Preparation method for polyethyleneimine-hybridized silicon dioxide aerogel

Abstract

A preparation method for a polyethyleneimine-hybridized silicon dioxide aerogel, relating in particular to using a polyethyleneimine-functionalized silane coupling agent to generate the polyethyleneimine-hybridized silicon dioxide aerogel. The novel method is characterized by reacting polyethyleneimine with 3-(2,3-epoxypropoxy)propyltrimethoxysilane to prepare the polyethyleneimine-functionalized silane coupling agent, the polyethyleneimine-functionalized silane coupling agent being used as a preparation reaction precursor to obtain the polyethyleneimine-hybridized silicon dioxide aerogel. The polyethyleneimine-hybridized silicon dioxide aerogel prepared using the method has good mechanical properties, a large surface area, and an excellent pore structure, and exhibits good adsorption performance.

Description

A method for preparing polyethyleneimine hybrid silica aerogel Technical Field

[0001] The invention relates to a technology for preparing polyethyleneimine hybrid silica aerogel. Background Art

[0002] Silica aerogel is a three-dimensional porous material with large surface area and strong adsorption performance. It has been used in thermal insulation materials, catalyst carriers, heavy metal adsorbents in water, etc. Silica aerogel also has some disadvantages.

[0003] Pure silica aerogels are prone to fragmentation due to their limited adsorption selectivity due to their limited number of adsorption functional groups. To overcome these issues, chemical modification with organic groups is often used to develop high-performance functionalized silica aerogel materials. Polyethyleneimine is a type of organic macromolecule with multiple amine groups that interacts strongly with polycyclic aromatic hydrocarbons and anions. Using it to functionalize silica aerogels can significantly enhance not only their mechanical properties but also their adsorption performance. By reacting the amine groups within the polyethyleneimine molecule with a silane coupling agent, multiple silane coupling agent groups are grafted onto the molecule, facilitating chemical bonding during the silica aerogel preparation reaction. Polyethyleneimine-functionalized silane coupling agents are introduced into the silica aerogel preparation reaction precursor and reacted with ethyl orthosilicate in a specific ratio to prepare polyethyleneimine hybrid silica aerogels, a promising aerogel material. Summary of the Invention

[0004] The present invention aims to provide a technology for preparing polyethyleneimine hybrid silica aerogel. The present invention is based on the preparation of silica aerogel using polyethyleneimine functionalized silane coupling agent. The preparation steps are as follows:

[0005] (1) Preparation of polyethyleneimine functionalized silane coupling agent

[0006] In a reactor, polyethyleneimine and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are dissolved in ethanol at a mass ratio of 1:5-8, with the total mass fraction of the two in the reaction solution being 40-60%. Triethylamine is used as a catalyst, and the mixture is stirred and refluxed for 16-24 hours. The ethanol and triethylamine are removed to obtain a polyethyleneimine-functionalized silane coupling agent.

[0007] (2) Preparation of polyethyleneimine hybrid silica aerogel

[0008] In a reactor, using ethanol as a solvent, a polyethyleneimine functionalized silane coupling agent and ethyl orthosilicate are uniformly mixed in a mass ratio of 1:2-3, the mass percentage of the reactants is controlled to be 40-60%, the pH value of the solution is adjusted to 1-2 with hydrochloric acid, and the mixture is stirred for 6-8 hours to form a sol. Ammonia water is then added to adjust the pH value to 9, the temperature is raised to between 60-80°C, and the mixture is allowed to stand for 3-5 hours to form a gel. The solvent is replaced with ethanol and then freeze-dried to obtain a polyethyleneimine hybrid silica aerogel.

[0009] In the preparation step of the polyethyleneimine hybrid silica aerogel of the present invention, the concentration of hydrochloric acid is 1-2 mol / L.

[0010] In the preparation step of the polyethyleneimine hybrid silica aerogel of the present invention, the concentration of the ammonia water is 1-2 mol / L.

[0011] The invention relates to a polyethyleneimine hybrid silica aerogel prepared in the polyethyleneimine hybrid silica aerogel preparation step.

[0012] The polyethyleneimine hybrid silica aerogel prepared by the present invention has the following advantages:

[0013] Functionalization of polyethyleneimine not only enhances the mechanical strength of silica aerogel but also improves the extraction performance.

[0014] The introduction of polyethyleneimine molecular skeleton in silica aerogel makes the extraction coating positively charged in water and has good adsorption properties for anions and large π-conjugated molecules. DETAILED DESCRIPTION

[0015] In order to better understand the present invention, the following examples are provided:

[0016] Example 1:

[0017] (1) Preparation of polyethyleneimine functionalized silane coupling agent

[0018] In a reactor, polyethyleneimine and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are dissolved in ethanol at a mass ratio of 1:8, with a total mass fraction of the two in the reaction solution being 40%. Triethylamine is used as a catalyst, and the mixture is stirred and refluxed for 24 hours. The ethanol and triethylamine are then removed to obtain a polyethyleneimine-functionalized silane coupling agent.

