibiotic wastewater, can realize efficient removal of antibiotics in wastewater under the condition of visible light, has the advantages of simple process, convenience in operation, low cost, high treatment efficiency, good removal effect, environment friendliness and the like, and has wide application prospects. The method has important promotion significance on purification of organic pollutant wastewater, and is high in use value and good in application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalysis and relates to a bismuth-based metal organic framework material and a preparation method and application thereof. Background Art

[0002] Compared with traditional sewage treatment methods, photocatalytic methods are not only cheap and green and sustainable, but also have high decomposition and mineralization capabilities. They have been proven to be an effective means of removing antibiotics (such as tetracycline hydrochloride) from water bodies.

[0003] Bismuth-based metal-organic framework materials (Bi-MOFs) have irreplaceable advantages in photocatalytic technology due to their biosafety, structural adjustability and multifunctional catalytic activity. Existing bismuth-based metal-organic framework materials use carboxylic acid (such as terephthalic acid, trimesic acid) ligands as the main building blocks, have stable microporous structures, and perform outstandingly in the field of environmental governance. However, these bismuth-based metal-organic framework materials (such as CAU-17) have shortcomings in wide band gap characteristics, rapid recombination of photogenerated carriers, and visible light response capabilities, resulting in poor photocatalytic performance under mild light conditions and difficulty in efficiently degrading high-concentration pollutants. In addition, some researchers have proposed using histidine and 2-aminoterephthalic acid as organic ligands to prepare bismuth-based metal-organic framework materials. However, the bismuth-based metal-organic framework materials prepared in this way still have shortcomings such as poor light absorption capacity and poor photocatalytic activity. In particular, the bismuth-based metal-organic framework materials prepared from 2-aminoterephthalic acid basically have no photocatalytic performance and cannot be used as a photocatalyst for the photocatalytic degradation of antibiotics in water. In addition, the above-mentioned method for preparing bismuth-based metal-organic framework materials using hydrothermal synthesis still has the following drawbacks: the use of alcohols as solvents or the hydrothermal temperature as high as 160°C are also not conducive to the preparation of bismuth-based metal-organic framework materials with excellent photocatalytic performance. Therefore, obtaining a bismuth-based metal-organic framework material with a large specific surface area, a wide light absorption range, and high photocatalytic activity, and a matching preparation method with simple process, convenient operation, low cost, and suitability for large-scale preparation is of great significance for promoting the widespread application of bismuth-based metal-organic framework materials in the field of photocatalysis. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a bismuth-based metal organic framework material with large specific surface area, large light absorption range and high photocatalytic activity, as well as a preparation method and application thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a bismuth-based metal-organic framework material comprises using a bismuth salt as a metal salt, p-aminobenzoic acid as an organic ligand, and N,N-dimethylformyl as a solvent to prepare the bismuth-based metal-organic framework material through a solvent thermal reaction.

[0007] The above preparation method is further improved and comprises the following steps:

[0008] S1. Mixing bismuth salt, p-aminobenzoic acid, and N,N-dimethylformyl, and stirring to obtain a mixed solution;

[0009] S2. Performing a solvothermal reaction on the mixed solution to obtain a bismuth-based metal-organic framework material.

[0010] The above preparation method is further improved, in step S1, the molar ratio of the bismuth salt and para-aminobenzoic acid is 1:0.5-4; the ratio of the bismuth salt to N,N-dimethylformyl is 1mmoL:60mL; the bismuth salt is at least one of bismuth acetate, bismuth sulfate, bismuth chloride, bismuth nitrate, bismuth hydroxide, bismuth bromide, and bismuth iodide.

[0011] The above preparation method is further improved, in step S1, the molar ratio of the bismuth salt to p-aminobenzoic acid is 1:1-3.

[0012] The above preparation method is further improved, in which in step S2, the solvent thermal reaction is carried out at a temperature of 80°C to 120°C; the solvent thermal reaction time is 12h to 24h; and after the solvent thermal reaction is completed, the following treatment is also included: filtering the product after the solvent thermal reaction, collecting the solid product, washing the solid product with ethanol and N,N-dimethylformyl, and drying under vacuum conditions at a temperature of 50°C to 80°C.

