Preparation method of iron-based MOF bismuth tungstate composite material

Abstract

The invention discloses a preparation method of an iron-based MOF bismuth tungstate composite material, and belongs to the technical field of photocatalytic composite material preparation. The preparation method comprises the following steps: adding MIL-101 (Fe) into a DMF (dimethylformamide) solution, then adding Bi2WO6, and vigorously stirring to uniformly disperse Bi2WO6 in the solution; heating the solution at 110-130 DEG C, naturally cooling to room temperature after the reaction is completed, and repeatedly washing to obtain a precipitate; and precipitating, drying, and uniformly grinding to obtain the MIL-101 (Fe) / Bi2WO6 composite material. The prepared composite material has good visible light response, the aflatoxin B1 catalytic degradation performance is obviously improved compared with that of single MIL-101 (Fe) and Bi2WO6, aflatoxin B1 in a solution can be completely degraded within 40 min, and the degradation speed and effect are very remarkable.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of photocatalytic composite materials, and particularly relates to a preparation method of an iron-based MOF bismuth tungstate composite material. Background Art

[0002] Aflatoxins are a class of toxic metabolites produced by Aspergillus flavus, belonging to the class of difuranocoumarin compounds and having extremely strong toxicity and carcinogenicity. Commonly seen ones include aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2), among which aflatoxin B1 has the greatest toxicity and the strongest carcinogenicity.

[0003] Photocatalytic degradation of aflatoxins is a new and effective method. The principle lies in using the redox ability of photocatalysts under light irradiation conditions to decompose and transform aflatoxins, so as to achieve the purpose of removal. Photocatalysis can significantly reduce the content of aflatoxins in a relatively short time, and also has the advantages of simple operation and low cost.

[0004] Chinese patent document CN114514979B discloses a green method for reducing aflatoxins. A sample containing aflatoxins is fully contacted with a composite film for reducing aflatoxins. The composite film first selectively adsorbs and removes aflatoxins in the sample, and then the composite film is placed under sunlight or xenon light source for irradiation to gradually degrade aflatoxins. The composite film for reducing aflatoxins includes a substrate and a g-C3N4 / WO3 composite material on the substrate. g-C3N4 has a lamellar structure, and WO3 nanoparticles are uniformly dispersed on the surface of the lamellar g-C3N4 and are tightly combined to form a composite semiconductor photocatalytic material.

[0005] However, the preparation method of the composite film used in the above patent document has relatively high requirements. For example, "the size of the g-C3N4 lamellae is 100-200 nm, and the high-temperature exfoliation temperature is 580-600 °C and maintained for 2-3 h", and another example is "after uniformly grinding by crystallization, put it into a crucible, cover it, and then place it in a tube furnace or a muffle furnace, heat it up to 550-560 °C and maintain for 3-4 h", etc. High-temperature treatment is required multiple times during the production process, resulting in high production process requirements and high production costs, which is not conducive to popularization and application. Summary of the Invention

[0006] The present invention provides a preparation method of an iron-based MOF bismuth tungstate composite material to solve the above technical problems.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A preparation method of an iron-based MOF bismuth tungstate composite material includes:

[0009] MIL-101(Fe) was added to a DMF (dimethylformamide) solution, and then Bi2WO6 was added. The mixture was vigorously stirred to uniformly disperse Bi2WO6 in the solution;

[0010] The above solution was heat-treated at 110 - 130 °C, and after the reaction was completed, it was naturally cooled to room temperature and then washed repeatedly to obtain a precipitate;

[0011] The precipitate was dried and then ground evenly to prepare the MIL-101(Fe) / Bi2WO6 composite material.

[0012] Further, the repeated washing was first with ultrapure water and then with absolute ethanol.

[0013] Further, the repeated washing was centrifugal washing, and the centrifugal speed was 6000 - 9000 rpm / min.

[0014] Further, the drying temperature was 70 - 90 °C.

[0015] Further, the MIL-101(Fe) / Bi2WO6 composite material was used to degrade aflatoxin B1.

[0016] Further, the preparation method of MIL-101(Fe) included:

[0017] An appropriate amount of FeCl3·6H2O and H2BDC (terephthalic acid) were respectively added to a DMF solution and vigorously stirred to dissolve them;

[0018] The above solution was heat-treated at 110 - 130 °C;

[0019] After the reaction was completed, it was naturally cooled to room temperature and washed repeatedly to obtain a precipitate;

[0020] The precipitate was dried and ground evenly to prepare MIL-101(Fe).

