Application of PEG modified MIL-101 (Cr) in removing cholesterol in fish oil

Abstract

The invention provides application of PEG (polyethylene glycol) modified MIL-101 (Cr) in removal of cholesterol in fish oil, and particularly relates to the technical field of preparation of fish oil. The invention provides an adsorbent PEG modified MIL-101 (Cr) with better performance for removing cholesterol from fish oil, adsorption equilibrium can be quickly achieved within 5 minutes, the removal efficiency is remarkably improved, the production cycle is shortened, and the site cost is reduced. The rapid adsorption equilibrium also reduces the risk of oxidative deterioration of the fish oil, and is helpful for maintaining the quality of the fish oil. The high adsorption efficiency is crucial to the production of high-quality and low-cholesterol fish oil because the production efficiency is improved and the operation cost is reduced. In addition, the quick adsorption characteristic of the material enhances the flexibility of fish oil processing, so that the fish oil can quickly adapt to market requirements. In industrial scale production, the rapid adsorption equilibrium capability of PEG modified MIL-101 (Cr) promotes technical progress and product innovation of related industries.

Description

Technical Field

[0001] The invention relates to the technical field of fish oil preparation, in particular to application of PEG-modified MIL-101 (Cr) in removing cholesterol from fish oil. Background Art

[0002] Fish oil, as a functional health food, is widely recognized for its rich content of ω-3 polyunsaturated fatty acids such as EPA and DHA. These ingredients have significant effects in regulating blood lipids, blood sugar, enhancing intelligence, and improving athletic ability, so they have great application potential in the medical and food fields. However, the cholesterol contained in fish oil may pose a health hazard. Hypercholesterolemia is associated with a variety of diseases, such as gallstones, coronary heart disease, and cerebral thrombosis. When the human body consumes excessive cholesterol, these substances may accumulate on the blood vessel walls, forming plaques and inducing atherosclerosis, thereby increasing the risk of cardiovascular and cerebrovascular diseases. Therefore, it is particularly important to develop an effective method to remove cholesterol from fish oil.

[0003] When exploring methods to remove cholesterol from fish oil, existing technologies include molecular distillation, supercritical extraction, and adsorption. Although molecular distillation and supercritical extraction have significant removal effects, they are generally not used specifically for cholesterol removal due to their large equipment investment. In contrast, adsorption has become a more ideal choice due to its lower investment and easy operation.

[0004] In practical applications, the removal time is an important parameter for evaluating the applicability of the adsorption method. For example, it takes up to 2 hours to remove cholesterol using neutral alumina, which limits its application in industrial production because too long a removal time not only increases the production cycle, but may also cause fish oil oxidation and deterioration, increasing site occupation costs. β-cyclodextrin derivatives have been studied for their high complexing efficiency with cholesterol, among which hydroxypropyl-β-cyclodextrin shows stronger binding ability than methyl-β-cyclodextrin and sulfobutyl-β-cyclodextrin. β-cyclodextrin derivatives have low adsorption selectivity for cholesterol and poor complexing ability and stability, which affects the removal efficiency of cholesterol.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide an application of PEG-modified MIL-101(Cr) in removing cholesterol from fish oil, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0007] In order to solve the above technical problems, the present invention particularly adopts the following technical solutions: The first aspect of the present invention provides a use of PEG-modified MIL-101(Cr) in removing cholesterol from fish oil.

[0008] Furthermore, PEG-modified MIL-101(Cr) was added to fish oil for cholesterol removal.

[0009] Furthermore, the usage amount of the PEG-modified MIL-101(Cr) is 0.01-0.1 g / g fish oil.

[0010] Furthermore, the removal temperature is 30-50°C.

[0011] Furthermore, the removal time is 2 min to 8 min.

[0012] Furthermore, the preparation method of the PEG-modified MIL-101(Cr) is as follows: A. Mixing soluble chromium salt, organic ligand, solvent, regulator and PEG in a reactor, and then performing a hydrothermal reaction; B. After the hydrothermal reaction is completed, the materials in the reactor are separated into solid and liquid, and the obtained solid is washed, dried and ground to obtain the PEG-modified MIL-101 (Cr).