[0013] The above preparation method is further improved in that in step S2, the solvent thermal reaction is carried out at a temperature of 90°C to 110°C.

[0014] As a general technical concept, the present invention also provides a bismuth-based metal-organic framework material prepared by the above preparation method.

[0015] As a general technical concept, the present invention also provides a use of the above-mentioned bismuth-based metal organic framework material as a photocatalyst in treating antibiotic wastewater.

[0016] The above application is further improved, using bismuth-based metal-organic framework materials as photocatalysts to degrade antibiotic wastewater, including the following steps: mixing the bismuth-based metal-organic framework material and antibiotic wastewater, and performing a photocatalytic reaction under visible light conditions to complete the degradation of antibiotics in the wastewater; the amount of the bismuth-based metal-organic framework material added is 0.8g to 1.4g per liter of antibiotic wastewater.

[0017] The above application is further improved in that the concentration of the antibiotic in the antibiotic wastewater is ≤30 mg / L; the antibiotic is tetracycline hydrochloride; and the time of the photocatalytic reaction is 30 min to 60 min.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] (1) In view of the shortcomings of existing bismuth-based metal-organic framework materials, such as small specific surface area, narrow light absorption range, and poor photocatalytic activity, the present invention creatively proposes a method for preparing a bismuth-based metal-organic framework material, using bismuth salt as metal salt, p-aminobenzoic acid as organic ligand, and N,N-dimethylformyl as solvent to prepare the bismuth-based metal-organic framework material after a solvent thermal reaction. Compared with conventional organic ligands (such as histidine and 2-aminoterephthalic acid), in the present invention, p-aminobenzoic acid is used as the organic ligand, which contains carboxyl and amino groups. On the one hand, the amino group (-NH2) is a typical Lewis base with the dual functions of proton acceptor and electron donor. At the same time, the amino group exhibits significant energy level regulation characteristics, which can optimize the band gap width (Eg) of the material. At the same time, the carboxyl group can make the material have a porous structure corresponding to the specific surface area, and the amino group can make the material have a larger light absorption range and a smaller band gap, which are conducive to improving the photocatalytic performance. On the other hand, the lone pair of electrons of the organic ligand can reconstruct the electron cloud distribution of the aromatic system through the π-π conjugation effect, induce the highest occupied molecular orbital energy level to rise, thereby expanding the light response boundary to the visible light band; more importantly, in the present invention, N,N-dimethylformyl is used as the solvent, which has strong solubility and complexing ability, not only can the various raw materials in the system be evenly dispersed, but also can effectively avoid the local concentration being too high. The side reactions caused are beneficial to improving the purity and uniformity of the product, providing an efficient and controllable reaction environment for material synthesis, and ensuring that the ligands are fully dissociated and precisely bonded to the metal nodes, giving the bismuth-based metal-organic framework material a narrow band gap and visible light response characteristics, so that the bismuth-based metal-organic framework material has excellent adsorption and photocatalytic properties, and can efficiently adsorb and photocatalytically degrade organic pollutants. On this basis, a solvothermal reaction is carried out in a polar solvent system constructed by N,N-dimethylformamide, which can promote the coordination self-assembly of bismuth metal ions and para-aminobenzoic acid, and then can directionally construct a bismuth-based metal-organic framework material with a large specific surface area, a large number of active sites, a large light absorption range, and high photocatalytic activity. At the same time, this bismuth-based metal-organic framework material, as a new visible light photocatalyst with excellent photocatalytic performance, can be used to widely treat antibiotic wastewater and can achieve efficient removal of antibiotics in wastewater under visible light conditions. It has high use value and good application prospects. At the same time, the preparation method of the bismuth-based metal organic framework material of the present invention also has the advantages of simple process, convenient operation, mild reaction conditions, low cost, and green environmental protection. It can be used for large-scale preparation and is convenient for industrial utilization.

[0020] (2) In the preparation method of the present invention, by optimizing the molar ratio of bismuth salt to p-aminobenzoic acid to 1:0.5-4, and particularly when the molar ratio is 1:1-3, the ratio of the reactants is precisely controlled to achieve the controllable preparation of high-purity, high-performance materials while reducing costs and resource waste. However, a high or low ratio of the reactants may introduce defects, impurities, or morphological degradation, directly impairing the performance of the material and hindering the production of bismuth-based metal-organic frameworks with excellent performance.

