Methods for preparing silica composite materials

Abstract

This invention belongs to the field of silica technology, specifically relating to a method for preparing silica composite materials: silica microspheres or a silica mixture are added to a chitosan solution, followed by the addition of a PEI aqueous solution and stirring. A glutaraldehyde solution is then added, and the mixture is stirred again to obtain a gel-like product, which is then dried to obtain the silica composite material. The silica mixture includes a silica sponge-skeletal mixture, which is prepared by adding sponge-skeletal needles to a silica sol. This invention simplifies the preparation process of silica composite materials and improves the synergistic effect between silica and the matrix.

Description

Technical Field

[0001] This invention belongs to the field of silicon dioxide technology, specifically relating to a method for preparing silicon dioxide composite materials. Background Technology

[0002] Silica, as a common inorganic material, has wide applications in catalysis, adsorption, drug purification, chromatographic separation, and composite material preparation due to its chemical stability, thermal stability, biocompatibility, and high specific surface area.

[0003] In the field of composite materials, while individual silica microspheres possess certain functionalities, their applications are often limited. For example, silica microspheres have a low density of adsorption sites and are prone to particle aggregation, leading to a decrease in effective specific surface area. Moreover, the preparation process of composite materials is complex, involving multiple reaction steps and interface control. Achieving synergistic effects between silica and the matrix remains a challenge for current research. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a method for preparing silica composite materials.

[0005] The technical solution of this invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing silica microspheres, comprising the following steps:

[0007] Anhydrous ethanol, TEOS, and PEG were mixed and cooled to obtain solution A; ammonia solution was cooled to obtain solution B; solution B was added dropwise to solution A while stirring, and the reaction was continued; after the reaction, the mixture was centrifuged twice and dried to obtain silica microspheres.

[0008] It should be noted that in existing technologies, nano-sized silica particles have high surface energy and are prone to agglomeration, leading to a decrease in effective specific surface area. This application effectively inhibits agglomeration and significantly improves dispersibility and specific surface area through low-temperature preparation, PEG stabilizers, and freeze-drying techniques.

[0009] In one embodiment, the method of centrifuging twice after the reaction includes the following steps: transferring the reacted solution to a centrifuge tube, centrifuging at 10,000-15,000 rpm, discarding the supernatant, adding a small amount of pre-cooled anhydrous ethanol, ultrasonically dispersing, centrifuging again at 10,000-15,000 rpm, and washing.

[0010] Secondly, the present invention provides a method for preparing a silica sponge-bone needle mixture, comprising the following steps:

[0011] Add the sponge bone needles to the acid solution, stir, and dry to obtain the dried sponge bone needles;

[0012] APTES was added to anhydrous ethanol to obtain an APTES ethanol solution;

[0013] The dried sponge spicules were added to an APTES ethanol solution, stirred, and dried to obtain the modified sponge spicules.

[0014] Anhydrous ethanol, TEOS, and PEG were mixed and cooled to obtain solution A; ammonia solution was cooled to obtain solution B; solution B was added dropwise to solution A while stirring, and the reaction was continued; after the reaction, silica sol was obtained.

[0015] The modified sponge needles were added to the silica sol, mixed, and allowed to stand to obtain a gelled sol. The gelled sol was then allowed to age further and dried to obtain a silica sponge needle mixture.

[0016] In one embodiment, the concentration of APTES in the APTES ethanol solution is 0.5-2%.

[0017] In the first and second aspects, preferably, the cooling temperature is -30~0℃.

[0018] It should be noted that existing methods for preparing silica microspheres are typically carried out at room temperature or higher temperatures, resulting in rapid reaction rates and making it difficult to precisely control particle size and dispersion. This leads to uneven particle size distribution and limited specific surface area in the prepared silica microspheres, thus limiting their application in high-performance composite materials. Unlike existing technologies, this application selects to prepare silica microspheres at low temperatures.

