Preparation method of photocatalyst for degrading aflatoxin B1

Abstract

The invention discloses a preparation method of a photocatalyst for degrading aflatoxin B1, and belongs to the technical field of aflatoxin catalysts. The preparation method comprises the following steps: step 1, dissolving Bi (NO3) 3.5 H2O and Na2MoO4. 2H2O in ethylene glycol by ultrasonic waves, then adding ethanol into a solution obtained by ultrasonic dissolution while stirring, and stirring for 10-60 minutes to obtain a solution I; 2, pouring the solution I obtained in the step 1 into a reaction kettle, and reacting for 12 hours at the temperature of 120-200 DEG C to obtain crude Bi2MoO6; 3, after the reaction is finished, the temperature is reduced to the room temperature, deionized water and ethyl alcohol are used for washing till supernatant liquid is clear, drying is conducted, and pure Bi2MoO6 is obtained; 4, dissolving TCPP in ethanol through ultrasonic waves, adding the pure Bi2MoO6 obtained in the step 3 after dissolving is completed, and stirring to obtain a solution 2; and 5, heating the solution 2 in the step 4 in a water bath until the ethanol is evaporated, and then drying to obtain the TCPP / BMO. The photocatalytic degradation rate of the TCPP / BMO prepared by the preparation method disclosed by the invention is higher than that of Bi2MoO6.

Description

Technical Field

[0001] The invention belongs to the technical field of aflatoxin catalyst preparation, and particularly relates to a method for preparing a photocatalyst for degrading aflatoxin B1. Background Art

[0002] Mycotoxin contamination is an important video safety issue worldwide. Among them, aflatoxin B1 (AFB1) is extremely toxic and has been identified as a Class 1 carcinogen by the International Agency for Research on Cancer. Traditional methods for degrading aflatoxin B1 include physical, chemical and biological methods. Physical methods commonly use ultraviolet irradiation, high temperature, adsorption, etc., chemical methods commonly use acid treatment and alkali treatment, and biological methods use enzymes and microorganisms to control or decompose aflatoxin B1. However, there are problems such as complex processes, high energy consumption, and easy secondary pollution.

[0003] Photocatalytic degradation is a more advanced toxic substance degradation technology in the existing technology. It is widely used in the removal of organic pollutants in the environment. It has the characteristics of green environmental protection, simple process, no secondary pollution and low cost. The photocatalytic degradation process can be summarized into five main steps: light absorption, excitation and separation of photogenerated carriers, capture of reaction species on the surface, surface redox reaction and desorption of the final product.

[0004] At present, many researchers have found that Bi2MoO6 (bismuth molybdate) has a large specific surface area and abundant reactive sites. At the same time, Bi2MoO6 has excellent ferroelectric properties, superplasticity, and microwave dielectric properties, which can degrade aflatoxin B1. However, the high electron-hole recombination rate and limited light response range limit the degradation effect. In order to overcome the problems of the existing Bi2MoO6 (bismuth molybdate) with high electron-hole recombination rate, limited light response range, and limited degradation effect, the present application provides a photocatalyst for degrading aflatoxin B1 and a preparation method thereof. Summary of the invention

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] A method for preparing a photocatalyst for degrading aflatoxin B1 comprises the following steps:

[0007] Step 1: dissolving Bi(NO3)3·5H20 and Na2MoO4·2H2O in ethylene glycol by ultrasonic wave, then adding ethanol to the ultrasonic wave-dissolved solution while stirring, and continuing stirring for 10 to 60 minutes to obtain solution 1;

[0008] Step 2: Pour the solution 1 of step 1 into a reaction kettle, react at a temperature of 120°C-200°C for 12 hours to obtain crude Bi2MoO6;

[0009] Step 3: After the reaction is completed, the temperature is lowered to room temperature, and then washed with deionized water and ethanol until the supernatant is clear and transparent, and then dried to obtain pure Bi2MoO6;

[0010] Step 4: dissolve TCPP in ethanol by ultrasonication, add pure Bi2MoO6 obtained in step 3 after dissolution is complete, and stir to obtain solution 2;

[0011] Step 5: Heat the solution in step 4 in a water bath until the ethanol evaporates, and then dry to obtain TCPP / BMO.

