Application of modified montmorillonite in the adsorption of mycotoxins

Abstract

The present invention discloses a modified montmorillonite for use in mycotoxin adsorption. The invention utilizes a specific organic solvent for thermal swelling and exfoliation treatment of the montmorillonite, exposing more adsorption active sites on the montmorillonite's two-dimensional surface. This increases the specific surface area of ​​the montmorillonite nanosheets and enhances their adsorption capacity for weakly polar compounds. Combined with thermal activation and ultrasonic treatment, the modified montmorillonite further enhances its surface area, ultra-thin montmorillonite nanosheets, and a high proportion of coordinatively unsaturated surface sites. This increased number of active sites enables the modified montmorillonite to exhibit strong adsorption capacity in mycotoxin adsorption applications, particularly significantly improving adsorption efficiency for weakly polar mycotoxins such as zearalenone and vomitoxin by at least 93.17% and 49.31%, respectively, compared to unmodified sodium montmorillonite.

Description

Technical Field

[0001] The present invention relates to the technical field of mycotoxin adsorbents, and more specifically, to the application of modified montmorillonite in the adsorption of mycotoxins. Background Art

[0002] Mycotoxins are toxic secondary metabolites produced by certain molds when they grow and reproduce on grains or feed. To date, over 400 mycotoxins have been isolated and identified, with aflatoxins, vomitoxin, and zearalenone being the most harmful. These toxins are resistant to high temperatures and various processing steps during processing, are highly toxic, and pose significant risks to humans and animals. According to statistics, mycotoxins contaminate approximately 25% of the world's grain, posing a significant threat to humans and animals. Mycotoxins, as stable organic compounds, are difficult to remove during normal processing and distribution. Each year, approximately 2% of grain is contaminated with mycotoxins and rendered inedible. Even grain that meets national standards can accumulate mycotoxins as byproducts through further processing. Chemical, biodegradation, and photocatalytic methods face significant challenges in large-scale application, while physical adsorption methods are relatively simple and practical. Commercially available physical adsorbents primarily include natural aluminosilicates, carbon materials, and organic polymers. Aluminosilicates such as attapulgite, montmorillonite, kaolin, and zeolite are widely used due to their low cost. The adsorption capacity of natural aluminosilicates for mycotoxins depends not only on the total charge, charge distribution, pore size, and available surface area of ​​the adsorbent, but also on the polarity, solubility, molecular size, shape, and charge distribution of the adsorbed toxin molecules. These adsorbents have been found to exhibit good adsorption for aflatoxins with polar groups, but relatively poor adsorption for weakly polar zearalenone and vomitoxin, with low adsorption capacity and inefficiency, and even near-total absence of adsorption capacity for some weakly polar mycotoxins. This poses a serious safety risk in practical applications.

[0003] Therefore, there is an urgent need to study a modified montmorillonite that is effective against both strong and weak polar mycotoxins and apply it in the field of mycotoxin adsorption. Summary of the Invention

[0004] To address these shortcomings, the present invention aims to provide a modified montmorillonite for use in mycotoxin adsorption. Using a specific method to modify the montmorillonite, it effectively adsorbs mycotoxins, particularly weakly polar zearalenone and vomitoxin, demonstrating strong adsorption, promising applications in grain and oil processing.

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

[0006] The present invention provides an application of modified montmorillonite in the adsorption of mycotoxins, wherein the modified montmorillonite is added to a mycotoxin solution for light-shielding adsorption;

[0007] The modified montmorillonite is prepared by the following method:

[0008] S1, converting calcium montmorillonite into sodium montmorillonite by sodium treatment, and then performing thermal activation treatment;

[0009] S2. Disperse the heat-activated montmorillonite in an organic solvent, perform heat swelling and exfoliation treatment in a water bath, transfer the heat-swollen and exfoliated montmorillonite to deionized water after centrifugation, and ultrasonicate for 2-12 hours under nitrogen protection to obtain the product.

