Method for preparing silica film with hierarchical pore structure using eggshell inner membrane as template

Abstract

The present invention provides a method for preparing a hierarchical pore structure silicon dioxide film using an eggshell inner membrane as a template, wherein the eggshell inner membrane is used as a hard template, and the fibers constituting the eggshell inner membrane are burned to form macropores; a surfactant is used as a soft template, and mesopores are formed by burning to finally obtain a film with a macroporous-mesoporous hierarchical structure. The film obtained by the present invention has macropores and mesoporous structures, has a large specific surface area and pore volume, is not only suitable for preparing separation and purification films, but also can be conveniently further compounded with functional materials to prepare composite functional materials. At the same time, this method has the characteristics of low cost and has a guiding role in the synthesis of other mesoporous film materials.

Description

Technical Field

[0001] The invention relates to the technical field of mesoporous film materials, in particular to a method for preparing a silicon dioxide film with a graded pore structure by using an eggshell inner membrane as a template. Background Art

[0002] As people's living standards continue to improve, the consumption of poultry eggs continues to increase, and a large number of eggshells are discarded as waste. From the perspective of environmental protection and resource utilization, positive and beneficial research should be conducted on eggshells to achieve recycling and reuse. According to the structure and properties of the eggshell membrane, it can be applied in corresponding fields to create more value. The inner eggshell membrane (ESM) is a double-layer semipermeable biomembrane composed of interwoven and aggregated fibers with diameters ranging from 0.5 to 1 mm, a pore size of 1-3 mm, and a thickness of 65 to 96 μm. About 90% of the components in the inner membrane are proteins, mainly ovalbumin and collagen, etc., which have been used as templates to improve the porosity of various materials. Eggshell inner membrane fibers are composed of a collagen core within a glycoprotein with various functional groups on the surface. These fiber structures can be replicated with inorganic materials through template-assisted synthesis to produce hierarchical woven structures with enhanced surface area. The developed interwoven structures can be used as candidate materials for many applications.

[0003] Mesoporous silica thin film materials have special size effects and functionality that ordinary porous silica thin films do not have, which can make up for the shortcomings of some thin film materials and are widely used. An important issue in the application of mesoporous materials is the orientation of the pores. For example, channel pores can be used as nanofluid channels in applications. In addition, smaller pores perpendicular to the surface of the composite membrane ensure the role or process of smaller unit filtration. Summary of the invention

[0004] In view of this, the present invention aims to propose a method for preparing a silica film with a hierarchical pore structure using an eggshell inner membrane as a template, so as to prepare a hierarchical macroporous-mesoporous silica film with mesopores, and the method is simple.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing a silica film with a hierarchical pore structure using an eggshell inner membrane as a template, wherein the eggshell inner membrane is used as a hard template, and fibers constituting the eggshell inner membrane are burned away to form macropores; a surfactant is used as a soft template, and fibers constituting the eggshell inner membrane are burned away to form mesopores;

[0007] The steps include:

[0008] 1) Wash the inner membrane of the eggshell and dry it;

[0009] 2) dissolving the surfactant in anhydrous ethanol, adding the precursor, and then adding the catalyst at room temperature, stirring evenly to form a sol;

[0010] 3) immersing the clean and dry eggshell inner membrane into the sol, and ensuring that the eggshell inner membrane is completely penetrated, and in the sol-gel process, after the eggshell inner membrane is taken out from the sol, the residual sol on the surface of the eggshell inner membrane is carefully scraped off to obtain an eggshell membrane / silicon dioxide composite film composited on the eggshell inner membrane;

[0011] 4) calcining the composite membrane at high temperature to remove the eggshell inner membrane and surfactant to obtain a film with a hierarchical pore structure.

[0012] Furthermore, the eggshell inner membrane is the eggshell inner membrane of poultry.

[0013] Furthermore, the poultry eggshell membrane is any one of the chicken egg membrane, duck egg membrane, goose egg membrane, bird egg membrane, quail egg membrane or goose egg membrane.