[0019] Preferably, when adding solution B to solution A while stirring, the dropping rate is 0.01-0.2 mL / min.

[0020] Preferably, the solid-liquid ratio of PEG to anhydrous ethanol and TEOS is 0.05-0.10g: 90-110mL: 0.12-0.18mL.

[0021] Thirdly, the present invention provides a method for preparing a silica composite material, comprising the following steps:

[0022] Add silica microspheres or silica mixtures to chitosan solution, add PEI aqueous solution, stir and react, add glutaraldehyde solution, stir and react to obtain gel-like product, and dry to obtain silica composite material;

[0023] The silica mixture includes a silica sponge needle mixture, which is prepared by adding sponge needles to silica sol.

[0024] Preferably, the silica microspheres are prepared in the first aspect, and the silica sponge-bone needle mixture is prepared in the second aspect.

[0025] Preferably, the concentration of chitosan in the chitosan solution is 0.5-2%.

[0026] Preferably, the concentration of PEI in the PEI aqueous solution is 0.5-2%.

[0027] It should be noted that PEI aqueous solution can be prepared by mixing PEI and deionized water.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] I. Monodisperse silica microspheres were prepared.

[0030] High particle size uniformity: By controlling the hydrolysis and condensation rate of TEOS under low temperature reaction conditions and extremely low dropping rate, the nucleation and growth process is slowed down, and monodisperse silica microspheres are prepared, avoiding rapid aggregation caused by excessively high local concentration.

[0031] High specific surface area and activity: Low-temperature preparation effectively inhibits particle aggregation. Combined with the steric hindrance effect of PEG as a stabilizer, it significantly improves the dispersibility and specific surface area of ​​silica microspheres, enhancing the exposure of active sites. Experimental results show that the monodisperse silica microspheres prepared in Example 1 have significantly better adsorption performance than existing silica (Comparative Example 2).

[0032] High process controllability: The use of low-concentration TEOS and ammonia, a longer reaction time, and freeze-drying technology ensures a full reaction and minimizes particle agglomeration. The process is simple and easy to industrialize.

[0033] II. A mixture of silica sponge and bone needles was prepared.

[0034] Synergistic effect of hierarchical porous structure: Utilizing the natural hierarchical porous structure of sponge spicules as a template and carrier, silica sol was prepared via a low-temperature sol-gel method, and combined with silane coupling modification of APTES to form a three-dimensional network structure on the surface and within the pores of the sponge spicules. Adsorption experiments verified that the silica-sponge-spicule mixture prepared in Example 2, combining the natural pores of the sponge spicules with the nanoporous structure of silica gel, significantly improved the specific surface area and adsorption site density.

[0035] Enhanced interfacial bonding: APTES enhances the interfacial bonding between silica and sponge spicules by introducing amino anchoring sites, preventing nanoparticle detachment or aggregation. In the adsorption experiment, the adsorption capacity of Example 2 was significantly higher than that of Example 1, demonstrating the synergistic effect of hierarchical pore structure and interface optimization.

[0036] Combining biocompatibility and functionality: As a natural biomaterial, sponge bone needles have good biocompatibility. Combined with the high specific surface area and chemical stability of silica, this mixture has potential application value in fields such as biomedicine, drug purification, and chromatographic separation.

[0037] III. Preparation of silica composite materials

[0038] Construction of a three-dimensional network structure: Through the cross-linking of chitosan, PEI and glutaraldehyde, a three-dimensional network structure with strong biocompatibility and excellent mechanical properties was constructed, which encapsulates a mixture of silica sponge needles or monodisperse silica microspheres to form an organic-inorganic hybrid composite material.

[0039] Synergistic effect of multiple adsorption sites: The positive charge functionalization of chitosan and PEI introduces abundant hydroxyl and amino sites, which can synergistically capture target objects, such as molecules, with APTES-modified amino groups through hydrogen bonding and electrostatic interactions. Glutaraldehyde crosslinking further enhances the stability of the network structure, prevents nanoparticle aggregation, and maintains the accessibility of active sites.