[0010] In the technical solution of the present application, the purchased montmorillonite needs to be modified first, and the modification steps include thermal activation treatment, thermal swelling and peeling treatment, ultrasonic treatment, etc. The thermal activation treatment can completely calcine the grease, stains, surface adsorbed water and interlayer water on the surface of the montmorillonite, thereby achieving preliminary cleaning of the montmorillonite surface, and the interlayer channels of the montmorillonite continue to increase, and the specific surface area increases; the inventors creatively discovered that thermal swelling and peeling treatment of montmorillonite with a specific organic solvent can prevent the agglomeration of montmorillonite, expose more adsorption active points on the two-dimensional surface of montmorillonite, and enhance its adsorption capacity for weakly polar compounds. With the help of the intercalation and dispersion properties of montmorillonite, the specific surface area of ​​montmorillonite nanosheets is increased, the number of exposed active sites on the surface of the nanosheets is increased, and its adsorption capacity for mycotoxins is enhanced; through ultrasonic treatment, ultra-thin nano-sheet montmorillonite can be obtained, so that the nanosheets are highly evenly dispersed in the solution, which is conducive to enhancing its adsorption capacity for mycotoxins. The modified montmorillonite obtained after the above treatment can effectively adsorb highly polar mycotoxins such as aflatoxins, as well as weakly polar mycotoxins such as vomitoxin and zearalenone. The adsorption efficiency of the weakly polar mycotoxins zearalenone and vomitoxin is particularly improved. The adsorption efficiency of the modified montmorillonite for zearalenone and vomitoxin is at least 93.17% and 49.31% higher than that of the unmodified sodium-montmorillonite, respectively. Furthermore, this application can be directly applied to industrial production, with easy industrial conversion and no scale-up effect.

[0011] Furthermore, the organic solvent is selected from an amide reagent or a sulfur-containing reagent. In one embodiment, the amide reagent includes, but is not limited to, one or more of formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, or N-methylpropionamide; and the sulfur-containing solvent includes, but is not limited to, one or both of dimethyl sulfoxide and dimethyl sulfone. After extensive experiments, the inventors discovered that only after treating montmorillonite with an amide reagent or a sulfur-containing reagent can the modified montmorillonite significantly improve its mycotoxin adsorption efficiency. This is because the organic solvent exfoliates the two-dimensional layered montmorillonite, increasing the specific surface area and the number of exposed active sites on the montmorillonite surface, thereby enhancing its adsorption capacity for mycotoxins. When other organic solvents, such as acetone, are used as the organic solvent, while they can also dissolve montmorillonite, they do not enhance its mycotoxin adsorption capacity.

[0012] Furthermore, the temperature of the thermal activation treatment is 300-500°C, and the thermal activation treatment time is 1-5 hours. When the calcination temperature is below 200°C, the surface adsorbed water of the montmorillonite is lost, the interlayer water is lost at 200-300°C, and the organic matter is decomposed above 300°C.

[0013] Furthermore, in step S2, the mass volume ratio of the heat-activated montmorillonite to the organic solvent is 1g:50-150ml.

[0014] Furthermore, the thermal swelling and peeling treatment is to control the water bath temperature to 30-80° C., disperse the montmorillonite in an organic solvent, and stir the mixture for 12-36 hours.

[0015] Furthermore, the concentration of the mycotoxin solution is 1-50 mg / L. For example, the concentration of the mycotoxin solution can also be 1-3 mg / L, 1-5 mg / L, 1-7 mg / L, 1-10 mg / L, 2-5 mg / L, 2-7 mg / L, 2-10 mg / L, 5-7 mg / L, 5-10 mg / L, 7-10 mg / L, 5-50 mg / L, 10-50 mg / L, 20-50 mg / L, 30-50 mg / L, 40-50 mg / L, 10-20 mg / L, 10-30 mg / L, 10-40 mg / L, 20-40 mg / L, 30-40 mg / L, etc.

[0016] Furthermore, during the adsorption treatment, the mass concentration of the modified montmorillonite is 1-5 wt‰. For example, the mass concentration of the modified montmorillonite can also be any interval formed between 1, 1.25 wt‰, 1.5 wt‰, 1.75 wt‰, 2 wt‰, 2.25 wt‰, 2.5 wt‰, 2.75 wt‰, 3 wt‰, 3.25 wt‰, 3.5 wt‰, 3.75 wt‰, 4 wt‰, 4.25 wt‰, 4.5 wt‰, 4.75 wt‰, and 5 wt‰.

[0017] Furthermore, the adsorption operation is performed at a constant temperature of 37-45° C. for 2-6 hours.

