Organic-inorganic hybrid mesoporous silica nanoparticles, self-template synthesis method and application thereof

Abstract

The present invention provides organic-inorganic hybrid mesoporous silica nanoparticles, their self-template synthesis method and application. Long-chain alkylamino groups are connected to the surface of silica nanoparticles, wherein the long-chain alkylamino groups are dialkyl-substituted alkylamino groups, and the length of the alkyl substituent on the nitrogen atom in the amino group is 1-3, thereby forming a mesoporous structure. The present invention uses the long-chain alkylamino groups as self-templates and synthesizes the mesoporous silica nanoparticle material by a reverse microemulsion method. The organic-inorganic hybrid mesoporous silica nanoparticle material can be used as an adsorbent to remove various organic pollutants in water and has a large adsorption capacity and high adsorption efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of silicon dioxide nanoparticle technology, and in particular relates to organic-inorganic hybrid mesoporous silicon dioxide nanoparticles, a self-template synthesis method and application thereof. Background Art

[0002] Mesoporous silica materials with high specific surface area and large pore size have a wide range of applications in catalysis, environmental protection, electronics and other industries. Generally speaking, mesoporous silica needs to be synthesized through template methods, including hard template method and soft template method.

[0003] The hard template method typically uses carbonaceous materials or polymers as templates, replicating similar mesoporous structures using existing mesoporous materials with specific structures (such as carbon and polymers). The synthesis process requires the use of corrosive acids such as HF and concentrated hydrochloric acid as etchants, or high-temperature calcination to create pores, which often produces pollutants such as waste acid and CO2. The soft template method generally forms mesoporous silica with an ordered structure through the self-assembly process of organic templates by adjusting the amount and ratio of inorganic precursors and organic template molecules. However, these mesoporous silica materials contain templates, and the template removal step significantly affects the properties of the silica-based mesoporous materials, including porosity, surface chemistry, and order. Furthermore, the template removal process is costly, and processes such as calcination to remove the template generate pollutants such as NO compounds and CO2, posing a significant threat to the environment.

[0004] Therefore, it is a challenging task to simultaneously synthesize mesoporous silica with high organic group content and large specific surface area without a template, which is a research difficulty in the field of green synthesis.

[0005] In addition, in recent years, the harm caused to the environment by new organic pollutants represented by polyfluoroalkyl compounds has become increasingly serious and has attracted more attention. It is urgent to develop new technologies for green and efficient purification technologies to eliminate organic pollutants such as polyfluoroalkyl compounds in water. Summary of the Invention

[0006] The present invention provides an organic-inorganic hybrid mesoporous silica nanoparticle, which has a mesoporous channel structure formed by substituted alkylamino groups. It has a large specific surface area and rich mesoporous structure and surface functional groups. It can be used as a high-efficiency adsorbent to efficiently remove various organic pollutants such as polyfluoroalkyl compounds in water bodies.

[0007] The technical solution provided by the present invention is: an organic-inorganic hybrid mesoporous silica nanoparticle material, in which long-chain alkylamino groups are connected to the surface of the silica nanoparticles, and the long-chain alkylamino groups are dialkyl-substituted alkylamino groups (that is, the number of alkyl substituents on the nitrogen atom in the amino group is 2), and the length of the alkyl substituents is 1-3; the long-chain alkylamino groups form a mesoporous structure.

[0008] The organic-inorganic hybrid mesoporous silica nanoparticle material can be labeled as DXAP-SiO2, where DXAP represents the English abbreviation of different types of long-chain alkylamino organic siloxanes. For example, when the alkylamino organic siloxane is N,N-dimethyl-3-(trimethoxysilyl)propylamine (i.e., the long-chain alkylamino group is N,N-dimethyl-3-propylamine), its English abbreviation is DMAP, and the organic-inorganic hybrid mesoporous silica nanoparticle material can be labeled as DMAP-SiO2.

[0009] The long-chain alkylamino group is not limited and can be one or more of N,N-dimethyl-3-propylamine, N,N-diethyl-3-propylamine, and N,N-dipropyl-3-propylamine.

[0010] Preferably, the particle size of the organic-inorganic hybrid mesoporous silica nanoparticles is 80 nanometers to 150 nanometers.

[0011] Preferably, the pore diameter of the mesopore is 4 nm to 10 nm.

[0012] Preferably, the specific surface area of ​​the organic-inorganic hybrid mesoporous silica nanoparticles is greater than 300 m 2 / g.

