A silica gel-modified ceramic membrane, its preparation method and application

Abstract

This disclosure relates to a silica gel-modified ceramic membrane, its preparation method, and its application. The method includes the following steps: (1) a silane coupling agent and a hydrophilic monomer are contacted in a first solvent to undergo a polymerization reaction to obtain a copolymer; (2) the copolymer, the ceramic membrane, and a second solvent are coupled under alkaline conditions; the silane coupling agent contains a C=C double bond in its structural formula; the hydrophilic monomer contains a C=C double bond in its structural formula. The method of this disclosure can simultaneously control the hydrophilicity and pore size of the ceramic membrane without significantly sacrificing its permeability. Compared with the original membrane, the obtained silica gel-modified ceramic membrane exhibits reduced hydrophilicity and a smaller decrease in water flux.

Description

Technical Field

[0001] This disclosure relates to the field of ceramic membranes, specifically to a silica gel-modified ceramic membrane, its preparation method, and its application. Background Technology

[0002] Inorganic ceramic membranes are widely used in many fields such as food, biomedicine, and fine chemicals due to their advantages such as high separation efficiency, stable performance, good chemical stability, resistance to acids and alkalis, resistance to organic solvents, antibacterial properties, high temperature resistance, antifouling properties, high mechanical strength, good regeneration performance, simple separation process, and low energy consumption. The surface of ceramic membranes has a large number of hydroxyl and ionic groups, which gives them natural hydrophilicity; however, this hydrophilicity also limits their application in certain fields. Summary of the Invention

[0003] The purpose of this disclosure is to provide a silica gel-modified ceramic membrane, its preparation method, and its application. This method can simultaneously control the hydrophilicity and pore size of the ceramic membrane surface, expanding the application of ceramic membranes in different situations.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing a silica gel-modified ceramic membrane, the method comprising the following steps:

[0005] (1) A silane coupling agent and a hydrophilic monomer are contacted in a first solvent to carry out a polymerization reaction to obtain a copolymer;

[0006] (2) The copolymer, ceramic film and second solvent are coupled under alkaline conditions;

[0007] The silane coupling agent contains a C=C double bond in its structural formula; the hydrophilic monomer contains a C=C double bond in its structural formula.

[0008] Optionally, step (2) includes:

[0009] (2-1) The ceramic membrane is immersed in alkaline conditions to obtain the immersed ceramic membrane;

[0010] (2-2) Dilute the copolymer with a third solvent to obtain a dip-coating solution;

[0011] (2-3) The wetted ceramic membrane is immersed in the coating solution to carry out the coupling reaction.

[0012] Optionally, in step (2-1), the soaking time is 1 to 5 hours, preferably 1 to 3 hours;

[0013] In step (2-2), the concentration of the dipping solution is 0.1wt% to 50wt%, preferably 0.5wt% to 30wt%, and more preferably 0.5wt% to 5wt%.

[0014] The third solvent is an organic solvent, preferably one of methanol, ethanol, acetone, and isopropanol, and more preferably ethanol;

[0015] The third solvent may be the same as or different from the first solvent and the second solvent, but preferably the same.

[0016] Optionally, the silane coupling agent is selected from one or more of vinyltriethoxysilane, 3-[tris(trimethylsiloxy)silyl]propyl methacrylate, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-(isobutenoyloxy)propyltrimethoxysilane, and allyltriethoxysilane; preferably 3-[tris(trimethylsiloxy)silyl]propyl methacrylate or vinyltri(β-methoxyethoxy)silane.

[0017] Optionally, the hydrophilic monomer is selected from one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, ethylene glycol diacrylate, acrylic acid, tetravinylpyridine, and divinylpyridine; preferably a hydrophilic monomer containing hydroxyl groups; more preferably one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylic acid, and hydroxypropyl methacrylate.