[0021] (3) In the preparation method of the present invention, by optimizing the solvent thermal reaction and carrying out the reaction at a temperature of 80°C to 120°C, in particular, when the solvent thermal reaction is carried out at a temperature of 90°C to 110°C, the diffusion and activation of the reactant molecules can be accelerated, the reaction can be promoted, and the occurrence of side reactions can be reduced, thereby being able to prepare a bismuth-based metal organic framework material with better photocatalytic performance. However, too high a reaction temperature may lead to catalyst deactivation, accompanied by safety risks and increased energy consumption. Too low a reaction temperature may lead to uneven products and solvent residues. More importantly, by regulating the reaction temperature and the metal / ligand molar ratio, the crystal growth kinetics and thermodynamic equilibrium can be optimized, thereby forming a stable porous structure, which is conducive to the preparation of a bismuth-based metal organic framework material with a larger specific surface area and a richer pore structure.

[0022] (4) The present invention also provides an application of a bismuth-based metal organic framework material as a photocatalyst in the treatment of antibiotic wastewater. Specifically, the bismuth-based metal organic framework material and antibiotic wastewater are mixed, and a photocatalytic reaction is carried out under visible light conditions. During the photocatalytic process, active substances such as superoxide anion radicals, holes, and singlet oxygen are generated. These active substances can then be used to efficiently degrade antibiotics in the wastewater. The method has the advantages of simple process, convenient operation, low cost, high treatment efficiency, good removal effect, and green environmental protection, and is of great significance for purifying wastewater containing organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] Figure 1 The nitrogen adsorption-desorption isotherms and corresponding pore size distribution diagrams of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0025] Figure 2 4. Fourier transform infrared spectra of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 of the present invention and Comparative Example 1.

[0026] Figure 3 1 and 2. The X-ray photoelectron spectra of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0027] Figure 4 These are UV-visible diffuse reflectance spectra of the bismuth-based metal-organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention.

[0028] Figure 5 This is a diagram showing the degradation effect of tetracycline hydrochloride in wastewater by the bismuth-based metal organic framework materials (Bi-AA, CAU-17) in Example 2 of the present invention under different illumination time conditions.

[0029] Figure 6 This is a diagram showing the degradation effect of tetracycline hydrochloride in wastewater by the bismuth-based metal organic framework materials (Bi-AA, A1-A7) in Example 2 of the present invention under different illumination time conditions.

[0030] Figure 7 This is a diagram showing the degradation effect of tetracycline hydrochloride in wastewater by the bismuth-based metal organic framework materials (Bi-AA, B1-B12) in Example 2 of the present invention under different illumination time conditions.

[0031] Figure 8 This is a diagram showing the degradation effect of the bismuth-based metal organic framework material (Bi-AA) on tetracycline hydrochloride in wastewater under different addition conditions in Example 3 of the present invention.

[0032] Figure 9 This is a diagram showing the degradation effect of tetracycline hydrochloride in wastewater by the bismuth-based metal organic framework material (Bi-AA) under different sacrificial agent conditions in Example 4 of the present invention.

[0033] Figure 10 This is the electron paramagnetic resonance image of the bismuth-based metal organic framework material (Bi-AA) in Example 4 of the present invention under different sacrificial agent conditions.

[0034] Figure 11 This is a schematic diagram of the degradation principle of tetracycline hydrochloride by the bismuth-based metal organic framework material (Bi-AA) in Example 4 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0036] In the following examples of the present invention, unless otherwise specified, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0037] Example 1:

[0038] A method for preparing a bismuth-based metal-organic framework material comprises: using a bismuth salt (Bi(NO3)3·5H2O) as a metal salt, p-aminobenzoic acid (PABA) as an organic ligand, and N,N-dimethylformyl (DMF) as a solvent to prepare the bismuth-based metal-organic framework material through a solvothermal reaction, comprising the following steps:

[0039] (1) Add 1 mmol of Bi(NO3)3·5H2O and 1 mmol of PABA to 60 mL of DMF and stir thoroughly to dissolve each raw material in DMF to obtain a mixed solution.

