A preparation method of a composite aerogel material for VOCs adsorption

Abstract

The application provides a preparation method of a composite aerogel material for VOCs adsorption, wherein 3-aminopropyl triethoxysilane is added into a nanocellulose aqueous solution, and a nanocellulose suspension N-CNF modified by amino is obtained through reaction; the N-CNF suspension is refrigerated overnight, and then dried in a drying box to obtain N-CNF aerogel; the N-CNF aerogel is reacted with a terephthaldehyde solution at 150 DEG C to obtain modified N-CNF aerogel; tetrakis(4-aminophenyl)methane, the terephthaldehyde solution and the N-CNF aerogel are put into a hydrothermal reaction kettle to react, washed with dioxane and ethanol, and dried under vacuum to obtain COF-300@N-CNF composite aerogel. The production cost of the application is low, the preparation process is simple, the adsorption amount of the composite COF-300 material for VOCs gas can be improved, and the VOCs gas treatment capacity can be enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite materials, and relates to the technical field of volatile organic compound (VOCs) adsorbing aerogel composite materials, in particular to a preparation method of a composite aerogel material for VOCs adsorption. BACKGROUND

[0002] Volatile organic compounds (VOCs) are one of the main sources of atmospheric pollutants, which have caused serious harm to human life and health, and even caused poisoning and carcinogenesis. VOCs are various, which can be divided into alkanes, alkenes, alkynes, aromatic hydrocarbons, oxygen-containing organic compounds and the like, and have various sources. Different types of VOCs are generated in the petroleum, coal chemical industry, pharmaceutical, paint and other industries. At present, the adsorption method is the most widely used VOCs treatment technology, which has the advantages of simple equipment, low cost and recyclability. At present, the materials used for adsorption mainly include carbon-based adsorbents, oxygen-containing adsorbents, polymer adsorbents and the like. These adsorbents are widely used due to simple preparation, but have problems of small adsorption capacity, easy plugging, low selectivity and difficult regeneration. Aerogel is a kind of porous material with nano structure, and its porosity is as high as 90% or more. Cellulose aerogel is the third generation of aerogel materials after inorganic aerogel and synthetic polymer aerogel. The cellulose aerogel has the advantages of low density, large specific surface area and high porosity, especially the special three-dimensional nano network and open pore structure, so that molecules can freely enter and exit and quickly diffuse / adsorb / desorb in the aerogel, which makes the aerogel a kind of excellent new adsorption and separation material. However, the single function of the aerogel limits its wide application. The easy functionalization of COFs provides a more effective and simple means for the modification and modification of aerogel materials, and the high porosity of COF provides more adsorption sites for aerogel, which can effectively increase the adsorption capacity.

[0003] Aerogel composite material is prepared by combining COF, MOF, molecular sieve and the like porous materials with aerogel material, and the synergistic effect between the materials plays an important role in realizing higher performance. By combining COF material with aerogel material, the hierarchical micro / mesoporosity can be easily controlled or adjusted, so that the diffusion and adsorption behavior of molecules is more easily carried out, and the mechanical properties and stability of the aerogel are improved. The combination of the microporosity and mesoporosity of COF and the mesoporosity and macroporosity of aerogel makes the aerogel a hierarchical porous material, which is widely used in the fields of adsorption and catalysis. In recent years, it has gradually developed to be used in the fields of water treatment and VOCs treatment.

[0004] At present, there is no literature report on the research on the VOCs adsorption performance and mechanical properties of aerogel by combining COF-300 with aerogel material. SUMMARY

[0005] The present application aims to provide a preparation method of a composite aerogel material for VOCs adsorption to solve the problems existing in the background art.

[0006] To achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] A preparation method of a composite aerogel material for VOCs adsorption adopts the following steps:

[0008] 1) Configure a nanocellulose suspension:

[0009] Add water and nanocellulose in a container, disperse them in an ultrasonic homogenizer, then add 3-aminopropyltriethoxysilane (APTES) in the nanocellulose aqueous solution at a certain proportion, stir at room temperature with a stirrer, obtain an amino-modified nanocellulose suspension, denoted as N-CNF.

[0010] 2) Preparation of N-CNF aerogel:

[0011] After the N-CNF suspension obtained above is refrigerated overnight, it is placed in a freeze dryer, then the sample is dried in a drying oven, and N-CNF aerogel is obtained.

[0012] 3) Modification of N-CNF aerogel:

[0013] The obtained N-CNF aerogel is reacted with a terephthaldehyde solution at 150℃ for 2h, and modified N-CNF aerogel is obtained.