[0018] Optionally, in step (1), the molar ratio of the silane coupling agent to the hydrophilic monomer is 1:(10-40), preferably 1:(20-30);

[0019] The conditions for the polymerization reaction include: a polymerization time of 4 to 12 hours, preferably 6 to 10 hours, and a polymerization temperature of 50 to 120°C, preferably 70 to 100°C.

[0020] The initiator for the polymerization reaction is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, persulfate and benzoyl peroxide; preferably azobisisobutyronitrile or azobisisoheptanenitrile.

[0021] The boiling point of the first solvent is below 100°C, preferably one of methanol, ethanol, acetone and isopropanol, and more preferably ethanol;

[0022] In step (1), the molecular weight of the copolymer is 10000 g / mol or higher.

[0023] Optionally, in step (2), the conditions for the coupling reaction include: a coupling temperature of 20–70°C, preferably 35–50°C; and a coupling time of 1–10 h, preferably 1–6 h.

[0024] Optionally, in step (2), the alkaline condition is selected from ammonia or an amino-containing solution, wherein the amino-containing solution is selected from one or more of triethylamine, tripropylamine, and diethylamine; preferably, it is ammonia.

[0025] The second solvent is an organic solvent, preferably one of methanol, ethanol, acetone, and isopropanol, and more preferably ethanol;

[0026] The first solvent may be the same as or different from the second solvent, preferably the same;

[0027] The ceramic membrane has an average pore size of 50 nm or more.

[0028] A second aspect of this disclosure provides a silica gel-modified ceramic membrane prepared by the method described in the first aspect of this disclosure, the silica gel-modified ceramic membrane comprising a ceramic membrane substrate and a gel layer; the gel layer is coated on the surface of the ceramic membrane substrate, and at least a portion of the gel layer extends into the pores of the ceramic membrane substrate, wherein the silane groups of the gel layer and the hydroxyl groups of the ceramic membrane substrate undergo a coupling reaction and are connected by covalent bonds.

[0029] Optionally, the average pore size of the silica gel-modified ceramic membrane is 20–40 nm; the molar content of hydroxyl groups in the silica gel-modified ceramic membrane is 15–30%.

[0030] A third aspect of this disclosure provides the use of the silica gel-modified ceramic membrane described in the second aspect of this disclosure for the solid-liquid separation of nanoparticles.

[0031] Through the above technical solution, this disclosure obtains a random copolymer by free radical polymerization of a silane coupling agent containing C=C double bonds and a hydrophilic monomer containing C=C double bonds. Then, a ceramic membrane is coupled to the copolymer solution to form covalent bonds between the copolymer and the ceramic membrane, resulting in a silica gel-modified ceramic membrane. This method allows for simultaneous control of the hydrophilicity and pore size of the ceramic membrane without significantly sacrificing its permeability. Compared to the original membrane, the obtained silica gel-modified ceramic membrane exhibits reduced hydrophilicity and a smaller decrease in water flux.

[0032] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 The images are scanning electron microscope (SEM) images of the unmodified ceramic membrane of this disclosure and the silica gel-modified ceramic membranes of Examples 1-3.

[0035] Figure 2 The infrared spectra of the unmodified ceramic membrane of this disclosure and the silica gel-modified ceramic membranes in Examples 1-2 are shown.

[0036] Figure 3 The surface contact angles of the unmodified ceramic membrane of this disclosure and the silica gel-modified ceramic membranes of Examples 1-4 are shown in the figure.

[0037] Figure 4 The graph shows the membrane flux of the unmodified ceramic membrane of this disclosure and the silica gel modified ceramic membranes of Examples 1-4 as a function of the concentration of the dip coating solution. Detailed Implementation

[0038] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0039] The first aspect of this disclosure provides a method for preparing a silica gel-modified ceramic membrane, the method comprising the following steps:

[0040] (1) A silane coupling agent and a hydrophilic monomer are contacted in a first solvent to carry out a polymerization reaction to obtain a copolymer;

[0041] (2) The copolymer, ceramic film and second solvent are coupled under alkaline conditions;

[0042] The silane coupling agent contains a C=C double bond in its structural formula; the hydrophilic monomer contains a C=C double bond in its structural formula.