[0021] Further, the repeated washing was centrifugal washing with ultrapure water and then absolute ethanol in sequence, and the centrifugal speed was 6000 - 9000 rpm / min.

[0022] Further, the drying temperature was 70 - 90 °C.

[0023] Further, the preparation method of Bi2WO6 included:

[0024] Na2WO4·2H2O was added to an ethylene glycol solution and vigorously stirred to dissolve it, obtaining a Na2WO4·2H2O solution;

[0025] Dissolve Bi(NO3)3·5H2O in purified water, and then dropwise add it to the Na2WO4·2H2O solution, and stir vigorously at room temperature to obtain a mixture solution;

[0026] Heat-treat the mixture solution at 175 - 185 °C, naturally cool it to room temperature after the reaction is completed, and wash it repeatedly to obtain a precipitate;

[0027] Dry the precipitate and grind it evenly to prepare Bi2WO6.

[0028] Furthermore, for repeated washing, ultra-pure water and absolute ethanol are used for centrifugal washing in sequence, and the centrifugal speed is 6000 - 9000 rpm / min.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The MIL-101(Fe) / Bi2WO6 composite material prepared by the present invention has good visible light response, and the performance of catalytic degradation of aflatoxin B1 is significantly improved compared with that of individual MIL-101(Fe) and Bi2WO6.

[0031] From the data of the examples, the M / BWO-6 group can completely degrade aflatoxin B1 in a 0.6 μg / mL solution within 40 min, and the degradation rate is 100%; the degradation rate of the composite material MIL-101(Fe) / BiFeO3 in Comparative Example 1 is 80.9%, and the degradation rate of the composite material MIL-101(Fe) / Bi2MoO6 in Comparative Example 2 is 26.8%; it can be seen that the speed and effect of the composite material prepared by the present invention in degrading aflatoxin B1 are very remarkable.

[0032] One of the raw materials prepared by the present invention, Bi2WO6, has an energy band structure that enables it to absorb visible light and can effectively catalytically degrade organic pollutants under sunlight irradiation. The MOF material has a high specific surface area, good pore structure, and adjustable chemical environment. Combining MIL-101(Fe) with Bi2WO6 can provide a larger reaction interface for Bi2WO6, and by increasing the contact area of the photocatalytic reaction, the photocatalytic efficiency can be improved.

[0033] The composite material prepared by the present invention can be applied to the degradation treatment of aflatoxin B1 in fields such as food. Description of the Drawings

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0035] Figure 1 SEM morphology characterization of the MIL-101(Fe) / Bi2WO6 composite material prepared according to the present invention.

[0036] Figure 2 For Figure 1 Partial enlarged schematic diagram.

[0037] Figure 3 UV-Vis diffuse reflectance spectra of the composite materials prepared in Examples 1-4.

[0038] Figure 4 Response intensities of the composite materials prepared in Examples 1-4 at different wavelengths.

[0039] Figure 5 Ultraviolet band gap widths of the composite materials prepared in Examples 1-4.

[0040] Figure 6 Results of the degradation of aflatoxin B1 by the composite materials prepared in Examples 1-4.

[0041] Figure 7 Results of the degradation of aflatoxin B1 by Example 3 and Comparative Examples 1-2. Detailed implementation manners

[0042] To better understand the present invention, it is illustrated by the following examples in conjunction with the accompanying drawings. These examples belong to the protection scope of the present invention, but do not limit the protection scope of the present invention.

[0043] Example 1

[0044] A preparation method of an iron-based MOF bismuth tungstate composite material, comprising:

[0045] Adding MIL-101(Fe) to a DMF (dimethylformamide) solution, and then adding Bi2WO6, and vigorously stirring to uniformly disperse Bi2WO6 in the solution;

[0046] Transferring the above solution to a stainless steel autoclave with a polytetrafluoroethylene liner, and heating at 110 °C for 15 h. After the reaction is completed, it is naturally cooled to room temperature, and then washed repeatedly to obtain a precipitate;

[0047] The precipitate is dried and then ground evenly to obtain the MIL-101(Fe) / Bi2WO6 composite material.

[0048] The repeated washing is to first wash with ultrapure water and then wash with absolute ethanol.