[0012] As a further improvement of the technical solution, in step 4, the mass ratio of TCPP to pure Bi2MoO6 is 1-2.5:200.

[0013] As a further improvement of the technical solution, in step 4, the mass ratio of TCPP to pure Bi2MoO6 is 2:200

[0014] As a further improvement of the technical solution, the water bath temperature of solution 2 in step 5 is between 50°C and 80°C.

[0015] As a further improvement of the technical solution, the water bath temperature of solution 2 in step 5 is 60°C.

[0016] As a further improvement of the technical solution, in step five, the drying temperature is 70°C-100°C.

[0017] As a further improvement of the technical solution, in step five, the drying temperature is 80°C.

[0018] The present application also provides a photocatalyst for degrading aflatoxin B1, which is prepared by the above-mentioned preparation method.

[0019] As a further improvement of the technical solution, it was applied to the degradation of aflatoxin B1 at a concentration of 1ug / mL.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The photocatalytic degradation rate of TCPP / BMO prepared in this application is higher than that of Bi2MoO6. This is mainly because the carboxyl group of TCPP can be tightly combined with BMO (Bi2MoO6). Compared with TCPP and Bi2MoO6, it has a larger visible light absorption range and a stronger electron-hole separation effect. The energy bands of the two are matched. TCPP has the weakest degradation effect, followed by Bi2MoO6. When the degradation time is up to 75 minutes, the photocatalytic degradation rate of TCPP is only 28.4%, and the photocatalytic degradation rate of Bi2MoO6 is 68.9%. O, the photocatalytic degradation rates of TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3 and TCPP / BMO-4 were 81.3%, 85.7%, 93.8% and 83.7% respectively when the degradation time was up to 75 minutes. It can be seen that the photocatalytic degradation rate of TCPP / BMO-3 is higher than that of TCPP / BMO-1, TCPP / BMO-2 and TCPP / BMO-4, indicating that TCPP / BMO prepared with a mass ratio of TCPP to pure Bi2MoO6 of 2:200 has the best photocatalytic degradation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD patterns of different samples provided in Example 10 of the present invention;

[0023] Figure 2 FT-IR spectra of different samples provided in Example 11 of the present invention;

[0024] Figure 3 The UV-visible diffuse reflectance spectra of different samples provided in Example 12 of the present invention.

[0025] Figure 4 Photoluminescence spectra of different samples provided in Example 13 of the present invention;

[0026] Figure 5 The effect spectrum of different samples for degrading AFB1 provided in Example 14 of the present invention Figure 1 ;

[0027] Figure 6 The effect spectrum of different samples for degrading AFB1 provided in Example 14 of the present invention Figure 2 ;

[0028] Figure 7 This is a spectrum of the effect of TCPP / BMO-3 on AFB1 degradation provided in Example 15 of the present invention; DETAILED DESCRIPTION

[0029] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples described. The experimental methods for specific adjustments not specified in the following examples are selected according to the product specifications. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0030] Embodiment 1:

[0031] A method for preparing a photocatalyst for degrading aflatoxin B1 comprises the following steps:

[0032] Step 1: ultrasonically dissolve 2 mmol of Bi(NO3)3·5H20 and 1 mmol of Na2MoO4·2H2O in 15 ml of ethylene glycol, then add 35 ml of ethanol to the ultrasonically dissolved solution while stirring, and continue stirring for 30 minutes to obtain solution 1;

[0033] Step 2: Pour the solution 1 of step 1 into a 100 ml reactor, react at 160°C for 12 hours to obtain crude Bi2MoO6;

[0034] Step 3: After the reaction is completed, wait for the temperature to drop to room temperature, then wash with deionized water and ethanol until the supernatant is clear and transparent, and place in an oven at 60°C to dry overnight to obtain pure Bi2MoO6;

[0035] Step 4: Dissolve 2 mg of TCPP (meso-tetrakis(4-carboxyphenyl)porphine) in 50 ml of ethanol by ultrasonication. After dissolution, add 200 mg of pure Bi2MoO6 obtained in step 3 and stir at 25°C for 12 hours to obtain solution 2. It should be noted that TCPP is meso-tetrakis(4-carboxyphenyl)porphine, which has a narrow band gap of a conjugated macrocyclic P electronic structure, a wide visible light absorption range, and high stability.