[0040] Significantly improved adsorption performance: In the adsorption tests, the adsorption performance of Examples 3 and 4 was superior to that of Comparative Examples 1 and 2, indicating that the silica materials prepared in this application (whether sponge-bone needle mixture or monodisperse microspheres) exhibited higher adsorption capacity and rate after being combined with chitosan / PEI. This is attributed to the synergistic effect of hierarchical porous structure, high specific surface area, and multiple adsorption sites.

[0041] In summary, this application simplifies the preparation process of silica composite materials and improves the synergistic effect between silica and the matrix. Furthermore, this application significantly enhances the adsorption performance of the material by optimizing the preparation process of silica microspheres, constructing a silica sponge-bone needle mixture with a hierarchical porous structure, and using silica composite materials. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is an electron microscope image of the monodisperse silica microspheres of the present invention. It should be noted that the relevant parameters are: EHT=5.00KV, WD=8.6mm, Signal A=SE2, Mag=1.00KX. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] In existing technologies, nano-sized silica particles have high surface energy and are prone to agglomeration, even with the protection of stabilizers. This invention provides a novel method for preparing silica particles to address this problem.

[0046] The following raw materials are involved:

[0047] Tetraethyl orthosilicate: TEOS, ultrapure grade;

[0048] Anhydrous ethanol: Ultrapure grade;

[0049] Ammonia solution: analytical grade;

[0050] Polyethylene glycol: PEG 200, analytical grade;

[0051] Sponge spicules: 99% purity, medical grade;

[0052] Sodium hypochlorite: analytical grade;

[0053] Hydrochloric acid: analytical grade;

[0054] 3-Aminopropyltriethoxysilane: APTES, 98% purity;

[0055] Chitosan: Deacetylation degree ≥85%, molecular weight 50-190kDa, available at Sigma-Aldrich;

[0056] PEI: Polyethyleneimine, branched type, molecular weight 1.8-10kDa.

[0057] PEI aqueous solution can be prepared by PEI and deionized water, which is a conventional method.

[0058] Unless otherwise specified, the experimental methods used below are all conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0059] Method 1:

[0060] The specific steps for preparing monodisperse silica microspheres are as follows:

[0061] Add 80-100 mL of anhydrous ethanol, 0.1-0.2 mL of TEOS, and 0.05-0.1 g of PEG200 to a low-temperature reaction vessel. Stir magnetically until completely dissolved. Cool the solution to -20°C to obtain solution A.

[0062] Add 30-50 mL of deionized water and 0.05-0.1 mL of ammonia to a flask, stir magnetically until homogeneous, and cool the solution to -20°C to obtain solution B.

[0063] Keep solution A in a low-temperature bath and, while stirring magnetically, slowly add solution B dropwise at a rate of 0.01 mL / min to solution A. After the addition is complete, continue stirring the reaction at low temperature for 24-48 hours.

[0064] Transfer the reacted solution to a cryogenic centrifuge tube and centrifuge at high speed for 30-60 minutes. Discard the supernatant, add a small amount of pre-cooled anhydrous ethanol, sonicate to disperse, centrifuge again at high speed for 30-60 minutes, wash, and freeze-dry to obtain monodisperse silica microspheres of 20-5000 nm.

[0065] It should be noted that this application utilizes low temperature to suppress the rapid hydrolysis and polycondensation of TEOS to prepare monodisperse silica microspheres.