[0043] The method disclosed herein is simple and easy to implement, with mild conditions, and achieves coordinated control of pore size and hydrophilicity without significantly sacrificing the permeability of the ceramic membrane. The ceramic membrane pores have a hydrophilic environment, and the method disclosed herein allows the hydrophilic crosslinking agent to enter the ceramic membrane pores, forming a continuous gel coating inside the ceramic membrane pores.

[0044] In this disclosure, in step (1), the silane coupling agent undergoes double bond polymerization with the hydrophilic monomer to form a long polymer chain, resulting in a random copolymer. The random copolymer contains a large number of siloxane bonds and hydroxyl groups, and has abundant crosslinking points. In step (2), a coupling reaction occurs to form a gel layer, and a covalent bond is formed between the gel layer and the ceramic membrane. The coupling reaction includes the coupling of hydroxyl groups on the ceramic membrane with silanes in the random copolymer, and also includes the coupling reaction of hydroxyl groups of the long chain of the random copolymer with its own silane.

[0045] According to one embodiment of this disclosure, step (2) includes:

[0046] (2-1) The ceramic membrane is immersed in alkaline conditions to obtain the immersed ceramic membrane;

[0047] (2-2) Dilute the copolymer with a third solvent to obtain a dip-coating solution;

[0048] (2-3) The wetted ceramic membrane is immersed in the coating solution to carry out the coupling reaction. The above-described embodiment is beneficial for fully wetting the inner and outer surfaces of the ceramic membrane, making the subsequent reaction more uniform and orderly, increasing the hydroxyl content of the ceramic membrane, and providing an alkaline environment to induce the subsequent coupling reaction.

[0049] According to one embodiment of this disclosure, in step (2-1), the immersion time is 1-5 hours, preferably 1-3 hours; in step (2-2), the concentration of the coating solution is 0.1 wt%-50 wt%, preferably 0.5 wt%-30 wt%, more preferably 0.5-5 wt%; the third solvent is an organic solvent, preferably one of methanol, ethanol, acetone, and isopropanol, more preferably ethanol; the third solvent may be the same as or different from the first solvent and the second solvent, preferably the same. These preferred embodiments enable the silica gel-modified ceramic membrane of this disclosure to achieve controlled hydrophilicity and pore size while minimizing the decrease in permeability.

[0050] According to one embodiment of this disclosure, the silane coupling agent is a C5-C15 organosilane coupling agent, selected from one or more of vinyltriethoxysilane (KH-151), 3-[tris(trimethylsiloxy)silyl]propyl methacrylate, vinyltrimethoxysilane (KH-171), vinyltris(β-methoxyethoxy)silane (KH-172), 3-(isobutenoyloxy)propyltrimethoxysilane, and allyltriethoxysilane; preferably 3-[tris(trimethylsiloxy)silyl]propyl methacrylate or vinyltris(β-methoxyethoxy)silane.

[0051] According to one embodiment of this disclosure, the hydrophilic monomer is a C5 to C50 monomer, selected from one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, ethylene glycol diacrylate, acrylic acid, tetravinylpyridine, and divinylpyridine; preferably a hydrophilic monomer containing hydroxyl groups; more preferably one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylic acid, and hydroxypropyl methacrylate.

[0052] According to one embodiment of this disclosure, in step (1), the molar ratio of the silane coupling agent to the hydrophilic monomer is 1:(10-40), preferably 1:(20-30); the polymerization reaction conditions include: polymerization time of 4-12 h, preferably 6-10 h, polymerization temperature of 50-120 °C, preferably 70-100 °C; the initiator of the polymerization reaction is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, persulfate, and benzoyl peroxide; preferably azobisisobutyronitrile or azobisisoheptanenitrile; the boiling point of the first solvent is below 100 °C, preferably one of methanol, ethanol, acetone, and isopropanol, more preferably ethanol; in step (1), the molecular weight of the copolymer is 10000 g / mol or higher. The above preferred embodiments result in the silica gel-modified ceramic membrane of this disclosure having good stability, with a small decrease in permeability, and controlled hydrophilicity and pore size.