[0014] 4) Preparation of COF-300@N-CNF:

[0015] First, dissolve tetrakis(4-aminophenyl)methane and terephthaldehyde in dioxane, add trimesylformaldehyde, and then add acetic acid solution, ultrasonic for 20min to obtain a clear solution, then transfer the solution to a hydrothermal reactor, and also put the modified N-CNF aerogel into the hydrothermal reactor for reaction, finally, after the aerogel is naturally cooled, wash the aerogel with dioxane and ethanol, and dry it under vacuum, to obtain COF-300@N-CNF composite aerogel.

[0016] Further, the weight ratio of water to nanocellulose in step (1) is 150-250:1.

[0017] Further, the mass ratio of APTES to nanocellulose in step (1) is 0.2-5:1.

[0018] Further, the aerogel preparation in step (2) comprises freezing the obtained N-CNF suspension in a refrigerator for 24 hours, then placing it in a freeze dryer for 24 hours, and then drying the sample in a drying oven at 90 DEG C for 1-3 hours to obtain the N-CNF aerogel.

[0019] Further, the 1ml dioxane solution in step (3) contains 5-20mg of terephthaldehyde.

[0020] Further, the mass ratio of tetra(4-aminophenyl)methane to terephthaldehyde in step (4) is 1:0.8-1.5, the volume ratio of dioxane:trimesic aldehyde:3M acetic acid solution is 3-6:0.6-1:1, and the mass fraction of tetra(4-aminophenyl)methane is 0.8-2%.

[0021] Further, the preparation of the COF-300@N-CNF composite aerogel material comprises slowly adding the ultrasonic obtained tetra(4-aminophenyl)methane and terephthaldehyde clear solution into a hydrothermal reactor, and placing the modified N-CNF aerogel horizontally, with the solution surface higher than the aerogel. The hydrothermal reactor is reacted at 120 DEG C for 3 days, and after the aerogel is naturally cooled, it is washed with dioxane and ethanol three times, and vacuum dried at 80 DEG C for 12 hours to obtain the COF-300@N-CNF composite aerogel.

[0022] The beneficial effects of the present application are:

[0023] 1. The single nanocellulose aerogel can only rely on its own polar active groups and van der Waals force to adsorb VOCs gas, so it has the problems of low adsorption strength, weak adsorption interaction for nonpolar molecules, and large pore size of the aerogel itself, and the amount of VOCs gas that can be adsorbed is also small. The COF-300@N-CNF composite aerogel material of the present application can increase the adsorption of VOCs gas through hydrogen bond interaction, Π-Π interaction and lipophilicity of COF material while ensuring the adsorption performance of the aerogel itself.

[0024] 2. The three-dimensional COFs material with large specific surface area and high porosity can provide additional adsorption sites for the aerogel material, and the three-dimensional channel is beneficial to the contact of VOCs gas with the adsorption site, increases the VOCs adsorption capacity, and improves the VOCs treatment capacity. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0026] The technical solutions of the present application are described in detail below through some examples. The following examples are only exemplary and can only be used to explain and illustrate the technical solutions of the present application, but cannot be interpreted as a limitation of the technical solutions of the present application.

[0027] The present application provides a preparation method of COF-300@N-CNF composite aerogel, as shown in Figure 1 The preparation method adopts steps S100-S400.

[0028] S100, configure a nanocellulose suspension:

[0029] Water and nanocellulose are added to a container, which is dispersed in an ultrasonic homogenizer, then 3-aminopropyltriethoxysilane (APTES) is added to the nanocellulose in a certain proportion, and the mixture is stirred at room temperature with a stirrer to obtain an amino-modified nanocellulose suspension, denoted as N-CNF.

[0030] In some embodiments, the weight ratio of water to nanocellulose in step (1) is 150-250:1.

[0031] In some embodiments, the mass ratio of APTES to nanocellulose in step (1) is 0.2-5:1.

[0032] S200, N-CNF aerogel preparation:

[0033] The obtained N-CNF suspension is frozen overnight in a refrigerator and then placed in a freeze dryer, and then the sample is dried in a drying oven to obtain N-CNF aerogel.

[0034] In some embodiments, the preparation of aerogel in step (2) includes freezing the obtained N-CNF suspension in a refrigerator for 24 hours, placing it in a freeze dryer, freeze-drying for 24 hours, and then drying the sample in a drying oven at 90°C for 1-3 hours to obtain N-CNF aerogel.

