A method for preparing modified mesoporous silica for removing toxins and heavy metals in corn oil

Abstract

The application discloses a preparation method of modified mesoporous silica for removing toxins and heavy metals in corn oil, and adopts rice husks as raw materials, optimizes the use of a pore expander, prepares mesoporous silica with a suitable pore size, and is modified by octyl and mercapto in cooperation, so that the prepared modified mesoporous silica has good adsorption effects on four common toxins AFB1, ZEN, OTA and DON in corn oil, and the prepared modified mesoporous silica also has good adsorption effects on heavy metal ions in corn oil. The modified mesoporous silica can be used to simultaneously adsorb various toxins and heavy metal ions, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing modified mesoporous silica for the removal of toxins and heavy metals from corn oil, belonging to the fields of fine inorganic chemicals and food contamination control. Background Technology

[0002] Corn production ranks third among China's grain crops after rice and wheat, making a significant contribution to ensuring national food security. Besides being an important food crop, corn is also a crucial feed crop. Nearly 65% ​​of the world's corn is used as animal feed. Mycotoxins, byproducts of secondary metabolism in filamentous fungi, are widely distributed in nature. Most mycotoxins have carcinogenic, teratogenic, and mutagenic effects, and their transmission through the food chain poses serious health risks. To date, nearly 400 mycotoxins have been discovered, among which the most harmful and contaminating are aflatoxin B1 (AFB1), zearalenone (ZEN), ochratoxin A (OTA), and vomitoxin (DON).

[0003] Besides fungal toxins, heavy metals are also common pollutants in corn, mainly including lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), chromium (Cr), and copper (Cu). Among these heavy metals, cadmium (Cd) is generally considered one of the most significant heavy metal toxins because it is highly mobile in the environment, easily absorbed by plants, and accumulates in the food chain. Cadmium pollution poses a significant threat to human health; long-term intake can lead to kidney damage and other health problems. Furthermore, lead (Pb) pollution levels are also high, especially in some lead-zinc mining areas where the lead exceedance rate reaches 34.78%.

[0004] US 2004 / 0028678 A1 describes the use of acid-activated layered silicates to adsorb aflatoxin, ochratoxin, fumonisin, zearalenone, vomitoxin, T-2 toxin, and ergotamine. This method can effectively improve the adsorption efficiency of layered silicates for aflatoxin and ochratoxin, but the improvement in the adsorption efficiency for zearalenone and vomitoxin is very limited.

[0005] WO2017 / 221079A1 uses long-chain quaternary amines without polar groups (such as those with octadecyltrimethylamine, octadecyltrimethylamine, octadecyldimethylamine, dodecylamine and similar compounds) to modify organosilicon. It has a good adsorption effect on aflatoxin and zearalenone, but a poor effect on vomitoxin.

[0006] CN 116459792 A discloses a mycotoxin adsorbent, which has good adsorption properties for vomitoxin, aflatoxin B1 and zearalenone, but does not mention the adsorption effect of ochratoxin A; and the mycotoxin adsorbent reduces the adsorption effect on metals.

[0007] CN106111071A discloses a method for preparing thiol-modified magnetic mesoporous SiO2 to reduce cadmium in wastewater. However, the disclosed method is for removing cadmium from water bodies. When the inventors tried to apply it to oil systems to adsorb heavy metals, the effect was not ideal, and the adsorption effect on toxins in oil systems was also not ideal.

[0008] CN109663572A discloses a method for preparing amino and mercapto bifunctionalized mesoporous silica and its application in arsenic removal. However, it is also used to remove arsenic from water and does not disclose the effect of adsorbing heavy metals and toxins in oil systems.