[0049] The repeated washing is centrifugal washing with a centrifugal speed of 6000 rpm / min.

[0050] The drying temperature is 70 °C.

[0051] The MIL-101(Fe) / Bi2WO6 composite material is used for degrading aflatoxin B1.

[0052] The preparation method of MIL-101(Fe) includes:

[0053] Take appropriate amounts of FeCl3·6H2O and H2BDC (terephthalic acid) and add them to the DMF solution respectively, and stir vigorously to dissolve them;

[0054] Transfer the above solution to a stainless-steel autoclave with a PTFE liner and heat it at 110 °C for 15 h;

[0055] After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly, and a precipitate is obtained;

[0056] The precipitate is dried and ground evenly to obtain MIL-101(Fe).

[0057] The repeated washing is centrifugal washing with ultrapure water and absolute ethanol in sequence, and the centrifugal speed is 6000 rpm / min.

[0058] The drying temperature is 70 °C.

[0059] The preparation method of Bi2WO6 includes:

[0060] Take Na2WO4·2H2O and add it to the ethylene glycol solution, stir vigorously to dissolve it, and obtain a Na2WO4·2H2O solution;

[0061] Take Bi(NO3)3·5H2O and dissolve it in purified water, and then add it dropwise to the Na2WO4·2H2O solution, and stir vigorously at room temperature for 30 min to obtain a mixture solution;

[0062] Transfer the mixture solution to a stainless-steel autoclave with a PTFE liner, heat it at 175 °C for 12 h, after the reaction is completed, it is naturally cooled to room temperature, washed repeatedly, and a precipitate is obtained;

[0063] The precipitate is dried and ground evenly to obtain Bi2WO6.

[0064] The repeated washing is centrifugal washing with ultrapure water and absolute ethanol in sequence, and the centrifugal speed is 6000 rpm / min.

[0065] Example 2

[0066] A preparation method of an iron-based MOF bismuth tungstate composite material includes:

[0067] Add MIL-101(Fe) to a DMF (dimethylformamide) solution, and then add Bi2WO6. Stir vigorously to make Bi2WO6 evenly dispersed in the solution;

[0068] Transfer the above solution to a stainless-steel autoclave with a polytetrafluoroethylene lining and heat it at 115 °C for 15 h. After the reaction is completed, naturally cool it to room temperature, and then wash it repeatedly to obtain a precipitate;

[0069] Dry the precipitate, and then grind it evenly to obtain the MIL-101(Fe) / Bi2WO6 composite material.

[0070] Repeated washing is to first wash with ultrapure water and then wash with absolute ethanol.

[0071] Repeated washing is centrifugal washing, and the centrifugation speed is 6000 - 9000 rpm / min.

[0072] The drying temperature is 75 °C.

[0073] The MIL-101(Fe) / Bi2WO6 composite material is used for degrading aflatoxin B1.

[0074] The preparation method of MIL-101(Fe) includes:

[0075] Take appropriate amounts of FeCl3·6H2O and H2BDC (terephthalic acid) and add them to a DMF solution respectively, and stir strongly to dissolve them;

[0076] Transfer the above solution to a stainless-steel autoclave with a polytetrafluoroethylene lining and heat it at 115 °C for 15 h;

[0077] After the reaction is completed, naturally cool it to room temperature, wash it repeatedly, and obtain a precipitate;

[0078] Dry the precipitate, grind it evenly, and obtain MIL-101(Fe).

[0079] Repeated washing is centrifugal washing with ultrapure water and absolute ethanol in sequence, and the centrifugation speed is 7000 rpm / min.

[0080] The drying temperature is 75 °C.

[0081] The preparation method of Bi2WO6 includes:

[0082] Take Na2WO4·2H2O and add it to an ethylene glycol solution, and stir strongly to dissolve it to obtain a Na2WO4·2H2O solution;

[0083] Dissolve Bi(NO3)3·5H2O in purified water, and then add it dropwise to the Na2WO4·2H2O solution. Stir vigorously at room temperature for 30 min to obtain a mixture solution;

[0084] Transfer the mixture solution to a stainless-steel autoclave lined with polytetrafluoroethylene, heat it at 178 °C for 12 h, and naturally cool it to room temperature after the reaction is completed. Wash it repeatedly to obtain a precipitate;

[0085] Dry the precipitate, grind it evenly to obtain Bi2WO6.