[0040] (2) The mixed solution obtained in step (1) was transferred to a 100 mL reactor, and the reactor was placed in an oven for a solvothermal reaction at 100° C. for 24 h.

[0041] (3) The reaction product obtained after the solvent thermal reaction in step (2) was filtered and washed with DMF and ethanol for multiple times, and a solid sample was collected. The solid sample was placed in a drying oven at 60° C. and dried under vacuum conditions to obtain a bismuth-based metal organic framework material, which was recorded as Bi-AA.

[0042] In this example, bismuth-based metal-organic framework materials prepared in different solvents, different raw material ratios, and different solvent thermal reaction temperatures were also investigated. The differences are shown in Table 1, and other conditions are the same as in Example 1.

[0043] Table 1 Bismuth-based metal-organic framework materials prepared with different solvents, different raw material ratios, and different solvent thermal reaction temperatures

[0044]

[0045]

[0046] Comparative Example 1

[0047] A method for preparing a bismuth-based metal-organic framework material comprises: using a bismuth salt (Bi(NO3)3·5H2O) as a metal salt, trimesic acid (H3BTC) as an organic ligand, and methanol (MeOH) and ethylene glycol (EG) as solvents to prepare the bismuth-based metal-organic framework material through a solvothermal reaction, comprising the following steps:

[0048] 1 mol Bi(NO₃)₃·5H₂O and 1 mol H₃BTC were added to a mixture of 55 mL MeOH and 5 mL EG. After thorough stirring to dissolve, the mixture was transferred to a 100 mL reactor. The reactor was then placed in an oven for a solvothermal reaction at 120°C for 24 hours. After cooling, the reaction mixture was filtered, washed multiple times with MeOH and ethanol, and dried to yield a bismuth-based metal-organic framework (MOF) material designated CAU-17.

[0049] The nitrogen adsorption-desorption isotherms and the corresponding pore size distributions of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 were tested. The results are as follows: Figure 1 shown.

[0050] Figure 1 The nitrogen adsorption-desorption isotherms and corresponding pore size distribution diagrams of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention are shown. Figure 1 It can be seen that both Bi-AA and CAU-17 have typical IV isotherms and h3 hysteresis loops, indicating that they both have typical mesoporous structures. BET ) and pore volume (V pore ) are 7.9656m 2 / g and 0.0223cm 3 / g. The SBET and Vpore of Bi-AA are 27.7494m 2 / g and 0.1627cm 3 Compared with CAU-17, the specific surface area and pore volume of Bi-AA are more than three times that of CAU-17, which indicates that Bi-AA may be more conducive to photocatalytic reaction than CAU-17.

[0051] The Bi-AA and CAU-17 prepared in Example 1 were analyzed by Fourier transform infrared spectroscopy. Figure 2 shown.

[0052] Figure 2 The following are Fourier transform infrared spectra of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention. Figure 2 It can be seen that compared with CAU-17, Bi-AA has more CN bonds, which indicates that the bismuth-based metal-organic framework material (Bi-AA) prepared by the present invention introduces a large number of amino groups. The introduction of amino groups makes the bismuth-based metal-organic framework material (Bi-AA) have a larger light absorption range and a smaller band gap, which is beneficial to improving the photocatalytic performance of the material.

[0053] The Bi-AA and CAU-17 prepared in Example 1 were subjected to X-ray photoelectron spectroscopy analysis, and the results were as follows: Figure 3 shown.

[0054] Figure 3 The X-ray photoelectron spectra of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG. Figure 3 It can be seen that Bi-AA has more nitrogen elements than CAU-17, which once again shows that Bi-AA has more amino groups compared to CAU-17 and was successfully synthesized.

[0055] Figure 4 The UV-visible diffuse reflectance spectra of the bismuth-based metal organic framework materials (Bi-AA, CAU-17) prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG. Figure 4 It can be seen that CAU-17 barely absorbs visible light due to its large band gap. In contrast, Bi-AA has a red-shifted absorption wavelength, with an absorption edge around 475nm, exhibiting strong visible light absorption.

[0056] Depend on Figure 1-4 The results show that compared with the conventional bismuth-based metal-organic framework material (CAU-17), the bismuth-based metal-organic framework material (Bi-AA) prepared in the present invention has a larger specific surface area, stronger visible light absorption capacity, and higher photocatalytic activity, and is a new type of visible light photocatalyst with excellent photocatalytic performance.