[0009] Rice husks are a high-volume byproduct of rice processing, with an annual output of approximately 40 million tons. They contain a large amount of amorphous silica (SiO2) (>20%), which can be converted into mesoporous SiO2 through calcination, alkali dissolution, and aging. Transmission electron microscopy revealed that this mesoporous SiO2 exhibits a highly regular, ordered, and porous amorphous hexagonal structure. Mesoporous SiO2 possesses numerous advantages, including a large specific surface area, regular pore structure, and abundant surface active sites. Our previous research focused on using magnetic mesoporous silica as an adsorbent to remove aflatoxin B1 from oil. The adsorbent interacts with aflatoxin B1 primarily through hydrogen bonds, hydrophobic interactions, and van der Waals forces, achieving good adsorption results. Furthermore, Fe3O4 nanoparticles in the magnetic mesoporous silica can chelate with the β-dicarbonyl group of aflatoxin B1, achieving a dual-immobilization physical adsorption of aflatoxin B1. Although magnetic mesoporous silica prepared from rice husks has a good adsorption effect on aflatoxin B1, its effect needs to be improved when adsorbing other toxins and heavy metal ions. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a modified mesoporous silica for removing toxins from corn oil. The prepared modified mesoporous silica exhibits good adsorption effects on four common toxins in corn oil: AFB1, ZEN, OTA, and DON. Furthermore, the modified mesoporous silica prepared by this invention also demonstrates good adsorption effects on heavy metal ions in corn oil. Therefore, the modified mesoporous silica of this invention can simultaneously adsorb multiple toxins and heavy metal ions, showing promising application prospects.

[0011] The first objective of this invention is to provide a method for preparing modified mesoporous silica for detoxification of corn oil, comprising the following steps:

[0012] S1. Rice husks are crushed and calcined to obtain rice husk ash, and the rice husk ash is dissolved in alkali to obtain rice husk ash solution.

[0013] S2. Prepare a pore-expanding agent solution. Add the rice husk ash solution prepared in step S1 to the pore-expanding agent solution at a volume ratio of 1:1~3. Adjust the pH to 10.0~12.0. Stir and react at 70~100℃ for 1~4 hours. After aging at a constant temperature, centrifuge and discard the supernatant. Wash the precipitate, dry it, and calcine it at 500~600℃ for 1~3 hours to obtain mesoporous silica. The pore-expanding agent solution is a hexadecyltrimethylammonium bromide / polyacrylic acid aqueous solution, with the concentration of hexadecyltrimethylammonium bromide being 0.02~0.04 mol / L and the concentration of polyacrylic acid being 0.02~0.04 mol / L.

[0014] S3. Disperse the mesoporous silica prepared in step S2 in toluene to obtain a mesoporous silica toluene solution; mix octyltrimethoxysilane with an aqueous methanol solution to obtain an octyltrimethoxysilane aqueous methanol solution; then add the octyltrimethoxysilane aqueous methanol solution to the mesoporous silica toluene solution according to a mass-to-volume ratio of mesoporous silica to octyltrimethoxysilane of 1 g: 0.8~1.2 mL, stir and react at 70~80℃ for 20~30 h, wash and dry the product to obtain octyl-modified mesoporous silica;

[0015] S4. Disperse the octyl-modified mesoporous silica obtained in step S3 in anhydrous methanol, then add glycerol and ultrasonically disperse to obtain a mixed solution of octyl-modified mesoporous silica; mix mercaptopropyltrimethoxysilane with anhydrous methanol to obtain a mercaptopropyltrimethoxysilane methanol solution; add the mercaptopropyltrimethoxysilane methanol solution to the mixed solution of octyl-modified mesoporous silica at a mass-to-volume ratio of 1g:0.8~1.2mL, add ammonia catalyst, and stir the reaction at 70~90℃ for 10~15h. Wash and dry the product to obtain octyl-mercaptomodified mesoporous silica.

[0016] In one embodiment of the present invention, in step S1, calcination is performed at 500-600°C for 4-6 hours.

[0017] In one embodiment of the present invention, in step S1, the alkaline dissolution of rice husk ash is achieved by mixing sodium hydroxide and rice husk ash in a mass ratio of 4 to 6:4 and then dissolving them by heating with water.

[0018] In one embodiment of the present invention, the mesoporous silica-toluene solution is obtained by mixing mesoporous silica and toluene at a mass-volume ratio of 1g:40~60mL and then ultrasonically dispersing them at 30~50℃ for 20~40 min.

[0019] In one embodiment of the present invention, the octyltrimethoxysilane methanol aqueous solution is obtained by mixing octyltrimethoxysilane and methanol aqueous solution at a volume ratio of 1:30~50 and ultrasonically treating for 20~40 min; wherein, the methanol aqueous solution is methanol:water = 85~95:10.

[0020] In one embodiment of the present invention, the octyl-modified mesoporous silica mixed solution is obtained by adding octyl-modified mesoporous silica to anhydrous methanol at a mass-volume ratio of 1g:40~60mL, ultrasonically dispersing for 20~40 min, then adding glycerol at a volume ratio of 1:0.8~1.2, and ultrasonically treating for 20~30 min.