[0013] The present invention also provides a self-template synthesis method of the organic-inorganic hybrid mesoporous silica nanoparticle material, using the long-chain alkylamino group as a self-template agent, comprising the following steps:

[0014] (1) Prepare a certain volume of reverse microemulsion;

[0015] Mixing tetramethoxysilane with a long-chain alkylamino organic siloxane, or mixing tetraethoxysilane with a long-chain alkylamino organic siloxane to obtain a mixed solution;

[0016] The long-chain alkylamino organic siloxane refers to an organic siloxane with the long-chain alkylamino group;

[0017] (2) adding the mixed solution to the reverse microemulsion under stirring, followed by hydrolysis and copolymerization to obtain a SiO2 material with the long-chain alkylamino groups on the surface, wherein the long-chain alkylamino groups form mesoporous channels;

[0018] (3) The product obtained in step (2) is subjected to demulsification and centrifugation operations, and the surface residue is washed off and then dried to obtain the organic-inorganic hybrid mesoporous silica nanoparticle material.

[0019] The long-chain alkylamino group is not limited and can be one or more of N,N-dimethyl-3-propylamine, N,N-diethyl-3-propylamine, and N,N-dipropyl-3-propylamine.

[0020] The organosiloxane is not limited and includes one or more of trimethoxysilane, triethoxysilane, tripropoxysilane, tributoxysilane, etc.

[0021] When the sum of the molar amounts of the long-chain alkylaminoorganosiloxane and tetraethyl(meth)oxysilane is 100, the molar amount of the long-chain alkylaminoorganosiloxane is n, and the molar amount of tetraethyl(meth)oxysilane is 100-n. In this case, the DXAP-SiO2 is marked as nDXAP-SiO2. Preferably, 10≤n≤70.

[0022] Preferably, the preparation method of the reverse microemulsion is as follows:

[0023] A surfactant, an organic phase, and a co-surfactant are mixed to form solution A; ammonia water and deionized water are mixed to obtain solution B; solution A and solution B are mixed to obtain a reverse microemulsion; wherein the surfactant is not limited and includes nonylphenol polyoxyethylene ether, etc.; the organic phase is not limited and includes cyclohexane, etc.; the co-surfactant is not limited and includes one or more of n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, etc.

[0024] As an implementation method, the solution B is composed of ammonia water and deionized water with a mass concentration of 25%-28%; in terms of mass parts, in the solution B, the mass of ammonia water with a mass concentration of 25%-28% accounts for 1 part to 3 parts, the mass of deionized water accounts for 5 parts to 6 parts, and in the solution A, the mass of the surfactant accounts for 10 parts to 20 parts, the mass of the organic phase accounts for 30 parts to 40 parts, and the mass of the co-surfactant accounts for 5 parts to 10 parts.

[0025] Preferably, in step (3), acetone is added to perform demulsification treatment, followed by centrifugation to collect the solid, and the solid is washed with ethanol at 70°C-80°C to remove residual organic molecules, and finally at 80°C. o C-150 o C drying to obtain the granular nanomaterial.

[0026] Compared with the existing technology, it has the following beneficial effects:

[0027] (1) The present invention introduces substituted alkylamino groups into the surface of SiO2 material, and the substituted alkylamino groups serve as self-templates to form a mesoporous channel structure, thereby forming a novel organic-inorganic hybrid mesoporous silica nanoparticle material;

[0028] (2) The nanoparticle material of the present invention has a large specific surface area, rich mesoporous structure and surface functional groups, and can serve as an adsorption site to efficiently remove organic pollutants in the aqueous phase. Therefore, it can be used for the adsorption of organic pollutants in the aqueous phase to achieve a fast adsorption speed, efficient adsorption effect and large adsorption capacity. For example, the adsorbable organic pollutants include but are not limited to one or more of sodium perfluorononenyloxybenzenesulfonate, amino black 10B, direct blue 6, acid blue 25, reactive blue 5, etc. For example, under the conditions of an adsorption reaction temperature of 10°C to 40°C and an adsorption time of 1 hour to 10 hours, the adsorption rate can be greater than or equal to 90%, and can even reach 99%; preferably, the adsorption amount of amino black 10B can be greater than 3000 mg / g, for example, it can reach 3960 mg / g;

[0029] In the present invention, the adsorption rate (%) = (initial concentration (ppm) - equilibrium concentration (ppm)) ÷ initial concentration (ppm) × 100%;

[0030] (3) The present invention adopts the reverse microemulsion method. The alkylamino organic siloxane with substituents not only serves as an organic silicon resource, but also serves as a self-template species in the synthesis process. Without the additional use of an organic template agent, a mesoporous silica composite material with specific alkylamino groups connected to the surface is synthesized. This is a green self-template synthesis method. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1. The transmission electron microscope image (A) and the scanning electron microscope image (B) of 30DMAP-SiO2 prepared in Example 1 of the present invention.