[0086] For repeated washing, first use ultrapure water and then anhydrous ethanol for centrifugal washing, and the centrifugal speed is 7000 rpm / min.

[0087] Example 3

[0088] A preparation method of an iron-based MOF bismuth tungstate composite material includes:

[0089] Add MIL-101(Fe) to the DMF (dimethylformamide) solution, and then add Bi2WO6. Stir vigorously to make Bi2WO6 evenly dispersed in the solution;

[0090] Transfer the above solution to a stainless-steel autoclave lined with polytetrafluoroethylene, and heat it at 120 °C for 15 h. Naturally cool it to room temperature after the reaction is completed, and then wash it repeatedly to obtain a precipitate;

[0091] Dry the precipitate, grind it evenly to obtain the MIL-101(Fe) / Bi2WO6 composite material.

[0092] For repeated washing, first wash with ultrapure water and then with anhydrous ethanol.

[0093] Repeated washing is centrifugal washing, and the centrifugal speed is 8500 rpm / min.

[0094] The drying temperature is 80 °C.

[0095] The MIL-101(Fe) / Bi2WO6 composite material is used for degrading aflatoxin B1.

[0096] The preparation method of MIL-101(Fe) includes:

[0097] Take appropriate amounts of FeCl3·6H2O and H2BDC (terephthalic acid) and add them to the DMF solution respectively, and stir strongly to dissolve them;

[0098] Transfer the above solution to a stainless-steel autoclave lined with polytetrafluoroethylene, and heat it at 120 °C for 15 h;

[0099] After the reaction is completed, it is naturally cooled to room temperature and washed repeatedly to obtain a precipitate;

[0100] The precipitate is dried and ground evenly to prepare MIL-101(Fe).

[0101] For repeated washing, centrifugal washing is carried out successively with ultrapure water and absolute ethanol, and the centrifugal speed is 8500 rpm / min.

[0102] The drying temperature is 80 °C.

[0103] The preparation method of Bi2WO6 includes:

[0104] Take Na2WO4·2H2O and add it to the ethylene glycol solution, and stir vigorously to dissolve it to obtain a Na2WO4·2H2O solution;

[0105] Take Bi(NO3)3·5H2O and dissolve it in purified water, and then dropwise add it to the Na2WO4·2H2O solution, and stir vigorously at room temperature for 30 min to obtain a mixture solution;

[0106] The mixture solution is transferred to a stainless steel autoclave with a polytetrafluoroethylene lining, heated at 180 °C for 12 h, naturally cooled to room temperature after the reaction is completed, and washed repeatedly to obtain a precipitate;

[0107] The precipitate is dried and ground evenly to prepare Bi2WO6.

[0108] For repeated washing, centrifugal washing is carried out successively with ultrapure water and absolute ethanol, and the centrifugal speed is 8500 rpm / min.

[0109] Example 4

[0110] A preparation method of an iron-based MOF bismuth tungstate composite material includes:

[0111] Add MIL-101(Fe) to the DMF (dimethylformamide) solution, and then add Bi2WO6, and stir vigorously to make Bi2WO6 evenly dispersed in the solution;

[0112] The above solution is transferred to a stainless steel autoclave with a polytetrafluoroethylene lining and heated at 130 °C for 15 h. After the reaction is completed, it is naturally cooled to room temperature, and then washed repeatedly to obtain a precipitate;

[0113] The precipitate is dried and then ground evenly to prepare the MIL-101(Fe) / Bi2WO6 composite material.

[0114] For repeated washing, first wash with ultrapure water and then wash with absolute ethanol.

[0115] Repeated washing is centrifugal washing, and the centrifugal speed is 9000 rpm / min.

[0116] The drying temperature is 90 °C.

[0117] The MIL-101(Fe) / Bi2WO6 composite material is used for degrading aflatoxin B1.

[0118] The preparation method of MIL-101(Fe) includes:

[0119] Appropriately take FeCl3·6H2O and H2BDC (terephthalic acid) and add them to the DMF solution respectively, and stir vigorously to dissolve them;

[0120] Transfer the above solution to a stainless steel autoclave with a polytetrafluoroethylene inner liner and heat it at 130 °C for 15 h;

[0121] After the reaction is completed, it is naturally cooled to room temperature and washed repeatedly to obtain a precipitate;

[0122] The precipitate is dried and ground evenly to obtain MIL-101(Fe).