[0021] In one embodiment of the present invention, the mercaptopropyltrimethoxysilane methanol solution is obtained by mixing mercaptopropyltrimethoxysilane with anhydrous methanol at a volume ratio of 1:20~40.

[0022] A second objective of this invention is to provide the preparation method described above for preparing modified mesoporous silica.

[0023] A third objective of this invention is to provide the application of the modified mesoporous silica in the removal of toxins and / or heavy metals from edible oils.

[0024] In one embodiment of the present invention, the edible oil is one or more of corn oil, peanut oil, and sunflower seed oil.

[0025] Beneficial effects of this application

[0026] This invention uses rice husks as raw material and optimizes the use of pore-expanding agents to prepare mesoporous silica with suitable pore size. Then, it is synergistically modified with octyl and mercapto groups. The resulting modified mesoporous silica exhibits good adsorption effects on four common toxins in corn oil: AFB1, ZEN, OTA, and DON. Furthermore, the modified mesoporous silica prepared in this invention also shows good adsorption effects on heavy metal ions in corn oil. The modified mesoporous silica of this invention can simultaneously adsorb multiple toxins and heavy metal ions, demonstrating promising application prospects. Detailed Implementation

[0027] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0028] Detection method:

[0029] The high-performance liquid chromatography (HPLC) detection method for AFB1 can be found in "Luo Xiaohu, Wang Ren, Wang Li, Li Yongfu, Li Yanan, Zhou Yunyu, Zhu Lijun, Chen Zhengxing. Study on the effect and degradation kinetics of ozone on the degradation of aflatoxin B1 in maize [J]. Food Science, 2015, 36(15): 45-49". Chromatographic column, C 18 Column (150 × 4.6 mm, 5 μm); fluorescence detector, excitation wavelength 360 nm, emission wavelength 460 nm; mobile phase, ultrapure water / methanol (chromatographic grade, 65 / 35, v / v); column temperature, 30 °C; flow rate, 1.0 mL / min; injection volume, 10 μL.

[0030] The high-performance liquid chromatography (HPLC) detection method for ZEN and OTA was based on the method described in "Li Ke, Pan Lihong, Luo Xiaohu, Wang Li, Wang Ren, Xing Jiali, Du Zhihong, Sun Dongling, Chen Zhengxing. Simultaneous determination of zearalenone and ochratoxin A in cereals by high performance liquid chromatography [J]. Food Research and Development, 2020, 41(6): 118-123". The chromatographic column was a ZORBAX SB-aq column (150×4.6mm, 5 μm); the fluorescence detector was set at excitation wavelength 325 nm and emission wavelength 455 nm; the mobile phase composition was 2% acetic acid / acetonitrile / methanol (60 / 30 / 10, v / v / v); the column temperature was 30℃; the flow rate was 1.0 mL / min; the injection volume was 50 μL; and the elution time was 25 min.

[0031] The high-performance liquid chromatography (HPLC) method for the detection of DON was based on the method described in "Li Ke, Pan Lihong, Luo Xiaohu, Wang Li, Wang Ren, Du Zhihong, Li Caiming, Chen Zhengxing. Electron beam irradiation degradation of zearalenone and vomitoxin in maize [J]. Food and Fermentation Industries, 2019, 45(21): 73-78". The chromatographic column was a ZORBAX SB-aq column (150×4.6 mm, 5 μm); the UV detector wavelength was 218 nm; the mobile phase composition was acetonitrile / water (6 / 94, v / v); the column temperature was 30℃; and the flow rate was 0.9 mL / min.

[0032] The method for detecting heavy metal ion concentration uses atomic absorption spectrometry, Cr 6+ Concentration determination was performed in accordance with GB 5009.123-2023, Cd 2+ Concentration determination was performed according to GB 5009.15-2014, Pb 2+ Concentration determination shall be performed in accordance with GB5009.12—2017.

[0033] Example 1: Preparation of octylthiol modified mesoporous silica

[0034] The steps for preparing octylthiol-modified mesoporous silica are as follows:

[0035] (1) Preparation of rice husk-based mesoporous silica:

[0036] Rice husk pretreatment: After washing, the rice husks are crushed and dried at 50℃ for 24 hours. After fully carbonizing the rice husks, they are calcined at 550℃ for 5 hours in a muffle furnace to obtain solid rice husk ash. The NaOH / rice husk ash is weighed and mixed according to the ratio of NaOH / rice husk ash = 5 / 4 (w / w), dissolved in deionized water by heating, and then brought to a final volume to obtain a rice husk ash solution.