[0036] Step 5: Heat the solution 2 in step 4 in a 60° C. water bath until the ethanol evaporates, and then place it in an oven at 80° C. to dry for 6 hours to obtain the photocatalyst TCPP / BMO-3.

[0037] Embodiment 2:

[0038] Compared with Example 1, the difference is that in step 4, the mass of TPCC is 1 mg, and the photocatalyst TCPP / BMO-1 is prepared.

[0039] Embodiment 3:

[0040] Compared with Example 1, the difference is that in step 4, the mass of TPCC is 1.5 mg, and the photocatalyst TCPP / BMO-2 is prepared.

[0041] Embodiment 4:

[0042] Compared with Example 1, the difference is that in step 4, the mass of TPCC is 2.5 mg, and the photocatalyst TCPP / BMO-4 is prepared.

[0043] Embodiment 5:

[0044] Compared with Example 1, the difference is that in step 5, the water bath temperature of solution 2 is 50°C.

[0045] Embodiment 6:

[0046] Compared with Example 1, the difference is that in step 5, the water bath temperature of solution 2 is 80°C.

[0047] Embodiment 7:

[0048] Compared with Example 1, the difference is that in step 5, the drying temperature is 70°C.

[0049] Embodiment 8:

[0050] Compared with Example 1, the difference is that in step 5, the drying temperature is 100°C.

[0051] Embodiment 9:

[0052] Compared with Example 1, the difference is that in step 1, 15 ml of ethanol is added.

[0053] Comparative Example:

[0054] Compared with Example 1, the difference is that only pure Bi2MoO6 is prepared, that is, after completing step three, steps four and five are no longer performed.

[0055] Embodiment 10:

[0056] X-ray diffraction (XRD) experiment: X-ray diffraction was used to test the crystal phase, crystallinity and grain size of Examples 1 to 4, Comparative Example and TCPP (tetrakis-(4-carboxyphenyl)porphine). Cu Kα radiation was used at a scanning rate of 10° / min, an accelerating voltage of 40 kV, and a current of 100 mA. Jade 6.0 software was used to compare and analyze the obtained sample data with the standard card.

[0057] The results are as follows Figure 1As shown, the XRD patterns of TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, TCPP / BMO-4, Bi2MoO6 and TCPP are shown. For pure Bi2MoO6, the crystal planes at 27.2°, 32.5°, 36.1°, 46.8°, 54.4° and 57.4° respectively correspond to (131), (002), (151), (260), (133), (134), (136) and (137), while for TCPP, it seems to be an amorphous structure rather than a crystalline structure, and a broad diffraction peak appears at 20.8°. In addition, no obvious diffraction peak of TCPP is found in the composite photocatalyst of TCPP / BMO. The possible reason is that the loading amount of TCPP is low. No impurity peak appears from the entire spectrum, indicating that the synthesized sample has high purity.

[0058] Embodiment 11:

[0059] Infrared spectroscopy (FT-IR) experiment: The functional groups of Examples 1 to 4, the comparative example and TCPP (tetrakis(4-carboxyphenyl)porphine) were analyzed using a Fourier transform infrared spectrometer with a scanning range of 400 to 2000 cm -1 .

[0060] The results are as follows Figure 2 As shown, TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, TCPP / BMO-4, Bi2MoO6 and TCPP were analyzed and detected by FTIR infrared spectroscopy. For pure Bi2MoO6, the vibration peak at 410-565cm-1 is the Bi-O stretching vibration, and the asymmetric and symmetric vibration modes of the Mo-O band in the MoO6 octahedron appear at 731-850cm-1. Absorption bands appear. For pure TCPP, 810cm-1 is the vibration of the tri-triazine ring unit of TCPP, 1100-1800cm-1 is the aromatic NC=N in the heterocyclic ring, 1403cm-1 is related to the C=C vibration in the benzene ring structure, and 1698cm-1 is the C=O vibration peak. These main characteristic peaks can be observed in a series of TCPP and BMO composite materials, proving the successful preparation of TCPP / BMO heterojunction.