[0066] This application 1) employs low temperature to effectively suppress the hydrolysis and condensation rate of TEOS, slowing down the nucleation and growth process, which is beneficial for the formation of small-sized particles. 2) Uses low concentrations of TEOS and ammonia to reduce nucleation sites and avoid rapid aggregation. 3) Uses PEG as a stabilizer, which can adsorb onto the surface of silica particles, providing steric hindrance and preventing particle agglomeration. Choosing a low molecular weight PEG is more suitable for preparing ultra-small particles. 4) Employs an extremely low dropping rate to facilitate control of the silica microsphere particle size. Highly uniform microsphere size promotes monodispersity, avoids excessively high local concentrations, and promotes uniform nucleation and growth. 5) The reaction time in this application is relatively long, and the reaction rate is very slow under low temperature and extremely diluted conditions; the longer reaction time ensures sufficient reaction. 6) High-speed centrifugation is used to effectively separate small-sized particles / microspheres. 7) This application selects freeze-drying from various drying methods, which can minimize particle agglomeration.

[0067] The following is a specific implementation method 1:

[0068] Example 1

[0069] The specific steps for preparing monodisperse silica microspheres using Method 1 are as follows:

[0070] Add 100 mL of anhydrous ethanol, 0.15 mL of TEOS, and 0.07 g of PEG 200 to a low-temperature reaction vessel, stir magnetically until completely dissolved, and cool the solution to -20°C to obtain solution A.

[0071] Add 50 mL of deionized water and 0.08 mL of ammonia to a flask, stir magnetically until homogeneous, and cool the solution to -20°C to obtain solution B.

[0072] Solution A was kept in a -20°C low-temperature bath. While stirring magnetically, solution B was slowly added dropwise to solution A at a rate of 0.01 mL / min. After the addition was completed, the reaction was continued to be stirred at -20°C for 36 hours.

[0073] Transfer the reacted solution to a cryogenic centrifuge tube and centrifuge at 15,000 rpm for 45 minutes. Discard the supernatant, add 2-5 mL of pre-cooled -20°C anhydrous ethanol to completely cover the precipitate, sonicate to disperse, centrifuge again at 15,000 rpm for 45 minutes, wash, and freeze-dry to obtain monodisperse silica microspheres of 1000 nm. For observation of the microstructure of the monodisperse silica microspheres, refer to [reference needed]. Figure 1 The monodisperse silica microspheres have a complete structure, good morphology, good dispersibility, and no aggregation.

[0074] It should be noted that traditional sol-gel methods or the preparation of silica microspheres are usually carried out at room temperature or higher temperatures. This experiment uses a low temperature, which allows for better control of the formation and growth of sol particles, resulting in more uniform silica microspheres. Silica microspheres prepared at this low temperature have a higher specific surface area and activity, thus improving the performance of the composite material.

[0075] The following section further investigates related composite materials based on silica microspheres prepared at low temperatures.

[0076] Example 2

[0077] Based on Method 1, a silica sponge-bone needle mixture was prepared, and the specific steps are as follows:

[0078] Activation: Add 10g of sponge spicules to 100mL of 1M hydrochloric acid solution and stir at room temperature for 1 hour. Wash repeatedly with deionized water until neutral, and dry in a vacuum drying oven at 60℃ for 12 hours to obtain dried sponge spicules.

[0079] Modification: 1 mL of APTES was added to 99 mL of anhydrous ethanol to prepare a 1% (v / v) APTES ethanol solution. 1 g of dried sponge spicules was added to 50 mL of the 1% (v / v) APTES ethanol solution, stirred at room temperature for 2 hours, and then washed repeatedly with anhydrous ethanol. The solution was then dried in a vacuum drying oven at 60 °C for 2 hours to obtain the modified sponge spicules.

[0080] Preparation of silica sol: 100 mL of anhydrous ethanol, 0.15 mL of TEOS, and 0.07 g of PEG 200 were added to a low-temperature reaction vessel and magnetically stirred until completely dissolved. The solution was then cooled to -20°C to obtain solution A. 50 mL of deionized water and 0.08 mL of ammonia were added to a flask and magnetically stirred until homogeneous. The solution was then cooled to -20°C to obtain solution B. Solution A was kept in a -20°C low-temperature bath, and while magnetically stirring, solution B was slowly added dropwise at a rate of 0.01 mL / min to solution A. After the addition was complete, the reaction was continued at -20°C with stirring for 36 hours to obtain silica sol.