[0057] Example 2

[0058] A bismuth-based metal-organic framework material is used as a photocatalyst in treating antibiotic wastewater, specifically using the bismuth-based metal-organic framework material prepared in Example 1 as a photocatalyst to degrade tetracycline hydrochloride wastewater, comprising the following steps:

[0059] 50 mg of bismuth-based metal-organic framework material was added to 50 mL of tetracycline hydrochloride wastewater with a concentration of 30 mg / L, and the mixture was stirred in the dark until adsorption equilibrium was reached. The photocatalytic reaction was carried out under visible light conditions (the light source used was a simulated sunlight light source, specifically a 300W xenon lamp) for 30 minutes to complete the removal of tetracycline hydrochloride in the wastewater.

[0060] In this embodiment, the bismuth-based metal organic framework materials used are Bi-AA, A1-A7, and B1-A12 prepared in Example 1.

[0061] Control group: CAU-17 prepared in Comparative Example 1 was used instead of Bi-AA prepared in Example 1, and other conditions were the same.

[0062] During the photocatalytic reaction, the residual concentration of tetracycline hydrochloride in the wastewater was sampled and tested, and the degradation efficiency of different bismuth-based metal-organic framework materials under different illumination time conditions was calculated. The results are as follows: Figure 5-Figure 7 shown.

[0063] Figure 5 This is a graph showing the degradation effect of tetracycline hydrochloride in wastewater by bismuth-based metal organic framework materials (Bi-AA, CAU-17) under different illumination time conditions in Example 2 of the present invention. Figure 5 It can be seen that after 30 minutes of illumination, the degradation efficiency of tetracycline hydrochloride by CAU-17 was only 42%, while the degradation efficiency of tetracycline hydrochloride by Bi-AA was 80%, which is 1.9 times that of CAU-17. This shows that Bi-AA has stronger photocatalytic degradation performance.

[0064] Figure 6 The figure shows the degradation effect of tetracycline hydrochloride in wastewater by bismuth-based metal organic framework materials (Bi-AA, A1-A7) under different illumination time conditions in Example 2 of the present invention. Figure 6 It can be seen that compared with the bismuth-based metal-organic framework materials (A1-A7) prepared in a mixed organic solvent of DMF and methanol / ethanol, the bismuth-based metal-organic framework material (Bi-AA) prepared in pure DMF solvent has the best degradation effect on tetracycline hydrochloride. This is because pure DMF as a solvent can provide a more uniform reaction environment, promote the uniform self-assembly of metal ions and organic ligands, thereby forming a highly crystalline MOFs material; at the same time, it can reduce the agglomeration of the material, thereby exposing more reaction sites. The bismuth-based metal-organic framework material prepared in this way has better photocatalytic performance and can more efficiently degrade tetracycline hydrochloride in wastewater.

[0065] Figure 7 The figure shows the degradation effect of tetracycline hydrochloride in wastewater by bismuth-based metal organic framework materials (Bi-AA, B1-B12) in Example 2 of the present invention under different illumination time conditions. Figure 7 It can be seen that compared with bismuth-based metal-organic framework materials (Bi-AA, B1-B12), bismuth-based metal-organic framework materials (Bi-AA, B1-B12) have the best degradation effect on tetracycline hydrochloride. This shows that by optimizing the raw material ratio and solvent thermal reaction conditions, high-purity, high-performance materials can be controllably prepared, which can improve the photocatalytic performance of the materials while reducing costs and avoiding waste of resources. In addition, it can also avoid the problems of defects, impurities, morphology degradation and solvent residues caused by unsuitable reaction conditions in the synthesis process, which is beneficial to improving the performance of the materials.