[0037] Mesoporous SiO2 synthesis: A hexadecyltrimethylammonium bromide (CTAB) / polyacrylic acid (PAA) aqueous solution was prepared with a concentration of 0.02 mol / L for both hexadecyltrimethylammonium bromide (CTAB) and polyacrylic acid (PAA). 100 mL of this solution was taken, stirred, and heated to 80 °C. Then, 50 mL of a pre-prepared rice husk ash solution was added, and the pH was adjusted to 11.0 with 1.0 mol / L HCl. The mixture was kept at 80 °C and stirred for 2 h. After aging at a constant temperature for a certain period of time, the supernatant was discarded by centrifugation, the mixture was washed three times with deionized water, dried overnight at 50 °C, and calcined at 550 °C for 2 h to obtain the mesoporous SiO2 adsorbent material.

[0038] (2) Octyl modification

[0039] Weigh 1.0 g of mesoporous silica and add it to 50 mL of toluene. Disperse the mixture ultrasonically at 40 °C for 30 min. Mix 1.0 mL of octyltrimethoxysilane with 40 mL of methanol-water solution (methanol:water = 90:10) and sonicate for 30 min. Then pour the mixture into the above mesoporous silica-toluene solution and stir at 75 °C for 24 h. Separate the obtained sample and wash it 2-3 times with methanol. Then dry the sample at 80 °C for 12 h to obtain octyl-modified mesoporous silica.

[0040] (3) Thiol modification

[0041] Accurately weigh 1.0 g of octyl-modified mesoporous silica, add 40 mL of anhydrous methanol, and sonicate for 30 min. Then add 40 mL of glycerol and sonicate for another 30 min. Mix 1.0 mL of mercaptopropyltrimethoxysilane with 30 mL of anhydrous methanol, pour the mixture into the above solution, add 1 mL of ammonia, and stir at 80 °C for 12 h. After the reaction is complete, pour off the residue, wash 2-4 times with methanol, wash with water until neutral, and dry at 80 °C for 12 h to obtain octyl-mercaptomodified mesoporous silica.

[0042] Example 2: Preparation of Octylthiol Modified Mesoporous Silica

[0043] The steps for preparing octylthiol-modified mesoporous silica are as follows:

[0044] (1) Preparation of rice husk-based mesoporous silica:

[0045] Rice husk pretreatment: After washing, the rice husks are crushed and dried at 50℃ for 24 hours. After fully carbonizing the rice husks, they are calcined in a muffle furnace at 500-600℃ for 4-6 hours to obtain solid rice husk ash. The NaOH / rice husk ash is weighed and mixed according to a ratio of 5 / 4 (w / w), dissolved in deionized water by heating, and then brought to a final volume to obtain a rice husk ash solution.

[0046] Synthesis of mesoporous SiO2: An aqueous solution of hexadecyltrimethylammonium bromide (CTAB) / polyacrylic acid (PAA) was prepared with a concentration of 0.02 mol / L and a concentration of 0.04 mol / L. 100 mL of this solution was taken, stirred and heated to 80 °C, and then 50 mL of a pre-prepared rice husk ash solution was added. The pH was adjusted to 11.0 with 1.0 mol / L HCl, and the mixture was stirred for 2 h while maintaining the temperature at 80 °C. After aging at a constant temperature for a certain period of time, the supernatant was discarded by centrifugation, the mixture was washed three times with deionized water, dried overnight at 50 °C, and calcined at 550 °C for 2 h to obtain the mesoporous SiO2 adsorbent material.

[0047] (2) Octyl modification

[0048] Weigh 1.0 g of mesoporous silica and add it to 50 mL of toluene. Disperse the mixture ultrasonically at 40 °C for 30 min. Mix 1.2 mL of octyltrimethoxysilane with 40 mL of methanol-water solution (methanol:water = 90:10) and sonicate for 30 min. Then pour the mixture into the above mesoporous silica-toluene solution and stir at 75 °C for 24 h. Separate the obtained sample and wash it 2-3 times with methanol. Then dry the sample at 80 °C for 12 h to obtain octyl-modified mesoporous silica.