[0081] Gelation treatment: Add 0.5g of modified sponge bone needles to silica sol, mix, sonicate for 10 minutes to obtain a mixture, transfer the mixture to a sealed container, and let it stand at room temperature for 24 hours to obtain a gelled sol.

[0082] Aging: The gelled sol was left at room temperature for 48 hours to age, and then dried to obtain a silica sponge-bone needle mixture.

[0083] It should be noted that this application prepared a silica sponge-bone needle mixture. The preparation of this material comprehensively utilizes the natural hierarchical porous structure of the sponge-bone needles, silane coupling modification with APTES, and low-temperature sol-gel technology. First, the sponge-bone needles were activated with hydrochloric acid to remove surface impurities and increase specific surface area and the number of silanol groups. Subsequently, the surface of the sponge-bone needles was modified with APTES, introducing amino groups as anchoring sites for subsequent silica bonding. The silica sol was prepared using a low-temperature sol-gel method, with TEOS as the silicon source, ammonia as the catalyst, and PEG 200 as the stabilizer. By controlling the hydrolysis and polycondensation rates, silica sol particles with uniform size and good dispersibility were obtained. The modified sponge-bone needles were added to the silica sol, ultrasonically dispersed, and then allowed to gel statically, allowing the silica sol to form a three-dimensional network structure on the surface and within the pores of the sponge-bone needles. APTES not only provides amino anchoring sites but may also form stronger interfacial bonds with the silica sol through hydrogen bonding or even dehydration condensation. The gelled sample was then aged to further enhance the strength of the gel network. Finally, the final mixture was obtained by drying.

[0084] This application uses method 1 to prepare silica microspheres; utilizes the natural porous structure of sponge spicules as a template and carrier; and uses APTES to construct a chemical bridge between the sponge spicules and silica. The synergistic effect of these three components produces a composite material (i.e., a silica-sponge spicule mixture), which has a unique hierarchical porous structure (the original porous structure of the sponge spicules + the porous structure of nano-silica gel), high specific surface area, and good interfacial bonding (the bridging effect of APTES).

[0085] The prepared silica sponge bone needle composite material or monodisperse silica microspheres are used as raw materials to further prepare composite materials.

[0086] Example 3

[0087] The preparation method of silica composite material is as follows:

[0088] Dissolve 1g of chitosan in 100mL of 2% (v / v) acetic acid solution and stir until completely dissolved to obtain a 1% (w / v) chitosan solution.

[0089] 1 g of the silica sponge-bone needle mixture prepared in Example 2 was added to 50 mL of 1% chitosan solution and ultrasonically dispersed for 30 minutes. 10 mL of 1% (w / v) PEI aqueous solution was added, and the mixture was stirred for 1 hour. 5 mL of 5% (v / v) glutaraldehyde solution was slowly added dropwise to the mixture, and the mixture was stirred for 2 hours. A gel-like product was obtained, washed, and freeze-dried to obtain the silica composite material.

[0090] It should be noted that in this embodiment, a cross-linked biopolymer network was constructed using chitosan, PEI (polyethyleneimine), and glutaraldehyde to encapsulate the silica sponge bone needle mixture prepared in Example 2.

[0091] Chitosan dissolves in acetic acid to form a positively charged polymer solution, which is then used as a matrix for composite materials due to its biocompatibility and film-forming properties. PEI, as a positively charged polymer, binds to chitosan through electrostatic interactions, enhancing the crosslinking degree and mechanical properties of the material.

[0092] An organic-inorganic hybrid composite material was formed by combining inorganic materials (a mixture of silica sponge and bone needles) with an organic biopolymer (chitosan / PEI). Through the biocompatibility of chitosan, the positive charge functionalization of PEI, and the cross-linking effect of glutaraldehyde, a three-dimensional network structure integrating biocompatibility, mechanical properties, and functionalization characteristics was constructed.