[0053] According to one embodiment of this disclosure, in step (2), the conditions for the coupling reaction include: a coupling temperature of 20–70°C, preferably 35–50°C; and a coupling time of 1–10 h, preferably 1–6 h. The above-mentioned preferred embodiments enable the silica gel-modified ceramic membrane of this disclosure to simultaneously regulate hydrophilicity and pore size while minimizing the decrease in permeability.

[0054] According to one embodiment of this disclosure, in step (2), the alkaline condition is selected from ammonia or an amino-containing solution, and the amino-containing solution is selected from one or more of triethylamine, tripropylamine and diethylamine; preferably ammonia; the second solvent is an organic solvent, preferably one of methanol, ethanol, acetone and isopropanol, and more preferably ethanol; the first solvent and the second solvent may be the same or different, preferably the same; the average pore size of the ceramic membrane is 50 nm or more.

[0055] The second aspect of this disclosure provides a silica gel-modified ceramic membrane prepared by the method described in the first aspect of this disclosure. The silica gel-modified ceramic membrane includes a ceramic membrane substrate and a gel layer. The gel layer is coated on the surface of the ceramic membrane substrate, and at least a portion of the gel layer extends into the pores of the ceramic membrane substrate. The silane groups of the gel layer and the hydroxyl groups of the ceramic membrane substrate undergo a coupling reaction and are then connected by covalent bonds.

[0056] According to one embodiment of this disclosure, the average pore size of the silica gel modified ceramic membrane is 20-40 nm; the molar content of hydroxyl groups in the silica gel modified ceramic membrane is 15-30%.

[0057] A third aspect of this disclosure provides the use of the silica gel-modified ceramic membrane described in the second aspect of this disclosure in the separation of nanoparticles in solid-liquid separation.

[0058] The present disclosure will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the scope of this disclosure in any way.

[0059] All raw materials used in the examples were commercially available and, unless otherwise specified, were of analytical grade. The ceramic membrane was made of alumina, with a microporous membrane thickness of approximately 6 mm and an effective area of ​​50 cm². 2 The product was purchased from Beijing Wote Water Treatment Technology Co., Ltd.; 3-[tris(trimethylsiloxy)silyl]propyl methacrylate was purchased from Anhui Zesheng Technology Co., Ltd., product with brand name A0208430250.

[0060] The molar content of hydroxyl groups in this disclosure was determined by nuclear magnetic resonance H-spectroscopy (Bruker, 500 MHz);

[0061] Water flux was tested on a Millipore 8050 instrument.

[0062] Scanning electron microscopy was performed on a Hitachi 8010 instrument; infrared spectroscopy was performed on an iS50 Nicolet instrument.

[0063] Example 1

[0064] (1) 2.5 mmol of 3-[tris(trimethylsiloxy)silyl]propyl methacrylate and 75 mmol of hydroxyethyl methacrylate were dissolved in 50 g of ethanol solution, and 1 mol% of azobisisobutyronitrile was added to the solution as an initiator for polymerization. After complete dissolution, the reaction solution was transferred to an oil bath at 90 °C and heated for 10 hours to obtain a random copolymer.

[0065] (2) The ceramic membrane was completely immersed in ammonia water (20% by mass) for 2 hours to obtain the immersed ceramic membrane; the copolymer was diluted with ethanol to obtain a coating solution with a copolymer mass fraction of 1 wt%; the immersed ceramic membrane was transferred to the coating solution; the immersed ceramic membrane and the copolymer were mixed in the presence of ethanol and ammonia water for 3 hours and a coupling reaction was carried out at 50°C; then the membrane was washed with deionized water with pH 6.5 for about 1 hour to remove the excess coating solution from the surface.