[0014] Furthermore, the surfactant is one or a mixture of two or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant or a compound surfactant.

[0015] The precursor is an organic silicon source or an inorganic silicon source, the organic silicon source is methyl orthosilicate, ethyl orthosilicate or butyl orthosilicate, and the inorganic silicon source is silicon tetrachloride or water glass.

[0016] Furthermore, the catalyst is an acidic substance or an alkaline substance, the acidic substance is any one of hydrochloric acid, sulfuric acid, and nitric acid, and the alkaline substance is any one of sodium hydroxide, potassium hydroxide, and ammonia water.

[0017] Furthermore, the catalyst is hydrochloric acid, and the concentration of the hydrochloric acid is 0.01 mol / L to 1 mol / L.

[0018] Furthermore, the mass ratio of the surfactant to the precursor is 0.1-2.

[0019] Furthermore, in step 3), the egg inner membrane is immersed in the sol for 2 hours to 48 hours, and the sol is formed during this time, and the egg inner membrane is taken out when the gelation process is in progress but not completely gelled.

[0020] Furthermore, the temperature of the high temperature calcination in step 4) is 450° C. to 800° C., and the time is 3 h to 6 h.

[0021] Compared with the prior art, the method of preparing a silica film with a hierarchical pore structure using the eggshell inner membrane as a template of the present invention has the following advantages:

[0022] (1) The inner membrane of eggshell is naturally available and is a green and environmentally friendly material. The template can be easily removed without destroying the morphology of the resulting mesoporous film. At the same time, this template method has the characteristics of low cost and can provide guidance for the synthesis of other mesoporous film materials.

[0023] (2) The film has a macroporous and mesoporous structure, with a large specific surface area and pore volume. It is not only suitable for the preparation of separation and purification films, but also can be easily further compounded with functional materials to prepare composite functional materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 a is a photo of the blank egg membrane in Comparative Example 1 and b is a photo of the egg membrane after composite silica obtained in Example 1;

[0026] Figure 2 Figures ad are scanning electron microscope (SEM) images of the blank egg inner membrane of comparative example 1, the composite membrane of example 1, the silicon dioxide thin film formed after high-temperature calcination of the composite membrane of example 1, and transmission electron microscope (TEM) images of the silicon dioxide thin film formed after high-temperature calcination of the composite membrane of example 1, respectively;

[0027] Figure 3 The nitrogen adsorption and desorption diagrams of the thin film with surfactant added in Example 1 and the thin film without surfactant added in Comparative Example 2 after high temperature calcination;

[0028] Figure 4 The pore size distribution diagram of the film with surfactant added in Example 1 and the film without surfactant added in Comparative Example 2 after high-temperature calcination. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] The present invention provides a method for preparing a silicon dioxide film with a hierarchical pore structure by using the inner membrane of an eggshell as a template. The method uses the inner membrane of an eggshell as a hard template, burns and removes fibers constituting the inner membrane of the eggshell to form macropores; uses a surfactant as a soft template, burns and removes fibers constituting the inner membrane of the eggshell to form mesopores;

[0031] The steps include:

[0032] 1) Wash the inner membrane of the eggshell and dry it;

[0033] 2) dissolving the surfactant in anhydrous ethanol, adding the precursor, and then adding the catalyst at room temperature, stirring evenly to form a sol;

[0034] 3) immersing the clean and dry eggshell inner membrane into the sol, and ensuring that the eggshell inner membrane is completely penetrated, in the sol-gel process, after taking the eggshell inner membrane out of the sol, carefully scraping off the residual sol on the surface of the eggshell inner membrane, to obtain an eggshell inner membrane / silicon dioxide composite film composited on the eggshell inner membrane; wherein the eggshell inner membrane / silicon dioxide composite film is a precursor for preparing a hierarchical pore structure silicon dioxide film;

[0035] 4) calcining the composite membrane at high temperature to remove the eggshell inner membrane and surfactant to obtain a silica film with a hierarchical pore structure.