[0018] Furthermore, the mycotoxins include vomitoxin, zearalenone or aflatoxins. In the present invention, the modified montmorillonite can not only adsorb aflatoxins with polar groups, but also exhibit good adsorption for weakly polar zearalenone and vomitoxin.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention uses a specific organic solvent to heat-swell and exfoliate montmorillonite, so that the two-dimensional surface of the montmorillonite exposes more adsorption active points, increases the specific surface area of ​​the montmorillonite nanosheets, and improves its adsorption capacity for weakly polar compounds. Combined with thermal activation treatment and ultrasonic treatment, it further provides its large specific surface area, ultra-thin montmorillonite nanosheet thickness, and a high proportion of coordinatively unsaturated surface sites. The increase in active sites enables the modified montmorillonite to exhibit strong adsorption capacity in the application of mycotoxin adsorption, especially significantly improving the adsorption efficiency of weakly polar mycotoxins such as zearalenone and vomitoxin, which are increased by 93.17% and 49.31% respectively compared with the sodium-based montmorillonite before modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Figure 1 1 is the XRD pattern of calcium montmorillonite (Ca-MMT), sodium montmorillonite (Na-MMT) and MMT-1 obtained in Example 1 of the present invention.

[0023] Figure 2 This is a SEM image of the calcium-montmorillonite of Example 1 of the present invention.

[0024] Figure 3 This is a SEM image of the sodium-montmorillonite of Example 1 of the present invention.

[0025] Figure 4 This is a SEM image of MMT-1 obtained in Example 1 of the present invention.

[0026] Figure 5 Graphs showing the adsorption rates of vomitoxin obtained in Test Examples 1-5 of the present invention.

[0027] Figure 6 This is a graph of the adsorption rate of zearalenone obtained in Test Examples 6-10 of the present invention. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0029] It should be noted that the needle filter selected in the present invention has no adsorption on mycotoxins.

[0030] Example 1

[0031] Step 1: Calcium montmorillonite (Ca-MMT) is converted into sodium montmorillonite (Na-MMT) by the sodium method, and then the sodium montmorillonite is thermally activated by calcination. The specific method is as follows: a certain amount of montmorillonite powder is weighed and placed in a muffle furnace for thermal activation treatment, the maximum temperature is set to 400°C, and the thermal activation time at 400°C is continued for 3 hours.

[0032] Step 2: The heat-activated montmorillonite is subjected to thermal swelling and exfoliation treatment. The specific method is as follows: 1 g of heat-activated montmorillonite powder is weighed and dissolved in 100 mL of dimethyl sulfoxide solution, stirred continuously in a 60°C water bath for 24 hours, and centrifuged to obtain the exfoliated montmorillonite. Then, 0.1 g of the above montmorillonite is weighed and placed in 100 mL of deionized water solution, and ultrasonicated under nitrogen protection for 6 hours to obtain a modified montmorillonite solution, which is recorded as MMT-1.

[0033] Figure 1 The XRD patterns of calcium montmorillonite, sodium montmorillonite and MMT-1 are shown. It proves that sodium montmorillonite and MMT-1 are successfully synthesized; the interlayer spacing of calcium montmorillonite is The interlayer spacing of sodium montmorillonite is The interlayer spacing of MMT-1 is The thermal expansion peeling was confirmed to be successful.

[0034] Figure 4 The SEM image of MMT-1 shows that the space structure between the montmorillonite layers is enlarged, exposing more adsorption sites. Figure 2 and Figure 3 The agglomeration of montmorillonite was significantly weakened.

[0035] Example 2

[0036] Step 1: convert calcium montmorillonite into sodium montmorillonite by sodium treatment, and then perform thermal activation treatment on the sodium montmorillonite by calcination. The specific method is as follows: weigh a certain amount of montmorillonite powder and place it in a muffle furnace for thermal activation treatment. The maximum temperature is set to 400°C, and the thermal activation time at 400°C is continued for 3 hours.

[0037] Step 2: The heat-activated montmorillonite is subjected to thermal swelling and exfoliation treatment. The specific method is as follows: 1 g of heat-activated montmorillonite powder is weighed and dissolved in 100 mL of N,N-dimethylformamide solution, stirred continuously in a 60°C water bath for 24 hours, and centrifuged to obtain the exfoliated montmorillonite. Then, 0.1 g of the above montmorillonite is weighed and placed in 100 mL of deionized water solution, and ultrasonicated under nitrogen protection for 6 hours to obtain a modified montmorillonite solution, which is recorded as MMT-2.