[0035] S300, modification of N-CNF aerogel:

[0036] The obtained N-CNF aerogel is reacted with a solution of terephthaldehyde at 150°C for 2h to obtain a modified N-CNF aerogel.

[0037] In some embodiments, the 1ml dioxane solution in step (3) contains 5-20mg of terephthaldehyde.

[0038] S400, preparation of COF-300@N-CNF:

[0039] The tetra(4-aminophenyl)methane and p-xylylene are first dissolved in dioxane, the trimesic aldehyde is added, and then the acetic acid solution is added, and a clear solution is obtained by ultrasonic treatment for 20 min, and then the solution is transferred to a reaction kettle. The modified N-CNF aerogel is also placed in the hydrothermal kettle for reaction, and finally the aerogel is naturally cooled, washed with dioxane and ethanol, and dried under vacuum to obtain the COF-300@N-CNF composite aerogel.

[0040] In some embodiments, the mass ratio of tetra(4-aminophenyl)methane to p-xylylene in step (4) is 1:0.8-1.5, and the volume ratio of dioxane:trimesic aldehyde:3M acetic acid solution is 3-6:0.6-1:1, and the mass fraction of tetra(4-aminophenyl)methane is 0.8-2%.

[0041] In some embodiments, the preparation of the COF-300@N-CNF composite aerogel material in step (4) includes slowly adding the ultrasonic clear solution of tetra(4-aminophenyl)methane and p-xylylene into a hydrothermal reaction kettle, and placing the modified N-CNF aerogel horizontally, with the solution level higher than the aerogel. The hydrothermal kettle is reacted at 120°C for 3 days, and after the aerogel is naturally cooled, it is washed with dioxane and ethanol three times, and dried under vacuum at 80°C for 12h to obtain the COF-300@N-CNF composite aerogel.

[0042] Example 1

[0043] The present embodiment provides a preparation method of a COF-300@N-CNF composite aerogel material for VOC adsorption, comprising the following steps:

[0044] 100ml of 0.5wt% nanocellulose suspension is weighed and dispersed in an ultrasonic homogenizer for 20min, then a certain proportion of nanocellulose is added to APTES, and stirred at room temperature for 2h to obtain an amino-modified nanocellulose suspension, denoted as N-CNF.

[0045] The N-CNF suspension obtained above is frozen in a refrigerator for 24h, then placed in a freeze dryer for 24h, and then the sample is dried in a drying oven at 90°C for 1h to obtain N-CNF aerogel.

[0046] The obtained N-CNF aerogel is reacted with p-xylylene solution (20mg / 4mL dioxane) at 150°C for 2h to obtain modified N-CNF aerogel.

[0047] Take 150 mg of tetra(4-aminophenyl)methane and 165 mg of p-xylylene aldehyde first dissolved in 10 ml of dioxane, then add 1.5 ml of mesityl aldehyde, then add 2 ml of 3M acetic acid solution, ultrasonic for 20 min to get a clear solution, then transfer the solution to a hydrothermal reactor. The modified N-CNF aerogel is also put into the hydrothermal reactor, reacted at 120° for 3d, and finally the aerogel is naturally cooled, washed with dioxane and ethanol, and vacuum dried at 80°C for 12h to obtain COF-300@N-CNF aerogel.

[0048] Example 2

[0049] The embodiment provides a preparation method of a COF-300@N-CNF composite aerogel material for VOCs adsorption, comprising the following steps:

[0050] Take 100 ml of 0.8wt% nanocellulose suspension, disperse it in an ultrasonic homogenizer for 20 min, then add APTES at a ratio of 3:1, stir at room temperature with a stirrer for 2h, and obtain an amino-modified nanocellulose suspension, denoted as N-CNF.

[0051] The N-CNF suspension obtained above is refrigerated for 24h, then put into a freeze dryer for 24h, then the sample is dried in a drying oven at 90°C for 1h to obtain N-CNF aerogel.

[0052] The obtained N-CNF aerogel is reacted with p-xylylene aldehyde solution (30mg / 4mL dioxane) at 150°C for 2h to obtain modified N-CNF aerogel.

[0053] Take 150 mg of tetra(4-aminophenyl)methane and 165 mg of p-xylylene aldehyde first dissolved in 10 ml of dioxane, then add 1.5 ml of mesityl aldehyde, then add 2 ml of 3M acetic acid solution, ultrasonic for 20 min to get a clear solution, then transfer the solution to a hydrothermal reactor. The modified N-CNF aerogel is also put into the hydrothermal reactor, reacted at 120° for 3d, and finally the aerogel is naturally cooled, washed with dioxane and ethanol, and vacuum dried at 80°C for 12h to obtain COF-300@N-CNF aerogel.