[0032] Figure 2 These are the transmission electron microscope images (A) and scanning electron microscope images (B) of 30AP-SiO2 prepared in Comparative Examples 1-2 of the present invention, as well as the transmission electron microscope images (C) and scanning electron microscope images (D) of 30MAAP-SiO2.

[0033] Figure 3 These are the N2 adsorption-desorption curves of 30AP-SiO2, 30MAAP-SiO2, and 30DMAP-SiO2 in Example 1 and Comparative Examples 1-2.

[0034] Figure 4 It is the pore size distribution diagram of 30AP-SiO2, 30MAAP-SiO2, and 30DMAP-SiO2 in Example 1 and Comparative Examples 1-2.

[0035] Figure 5 Schematic diagram of the molecular structure of alkylamino organosiloxane AP-TMOS, MAAP-TMOS, and DMAP-TMOS in Example 1 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the embodiments. It should be pointed out that the embodiments described below are intended to facilitate understanding of the present invention, and non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0037] The words “include”, “including” and the like used in the present invention should be interpreted as including rather than exclusive or exhaustive, that is, as “including but not limited to”. Example 1:

[0038] The organic-inorganic hybrid mesoporous silica nanoparticle material A is labeled as 30DMAP-SiO2, that is, the surface of the silica nanoparticles is connected with long-chain alkylamino groups, the long-chain alkylamino groups are N,N-dimethyl-3-propylamine-, and the long-chain alkylamino groups form a mesoporous structure.

[0039] The preparation of material A (30DMAP-SiO2) includes the following steps:

[0040] (1) 15 g of surfactant nonylphenol polyoxyethylene ether (NP-7), 35.1 g of organic phase cyclohexane, and 8.1 g of co-surfactant n-butanol were mixed to obtain solution A;

[0041] Add 2 g of ammonia to 5.35 g of deionized water to obtain solution B;

[0042] 3.64 g of tetraethoxysilane and 1.5527 g of N,N-dimethyl-3-(trimethoxysilyl)propylamine (DMAP-TMOS) were mixed to obtain a mixed solution;

[0043] (2) Pour solution B into solution A to obtain a reverse microemulsion;

[0044] (3) The mixed solution was added to the reverse microemulsion under vigorous stirring and stirred for 9 h; then, 10 ml of acetone was added, stirred for 30 min, and centrifuged to obtain a solid;

[0045] (4) Add ethanol to the solid obtained in step (3), reflux in a hot water bath at 70°C, heat and stir for 15 minutes, and centrifuge; repeat this step three times until the surfactant is completely removed;

[0046] (5) The product obtained in step (4) was dried at 80° C. to obtain a silica composite material A. Figure 1 Shown is a transmission electron microscope image of the silica composite material (see Figure 1 A in ) and scanning electron microscopy (see Figure 1 B in Figure ), and the nitrogen adsorption and desorption curves (see Figure 3 ), these figures show:

[0047] (1) The composite material is in the form of nanoparticles with a particle size of about 100 nanometers and a specific surface area of ​​about 445 m 2 / g;

[0048] (2) The nanoparticles have abundant worm-like mesopores with a pore size of approximately 5.1 nm.

[0049] Comparative Example 1:

[0050] This embodiment is a comparative example of embodiment 1.

[0051] In this example, material 30AP-SiO2 was prepared by the same method as in Example 1, except that 1.4480 g of 3-aminopropyltrimethoxysilane (AP-TMOS) was used to replace 1.5527 g of N,N-dimethyl-3-(trimethoxysilyl)propylamine (DMAP-TMOS) in Example 1 when preparing the mixed solution in step (1).

[0052] Comparative Example 2:

[0053] This embodiment is another comparative embodiment of embodiment 1.

[0054] In this example, material 30MAAP-SiO2 was prepared by the same method as in Example 1, except that 1.4476 g of (3-methylaminopropyl)trimethoxysilane (MAAP-TMOS) was used to replace 1.5527 g of N,N-dimethyl-3-(trimethoxysilyl)propylamine (DMAP-TMOS) in Example 1 when preparing the mixed solution in step (1).