[0066] Example 3

[0067] A bismuth-based metal-organic framework material is used as a photocatalyst in treating antibiotic wastewater, specifically using the bismuth-based metal-organic framework material prepared in Example 1 as a photocatalyst to degrade tetracycline hydrochloride wastewater, comprising the following steps:

[0068] According to the addition of 0.4 g, 0.6 g, 0.8 g, 1.0 g, 1.2 g, and 1.4 g of bismuth-based metal organic framework material per liter of tetracycline hydrochloride wastewater, the bismuth-based metal organic framework material (Bi-AA) prepared in Example 1 was taken and added to the tetracycline hydrochloride wastewater with a concentration of 30 mg / L, respectively. The mixture was stirred in the dark until adsorption equilibrium was reached, and the photocatalytic reaction was carried out under visible light conditions (the light source used was a simulated sunlight light source, specifically a 300 W xenon lamp) for 30 minutes to complete the removal of tetracycline hydrochloride in the wastewater.

[0069] During the photocatalytic reaction, the residual concentration of tetracycline hydrochloride in the wastewater was sampled and tested, and the degradation efficiency of the bismuth-based metal-organic framework material under different addition conditions was calculated. The results are as follows: Figure 8 shown.

[0070] Figure 8 The figure shows the degradation effect of tetracycline hydrochloride in wastewater under different addition conditions of bismuth-based metal organic framework material (Bi-AA) in Example 3 of the present invention. Figure 8 It can be seen that adding bismuth-based metal organic framework materials to tetracycline hydrochloride wastewater in an addition amount of 0.8g / L-1.4g / L can achieve effective degradation of tetracycline hydrochloride in the wastewater.

[0071] Example 4

[0072] A bismuth-based metal-organic framework material is used as a photocatalyst in treating antibiotic wastewater, specifically using the bismuth-based metal-organic framework material prepared in Example 1 as a photocatalyst to degrade tetracycline hydrochloride wastewater, comprising the following steps:

[0073] Take 3 parts of the bismuth-based metal organic framework material (Bi-AA) prepared in Example 1, 50 mg each, and add them to 50 mL of tetracycline hydrochloride wastewater with a concentration of 30 mg / L. Stir in the dark until adsorption equilibrium is reached, and add p-benzoquinone, tryptophan, and disodium ethylenediaminetetraacetic acid, respectively. The initial concentrations of p-benzoquinone, tryptophan, and disodium ethylenediaminetetraacetic acid in the system are 1 mM, 5 mM, and 5 mM, respectively. The photocatalytic reaction is carried out under visible light conditions (the light source used is a simulated sunlight light source, specifically a 300 W xenon lamp) for 30 minutes to complete the removal of tetracycline hydrochloride in the wastewater.

[0074] Control group: no sacrificial agent was added, and other conditions were the same.

[0075] Figure 9 This is a graph showing the degradation effect of tetracycline hydrochloride in wastewater by the bismuth-based metal organic framework material (Bi-AA) under different sacrificial agent conditions in Example 4 of the present invention. Figure 9 It can be seen that under normal conditions (without adding any sacrificial agent), Bi-AA can photocatalytically degrade 80% of tetracycline hydrochloride under light conditions for 30 minutes. Figure 9 It can be seen that the addition of p-benzoquinone (a sacrificial agent for superoxide anion radicals) significantly inhibited the degradation of tetracycline hydrochloride, reducing the degradation efficiency to below 60%. The addition of tryptophan (a sacrificial agent for singlet oxygen) also inhibited the degradation of tetracycline hydrochloride, but to a lesser extent. The addition of disodium ethylenediaminetetraacetic acid (a sacrificial agent for holes) significantly inhibited the degradation of tetracycline hydrochloride, reducing the degradation efficiency to below 50%. These results indicate that superoxide anion radicals and holes are likely the primary active species in the photocatalytic degradation reaction, with singlet oxygen being a secondary active species.

[0076] Figure 10 This is the electron paramagnetic resonance image of the bismuth-based metal organic framework material (Bi-AA) in Example 4 of the present invention under different sacrificial agent conditions. Figure 10 In the equation, (a) is the superoxide anion radical and (b) is the singlet oxygen. Figure 10 It can be seen that Bi-AA exhibits obvious superoxide anion radical and singlet oxygen signals under light, which proves that superoxide anion radical and singlet oxygen do exist in the photocatalytic reaction.