[0013] Furthermore, the soluble chromium salt includes chromium nitrate and / or chromium chloride.

[0014] The organic ligand includes terephthalic acid and / or 1,4-naphthalene dicarboxylic acid.

[0015] The solvent is water.

[0016] The regulator includes at least one of hydrofluoric acid, acetic acid and sodium acetate.

[0017] The PEG includes PEG-200.

[0018] Furthermore, the molar ratio of the soluble chromium salt to the organic ligand is 1:0.8-1.2.

[0019] Preferably, the amount of the solvent used is 8 to 10 times the total mass of the soluble chromium salt and the organic ligand.

[0020] Preferably, the amount of the regulator is 8-9% of the total mass of the soluble chromium salt and the organic ligand.

[0021] Preferably, the molar ratio of the soluble chromium salt to the PEG is 1:0.04-0.06.

[0022] Furthermore, the reactor has a polytetrafluoroethylene lining.

[0023] The temperature of the hydrothermal reaction is 180-220° C. and the time is 4-12 hours.

[0024] Further, ethanol and N,N-dimethylformamide are used for the washing respectively; Preferably, the obtained solid is first washed 2 to 5 times with ethanol, and then washed 2 to 5 times with N,N-dimethylformamide.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a PEG-modified MIL-101 (Cr) adsorbent with better performance for removing cholesterol from fish oil. The material can quickly reach adsorption equilibrium within 5 minutes, significantly improve removal efficiency, shorten production cycle, and reduce site costs. Rapid adsorption equilibrium also reduces the risk of oxidative deterioration of fish oil and helps maintain the quality of fish oil. Due to its high adsorption efficiency, PEG-modified MIL-101 (Cr) can significantly reduce the cholesterol content in fish oil in a short period of time, which is crucial for the production of high-quality, low-cholesterol fish oil because it not only improves production efficiency but also reduces operating costs. In addition, the rapid adsorption characteristics of the material enhance the flexibility of fish oil processing, allowing it to quickly adapt to market demand. In industrial-scale production, the rapid adsorption equilibrium ability of PEG-modified MIL-101 (Cr) promotes technological progress and product innovation in related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Fourier transform infrared spectra provided for characterization example 1; Figure 2 X-ray diffraction pattern provided for characterization example 2; Figure 3 Scanning electron microscope image provided for characterization example 3. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and shown herein can be arranged and designed in various different configurations.

[0029] The first aspect of the present invention provides a use of PEG-modified MIL-101(Cr) in removing cholesterol from fish oil.

[0030] The present invention provides a PEG-modified MIL-101 (Cr) adsorbent with better performance for removing cholesterol from fish oil. The material can quickly reach adsorption equilibrium within 5 minutes, significantly improve removal efficiency, shorten production cycle, and reduce site costs. Rapid adsorption equilibrium also reduces the risk of oxidative deterioration of fish oil and helps maintain the quality of fish oil. Due to its high adsorption efficiency, PEG-modified MIL-101 (Cr) can significantly reduce the cholesterol content in fish oil in a short period of time, which is crucial for the production of high-quality, low-cholesterol fish oil because it not only improves production efficiency but also reduces operating costs. In addition, the rapid adsorption characteristics of the material enhance the flexibility of fish oil processing, allowing it to quickly adapt to market demand. In industrial-scale production, the rapid adsorption equilibrium ability of PEG-modified MIL-101 (Cr) promotes technological progress and product innovation in related industries.

[0031] Metal-organic frameworks (MOFs) are porous network structures formed by the self-assembly of inorganic metal ions or clusters and organic linkers through coordination. The structures of MOFs materials are mainly divided into the following categories: (1) IRMOFs (Isoreticular Metal-Organic Frameworks) series; (2) MILs (Materials of Istitute Lavoisier) series; (3) ZIFs (Zeolitic Imidazolate Frameworks) series; (4) UIO (University of Olso) series; (5) PCN (Porous Coordination Network) series; (6) CPL (Coordination Pillared-Layer) series, etc. MIL-101 (Cr) belongs to one of the MILs series materials.