[0055] The transmission electron microscope and scanning electron microscope of the silicon dioxide composite material 30AP-SiO2 obtained in Comparative Example 1 are as follows: Figure 2 As shown in Figures A and B, the transmission electron microscope and scanning electron microscope of the silicon dioxide composite material 30MAAP-SiO2 obtained in Example 2 are as follows: Figure 2 As shown in Figures C and D.

[0056] The adsorption-desorption curves and pore size distribution diagrams of 30DMAP-SiO2, 30AP-SiO2 and 30MAAP-SiO2 in Example 1 and Comparative Examples 1-2 are shown in FIG. Figure 3 、4 shown.

[0057] From these figures we can see that:

[0058] (1) Materials 30AP-SiO2 and 30MAAP-SiO2 have no mesopores, while material 30DMAP-SiO2 forms a mesoporous structure. Therefore, compared with material 30DMAP-SiO2, the specific surface areas of materials 30AP-SiO2 and 30MAAP-SiO2 are smaller, among which the specific surface area of ​​30AP-SiO2 is 34m 2 / g, the specific surface area of ​​30MAAP-SiO2 is 24m 2 / g;

[0059] (2) Both materials 30AP-SiO2 and 30MAAP-SiO2 are microspherical silica, while material 30DMAP-SiO2 is composed of many small particles of about 5 nanometers stacked to form large particles. The particle size of material 30DMAP-SiO2 is about 100 nanometers, the particle size of material 30AP-SiO2 is about 100 nanometers, and the particle size of material 30MAAP-SiO2 is about 125 nanometers.

[0060] The molecular structures of the alkylamine organosiloxanes in Example 1 and Comparative Examples 1-2 are as follows: Figure 5 As shown, compared with DMAP-TMOS, there is no alkyl substituent on the nitrogen atom in the amino group of AP-TMOS, and there is only one alkyl substituent on the nitrogen atom in the amino group of MAAP-TMOS, and the carbon chain lengths of both are insufficient. According to the above figures, it is confirmed that AP-TMOS and MAAP-TMOS cannot exhibit the effect of self-templating agents, and no mesoporous structure is formed.

[0061] Example 2-4:

[0062] Organic-inorganic hybrid mesoporous silica nanoparticle materials B, C, and D are labeled as 30DMAP-SiO2, 30DEAP-SiO2, and 40DPAP-SiO2, respectively. That is, long-chain alkylamine groups are connected to the surface of the silica nanoparticles, and the long-chain alkylamine groups are N,N-dimethyl-3-propylamine-, N,N-diethyl-3-propylamine-, and N,N-diethyl-3-propylamine-, respectively, and these long-chain alkylamine groups form a mesoporous structure.

[0063] The preparation methods of materials B, C, and D are basically the same as the preparation method of material A in Example 1, except that the long-chain alkylamino organic siloxane and tetraethyl(meth)oxysilane are used, and the molar ratios of alkylamino silane to tetraethyl(meth)oxysilane are shown in Table 1 below.

[0064] Table 1: Material names and types and molar ratios of organosilanes used in the preparation of Examples 1-4

[0065]

[0066] Example 5:

[0067] The material A 30DMAP-SiO2 in Example 1 was used as an adsorbent to perform adsorption decontamination on an aqueous solution containing an organic pollutant, amino black 10B. The adsorption method and adsorption efficiency evaluation method are as follows:

[0068] 0.02g of 30DMAP-SiO2, material A from Example 1, was added as an adsorbent to a 150mL conical flask, followed by 100mL of an 800ppm aqueous solution of amido black 10B. The agitator was activated and the adsorption reaction was allowed to proceed at a constant temperature of 25°C. After 10 hours, the reaction was stopped and the absorbance values ​​obtained at each sampling point were analyzed using a UV-visible spectrophotometer. The amount of amido black 10B in the residual solution was calculated by comparing it with a standard curve. The maximum adsorption capacity of this material was 3960mg / g, and the adsorption rate of the pollutant was 99%.

[0069] Similarly, material BD in Example 2-4 was used as an adsorbent to adsorb organic pollutants in the aqueous solution. The adsorption method and the evaluation method of the adsorption efficiency were the same as those described above. The specific adsorbent type, pollutant type, pollutant concentration, adsorption conditions, and adsorption results are shown in Table 2 below.

[0070] Table 2: Adsorption results of different pollutants by different adsorbents

[0071]

[0072] Similarly, the materials 30AP-SiO2 and 30MAAP-SiO2 in Comparative Examples 1-2 were used as adsorbents to adsorb organic pollutants in aqueous solutions. The adsorption method and the evaluation method of the adsorption efficiency were the same as those described above. The specific adsorbent type, pollutant type, pollutant concentration, adsorption conditions, and adsorption results are shown in Table 3 below.