[0061] Embodiment 12:

[0062] Ultraviolet-visible diffuse reflectance absorption spectroscopy (UV-vis DRS) test: The light absorption characteristics of the composite catalyst are determined by a solid ultraviolet-visible diffuse reflectance spectrometer. At the same time, the energy band structure of the semiconductor photocatalyst can also be indirectly determined. The scanning band is 200-800nm.

[0063] The results are as follows Figure 3As shown, it can be seen that the visible light absorption sideband becomes larger with the increase of magnetic biochar loading, and there is strong visible light absorption near BMO and TCPP at 400-800. It is worth noting that the broad absorption band near the double peak band of 350nm and 440-460nm is called the "Soret" band. Due to the h-aggregates and j-aggregates of TCPP, this proves the formation of TCPP molecular aggregates. The spectrum of TCPP shows four characteristic q bands at 520, 556, 593, and 650nm. The "Soret" band and four Q bands can also be observed in the composite samples of the TCPP / BMO series. The absorption intensity increases with the increase of TCPP addition, proving that it has good visible light absorption.

[0064] Embodiment 13:

[0065] Photoluminescence spectroscopy (PL) test: The present invention analyzes the recombination of photogenerated electron-hole pairs of CPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, TCPP / BMO-4, and Bi2MoO6 catalysts through steady-state fluorescence spectroscopy.

[0066] The results are as follows Figure 4 As shown in the figure, TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, TCPP / BMO-4, and Bi2MoO6 all have a peak in the wavelength range of 450-550nm, among which the fluorescence intensity of Bi2MoO6 is higher than that of TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, and TCPP / BMO-4, which indicates that TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3, and TCPP / BMO-4 have better separation degree of photogenerated carriers than Bi2MoO6. Figure 4 It can be seen that the fluorescence intensity of TCPP / BMO catalysts is TCPP / BMO-4, TCPP / BMO-1, TCPP / BMO-2, and TCPP / BMO-3, respectively. This shows that TCPP / BMO-3 has a better degree of separation of photogenerated carriers than TCPP / BMO-4, TCPP / BMO-1, and TCPP / BMO-2. TCPP / BMO-3 has the smallest electron-hole recombination rate and the most outstanding photocatalytic performance.

[0067] Embodiment 14:

[0068] Experimental study on photocatalytic degradation of aflatoxin B1 (AFB1) by different catalysts

[0069] The photocatalytic performance of Examples 1 to 4, Comparative Examples and TCPP (meta-tetrakis(4-carboxyphenyl)porphine) catalysts on aflatoxin B1 (AFB1) under simulated visible light was studied.

[0070] 2 mg of the sample was dispersed in 20 mL of aflatoxin B1 solution with a concentration of 1 ug / mL, and stirred in the dark for 30 min to allow the system to reach equilibrium in adsorption and desorption. Then, a xenon lamp (300 W xenon lamp with cutoff filter, L Z420 nm, PLSXE300, Bofeilai Co., Ltd., China) was turned on for photocatalytic reaction. 50 μL of the solution was taken each time, diluted with 75% methanol, and analyzed for concentration using HPLC and Agilent Zorbax SB-C18 column (4.6 mm × 250 mm; 5 μm). The calculation formula for the photocatalytic degradation rate (D) of AFB1 is as follows:

[0071] D(%)=(C0-C t ) / C0×100%

[0072] In the formula, D is the photocatalytic degradation rate, C0 represents the concentration of aflatoxin B1 at time 0 (ug / mL), and C T Indicates the concentration of aflatoxin B1 at time T (ug / mL).

[0073] The results are as follows Figure 5 and Figure 6 As shown in the figure, it can be seen from the photocatalytic degradation spectrum that the photocatalytic degradation rates of TCPP / BMO are higher than those of TCPP and Bi2MoO6. This is mainly because the carboxyl group of TCPP can be tightly combined with BMO (Bi2MoO6), which has a larger visible light absorption range and a stronger electron-hole separation effect than TCPP and Bi2MoO6, and the energy bands of the two are matched. Among them, TCPP has the weakest degradation effect, followed by Bi2MoO6. The degradation time ends at 75 minutes, and the photocatalytic degradation rate of TCPP is only 28.4%, and the photocatalytic degradation rate of Bi2MoO6 is 68.9%. In TCPP / BMO, the degradation time ends at 75 minutes. Up to 75 minutes, the photocatalytic degradation rates of TCPP / BMO-1, TCPP / BMO-2, TCPP / BMO-3 and TCPP / BMO-4 were 81.3%, 85.7%, 93.8% and 83.7%, respectively. It can be seen that the photocatalytic degradation rate of TCPP / BMO-3 is higher than that of TCPP / BMO-1, TCPP / BMO-2 and TCPP / BMO-4, indicating that TCPP / BMO prepared with a mass ratio of TCPP to pure Bi2MoO6 of 2:200 has the best photocatalytic degradation effect and has better photocatalytic performance and excellent photocatalytic activity than other samples.