[0123] For repeated washing, centrifugal washing is carried out successively with ultrapure water and absolute ethanol, and the centrifugation speed is 9000 rpm / min.

[0124] The drying temperature is 90 °C.

[0125] The preparation method of Bi2WO6 includes:

[0126] Take Na2WO4·2H2O and add it to the ethylene glycol solution, and stir vigorously to dissolve it to obtain a Na2WO4·2H2O solution;

[0127] Take Bi(NO3)3·5H2O and dissolve it in purified water, and then add it dropwise to the Na2WO4·2H2O solution, and stir vigorously at room temperature for 30 min to obtain a mixture solution;

[0128] Transfer the mixture solution to a stainless steel autoclave with a polytetrafluoroethylene inner liner, heat it at 185 °C for 12 h, and after the reaction is completed, it is naturally cooled to room temperature and washed repeatedly to obtain a precipitate;

[0129] The precipitate is dried and ground evenly to obtain Bi2WO6.

[0130] For repeated washing, centrifugal washing is carried out successively with ultrapure water and absolute ethanol, and the centrifugation speed is 9000 rpm / min.

[0131] Comparative Example 1

[0132] In Example 3, except that the raw material Bi2WO6 is replaced with BiFeO3 and the prepared composite material becomes MIL-101(Fe) / BiFeO3, the rest remains unchanged.

[0133] Comparative Example 2

[0134] In Example 3, except that Bi2WO6 is replaced by Bi2MoO6 and the prepared composite material becomes MIL-101(Fe) / Bi2MoO6, the rest remains unchanged.

[0135] Composite materials were prepared by the methods of Examples 1-4 and Comparative Examples 1-2, and the amounts of main raw materials used in each group are shown in Table 1.

[0136]

[0137] Figures 3 - 5 The Bi2WO6 (BWO) in [[]] was obtained by the preparation method of Bi2WO6 in Example 3, and MIL-101(Fe) was obtained by the preparation method of Bi2WO6 in Example 3.

[0138] 1. Characterization tests

[0139] The main equipment is as follows:

[0140] Scanning electron microscope, Zeiss sigma300 in Germany;

[0141] X-ray diffractometer, Bruker D8 Advance in Germany;

[0142] UV-visible diffuse reflectance spectrometer, Shimadzu 3600 in Japan.

[0143] SEM morphology characterization was carried out on the MIL-101(Fe) / Bi2WO6 composite material prepared by the method of the present invention. From Figure 1 , Figure 2 it can be seen that Bi2WO6 is a microsphere with a diameter of about 2-6 μm, and MIL-101(Fe) is uniformly anchored on the Bi2WO6 microsphere through an in-situ growth process.

[0144] The phase purity of Bi2WO6, MIL-101(Fe) and the MIL-101(Fe) / Bi2WO6 heterojunction was examined by X-ray diffraction (XRD). From Figure 3It can be seen that the characteristic diffraction peaks of Bi2WO6 and MIL-101(Fe) / Bi2WO6 are relatively sharp, and both surfaces have good crystallinity. Bi2WO6 shows characteristic diffraction peaks at 28.9°, 33.1°, 47.6° and 56.2°. After in-situ growth of MIL-101(Fe), the XRD spectrum of the generated MIL / BWO heterojunction is basically consistent with that of Bi2WO6, and a characteristic peak consistent with MIL-101(Fe) appears at 10.6°, indicating that MIL-101(Fe) and Bi2WO6 are composited. The characteristic peaks of MIL-101(Fe) do not appear at other positions, which is related to the weak crystallinity and low content of MIL-101(Fe) and the strong peaks of Bi2WO6.

[0145] The UV-Vis DRS was used to detect Figure 4 As shown in the figure, both Bi2WO6 and MIL-101(Fe) / Bi2WO6 have good visible light response. When Bi2WO6 is compounded with MIL-101(Fe), the absorbance increases and the maximum absorption wavelength is significantly red-shifted, thereby enhancing the light absorption capacity of MIL-101(Fe). Figure 5 It can be seen that after Bi2WO6 is compounded with MIL-101(Fe), the band gap decreases from 2.6eV to 2.3eV.