[0077] Figure 11 The schematic diagram of the degradation of tetracycline hydrochloride by the bismuth-based metal organic framework material (Bi-AA) in Example 4 of the present invention is shown in FIG. Figure 11 It can be seen that under visible light irradiation, the bismuth-based metal organic framework material (Bi-AA) absorbs visible light. When the absorbed energy is greater than the band gap, electrons are excited to jump from the valence band to the conduction band, leaving holes in the valence band. At this time, oxygen (O2) and electrons (e - ) reacts to generate superoxide anion radical (·O2 - ), while some superoxide anion radicals (·O2 - ) reacts with holes (h+) to generate singlet oxygen ( 1 O2). Therefore, superoxide anion radical (·O2 - ), holes (h+) and singlet oxygen ( 1 O2) participates in the photocatalytic reaction, breaking down tetracycline hydrochloride into smaller molecules.

[0078] From the above results, it can be seen that compared with conventional bismuth-based metal-organic framework materials, in the preparation method of the present invention, by optimizing the raw material ratio, organic ligand type, solvent type and solvent thermal reaction conditions, a bismuth-based metal-organic framework material with a large specific surface area, a large light absorption range and high photocatalytic activity can be prepared. As a new type of visible light photocatalyst with excellent photocatalytic performance, the bismuth-based metal-organic framework material can be widely used to treat antibiotic wastewater and can achieve efficient removal of antibiotics in wastewater under visible light conditions. It has the advantages of simple process, convenient operation, low cost, high treatment efficiency, good removal effect, and green environmental protection, and is of great significance for purifying organic pollutant wastewater.

[0079] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of protection of the present invention are within the scope of protection of the present invention. It should be noted that improvements and modifications that can be made by a person skilled in the art without departing from the principles of the present invention are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a bismuth-based metal-organic framework material, characterized in that: Bismuth-based metal-organic framework materials are prepared by solvent thermal reaction using bismuth salt as metal salt, p-aminobenzoic acid as organic ligand and N,N-dimethylformyl as solvent.

2. The preparation method according to claim 1, characterized in that The following steps are involved: S1. Mixing bismuth salt, p-aminobenzoic acid, and N,N-dimethylformyl, and stirring to obtain a mixed solution; S2. Performing a solvothermal reaction on the mixed solution to obtain a bismuth-based metal-organic framework material.

3. The preparation method according to claim 2, characterized in that In step S1, the molar ratio of the bismuth salt to para-aminobenzoic acid is 1:0.5-4; the ratio of the bismuth salt to N,N-dimethylformyl is 1mmoL:60mL; and the bismuth salt is at least one of bismuth acetate, bismuth sulfate, bismuth chloride, bismuth nitrate, bismuth hydroxide, bismuth bromide, and bismuth iodide.

4. The preparation method according to claim 3, characterized in that In step S1, the molar ratio of the bismuth salt to p-aminobenzoic acid is 1:1-3.

5. The preparation method according to any one of claims 2 to 4, characterized in that In step S2, the solvent thermal reaction is carried out at a temperature of 80°C to 120°C; the solvent thermal reaction time is 12h to 24h; after the solvent thermal reaction is completed, the following treatment is also included: filtering the product after the solvent thermal reaction, collecting the solid product, washing the solid product with ethanol and N,N-dimethylformyl, and drying under vacuum conditions at a temperature of 50°C to 80°C.

6. The preparation method according to claim 5, characterized in that In step S2, the solvent thermal reaction is carried out at a temperature of 90°C to 110°C.

7. A bismuth-based metal-organic framework material, characterized in that The method is prepared according to any one of claims 1 to 6.

8. Use of the bismuth-based metal organic framework material as claimed in claim 7 as a photocatalyst in treating antibiotic wastewater.

9. The use according to claim 8, characterized in that The method uses a bismuth-based metal-organic framework material as a photocatalyst to degrade antibiotic wastewater, comprising the following steps: mixing the bismuth-based metal-organic framework material and antibiotic wastewater, and performing a photocatalytic reaction under visible light conditions to complete the degradation of the antibiotics in the wastewater; the amount of the bismuth-based metal-organic framework material added is 0.8g to 1.4g per liter of antibiotic wastewater.

10. The use according to claim 9, characterized in that The concentration of the antibiotic in the antibiotic wastewater is ≤30 mg / L; the antibiotic is tetracycline hydrochloride; and the time of the photocatalytic reaction is 30 min to 60 min.

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