[0074] Embodiment 15:

[0075] Stability of TCPP / BMO-3 towards photocatalytic degradation of aflatoxin B1 (AFB1)

[0076] The stability of the catalyst prepared in Example 1 on the photocatalytic degradation of aflatoxin B1 (AFB1) under simulated visible light was studied.

[0077] 2 mg of the sample was dispersed in 20 mL of aflatoxin B1 solution with a concentration of 1 ug / mL, and stirred in the dark for 30 min to allow the system to reach equilibrium in adsorption and desorption. Then, a xenon lamp (300 W xenon lamp with cutoff filter, L Z420 nm, PLSXE300, Bofeilai Co., Ltd., China) was turned on for photocatalytic reaction. 50 μL of the solution was taken each time, diluted with 75% methanol, and the concentration was analyzed using HPLC and Agilent Zorbax SB-C18 column (4.6 mm × 250 mm; 5 μm). The experiment was repeated 4 times. The calculation formula for the photocatalytic degradation rate (D) of AFB1 is as follows:

[0078] D(%)=(C0-Ct) / C0×100%

[0079] In the formula, D is the photocatalytic degradation rate, C0 represents the aflatoxin B1 concentration at time 0 (ug / mL), and CT represents the aflatoxin B1 concentration at time T (ug / mL).

[0080] The results are as follows Figure 7 As shown, after four cycles, the degradation curves of TCPP / BMO-3 for 1ug / mL aflatoxin B1 were roughly consistent, indicating that TCPP / BMO-3 has high stability in the photocatalytic degradation of aflatoxin B1 (AFB1).

[0081] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the present invention.

Claims

1. A method for preparing a photocatalyst for degrading aflatoxin B1, characterized in that: The following steps are involved: Step 1: dissolving Bi(NO3)3·5H20 and Na2MoO4·2H2O in ethylene glycol by ultrasonic wave, then adding ethanol to the ultrasonic wave dissolved solution while stirring, and continuing stirring for 10 to 60 minutes to obtain solution 1; Step 2: Pour the solution 1 of step 1 into a reaction kettle, react at a temperature of 120°C-200°C for 12 hours to obtain crude Bi2MoO6; Step 3: After the reaction is completed, the temperature is lowered to room temperature, and then washed with deionized water and ethanol until the supernatant is clear and transparent, and then dried to obtain pure Bi2MoO6; Step 4: dissolve TCPP in ethanol by ultrasonication, add pure Bi2MoO6 obtained in step 3 after dissolution is complete, and stir to obtain solution 2; Step 5: Heat the solution in step 4 in a water bath until the ethanol evaporates, and then dry to obtain TCPP / BMO.

2. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 1, characterized in that: In the step 4, the mass ratio of TCPP to pure Bi2MoO6 is 1-2.5:

200.

3. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 2, characterized in that: In the step 4, the mass ratio of TCPP to pure Bi2MoO6 is 2:

200.

4. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 1, characterized in that: The water bath temperature of the solution 2 in the step 5 is between 50°C and 80°C.

5. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 5, characterized in that: The water bath temperature of solution 2 in step 5 is 60°C.

6. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 1, characterized in that: In the step 5, the drying temperature is 70°C-100°C.

7. The method for preparing a photocatalyst for degrading aflatoxin B1 according to claim 6, characterized in that: In the step 5, the drying temperature is 80°C.

8. A photocatalyst for degrading aflatoxin B1, prepared by the photocatalyst preparation method for degrading aflatoxin B1 according to any one of claims 1 to 9.

9. The photocatalyst for degrading aflatoxin B1 according to claim 8, characterized in that: Applied to degrade aflatoxin B1 at a concentration of 1ug / mL.

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