[0073] Table 3: Comparison of adsorption of organic pollutants by 30AP-SiO2 and 30MAAP-SiO2

[0074]

[0075] The above embodiments provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An organic-inorganic hybrid mesoporous silica nanoparticle, characterized by: Long-chain alkylamino groups are connected to the surface of the silica nanoparticles. The long-chain alkylamino groups are dialkyl-substituted alkylamino groups, and the length of the alkyl substituent is 1-3. The long-chain alkylamino groups form mesoporous channels.

2. The organic-inorganic hybrid mesoporous silica nanoparticles according to claim 1, wherein: The long-chain alkylamino group is one or more of N,N-dimethyl-3-propylamine, N,N-diethyl-3-propylamine, and N,N-dipropyl-3-propylamine.

3. The organic-inorganic hybrid mesoporous silica nanoparticles according to claim 1, wherein: The particle size of the organic-inorganic hybrid mesoporous silica nanoparticles is 80 nanometers to 150 nanometers.

4. The organic-inorganic hybrid mesoporous silica nanoparticles according to claim 1, wherein: The pore diameter of the mesopore is 4 nanometers to 10 nanometers.

5. The organic-inorganic hybrid mesoporous silica nanoparticles according to claim 1, wherein: The specific surface area of ​​the organic-inorganic hybrid mesoporous silica nanoparticles is greater than 300 m 2 / g.

6. The method for self-templated synthesis of organic-inorganic hybrid mesoporous silica nanoparticles according to any one of claims 1 to 5, wherein: The steps include: (1) Prepare a certain volume of reverse microemulsion; Mixing tetramethoxysilane with a long-chain alkylamino organosiloxane, or mixing tetraethoxysilane with a long-chain alkylamino organosiloxane to obtain a mixed solution, wherein the long-chain alkylamino organosiloxane refers to an organosiloxane with the long-chain alkylamino group; (2) adding the mixed solution to the reverse microemulsion under stirring conditions to cause hydrolysis and copolymerization to obtain a SiO2 material having the long-chain alkylamino groups on the surface, wherein the long-chain alkylamino groups form mesoporous channels; (3) The product obtained in step (2) is subjected to demulsification and centrifugation operations, and the surface residue is washed off and then dried to obtain the organic-inorganic hybrid mesoporous silica nanoparticles.

7. The self-template synthesis method according to claim 6, wherein: The organosiloxane includes one or more of trimethoxysilane, triethoxysilane, tripropoxysilane, and tributoxysilane.

8. The self-template synthesis method according to claim 6, wherein: Satisfy at least one of the following conditions (1) to (3): (1) When the sum of the molar amounts of the long-chain alkylamino organic siloxane and tetramethoxysilane is 100, the molar amount of the long-chain alkylamino organic siloxane is n, and the molar amount of tetramethoxysilane or tetraethoxysilane is 100-n, 10≤n≤70; (2) The preparation method of the reverse microemulsion is as follows: Mixing a surfactant, an organic phase, and a cosurfactant to form a solution A; mixing ammonia water and deionized water to obtain a solution B; mixing solution A and solution B to obtain the reverse microemulsion; (3) In the step (3), acetone is added for demulsification treatment, and then the solid is collected by centrifugation. The solid is reflux washed with ethanol at 70°C-80°C to remove residual organic components, and finally dried at 80°C-150°C to obtain the organic-inorganic hybrid mesoporous silica nanoparticles.

9. Use of the organic-inorganic hybrid mesoporous silica nanoparticles according to any one of claims 1 to 5 as an adsorbent for adsorbing organic pollutants.

10. Use of the organic-inorganic hybrid mesoporous silica nanoparticles according to claim 9 as an adsorbent for adsorbing organic pollutants, characterized in that: The organic pollutants include one or more of sodium perfluorononenyloxybenzenesulfonate, amido black 10B, direct blue 6, acid blue 25, and reactive blue 5.

11. Use of the organic-inorganic hybrid mesoporous silica nanoparticles according to claim 9 as an adsorbent for adsorbing organic pollutants, characterized in that: Under the conditions of adsorption reaction temperature of 10℃-40℃ and adsorption time of 1 hour-10 hours, at least one of the following adsorption effects (1) to (2) is met: (1) Adsorption rate is greater than or equal to 90%; (2) The maximum adsorption capacity of amino black 10B is 3960 mg / g.

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