[0066] Examples 2-4

[0067] The methods in Examples 2-4 are the same as in Example 1, except that the mass fractions of the copolymer in the dipping solution are 5 wt%, 10 wt%, and 20 wt%, respectively.

[0068] Example 5

[0069] (1) Dissolve 3 mmol of vinyltris(β-methoxyethoxy)silane and 85 mmol of acrylic acid in 50 g of ethanol solution, and add 1 mol% of azobisisoheptanenitrile as an initiator for polymerization reaction. After complete dissolution, transfer the reaction solution to an oil bath at 100 °C and heat for 8 hours to obtain a random copolymer.

[0070] (2) The ceramic membrane was completely immersed in ammonia water (20% by mass) for 2 hours to obtain the immersed ceramic membrane; the copolymer was diluted with ethanol to obtain a coating solution with a copolymer mass fraction of 1 wt%; the immersed ceramic membrane was transferred to the coating solution; the immersed ceramic membrane and the copolymer were mixed in the presence of ethanol and ammonia water for 3 hours; and the coupling reaction was carried out at 65°C; then the membrane was washed with deionized water with pH 6.5 for about 1 hour to remove the excess coating solution from the surface.

[0071] Example 6

[0072] (1) Dissolve 4 mmol of vinyltriethoxysilane and 90 mmol of divinylpyridine in 50 g of ethanol solution, and add 1 mol% of benzoyl peroxide as an initiator for polymerization reaction. After complete dissolution, transfer the reaction solution to an oil bath at 100 °C and heat for 8 hours to obtain a random copolymer.

[0073] (2) The ceramic membrane was completely immersed in ammonia water (20% by mass) for 2 hours to obtain the immersed ceramic membrane; the copolymer was diluted with ethanol to obtain a 5 wt% copolymer dip coating solution, the immersed ceramic membrane was transferred to the dip coating solution, and the immersed ceramic membrane and copolymer were mixed in the presence of ethanol and ammonia water for 3 hours and the coupling reaction was carried out at 35°C; then the membrane was washed with deionized water with pH 6.5 for about 1 hour to remove the excess dip coating solution from the surface.

[0074] Example 7

[0075] (1) 1.8 mmol of vinyltris(β-methoxyethoxy)silane and 60 mmol of polyethylene glycol acrylate were dissolved in 50 g of ethanol solution, and 1 mol% of persulfate was added to the solution as an initiator for polymerization. After complete dissolution, the reaction solution was transferred to an oil bath at 90 °C and heated for 10 hours to obtain a random copolymer.

[0076] (2) The ceramic membrane was completely immersed in ammonia water (20% by mass) for 2 hours to obtain the immersed ceramic membrane; the copolymer was diluted with ethanol to obtain a coating solution with a copolymer mass fraction of 1 wt%; the immersed ceramic membrane was transferred to the coating solution; the immersed ceramic membrane and the copolymer were mixed in the presence of ethanol and ammonia water for 3 hours and a coupling reaction was carried out at 45°C; then the membrane was washed with deionized water with pH 6.5 for about 1 hour to remove the excess coating solution from the surface.

[0077] Example 8

[0078] The method in this embodiment 8 is the same as that in embodiment 1, except that in step (1), the molar ratio of the silane coupling agent to the hydrophilic monomer is 1:35.

[0079] Example 9

[0080] The method in Example 9 is the same as in Example 1, except that in step (1), the polymerization reaction temperature is 50°C and the time is 4 hours.

[0081] Example 10

[0082] The method of this embodiment 10 is the same as that of embodiment 1, except that in step (2), the coupling reaction temperature is 60°C and the time is 0.5h.