[0032] The structure of MIL-101(Cr) is composed of a medium cage with a diameter of 29Å and a large cage with a diameter of 34Å. The number ratio of the two cages is 2:1, and the cage volumes are 12700Å3 and 20600Å3, respectively. The medium cage contains only pentagonal windows (12Å), while the large cage contains pentagonal and hexagonal windows (16Å). MIL-101(Cr) not only has a high specific surface area and pore volume, with a specific surface area of ​​up to 5900m 2 / g, pore volume can reach 2m 3 / g, and the structure of MIL-101(Cr) is very stable. Even if it is exposed to air for several months, the structure will not be destroyed and it has high hydrothermal stability.

[0033] MIL-101(Cr) has a hydrophilic structure and generally combines with polar molecules in fish oil during the removal of fish oil cholesterol, resulting in low cholesterol adsorption and poor selectivity. Therefore, PEG is used to hydrophobically modify MIL-101(Cr) during the synthesis process to obtain PEG-modified MIL-101(Cr), thereby improving its cholesterol adsorption capacity.

[0034] Furthermore, PEG-modified MIL-101(Cr) was added to fish oil to remove cholesterol. PEG-modified MIL-101(Cr) has a high specific surface area and porous structure, which can provide a large number of adsorption sites. Cholesterol molecules are fixed in the pores of MIL-101(Cr) by physical adsorption. The introduction of PEG enhances this adsorption effect because PEG-200 is a hydrophobic polymer that can increase the compatibility of MIL-101(Cr) with oily media (such as fish oil), thereby promoting the adsorption of cholesterol.

[0035] Furthermore, the usage amount of the PEG-modified MIL-101(Cr) is 0.01-0.1 g / g fish oil.

[0036] Typically but not limiting, the usage amount of the PEG-modified MIL-101(Cr) can be, for example, 0.01 g / g, 0.02 g / g, 0.03 g / g, 0.04 g / g, 0.05 g / g, 0.06 g / g, 0.07 g / g, 0.08 g / g or 0.09 g / g fish oil, or any value within the range of 0.01 g / g to 0.1 g / g.

[0037] Furthermore, the removal temperature is 30-50°C.

[0038] Typically but not limiting, the removal temperature may be, for example, 30°C, 35°C, 40°C, 45°C or 50°C, or any value within the range of 30°C to 50°C.

[0039] Furthermore, the removal time is 2 min to 8 min.

[0040] Typically but not limiting, the removal time may be, for example, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min or 8 min, or any value within the range of 2 min to 8 min.

[0041] Furthermore, the preparation method of the PEG-modified MIL-101(Cr) is as follows: A. Mixing soluble chromium salt, organic ligand, solvent, regulator and PEG in a reactor, and then performing a hydrothermal reaction; B. After the hydrothermal reaction is completed, the materials in the reactor are separated into solid and liquid, and the obtained solid is washed, dried and ground to obtain the PEG-modified MIL-101 (Cr).

[0042] Furthermore, the soluble chromium salt includes chromium nitrate and / or chromium chloride.

[0043] The organic ligand includes terephthalic acid and / or 1,4-naphthalene dicarboxylic acid.

[0044] The solvent is water.

[0045] The regulator includes at least one of hydrofluoric acid, acetic acid and sodium acetate.

[0046] The PEG includes PEG-200.

[0047] The solvent includes deionized water, distilled water or double distilled water. Double distilled water is water distilled twice, also known as "double distilled water".

[0048] Furthermore, the molar ratio of the soluble chromium salt to the organic ligand is 1:0.8-1.2.

[0049] Typically but not limiting, the molar ratio of the soluble chromium salt to the organic ligand may be 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, or any value within the range of 1:0.8 to 1:1.2.

[0050] Preferably, the amount of the solvent used is 8 to 10 times the total mass of the soluble chromium salt and the organic ligand.

[0051] Typically but not limiting, the amount of the solvent can be 8 times, 8.5 times, 9 times, 9.5 times or 10 times the total mass of the soluble chromium salt and the organic ligand, or any value within the range of 8 to 10 times.