[0049] (3) Thiol modification

[0050] Accurately weigh 1.0 g of octyl-modified mesoporous silica and add it to 40 mL of anhydrous methanol. Disperse the silica using ultrasound for 30 min, then add 40 mL of glycerol and sonicate again for 30 min. Mix 0.8 mL of mercaptopropyltrimethoxysilane with 30 mL of anhydrous methanol and pour the mixture into the above solution. Add 1 mL of ammonia and stir at 80 °C for 12 h. After the reaction is complete, pour off the residue and wash 2-4 times with methanol, then wash with water until neutral. Dry at 80 °C for 12 h to obtain octyl-mercaptomodified mesoporous silica.

[0051] Example 3: Preparation of Octylthiol Modified Mesoporous Silica

[0052] The steps for preparing octylthiol-modified mesoporous silica are as follows:

[0053] (1) Preparation of rice husk-based mesoporous silica:

[0054] Rice husk pretreatment: After washing, the rice husks are crushed and dried at 50℃ for 24 hours. After fully carbonizing the rice husks, they are calcined in a muffle furnace at 500-600℃ for 4-6 hours to obtain solid rice husk ash. The NaOH / rice husk ash is weighed and mixed according to a ratio of 5 / 4 (w / w), dissolved in deionized water by heating, and then brought to a final volume to obtain a rice husk ash solution.

[0055] Synthesis of mesoporous SiO2: An aqueous solution of hexadecyltrimethylammonium bromide (CTAB) / polyacrylic acid (PAA) was prepared with a concentration of 0.04 mol / L and a concentration of 0.02 mol / L. 100 mL of this solution was taken, stirred and heated to 80 °C, and then 50 mL of a pre-prepared rice husk ash solution was added. The pH was adjusted to 11.0 with 1.0 mol / L HCl, and the mixture was stirred for 2 h while maintaining the temperature at 80 °C. After aging at a constant temperature for a certain period of time, the supernatant was discarded by centrifugation, the mixture was washed three times with deionized water, dried overnight at 50 °C, and calcined at 550 °C for 2 h to obtain the mesoporous SiO2 adsorbent material.

[0056] (2) Octyl modification

[0057] Weigh 1.0 g of mesoporous silica and add it to 50 mL of toluene. Disperse the mixture ultrasonically at 40 °C for 30 min. Mix 0.8 mL of octyltrimethoxysilane with 40 mL of methanol-water solution (methanol:water = 90:10) and sonicate for 30 min. Then pour the mixture into the above mesoporous silica-toluene solution and stir at 75 °C for 24 h. Separate the obtained sample and wash it 2-3 times with methanol. Then dry the sample at 80 °C for 12 h to obtain octyl-modified mesoporous silica.

[0058] (3) Thiol modification

[0059] Accurately weigh 1.0 g of octyl-modified mesoporous silica, add 40 mL of anhydrous methanol, and sonicate for 30 min. Then add 40 mL of glycerol and sonicate for another 30 min. Mix 1.2 mL of mercaptopropyltrimethoxysilane with 30 mL of anhydrous methanol, pour the mixture into the above solution, add 1 mL of ammonia, and stir at 80 °C for 12 h. After the reaction is complete, pour off the residue, wash 2-4 times with methanol, wash with water until neutral, and dry at 80 °C for 12 h to obtain octyl-mercaptomodified mesoporous silica.

[0060] Comparative Example 1: No octyl modification used

[0061] Based on Example 1, step (2) was omitted, and mercapto-modified mesoporous silica was prepared.

[0062] Comparative Example 2: No thiol modification used

[0063] Based on Example 1, step (3) was omitted, and octyl-modified mesoporous silica was prepared.

[0064] Comparative Example 3: Changing the modification ratio of octyl and thiol groups

[0065] Based on Example 1, the amount of octyltrimethoxysilane in step (2) was adjusted to 2.0 mL, and the amount of mercaptopropyltrimethoxysilane in step (3) was adjusted to 0.5 mL. The remaining steps were the same as in Example 1, and octyl mercapto-modified mesoporous silica was prepared.

[0066] Comparative Example 4: Changing the modification ratio of octyl and thiol groups

[0067] Based on Example 1, the amount of octyltrimethoxysilane in step (2) was adjusted to 0.5 mL, and the amount of mercaptopropyltrimethoxysilane in step (3) was adjusted to 2.0 mL. The remaining steps were the same as in Example 1, and octyl mercapto-modified mesoporous silica was prepared.