[0083] Test Example 1

[0084] Scanning electron microscopy (SEM), hydroxyl content, infrared spectroscopy, hydrophilic contact angle, and water flux were tested on the unmodified ceramic membrane and the modified ceramic membranes obtained in Examples 1-10. The test results are as follows: Figures 1-4 See Table 1.

[0085] Table 1

[0086]

[0087] Depend on Figure 1 It can be seen that the mass fraction of the copolymer in the dip-coating solution affects the pore size of the ceramic membrane and thus the degree of pore blockage. From... Figure 2 It can be seen that the 1720cm shown is... -1 The absorption peak at 1160 cm⁻¹ is attributed to the vibrational stretching of C=O in the silane polymer. This peak is absent in the unmodified ceramic film, and its intensity increases with increasing coating concentration. -1 The location is attributed to the stretching vibration of Si-O; 2929 cm -1 The location is attributed to the stretching vibrations of methyl and methylene groups on the random copolymer; furthermore, the silica gel-modified ceramic membrane at 3380 cm⁻¹... -1The presence of stronger OH stretching vibrations is attributed to the abundance of OH groups in the random copolymer and the hydrolysis reaction of the silane coupling agent in ammonia water, resulting in more -OH groups on the membrane surface.

[0088] Depend on Figure 3 , Figure 4 As shown in Table 1, the silica gel modified ceramic membrane obtained by the method of this disclosure achieves the adjustment of surface pore size and hydrophilicity without significantly reducing membrane permeability. The comparison of Examples 1 to 4 shows that the water flux of the silica gel modified ceramic membranes in Examples 1 and 2 decreased by less than 15%, the contact angle increased, and they still exhibited hydrophilicity, but the degree of hydrophilicity decreased. This indicates that within the preferred concentration range of 0.5 to 5 wt% of the dip coating solution in this disclosure, the permeability of the silica gel modified ceramic membrane decreased less, and the hydrophilicity of the ceramic membrane was better adjusted. A comparison of Examples 1 and 8 shows that, within the preferred molar ratio range of silane coupling agent to hydrophilic monomer in this disclosure, the permeability of the silica gel-modified ceramic membrane decreases less, while the hydrophilicity decreases. A comparison of Examples 1 and 9 shows that, within the preferred polymerization reaction conditions in this disclosure, the permeability of the silica gel-modified ceramic membrane decreases less, while the hydrophilicity decreases. A comparison of Examples 1 and 10 shows that, within the preferred coupling reaction conditions in this disclosure, the permeability of the silica gel-modified ceramic membrane decreases less, while the hydrophilicity decreases.

[0089] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0090] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0091] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing a silica gel-modified ceramic membrane, characterized in that, The method includes the following steps: (1) A silane coupling agent and a hydrophilic monomer are contacted in a first solvent to carry out a polymerization reaction to obtain a copolymer; (2) The copolymer, ceramic membrane and second solvent are coupled under alkaline conditions; Step (2) includes: (2-1) The ceramic membrane is immersed in alkaline conditions to obtain the immersed ceramic membrane; (2-2) Dilute the copolymer with a third solvent to obtain a dip-coating solution; (2-3) The wetted ceramic membrane is immersed in the dip-coating solution to carry out the coupling reaction; In step (1), the molar ratio of the silane coupling agent to the hydrophilic monomer is 1:(20~30); the structural formula of the silane coupling agent contains a C=C double bond; the structural formula of the hydrophilic monomer contains a C=C double bond; in step (2-2), the concentration of the dip-coating solution is 0.5~5 wt%.

2. The method according to claim 1, wherein, In step (2-1), the soaking time is 1~5 hours; In step (2-2), the third solvent is an organic solvent; The third solvent may be the same as or different from the first solvent and the second solvent.

3. The method according to claim 2, wherein, In step (2-1), the soaking time is 1 to 3 hours.

4. The method according to claim 2, wherein, In step (2-2), the third solvent is selected from methanol, ethanol, acetone and isopropanol.