[0052] Preferably, the amount of the regulator is 8-9% of the total mass of the soluble chromium salt and the organic ligand.

[0053] Typically but not limiting, the amount of the regulator can be 8%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8% or 9% of the total mass of the soluble chromium salt and the organic ligand, or any value within the range of 8% to 9%.

[0054] Preferably, the molar ratio of the soluble chromium salt to the PEG is 1:0.04-0.06.

[0055] Typically but not limiting, the molar ratio of the soluble chromium salt to the PEG can be 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06, or any value within the range of 1:0.04 to 1:0.06.

[0056] Furthermore, the reactor has a polytetrafluoroethylene lining, which has extremely high corrosion resistance and can resist the erosion of hydrofluoric acid, ensuring that during the chemical reaction, the reactor lining can protect the reactor body from corrosion, extend the service life of the equipment, and ensure the safety of the reaction process.

[0057] The temperature of the hydrothermal reaction is 180-220° C. and the time is 4-12 hours.

[0058] Typically but not limiting, the temperature of the hydrothermal reaction can be, for example, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C or 220°C, or any value in the range of 180°C to 220°C; the time of the hydrothermal reaction can be, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, or any value in the range of 4 hours to 12 hours.

[0059] Furthermore, ethanol and N,N-dimethylformamide were used for washing to remove the residual organic ligand and solvent in the pores of the PEG-modified MIL-101(Cr).

[0060] Preferably, the obtained solid is first washed 2 to 5 times with ethanol, and then washed 2 to 5 times with N,N-dimethylformamide.

[0061] Typically but not limiting, the number of times the solid is washed with ethanol may be 2, 3, 4 or 5 times, or any number within the range of 2 to 5 times; similarly, the number of times N,N-dimethylformamide is washed may be 2, 3, 4 or 5 times, or any number within the range of 2 to 5 times.

[0062] In the following, some embodiments of the present invention are described in detail in conjunction with the embodiments. In the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. The raw materials used in the present invention can be obtained by commercial purchase unless otherwise specified.

[0063] Example 1 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.98 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.3 g of polyethylene glycol 200, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0064] 2. Separate the solid and liquid from the materials in the reactor by centrifugation at a speed of 8000 rpm for 10 min, and discard the supernatant.

[0065] 3. Add 150 mL of 50°C ethanol to the solid, vortex mix for 1 min, centrifuge at 8000 rpm for 10 min, and discard the supernatant. Repeat three times.

[0066] 4. Then add 150 mL of N,N-dimethylformamide to the solid, vortex mix for 1 min, centrifuge at 8000 rpm for 10 min, and discard the supernatant. Repeat three times.

[0067] 5. Finally, the precipitate was collected, dried at 150°C for 5 h, and ground into powder to obtain PEG-modified MIL-101(Cr).

[0068] Example 2 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.00 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.3 g of polyethylene glycol 200, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0069] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0070] Example 3 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 6.00 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.3 g of polyethylene glycol 200, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0071] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0072] Example 4 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.98 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.24 g of polyethylene glycol 200, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0073] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0074] Example 5 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.98 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.36 g of polyethylene glycol 200, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0075] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0076] Example 6 This embodiment provides a PEG-modified MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.98 g of terephthalic acid, 150 mL of double distilled water, 1.5 g of 40% hydrofluoric acid and 0.3 g of polyethylene glycol 400, add to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0077] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0078] Comparative Example 1 This comparative example provides a MIL-101(Cr), the preparation method of which is as follows: 1. Weigh 12 g of chromium nitrate nonahydrate, 4.98 g of terephthalic acid, 150 mL of double distilled water, and 1.5 g of 40% hydrofluoric acid, add them to the polytetrafluoroethylene liner, stir magnetically for 10 min, then react at 180 ° C for 8 h and cool.

[0079] Steps 2 to 5 are the same as steps 2 to 5 in Example 1.