[0038] Example 3

[0039] Step 1: convert calcium montmorillonite into sodium montmorillonite by sodium treatment, and then perform thermal activation treatment on the sodium montmorillonite by calcination. The specific method is as follows: weigh a certain amount of montmorillonite powder and place it in a muffle furnace for thermal activation treatment. The maximum temperature is set to 400°C, and the thermal activation time at 400°C is continued for 3 hours.

[0040] Step 2: The heat-activated montmorillonite is subjected to thermal swelling and exfoliation treatment. The specific method is as follows: 1 g of heat-activated montmorillonite powder is weighed and dissolved in 100 mL of formamide, stirred continuously in a 60°C water bath for 24 hours, and centrifuged to obtain the exfoliated montmorillonite. Then, 0.1 g of the above montmorillonite is weighed and placed in 100 mL of deionized water solution, and ultrasonicated under nitrogen protection for 6 hours to obtain a modified montmorillonite solution, which is recorded as MMT-3.

[0041] Comparative Example 1

[0042] Step 1: convert calcium montmorillonite into sodium montmorillonite by sodium treatment, and then perform thermal activation treatment on the sodium montmorillonite by calcination. The specific method is as follows: weigh a certain amount of montmorillonite powder and place it in a muffle furnace for thermal activation treatment. The maximum temperature is set to 400°C, and the thermal activation time at 400°C is continued for 3 hours.

[0043] Step 2: The heat-activated montmorillonite is subjected to thermal swelling and exfoliation treatment. The specific method is as follows: 1 g of heat-activated montmorillonite powder is weighed and dissolved in 100 mL of acetone, stirred continuously in a 60°C water bath for 24 hours, and centrifuged to obtain the exfoliated montmorillonite. Then, 0.1 g of the above montmorillonite is weighed and placed in 100 mL of deionized water solution, and ultrasonicated under nitrogen protection for 6 hours to obtain a modified montmorillonite solution, which is recorded as MMT-4.

[0044] Comparative Example 2

[0045] Step 1: convert calcium montmorillonite into sodium montmorillonite by sodium treatment, and then perform thermal activation treatment on the sodium montmorillonite by calcination. The specific method is as follows: weigh a certain amount of montmorillonite powder and place it in a muffle furnace for thermal activation treatment. The maximum temperature is set to 400°C, and the thermal activation time at 400°C is continued for 3 hours.

[0046] Step 2: The heat-activated montmorillonite is subjected to an organic treatment. The specific method is as follows: 1 g of heat-activated montmorillonite powder is weighed and dissolved in 100 mL of water, 0.76 mmol of octadecyltrimethylammonium bromide is added, and the mixture is stirred continuously in a 60°C water bath for 24 hours. After centrifugation, the organic montmorillonite is obtained, which is recorded as MMT-5.

[0047] Test Examples 1 to 5

[0048] The performance of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was investigated using a mycotoxin adsorption test. The mycotoxin adsorption test mainly used an aqueous solution method. The mycotoxin solution selected was a vomitoxin solution with a concentration of 2 ppm. The specific steps were as follows:

[0049] The test samples prepared in Examples 1 to 3 and Comparative Example 1 were respectively weighed and placed in 4 mL of a vomitoxin solution. The concentration of the test sample was 1.25 wt‰. The vomitoxin solution was placed in a water bath and magnetically stirred at 37°C in the dark for 3 h. Then, 1 mL of the solution was drawn up using a syringe and filtered through a syringe filter into a liquid phase vial. The vomitoxin content in the solution was determined according to the method recommended by the National Feed Hygiene Standard (GB / T 30956-2014), and the adsorption rate was calculated. The results are shown in Table 1.

[0050] Table 1 Comparison of adsorption data of samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2

[0051] Samples to be tested MMT-1 MMT-2 MMT-3 MMT-4 MMT-5 Adsorption rate 49.29％ 49.31％ 40.39％ 11.99％ 12.64％

[0052] Table 1 shows the adsorption rates of vomitoxin by the samples prepared in Examples 1-3 and Comparative Examples 1-2. The montmorillonite modified with amides or sulfur-containing organic solvents in Examples 1-3 exhibits significantly higher adsorption rates for vomitoxin than the unmodified sodium-based montmorillonite, demonstrating that this method effectively enhances the adsorption capacity of montmorillonite for vomitoxin. Comparative Examples 1-2 show that montmorillonite treated with other solvents or organic amines exhibits lower adsorption rates for vomitoxin. The results in Table 1 demonstrate that the modification methods employed in Examples 1-3 and Comparative Examples 1-2 differ significantly.