[0146] 2. Catalytic performance test of the present invention

[0147] Weigh 10 mg of the following catalyst materials respectively:

[0148] Bi2WO6, obtained by the preparation method of Example 3;

[0149] MIL-101(Fe), obtained by the preparation method of Example 3;

[0150] MIL-101(Fe) / Bi2WO6 were obtained by the preparation methods of Examples 1-4, respectively.

[0151] Aflatoxin B1 solution standard substance, concentration 100 mg / L, purchased from Shanghai Anpu Cuishi Standard Technology Service Co., Ltd., number: CDAA-S-290028-JA-1.2mL; diluted with acetonitrile to a concentration of 0.6 μg / mL before use.

[0152] The main equipment is as follows:

[0153] High performance liquid chromatograph, Waters 2695 (2414FRL fluorescence detector).

[0154] The above catalyst materials were respectively added to a 0.6 μg / mL aflatoxin B1 solution, and a blank group Blank was set up. Each group was stirred in the dark for 45 min to reach adsorption-desorption equilibrium, and then continuously irradiated for 60 min under the condition of a 300 W xenon lamp equipped with an ultraviolet filter (λ > 400 nm) as the only light source, during which a certain stirring speed needed to be maintained. 1 mL was taken as a test sample every 10 min, and the determination was carried out using the pre-column derivatization method of high performance liquid chromatography in "National Food Safety Standard - Determination of Aflatoxins B and G in Foods" (GB 5009.22 - 2016).

[0155] The measurement results are as Figure 6 shown. The vertical axis in the figure is C / C0, and the horizontal axis is time; C is the concentration of aflatoxin B1 at the corresponding time point, and C0 is the initial concentration of aflatoxin B1.

[0156] The concentration of aflatoxin B1 in the blank group basically did not change; while each group added with the catalyst material had different degradation effects; as Figure 6 can be seen, the catalytic degradation performance of the MIL-101(Fe) / Bi2WO6 composite material was significantly improved compared with that of the individual MIL-101(Fe) and Bi2WO6. The composite material began to rapidly degrade aflatoxin B1 within the time period of 0 - 20 min. As time went by, the aflatoxin B1 in the solution decreased, and the degradation rate decreased. When the reaction reached 60 min, the aflatoxin B1 in the M / BWO-4, M / BWO-6, and M / BWO-8 groups was completely degraded, while the concentration of aflatoxin B1 in the MIL-101(Fe), Bi2WO6, and M / BWO-2 groups was about 0.4 μg / mL, and the degradation results were relatively poor.

[0157] In addition, as Figure 6 can be seen from the data comparison of Examples 1 - 4, the M / BWO-6 group (Example 3) is the best example, and the aflatoxin B1 was completely degraded when the reaction reached 40 min.

[0158] 3. Catalytic performance test of Example 3 and comparative examples

[0159] Weigh 10 mg of the following catalyst materials respectively:

[0160] MIL-101(Fe) / BiFeO3 (M / BF0), obtained by the preparation method of Comparative Example 1;

[0161] MIL-101(Fe) / Bi2MoO6 (M / BM0), obtained by the preparation method of Comparative Example 2;

[0162] MIL-101(Fe) / Bi2WO6(M / BWO) were obtained by the preparation method of Example 3.

[0163] Aflatoxin B1 solution standard substance, concentration 100 mg / L, purchased from Shanghai Anpu Cuishi Standard Technology Service Co., Ltd., number: CDAA-S-290028-JA-1.2mL; diluted with acetonitrile to a concentration of 0.6 μg / mL before use.

[0164] The main equipment is as follows:

[0165] High performance liquid chromatograph, Waters 2695 (2414FRL fluorescence detector).

[0166] The above catalyst materials were added to a 0.6 μg / mL aflatoxin B1 solution. Each group was stirred in the dark for 45 minutes to reach adsorption-desorption equilibrium, and then continuously irradiated for 60 minutes under the condition of a 300W xenon lamp equipped with a UV filter as the only light source (λ>400nm), during which a certain stirring speed was required. 1 mL was taken as a test sample every 10 minutes, and the high performance liquid chromatography-pre-column derivatization method of the "National Food Safety Standard for the Determination of Aflatoxins B and G in Food" (GB 5009.22-2016) was used for determination.