[0080] Application Example 1 1.8 g of the materials of the embodiment and the comparative example were added to 30 g of fish oil respectively. The mixture was removed at 40° C. and 350 rpm for 90 min. Samples were taken at regular intervals to calculate the adsorption capacity of the materials.

[0081] The data are recorded in Table 1 below.

[0082] Table 1

[0083] As can be seen from Table 1, in Example 1, when the removal time increased from 0 min to 5 min, the adsorption capacity of the material increased significantly from 0 mg / g to 11.68 mg / g; when the removal time continued to increase to 90 min, the adsorption capacity of the material increased slightly to 12.08 mg / g, with no significant difference. The material provided in Example 1 can reach adsorption equilibrium within 5 min. In Example 2, the adsorption capacity of the material increased significantly from 0 mg / g to 8.65 mg / g within 0-10 min, and then the adsorption capacity did not change significantly with the increase of time; in Example 3, the adsorption capacity increased significantly from 0 mg / g to 11.74 mg / g within 5 min, and then the adsorption capacity did not change significantly with the increase of time, indicating that the effect of excess organic ligand on the adsorption capacity is not obvious. The adsorption capacity of Example 4 increased significantly from 0 mg / g to 9.98 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased; the adsorption capacity of Example 5 increased significantly from 0 mg / g to 8.73 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased, indicating that excessive PEG200 had an adverse effect on the adsorption capacity, which was attributed to the agglomeration of the polymer at a higher dose, thereby interrupting and reducing the crystallinity of the original MIL-101 (Cr), affecting the adsorption capacity of the material. The adsorption capacity of Example 6 increased significantly from 0 mg / g to 9.53 mg / g within 5 min, and then there was no significant change in the adsorption capacity as time increased. This may be because the PEG chain is too long, which affects the distribution of cholesterol in the cavity and affects the adsorption capacity of the material. The adsorption capacity of Comparative Example 1 increased significantly from 0 mg / g to 9.33 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased. The adsorption capacity was significantly lower than the result of Example 1, proving that the introduction of PEG200 can significantly improve the adsorption capacity of the material for cholesterol.

[0084] Application Example 2 0.3 g of the materials of the embodiment and the comparative example were added to 30 g of fish oil respectively. The mixture was removed at 40° C. and 350 rpm for 90 min. Samples were taken at regular intervals to calculate the adsorption capacity of the materials.

[0085] The data are recorded in Table 2 below.

[0086] Table 2

[0087] As can be seen from Table 2, in Example 1, when the removal time increased from 0 min to 5 min, the adsorption capacity of the material increased significantly from 0 mg / g to 21.64 mg / g; when the removal time continued to increase to 90 min, the adsorption capacity of the material increased slightly to 21.89 mg / g, with no significant difference. The material provided in Example 1 can reach adsorption equilibrium within 5 min. In Example 2, the adsorption capacity of the material increased significantly from 0 mg / g to 19.67 mg / g within 0-10 min, and then the adsorption capacity did not change significantly with the increase of time; in Example 3, the adsorption capacity increased significantly from 0 mg / g to 21.43 mg / g within 10 min, and then the adsorption capacity did not change significantly with the increase of time, indicating that the effect of excess organic ligand on the adsorption capacity is not obvious. The adsorption capacity of Example 4 increased significantly from 0 mg / g to 20.87 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased; the adsorption capacity of Example 5 increased significantly from 0 mg / g to 18.24 mg / g within 5 min, and then there was no significant change in the adsorption capacity as time increased, indicating that excessive PEG200 had an adverse effect on the adsorption capacity, which was attributed to the agglomeration of the polymer at a higher dose, thereby interrupting and reducing the crystallinity of the original MIL-101 (Cr), affecting the adsorption capacity of the material. The adsorption capacity of Example 6 increased significantly from 0 mg / g to 19.59 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased, which may be due to the excessive length of the PEG chain, which affected the distribution of cholesterol in the cavity and affected the adsorption capacity of the material; the adsorption capacity of Comparative Example 1 increased significantly from 0 mg / g to 19.42 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased, and the adsorption capacity was significantly lower than the result of Example 1, proving that the introduction of PEG200 can significantly improve the adsorption capacity of the material for cholesterol. Compared with the results in Table 1, the adsorption capacity of all materials increased significantly. This may be because the amount of adsorption material was low and after adsorption equilibrium, more adsorption sites of the adsorption material were bound to cholesterol.