[0093] Example 4

[0094] Unlike Example 3, the silica sponge-bone needle mixture prepared in Example 2 was replaced with the monodisperse silica microspheres prepared in Example 1.

[0095] The rest is the same as in Example 3.

[0096] It should be noted that, unlike Example 3, a different composite material was constructed in this example, which combines inorganic materials (monodisperse silica microspheres prepared in Example 1) with organic biopolymers (chitosan / PEI) to form an organic-inorganic hybrid composite material.

[0097] Comparative Example 1

[0098] Unlike Example 3, the silica sponge-bone needle mixture prepared in Example 2 was replaced with existing monodisperse silica (manufacturer: Sigma-Aldrich; model: 938254).

[0099] The rest is the same as in Example 3.

[0100] Comparative Example 2

[0101] The existing monodisperse silica (manufacturer: Sigma-Aldrich; model: 938254) was used directly as the adsorbent.

[0102] Detection and adsorption tests were conducted.

[0103] Preparation of tetracycline solution: Weigh 0.1g of tetracycline, dissolve it in 1L of deionized water, stir well, and adjust the pH to 7.0 to obtain a 100mg / L tetracycline solution.

[0104] The absorbance of the initial solution was measured using a UV-Vis spectrophotometer.

[0105] Take 1 mL of tetracycline solution (100 mg / L) and measure the absorbance at a wavelength of 357 nm. Record the initial absorbance of tetracycline as A0.

[0106] The adsorption performance of different materials for tetracycline was measured below.

[0107] Weigh 0.1g of the materials prepared in Examples 1-4, Comparative Example 1 and Comparative Example 2 respectively, and place them in 50mL centrifuge tubes.

[0108] Add 50 mL of 100 mg / L tetracycline solution to each centrifuge tube. Place the centrifuge tubes in a constant temperature shaker and shake at 150 rpm and 25°C.

[0109] Samples were collected at different time points (0h, 0.5h, 1h, 2h, 4h, 8h, and 24h). Immediately after collection, the samples were centrifuged at 10,000 rpm for 5 minutes. 1 mL of the supernatant was pipetted into a UV-Vis cuvette. The absorbance of tetracycline was measured at 350 nm and denoted as A. t (Absorbance at time t).

[0110] Calculate the tetracycline concentration C at time t using Beer-Lambert's law. t (mg / L):

[0111] C t =C0×(A t / A0)

[0112] Where C0 is the initial concentration (100 mg / L), A0 is the initial absorbance, and A t Let be the absorbance at time t.

[0113] Calculate the adsorption amount / adsorption capacity q at each time point. t (mg / g):

[0114] q t =[(C0-C t )×V] / m

[0115] Where V is the solution volume (0.05L) and m is the mass of the added material (sample) (0.1g).

[0116] q t The results are shown in Table 1 below:

[0117] Table 1

[0118]

[0119] analyze:

[0120] According to the experimental results, Example 3 had the highest adsorption capacity, while Comparative Example 2 had the lowest adsorption capacity.

[0121] Example 3: The natural pores of the sponge spicules form hierarchical channels with silica, significantly increasing the specific surface area and exposing more adsorption sites. The amino groups introduced by APTES modification form multiple adsorption sites with the hydroxyl and amino groups of chitosan / PEI, capturing tetracycline through hydrogen bonding and electrostatic interactions. The chitosan-PEI-glutaraldehyde three-dimensional network immobilizes the silica sponge spicule mixture, further forming a stable porous structure, preventing nanoparticle aggregation, and maintaining the accessibility of active sites.

[0122] Comparative Example 2: Existing silica surfaces are inert, relying on physical adsorption and a small amount of silanol groups, resulting in a low density of adsorption sites. Without a support, particles easily aggregate, leading to a low specific surface area and thus a significant decrease in effective adsorption area.