[0036] The eggshell inner membrane is a poultry eggshell inner membrane, and the poultry eggshell inner membrane can be any one of a chicken egg inner membrane, a duck egg inner membrane, a goose egg inner membrane, a bird egg inner membrane, a quail egg inner membrane or a goose egg inner membrane.

[0037] The surfactant may be one or a mixture of two or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant or a compound surfactant.

[0038] Preferably, the surfactant is a nonionic surfactant, and the nonionic surfactant is preferably F127 and P123.

[0039] Wherein, the precursor is an organic silicon source or an inorganic silicon source, the organic silicon source is methyl orthosilicate, ethyl orthosilicate or butyl orthosilicate, and the inorganic silicon source is silicon tetrachloride or water glass.

[0040] Preferably, the precursor is tetraethyl orthosilicate.

[0041] The catalyst is an acidic substance or an alkaline substance. The acidic substance may be hydrochloric acid, sulfuric acid, nitric acid and other typical acids. The alkaline substance may be sodium hydroxide, potassium hydroxide, ammonia water and other typical alkaline substances.

[0042] Preferably, the catalyst is hydrochloric acid, and the concentration of the hydrochloric acid is 0.01 mol / L to 1 mol / L.

[0043] The ratio of the surfactant to the precursor is 0.1-2.

[0044] Preferably, the ratio of surfactant to tetraethyl orthosilicate is 1:6.

[0045] In step 3), the egg inner membrane is immersed in the sol for 2 hours to 48 hours, during which the sol is formed, and the egg inner membrane is taken out when it is in the gelling process but not completely gelled.

[0046] The temperature of the high temperature calcination in step 4) is 450° C. to 800° C., and the time is 3 h to 6 h.

[0047] In addition, the method for preparing the hierarchical pore structure silicon dioxide film includes preparing silicon dioxide films but is not limited to silicon dioxide films, and is applicable to other inorganic oxides such as titanium dioxide, aluminum oxide, zinc oxide, etc. that can be obtained by a sol-gel method.

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0049] Taking the preparation of silica film by sol-gel method as an example, the hierarchical macroporous-mesoporous silica film is prepared by using egg inner membrane as hard template, surfactant as soft template and high temperature calcination to remove the template. The method comprises the following steps:

[0050] 1) Wash the egg membrane and let it dry naturally;

[0051] 2) dissolving the surfactant in anhydrous ethanol, then adding tetraethyl orthosilicate, the ratio of surfactant to tetraethyl orthosilicate is 1:6, and adding hydrochloric acid with a concentration of 0.02 mol / L, stirring at room temperature for 2 hours to form a sol;

[0052] 3) Immersing the clean and dry egg inner membrane in the sol for 2 hours and ensuring complete penetration, taking the egg inner membrane out of the sol during the gelation process, drying in air for 48 hours, and carefully scraping off the residual sol on the surface of the egg inner membrane to obtain an egg inner membrane / silicon dioxide composite film composited on the egg inner membrane;

[0053] 4) The composite membrane was calcined at 450°C for 3 h to remove the egg membrane and surfactant to obtain a graded macroporous-mesoporous silica film.

[0054] The specific surface area, pore volume and pore size of the graded macroporous-mesoporous silica films prepared by adding different surfactants are shown in Table 1 below.

[0055] Table 1 Specific surface area, pore volume and pore diameter results

[0056]

[0057] It can be seen from the table that the specific surface area, pore volume and measurable mesopore diameter of the films obtained under different surfactants are very different. Therefore, the pore diameter can be adjusted to a certain extent by changing the type of surfactant.

[0058] Table 2 Comparison of Comparative Examples 1-2

[0059] Comparative Example 1 Blank egg membrane Comparative Example 2 Based on Example 1, no surfactant was added

[0060] Depend on Figure 1It can be seen that the egg membrane ( Figure 1 a) After compounding with silicon dioxide, it changes from opaque to transparent ( Figure 1 b), which is also an apparent feature to test whether silica has effectively penetrated.