[0053] Test Examples 6 to 10

[0054] The performance of the samples prepared in Examples 1 to 3 and Comparative Example 1 was investigated using a mycotoxin adsorption experiment. The mycotoxin adsorption experiment mainly used an aqueous solution method. The mycotoxin solution selected was a 1 ppm zearalenone solution. The specific steps were as follows:

[0055] The samples prepared in Examples 1 to 3 and Comparative Example 1 were respectively weighed and placed in 4 mL of a 1 ppm zearalenone solution. The concentration of the sample to be tested was 2.5 wt‰. The solution was placed in a water bath and magnetically stirred at a temperature of 37 ° C. under light-proof conditions for 3 h. Then, 1 mL of the solution was drawn using a syringe and filtered through a needle filter into a liquid phase vial. According to the recommended method of the national standard for feed hygiene (GB / T 28716-2012), the content of zearalenone in the solution was determined, and the adsorption rate was calculated. The results are shown in Table 2.

[0056] Table 2 Comparison of adsorption data of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2

[0057] Samples to be tested MMT-1 MMT-2 MMT-3 MMT-4 MMT-5 Adsorption rate 99.3％ 97.81％ 98.6％ 22.37％ 31.4％

[0058] Table 2 shows the adsorption rates of zearalenone by the samples prepared in Examples 1-3 and Comparative Examples 1-2. The montmorillonite modified with amides or sulfur-containing organic solvents in Examples 1-3 exhibits significantly higher zearalenone adsorption rates than the unmodified sodium-based montmorillonite, demonstrating that this method can effectively enhance the adsorption capacity of montmorillonite for zearalenone. Comparative Examples 1-2 show that montmorillonite modified with other solvents or organic amines exhibits lower adsorption rates for zearalenone. The results in Table 1 demonstrate that the modification methods employed in Examples 1-3 and Comparative Examples 1-2 are significantly different.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. The application of modified montmorillonite in the adsorption of mycotoxins is characterized by: The modified montmorillonite was added to the mycotoxin solution for light-proof adsorption; The modified montmorillonite is prepared by the following method: S1, converting calcium montmorillonite into sodium montmorillonite by sodium treatment, and then performing thermal activation treatment; S2. Dispersing the heat-activated montmorillonite in an organic solvent, performing heat swelling and exfoliation treatment in a water bath, transferring the heat-swelled and exfoliated montmorillonite to deionized water after centrifugation, and ultrasonicating under nitrogen protection for 2-12 hours to obtain; The organic solvent is selected from sulfur-containing reagents, and the sulfur-containing reagents include one or both of dimethyl sulfoxide and dimethyl sulfone; In step S2, the mass volume ratio of the thermally activated montmorillonite to the organic solvent is 1 g:50-150 ml; The temperature of the thermal activation treatment is 300-500°C, and the thermal activation treatment time is 1-5h; The thermal swelling and peeling treatment is to control the water bath temperature to 30-80°C, disperse the montmorillonite in an organic solvent and stir the mixture for 12-36 hours; The mycotoxin is vomitoxin or zearalenone.

2. The use according to claim 1, characterized in that The concentration of the mycotoxin solution is 1-50 mg / L.

3. The use according to claim 1, characterized in that The concentration of the mycotoxin solution is 1-10 mg / L.

4. The use according to claim 1, characterized in that The concentration of the mycotoxin solution is 1-5 mg / L.

5. The use according to claim 1, characterized in that The concentration of the mycotoxin solution is 5-10 mg / L.

6. The use according to claim 1, characterized in that During adsorption treatment, the mass concentration of the modified montmorillonite is 1-5 wt‰.

7. The use according to claim 1, characterized in that During adsorption treatment, the mass concentration of the modified montmorillonite is 1-2.5 wt‰.

8. The use according to claim 1, characterized in that During adsorption treatment, the mass concentration of the modified montmorillonite is 1-1.25 wt‰.

9. The use according to claim 1, characterized in that During adsorption treatment, the mass concentration of the modified montmorillonite is 1.25-2.5 wt‰.

10. The use according to claim 1, characterized in that The adsorption operation is performed at a constant temperature of 37-45° C. for 2-6 hours.

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