5. The method according to claim 4, wherein, In step (2-2), the third solvent is ethanol.

6. The method according to claim 2, wherein, The third solvent is the same as the first solvent and the second solvent.

7. The method according to claim 1, wherein, The silane coupling agent is selected from one or more of vinyltriethoxysilane, 3-[tris(trimethylsiloxy)methsilyl]propyl methacrylate, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-(isobutenoyloxy)propyltrimethoxysilane, and allyltriethoxysilane.

8. The method according to claim 7, wherein, The silane coupling agent is 3-[tris(trimethylsiloxy)silyl]propyl methacrylate or vinyltris(β-methoxyethoxy)silane.

9. The method according to claim 1, wherein, The hydrophilic monomer is selected from one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, ethylene glycol diacrylate, acrylic acid, tetravinylpyridine, and divinylpyridine.

10. The method according to claim 9, wherein, The hydrophilic monomer is a hydrophilic monomer containing a hydroxyl group.

11. The method according to claim 10, wherein, The hydrophilic monomers are one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylic acid, and hydroxypropyl methacrylate.

12. The method according to claim 1, wherein, In step (1), the conditions for the polymerization reaction include: polymerization time of 4~12h and polymerization temperature of 50~120℃; The initiator for the polymerization reaction is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, persulfate and benzoyl peroxide; The boiling point of the first solvent is below 100 °C; In step (1), the molecular weight of the copolymer is 10,000 g / mol or higher.

13. The method according to claim 12, wherein, In step (1), the conditions for the polymerization reaction include: polymerization time of 6-10 h and polymerization temperature of 70-100 ℃.

14. The method according to claim 12, wherein, In step (1), the initiator of the polymerization reaction is azobisisobutyronitrile or azobisisoheptanenitrile.

15. The method according to claim 12, wherein, In step (1), the first solvent is one of methanol, ethanol, acetone and isopropanol.

16. The method according to claim 15, wherein, In step (1), the first solvent is ethanol.

17. The method according to claim 1, wherein, In step (2), the conditions for the coupling reaction include: coupling temperature of 20~70℃ and coupling time of 1~10h.

18. The method according to claim 17, wherein, In step (2), the conditions for the coupling reaction include: coupling temperature of 35~50℃; coupling time of 1~6h.

19. The method according to claim 1, wherein, In step (2), the alkaline condition is selected from ammonia or an amino-containing solution, and the amino-containing solution is selected from one or more of triethylamine, tripropylamine and diethylamine; The second solvent is an organic solvent; The first solvent may be the same as or different from the second solvent; The ceramic membrane has an average pore size of 50 nm or more.

20. The method according to claim 19, wherein, In step (2), the alkaline condition is selected from ammonia solution.

21. The method according to claim 19, wherein, In step (2), the second solvent is one of methanol, ethanol, acetone and isopropanol.

22. The method according to claim 21, wherein, In step (2), the second solvent is ethanol.

23. The method according to claim 19, wherein, The first solvent is the same as the second solvent.

24. The silica gel-modified ceramic membrane prepared by the method according to any one of claims 1 to 23, characterized in that, The silica gel-modified ceramic membrane includes a ceramic membrane substrate and a gel layer. The gel layer is coated on the surface of the ceramic membrane substrate, and at least a portion of the gel layer extends into the pores of the ceramic membrane substrate. The silane groups of the gel layer and the hydroxyl groups of the ceramic membrane substrate undergo a coupling reaction and are then connected by covalent bonds.

25. The silica gel-modified ceramic membrane according to claim 24, wherein, The average pore size of the silica gel-modified ceramic membrane is 20-40 nm; the molar content of hydroxyl groups in the silica gel-modified ceramic membrane is 15-30%.

26. Use of the silica gel-modified ceramic membrane according to any one of claims 24-25 for separating nanoparticles in solid-liquid separation.

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