[0123] Example 1 showed a higher adsorption capacity than Comparative Example 2: This demonstrates that the monodisperse silica microspheres prepared at low temperatures using the method described in this application exhibit better tetracycline adsorption performance than commercially available silica, even without a carrier material. This is likely due to the improved specific surface area and number of active sites of silica prepared using the method described in this application.

[0124] Example 1 showed a higher adsorption capacity than Comparative Example 1, indicating that the silica microspheres prepared at low temperature using the method of this application have better adsorption performance than existing silica microspheres. This may be due to the higher specific surface area and activity of the silica microspheres prepared at low temperature.

[0125] Example 4 showed a higher adsorption capacity than Comparative Example 1, indicating that even without the hierarchical porous structure of sponge-bone needle composite, the monodisperse silica microspheres prepared at low temperature by the method of this application, after being combined with chitosan / PEI, still have better adsorption performance than existing silica microspheres.

[0126] The monodisperse silica microspheres, silica sponge-bone needle mixture, and silica composite materials prepared in this application have potential applications in adsorption, catalysis, and biomedicine, especially in specific fields such as drug purification and chromatographic separation.

[0127] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing silica composite materials, characterized in that, Includes the following steps: Add silica microspheres or silica mixtures to chitosan solution, add PEI aqueous solution, stir and react, add glutaraldehyde solution, stir and react to obtain gel-like product, and dry to obtain silica composite material; The preparation method of silica microspheres includes the following steps: Anhydrous ethanol, TEOS, and PEG were mixed and cooled to obtain solution A; ammonia solution was cooled to obtain solution B; solution B was added dropwise to solution A while stirring, and the reaction was continued; after the reaction, the mixture was centrifuged twice and dried to obtain silica microspheres; The silica mixture includes a silica sponge-spin mixture, which is prepared by adding sponge-spins to silica sol. Specifically, the preparation method of the silica sponge-spin mixture includes the following steps: Add the sponge bone needles to the acid solution, stir, and dry to obtain the dried sponge bone needles; APTES was added to anhydrous ethanol to obtain an APTES ethanol solution; The dried sponge spicules were added to an APTES ethanol solution, stirred, and dried to obtain the modified sponge spicules. Anhydrous ethanol, TEOS, and PEG were mixed and cooled to obtain solution A; ammonia solution was cooled to obtain solution B; solution B was added dropwise to solution A while stirring, and the reaction was continued; after the reaction, silica sol was obtained. The modified sponge needles were added to the silica sol, mixed, and allowed to stand to obtain a gelled sol. The gelled sol was then allowed to age further and dried to obtain a silica sponge needle mixture.

2. The method for preparing silica composite material according to claim 1, characterized in that, The temperature range for cooling is -30 to 0℃.

3. The method for preparing silica composite material according to claim 1, characterized in that, When adding solution B dropwise to solution A while stirring, the dropping rate is 0.01-0.2 mL / min.

4. The method for preparing silica composite material according to claim 1, characterized in that, The method of centrifuging twice after the reaction includes the following steps: Transfer the reacted solution to a centrifuge tube, centrifuge at 10,000-15,000 rpm, discard the supernatant, add a small amount of pre-cooled anhydrous ethanol, sonicate to disperse, centrifuge again at 10,000-15,000 rpm, and wash.

5. The method for preparing silica composite material according to claim 1, characterized in that, The concentration of APTES in the APTES ethanol solution is 0.5-2%.

6. The method for preparing silica composite material according to claim 1, characterized in that, The solid-liquid ratio of PEG, anhydrous ethanol, and TEOS is 0.05-0.10g:90-110mL:0.12-0.18mL.

7. The method for preparing silica composite material according to claim 1, characterized in that, The concentration of chitosan in the chitosan solution is 0.5-2%.

8. The method for preparing silica composite material according to claim 1, characterized in that, The concentration of PEI in the PEI aqueous solution is 0.5-2%.

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