[0019] (2) Preparation of polyethyleneimine hybrid silica aerogel

[0020] In a reactor, using ethanol as a solvent, polyethyleneimine functionalized silane coupling agent and ethyl orthosilicate were evenly mixed in a mass ratio of 1:3, and the mass percentage of the reactants was controlled to be 40%. The pH of the solution was adjusted to 2 with 1 mol / L hydrochloric acid, and stirred for 8 hours to form a sol. Then, 1 mol / L ammonia water was added to adjust the pH to 9, and the temperature was raised to 60°C. The mixture was allowed to stand for 5 hours to form a gel. The solvent was replaced with ethanol and then freeze-dried to obtain polyethyleneimine hybrid silica aerogel.

[0021] Example 2:

[0022] (1) Preparation of polyethyleneimine functionalized silane coupling agent

[0023] In a reactor, polyethyleneimine and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are dissolved in ethanol at a mass ratio of 1:5, with the total mass fraction of the two in the reaction solution being 60%. Triethylamine is used as a catalyst, and the mixture is stirred and refluxed for 16 hours. The ethanol and triethylamine are then removed to obtain a polyethyleneimine-functionalized silane coupling agent.

[0024] (2) Polyethyleneimine hybrid silica aerogel

[0025] In a reactor, using ethanol as a solvent, polyethyleneimine functionalized silane coupling agent and ethyl orthosilicate were evenly mixed in a mass ratio of 1:2, and the mass percentage of the reactants was controlled to be 60%. The pH of the solution was adjusted to 1 with 2 mol / L hydrochloric acid, and stirred for 6 hours to form a sol. Then, 2 mol / L ammonia water was added to adjust the pH to 9. The temperature was raised to 80°C, and the mixture was allowed to stand for 3 hours to form a gel. The solvent was replaced with ethanol and then freeze-dried to obtain polyethyleneimine hybrid silica aerogel.

[0026] Example 3:

[0027] (1) Preparation of polyethyleneimine functionalized silane coupling agent

[0028] In a reactor, polyethyleneimine and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are dissolved in ethanol at a mass ratio of 1:6, with the total mass fraction of the two in the reaction solution being 50%. Triethylamine is used as a catalyst, and the mixture is stirred and refluxed for 20 hours. The ethanol and triethylamine are then removed to obtain a polyethyleneimine-functionalized silane coupling agent.

[0029] (2) Polyethyleneimine hybrid silica aerogel

[0030] In a reactor, using ethanol as a solvent, polyethyleneimine functionalized silane coupling agent and ethyl orthosilicate were evenly mixed in a mass ratio of 1:2.5, the mass percentage of the reactants was controlled to 50%, the pH of the solution was adjusted to 1.5 with 1.5 mol / L hydrochloric acid, and stirred for 7 hours to form a sol. Then, 1.5 mol / L ammonia water was added to adjust the pH to 9, the temperature was raised to 70°C, and the mixture was allowed to stand for 4 hours to form a gel. The solvent was replaced with ethanol and then freeze-dried to obtain polyethyleneimine hybrid silica aerogel.

Claims

1. A preparation method of a polyethyleneimine hybrid silica aerogel, characterized in that, The method has the following technological steps: (1) Preparation of polyethyleneimine-functionalized silane coupling agent In a reactor, polyethyleneimine and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are dissolved in ethanol at a mass ratio of 1:5 - 8, and their total mass fraction in the reaction solution is 40 - 60%. Triethylamine is used as a catalyst, and the mixture is stirred and refluxed for 16 - 24 hours. Then, ethanol and triethylamine are removed to obtain the polyethyleneimine-functionalized silane coupling agent; (2) Preparation of polyethyleneimine hybrid silica aerogel In a reactor, using ethanol as a solvent, the polyethyleneimine-functionalized silane coupling agent and tetraethyl orthosilicate are mixed evenly at a mass ratio of 1:2 - 3. The mass percentage content of the reactants is controlled to be 40 - 60%. The pH of the solution is adjusted to 1 - 2 with hydrochloric acid, and the mixture is stirred for 6 - 8 hours to form a sol. Then, ammonia water is added to adjust the pH to 9, the temperature is raised to 60 - 80 °C, and the mixture is left standing for 3 - 5 hours to form a gel. After solvent replacement with ethanol, freeze-drying is carried out to obtain the polyethyleneimine hybrid silica aerogel.

2. The preparation method of a polyethyleneimine hybrid silica aerogel according to claim 1, wherein, The concentration of the hydrochloric acid described in step (2) is 1 - 2 mol / L.

3. The preparation method of a polyethyleneimine hybrid silica aerogel according to claim 1, characterized in that, The concentration of the ammonia water described in step (2) is 1 - 2 mol / L.

4. Polyethyleneimine hybrid silica aerogel prepared by the preparation method of a polyethyleneimine hybrid silica aerogel described in claim 1.