[0088] Application Example 3 3 g of the materials of the embodiment and the comparative example were added to 30 g of fish oil respectively. The mixture was removed at 40° C. and 350 rpm for 90 min. Samples were taken at regular intervals to calculate the adsorption capacity of the materials.

[0089] The data are recorded in Table 3 below.

[0090] Table 3

[0091] As can be seen from Table 3, in Example 1, when the removal time increased from 0 min to 5 min, the adsorption capacity of the material increased significantly from 0 mg / g to 7.20 mg / g; when the removal time continued to increase to 90 min, the adsorption capacity of the material increased slightly to 7.35 mg / g, with no significant difference. The material provided in Example 1 can reach adsorption equilibrium within 5 min. In Example 2, the adsorption capacity of the material increased significantly from 0 mg / g to 6.63 mg / g within 0-10 min, and then the adsorption capacity did not change significantly with the increase of time; in Example 3, the adsorption capacity increased significantly from 0 mg / g to 7.24 mg / g within 10 min, and then the adsorption capacity did not change significantly with the increase of time, indicating that the effect of excess organic ligand on the adsorption capacity is not obvious. The adsorption capacity of Example 4 increased significantly from 0 mg / g to 6.52 mg / g within 5 min, and then there was no significant change in the adsorption capacity as time increased; the adsorption capacity of Example 5 increased significantly from 0 mg / g to 5.88 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased, indicating that excessive PEG200 had an adverse effect on the adsorption capacity, which was attributed to the agglomeration of the polymer at a higher dose, thereby interrupting and reducing the crystallinity of the original MIL-101 (Cr), affecting the adsorption capacity of the material. The adsorption capacity of Example 6 increased significantly from 0 mg / g to 6.47 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased. This may be because the PEG chain is too long, which affects the distribution of cholesterol in the cavity and affects the adsorption capacity of the material; the adsorption capacity of Comparative Example 1 increased significantly from 0 mg / g to 6.47 mg / g within 10 min, and then there was no significant change in the adsorption capacity as time increased, and the adsorption capacity was significantly lower than the result of Example 1, proving that the introduction of PEG200 can significantly improve the adsorption capacity of the material for cholesterol. Compared with the results in Table 1 , the adsorption capacity of all materials decreased, which may be because the amount of adsorption material was high and the adsorption sites of the adsorption material did not fully bind cholesterol after adsorption equilibrium.

[0092] Characterization Example 1 The PEG-modified MIL-101(Cr) and potassium bromide obtained in Example 1 were dried at 105°C for 4 h, mixed and ground at a weight ratio of PEG-modified MIL-101(Cr) to potassium bromide = 1:100, and pressed into a tablet machine at 4000-400 cm -1 The infrared spectrum of PEG-modified MIL-101(Cr) was analyzed by range analysis, and the spectrum obtained was as follows Figure 1 shown.

[0093] exist Figure 1 Medium, 1020cm -1 and 750cm -1 The absorption peak at 585cm is the deformation and out-of-plane bending vibration of the CH bond of the benzene ring.-1 The absorption peak at 1157 cm represents the stretching vibration of the Cr-O bond, indicating that MIL-101 (Cr) was successfully synthesized. -1 The absorption peak at represents the stretching vibration of the COC bond, indicating that polyethylene glycol is successfully combined with MIL-101 (Cr). Characterization Example 2 The PEG-modified MIL-101(Cr) powder obtained in Example 1 was subjected to X-ray diffraction analysis. The obtained spectrum is as follows: Figure 2 shown.

[0094] from Figure 2 It can be seen that the main diffraction peaks of MIL-101 (Cr) appear within 10° and at 16.5° 2θ, and the addition of polyethylene glycol does not affect the expression of the main diffraction peaks of MIL-101 (Cr).