[0167] The results of the test are as follows Figure 7 As shown in the figure, the vertical axis is C / C0 and the horizontal axis is time; C is the concentration of aflatoxin B1 at the corresponding time point, and C0 is the initial concentration of aflatoxin B1.

[0168] Depend on Figure 7 The test results show that the degradation rate of MIL-101(Fe) / BiFeO3 is slow and the effect is poor. Even after 60 minutes of reaction, the concentration of aflatoxin B1 in the solution is still above 0.485μg / mL. The degradation rate of MIL-101(Fe) / Bi2MoO6 is slightly increased. After 60 minutes of reaction, the concentration of aflatoxin B1 is still above 0.16μg / mL. The degradation rate of MIL-101(Fe) / Bi2WO6 is faster. At 40 minutes, aflatoxin B1 has been completely degraded.

[0169] After calculation, when the reaction lasted for 60 minutes, the degradation rate of MIL-101(Fe) / Bi2WO6 was 100%, the degradation rate of MIL-101(Fe) / BiFeO3 was 80.9%, and the degradation rate of MIL-101(Fe) / Bi2MoO6 was 26.8%. Therefore, compared with comparative examples 1-2, the degradation rate and degradation effect of aflatoxin B1 in the present invention are very significant.

[0170] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0171] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an iron-based MOF bismuth tungstate composite material, characterized in that Including: MIL-101(Fe) is added to a DMF (dimethylformamide) solution, and then Bi2WO6 is added. Stir vigorously to make Bi2WO6 uniformly dispersed in the solution. The above solution is heat-treated at 110 - 130 °C. After the reaction is completed, it is naturally cooled to room temperature and then washed repeatedly to obtain a precipitate. The precipitate is dried and then ground evenly to obtain the MIL-101(Fe) / Bi2WO6 composite material.

2. The preparation method of a bismuth tungstate composite material based on iron-based MOF according to claim 1, characterized in that, Repeated washing is first with ultrapure water and then with absolute ethanol.

3. The preparation method of an iron-based MOF bismuth tungstate composite material according to claim 2, characterized in that, Repeated washing is centrifugal washing, and the centrifugal speed is 6000 - 9000 rpm / min.

4. The preparation method of an iron-based MOF bismuth tungstate composite material according to claim 3, characterized in that, The drying temperature is 70 - 90 °C.

5. The preparation method of an iron-based MOF bismuth tungstate composite material according to claim 4, wherein, The MIL-101(Fe) / Bi2WO6 composite material is used for degrading aflatoxin B1.

6. A method for preparing an iron-based MOF bismuth tungstate composite material according to any one of claims 1-5, characterized in that, The preparation method of MIL-101(Fe) includes: Appropriate amounts of FeCl3·6H2O and H2BDC (terephthalic acid) are respectively added to a DMF solution and stirred strongly to dissolve them. The above solution is heat-treated at 110 - 130 °C. After the reaction is completed, it is naturally cooled to room temperature and washed repeatedly to obtain a precipitate. The precipitate is dried and ground evenly to obtain MIL-101(Fe).

7. The preparation method of an iron-based MOF bismuth tungstate composite material according to claim 6, characterized in that, Repeated washing is centrifugal washing successively with ultrapure water and absolute ethanol, and the centrifugal speed is 6000 - 9000 rpm / min.

8. The preparation method of an iron-based MOF bismuth tungstate composite material according to claim 7, characterized in that, The drying temperature is 70 - 90 °C.

9. The preparation method of a bismuth tungstate composite material of iron-based MOF according to any one of claims 1-5, characterized in that, The preparation method of Bi2WO6 includes: Na2WO4·2H2O is added to an ethylene glycol solution and stirred strongly to dissolve it to obtain a Na2WO4·2H2O solution. Bi(NO3)3·5H2O is dissolved in purified water and then added dropwise to the Na2WO4·2H2O solution and stirred vigorously at room temperature to obtain a mixture solution. The mixture solution is heat-treated at 175 - 185 °C. After the reaction is completed, it is naturally cooled to room temperature and washed repeatedly to obtain a precipitate. The precipitate is dried and ground evenly to obtain Bi2WO6.

10. The preparation method of a bismuth tungstate composite material based on iron-based MOF according to claim 9, characterized in that, Repeated washing is centrifugal washing successively with ultrapure water and absolute ethanol, and the centrifugal speed is 6000 - 9000 rpm / min.

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