[0068] Comparative Example 5: Mesoporous silica without octyl and mercapto modification

[0069] Based on Example 1, steps (2) and (3) are deleted, and the remaining steps are the same as in Example 1, to prepare unmodified mesoporous silica.

[0070] Comparative Example 6: Using dodecyltrimethoxysilane

[0071] Based on Example 1, octyltrimethoxysilane in step (2) was replaced with dodecyltrimethoxysilane, and the remaining steps were the same as in Example 1, to prepare dodecyl mercapto-modified mesoporous silica.

[0072] Comparative Example 7: Changing the proportion of pore expander

[0073] Based on Example 1, in step (1), during the synthesis of mesoporous SiO2, an aqueous solution of hexadecyltrimethylammonium bromide (CTAB) / polyacrylic acid (PAA) was prepared with a concentration of 0.01 mol / L for hexadecyltrimethylammonium bromide (CTAB) and a concentration of 0.05 mol / L for polyacrylic acid (PAA). The remaining steps were the same as in Example 1, and octylthiol modified mesoporous silica was obtained.

[0074] Comparative Example 8: Changing the proportion of pore expander

[0075] Based on Example 1, in step (1), during the synthesis of mesoporous SiO2, an aqueous solution of hexadecyltrimethylammonium bromide (CTAB) / polyacrylic acid (PAA) was prepared with a concentration of 0.05 mol / L for CTAB and a concentration of 0.01 mol / L for PAA. The remaining steps were the same as in Example 1, and octylthiol modified mesoporous silica was obtained.

[0076] Example 4: Testing the detoxification effect

[0077] The detoxification effects of the octylthiol modified mesoporous silica prepared in Examples 1, 2, and 3, and the materials prepared in Comparative Examples 1-8, were tested.

[0078] (1) Adsorption experiment of toxins in edible oil

[0079] Edible oils containing the toxins AFB1, ZEN, OTA, and DON at initial concentrations of 1.2 μg / mL were prepared. 10 mL of each toxin was placed in different sample vials, and 10 mg of adsorbent material (Examples 1-3, Comparative Examples 1-8) was added to each. The samples were placed in a shaker and oscillated at 150 r / min at 20 °C for 5 h. The supernatant was collected by centrifugation, and the toxins were extracted from the oil using acetonitrile / water (84 / 16, v / v). The toxin content in the extract was determined by high-performance liquid chromatography (HPLC), and the residual toxin content was calculated. The adsorption rate of the adsorbent material for the toxins in the oil was then investigated. The formula for calculating the adsorption rate of the toxins is as follows:

[0080]

[0081] (2) Adsorption experiment of heavy metal ions in edible oil

[0082] Edible oils containing chromium, cadmium, and lead at an initial concentration of 1.50 mg / L were prepared separately. 10 mL of each oil was placed in different sample bottles, and 10 mg of adsorbent material (Examples 1-3, Comparative Examples 1-8) was added to each. The bottles were then placed in a shaker and kept at a constant temperature of 30°C under initial pH 5 conditions. o After adsorption at C for 6 h, the concentration of heavy metal ions in the edible oil was measured, and the adsorption rate of the adsorbent material for heavy metal ions in the oil was calculated to examine the adsorption effect of the adsorbent material on heavy metal ions in the oil. The formula for calculating the adsorption rate of heavy metal ions is as follows:

[0083]

[0084] or The adsorption rate is %; C o The initial concentration of the heavy metal ion standard solution is in mg / L.C e The concentration of heavy metal ions in the solution after adsorption is in mg / L.

[0085] The adsorption rates of toxins and heavy metal ions are shown in Table 1.

[0086] Table 1 Detoxification effect

[0087]

[0088] Table 1 shows that the synergistic modification with octyl and mercapto groups resulted in good adsorption of several toxins and heavy metal ions. Octyl modification alone showed good adsorption of metal ions but poor adsorption of toxins. Mercapto modification alone, due to the increased hydrophilicity of the material, did not effectively adsorb either metal ions or toxins from the oil system. A comparison between Comparative Example 6 and Example 1 shows that replacing octyl modification with dodecyl modification resulted in weaker adsorption of toxins and a less effective adsorption of metal ions compared to octyl modification.