[0061] Figure 2 In the figure, a is the blank egg inner membrane of comparative example 1, b is the composite membrane obtained in example 1, c is the scanning electron microscope (SEM) image of the silicon dioxide film formed after high-temperature calcination obtained in example 1, and d is the transmission electron microscope (TEM) image of the silicon dioxide film formed after high-temperature calcination obtained in example 1. It can be seen from figure a that the egg inner membrane is composed of network-like fibers with obvious gaps between the fibers. It can be seen from figure b that after the introduction of silicon dioxide through the sol-gel process, the network-like fibers become thicker and the gaps between the fibers are filled. It can be seen from figure c that after the egg inner membrane is successfully removed through high-temperature calcination, obvious dents are formed after the fibers are removed, which are the macropores formed by the removal of the hard template. It can be seen from figure d (transmission electron microscope) that two types of obvious channels are formed: one type is the macropores formed after the egg inner membrane is removed, and the other type is the relatively ordered mesopores left after the surfactant is removed; this type of silicon dioxide film with a multi-level channel structure has a large specific surface area and pore volume, which is not only suitable for preparing separation and purification films, but also can be conveniently further compounded with functional materials to prepare composite functional materials.

[0062] from Figure 3 and Figure 4 It can be seen that the addition of surfactant makes the specific surface area and pore volume of the prepared mesoporous silica film much larger than those of the mesoporous silica film prepared without surfactant.

[0063] The present invention adopts the sol-gel method and uses the egg inner membrane as a template to successfully prepare a hierarchical macroporous-mesoporous silica film. This type of silica film with a multi-level pore structure has a large specific surface area and pore volume, is not only suitable for preparing separation and purification films, but also can be conveniently further compounded with functional materials to prepare composite functional materials.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template, characterized in that: The method uses the eggshell inner membrane as a hard template, burns and removes the fibers constituting the eggshell inner membrane to form macropores; uses a surfactant as a soft template, burns and removes it to form mesopores; The steps include: 1) Wash the inner membrane of the eggshell and dry it; 2) dissolving the surfactant in anhydrous ethanol, adding the precursor, and then adding the catalyst at room temperature, stirring evenly to form a sol; the mass ratio of the surfactant to the precursor is 0.1 to 2; 3) Immersing the clean and dry eggshell inner membrane into the sol, and ensuring that the eggshell inner membrane is completely penetrated, in the sol-gel process, after taking out the eggshell inner membrane from the sol, carefully scraping off the residual sol on the surface of the eggshell inner membrane, to obtain an eggshell membrane / silicon dioxide composite film composited on the eggshell inner membrane; the egg inner membrane is immersed in the sol for 2h to 48h, and the sol is formed during this time, and the egg inner membrane is taken out when the gelation process is in progress but not completely gelled; 4) calcining the composite membrane at high temperature to remove the eggshell inner membrane and surfactant to obtain a film with a graded pore structure; the high temperature calcination temperature is 450° C. to 800° C., and the time is 3 h to 6 h.

2. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 1, characterized in that: The eggshell inner membrane is the eggshell inner membrane of poultry.

3. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 2, characterized in that: The poultry eggshell membrane is any one of the chicken egg membrane, duck egg membrane, goose egg membrane, quail egg membrane or goose egg membrane.

4. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 1, characterized in that: The surfactant is one or a mixture of two or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant or a compound surfactant.

5. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 1, characterized in that: The precursor is an organic silicon source or an inorganic silicon source, the organic silicon source is methyl orthosilicate, ethyl orthosilicate or butyl orthosilicate, and the inorganic silicon source is silicon tetrachloride or water glass.

6. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 1, characterized in that: The catalyst is an acidic substance or an alkaline substance. The acidic substance is any one of hydrochloric acid, sulfuric acid and nitric acid. The alkaline substance is any one of sodium hydroxide, potassium hydroxide and ammonia water.

7. The method for preparing a silica film with a hierarchical pore structure using eggshell inner membrane as a template according to claim 6, characterized in that: The catalyst is hydrochloric acid, and the concentration of the hydrochloric acid is 0.01 mol / L to 1 mol / L.

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