[0095] Characterization Example 3 The PEG-modified MIL-101(Cr) powder obtained in Example 1 was dispersed in water and sprayed with gold. The microscopic morphology of the PEG-modified MIL-101(Cr) was observed under a scanning electron microscope. The scanning electron microscope image obtained is as follows: Figure 3 shown.

[0096] Figure 3 a in the figure is a scanning electron microscope image at a scale of 500 nm; Figure 3 b in the figure is a scanning electron microscope image at a scale of 200 nm. Figure 3 In the experiment, PEG-modified MIL-101(Cr) exhibited a regular octahedral morphology because the addition of polyethylene glycol would interact with Cr. 3+ The interaction results in the materials not being completely consistent in size.

[0097] Results The quality of the fish oil before and after the removal of cholesterol in Example 1 of Example 1 is measured, including the determination of acid value, peroxide value, anisidine value, iodine value and color.

[0098] The acid value is determined by the cold solvent automatic potentiometric titration method according to GB 5009.229-2016 "Determination of acid value in food". The peroxide value is determined by the potentiometric titration method according to GB 5009.227-2023 "Determination of peroxide value in food". The anisidine value is determined by referring to GB / T 24304-2009 "Determination of anisidine value of animal and vegetable fats and oils". The iodine value is determined by referring to GB / T5532-2022 "Determination of iodine value of animal and vegetable fats and oils".

[0099] The results are shown in Table 4 below.

[0100] Table 4

[0101] Note: Different letters in the same row indicate significant differences in fish oil before and after cholesterol removal (P<0.05), the same below.

[0102] The higher the acid value, peroxide value and anisidine value, the deeper the oxidation degree of the fish oil. As can be seen from Table 4, after S1 removes cholesterol from fish oil, the acid value, peroxide value and anisidine value of the fish oil decrease significantly, the color difference (ΔE) and iodine value do not change significantly, and the brightness (L*) of the fish oil changes significantly, which improves the quality of the fish oil overall.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of PEG-modified MIL-101(Cr) in removing cholesterol from fish oil.

2. The use according to claim 1, characterized in that: PEG-modified MIL-101(Cr) was added to fish oil for cholesterol removal.

3. The use according to claim 2, characterized in that: The usage amount of the PEG-modified MIL-101(Cr) is 0.01-0.1 g / g fish oil.

4. The use according to claim 2, characterized in that: The removal temperature is 30-50°C.

5. The use according to claim 2, characterized in that: The removal time is 2min~8min.

6. The use according to any one of claims 1 to 5, characterized in that: The preparation method of the PEG-modified MIL-101(Cr) is as follows: A. Mixing soluble chromium salt, organic ligand, solvent, regulator and PEG in a reactor, and then performing a hydrothermal reaction; B. After the hydrothermal reaction is completed, the materials in the reactor are separated into solid and liquid, and the obtained solid is washed, dried and ground to obtain the PEG-modified MIL-101 (Cr).

7. The use according to claim 6, characterized in that: The soluble chromium salt includes chromium nitrate and / or chromium chloride; The organic ligand comprises terephthalic acid and / or 1,4-naphthalene dicarboxylic acid; The solvent is water; The regulator includes at least one of hydrofluoric acid, acetic acid and sodium acetate; The PEG includes PEG-200.

8. The use according to claim 6, characterized in that: The molar ratio of the soluble chromium salt to the organic ligand is 1:0.8-1.2; The amount of the solvent is 8 to 10 times the total mass of the soluble chromium salt and the organic ligand; The amount of the regulator is 8-9% of the total mass of the soluble chromium salt and the organic ligand; The molar ratio of the soluble chromium salt to the PEG is 1:0.04-0.

06.

9. The use according to claim 6, characterized in that: The reactor has a polytetrafluoroethylene lining; The temperature of the hydrothermal reaction is 180-220° C. and the time is 4-12 hours.

10. The use according to claim 6, characterized in that: The washing is performed using ethanol and N,N-dimethylformamide respectively; The obtained solid was first washed 2 to 5 times with ethanol, and then washed 2 to 5 times with N,N-dimethylformamide.

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