[0089] Furthermore, the present invention optimizes the proportion of pore-expanding agent. The pore size of the mesoporous silica prepared by the method of the present invention, combined with the synergistic modification of mercapto and octyl groups, enables the final octyl-mercapto-modified mesoporous silica to have good adsorption properties for AFB1, ZEN, OTA and DON, and can also adsorb heavy metal ions in the oil system.

[0090] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing modified mesoporous silica for the removal of toxins and heavy metals from corn oil, characterized in that, Includes the following steps: S1. Rice husks are crushed and calcined to obtain rice husk ash, and the rice husk ash is dissolved in alkali to obtain rice husk ash solution. S2. Prepare a pore-expanding agent solution. Add the rice husk ash solution prepared in step S1 to the pore-expanding agent solution at a volume ratio of 1:1~3. Adjust the pH to 10.0~12.

0. Stir and react at 70~100℃ for 1~4 hours. After aging at a constant temperature, centrifuge and discard the supernatant. Wash the precipitate, dry it, and calcine it at 500~600℃ for 1~3 hours to obtain mesoporous silica. The pore-expanding agent solution is a hexadecyltrimethylammonium bromide / polyacrylic acid aqueous solution, with the concentration of hexadecyltrimethylammonium bromide being 0.02~0.04 mol / L and the concentration of polyacrylic acid being 0.02~0.04 mol / L. S3. Disperse the mesoporous silica prepared in step S2 in toluene to obtain a mesoporous silica toluene solution; mix octyltrimethoxysilane with an aqueous methanol solution to obtain an octyltrimethoxysilane aqueous methanol solution; then add the octyltrimethoxysilane aqueous methanol solution to the mesoporous silica toluene solution according to a mass-to-volume ratio of mesoporous silica to octyltrimethoxysilane of 1 g: 0.8~1.2 mL, stir and react at 70~80℃ for 20~30 h, wash and dry the product to obtain octyl-modified mesoporous silica; S4. Disperse the octyl-modified mesoporous silica obtained in step S3 in anhydrous methanol, then add glycerol and ultrasonically disperse to obtain a mixed solution of octyl-modified mesoporous silica; mix mercaptopropyltrimethoxysilane with anhydrous methanol to obtain a mercaptopropyltrimethoxysilane methanol solution; add the mercaptopropyltrimethoxysilane methanol solution to the mixed solution of octyl-modified mesoporous silica at a mass-to-volume ratio of 1g:0.8~1.2mL, add ammonia catalyst, and stir the reaction at 70~90℃ for 10~15h. Wash and dry the product to obtain octyl-mercaptomodified mesoporous silica.

2. The preparation method according to claim 1, characterized in that, In step S1, calcination is carried out at 500~600℃ for 4~6 hours.

3. The preparation method according to claim 1, characterized in that, In step S1, the alkaline dissolution of rice husk ash involves mixing sodium hydroxide and rice husk ash at a mass ratio of 4~6:4 and then heating them with water to dissolve them.

4. The preparation method according to claim 1, characterized in that, The mesoporous silica-toluene solution is obtained by mixing mesoporous silica and toluene at a mass-volume ratio of 1g:40~60mL and then ultrasonically dispersing the mixture at 30~50℃ for 20~40 min.

5. The preparation method according to claim 1, characterized in that, Octyltrimethoxysilane methanol aqueous solution is obtained by mixing octyltrimethoxysilane and methanol aqueous solution at a volume ratio of 1:30~50 and then ultrasonically treating for 20~40 min; wherein, the methanol aqueous solution is methanol:water = 85~95:

10.

6. The preparation method according to claim 1, characterized in that, The octyl-modified mesoporous silica mixture is prepared by adding octyl-modified mesoporous silica to anhydrous methanol at a mass-volume ratio of 1g:40~60mL, ultrasonically dispersing for 20~40min, then adding glycerol at a volume ratio of 1:0.8~1.2, and ultrasonically treating for 20~30min.

7. The preparation method according to claim 1, characterized in that, The mercaptopropyltrimethoxysilane methanol solution is obtained by mixing mercaptopropyltrimethoxysilane with anhydrous methanol at a volume ratio of 1:20~40.

8. A modified mesoporous silica is prepared by any one of claims 1 to 7.

9. The application of the modified mesoporous silica according to claim 8 in the removal of toxins and / or heavy metals from edible oils.

10. The application according to claim 9, characterized in that, The edible oil is one or more of corn oil, peanut oil, and sunflower seed oil, or a mixture thereof.

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