[0054] Example 3

[0055] The embodiment provides a preparation method of a COF-300@N-CNF composite aerogel material for VOCs adsorption, comprising the following steps:

[0056] Take 100 ml of 0.6wt% nanocellulose suspension, disperse it in an ultrasonic homogenizer for 20 min, then add APTES at a ratio of 1:2 of nanocellulose, stir at room temperature with a stirrer for 2 h, to obtain amino-modified nanocellulose suspension, denoted as N-CNF.

[0057] After freezing the N-CNF suspension obtained above in the refrigerator for 24 h, put it into a freeze dryer for 24 h, then dry the sample in a drying oven at 90°C for 1 h, to obtain N-CNF aerogel.

[0058] React the obtained N-CNF aerogel with terephthaldehyde solution (35 mg / 4 mL dioxane) at 150°C for 2 h, to obtain modified N-CNF aerogel.

[0059] Dissolve 150 mg of tetrakis(4-aminophenyl)methane and 120 mg of terephthaldehyde in 18 ml of dioxane, then add 1.8 ml of mesityl aldehyde, and then add 3 ml of 3M acetic acid solution, ultrasonic for 20 min to obtain a clear solution, then transfer the solution to a hydrothermal reactor. Put the modified N-CNF aerogel into the hydrothermal reactor as well, react at 120° for 3 d, and finally, after the aerogel is naturally cooled, wash the aerogel with dioxane and ethanol, and vacuum dry at 80°C for 12 h, to obtain COF-300@N-CNF aerogel.

[0060] Example 4

[0061] 1. Use the COF composite aerogel materials prepared in Examples 1, 2, and 3, and the cellulose aerogel material without COF (denoted as 4) to treat typical nonpolar substances in VOCs, decane: take 100 mg of composite aerogel, load into A, B, and C adsorption columns, respectively, connect 10 mg / L decane gas circuit to the lower mouth of A, B, and C adsorption columns, and perform column breakthrough adsorption at the same gas flow rate. 300 L of gas passes through A, B, and C adsorption columns, respectively, and is collected with Tedlar bags. The decane concentration is detected by gas chromatography. The adsorption efficiency of the aerogel composite material is calculated by calculating the gas volume and concentration in the plastic bag (see Table 1).

[0062] Adsorption rate of aerogel composite material C r = (1-V2C2 / V1C1) x 100%, wherein V1 is the gas volume (L), C1 is the gas concentration (mg / L), V2 is the gas volume after passing through the adsorption column (L), and C2 is the gas concentration after passing through the adsorption column (mg / L).

[0063] 2. Use the composite aerogel materials prepared in Examples 1, 2, and 3, and the cellulose aerogel material without COF (denoted as 4) to treat methyl acetate-containing gas: the method is the same as treating decane-containing air (see Table 2).

[0064] Table 1 is the result of the composite aerogel material adsorbing treatment of air containing decane

[0065]

[0066] Table 2 is the result of the composite aerogel material adsorbing treatment of air containing methyl acetate

[0067]

[0068] From Table 1 and Table 2, it can be seen that the cellulose aerogel material without COF has more polar groups, and the adsorption effect of polar substances in VOCs is good, but the adsorption effect of non-polar substances is not good; the aerogel material after the composite COF particles increases the lipophilicity and the π-π bond interaction, greatly improves the adsorption effect of non-polar substances, and the hydrogen bond interaction provided by the -NH group in COF-300 also increases the effect of the aerogel material on polar substances, and the adsorption capacity also increases. The adsorption of the composite aerogel material to air containing decane can reach 91.4%, and the adsorption effect of the composite aerogel material to air containing methyl acetate can reach 99.0%.

[0069] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite aerogel material for VOCs adsorption, characterized in that, The following steps are adopted: 1) Preparation of nanocellulose suspension: Water and nanocellulose were added to a container and ultrasonically dispersed to obtain an aqueous solution of nanocellulose. Then, 3-aminopropyltriethoxysilane was added to the aqueous solution of nanocellulose in a certain proportion, with the mass ratio of 3-aminopropyltriethoxysilane to nanocellulose being 0.2~5:

1. The mixture was stirred at room temperature to obtain an amino-modified nanocellulose suspension, denoted as N-CNF. 2) Preparation of N-CNF aerogel: The N-CNF suspension obtained above was frozen overnight in a refrigerator and then placed in a freeze dryer. The sample was then dried in a drying oven to obtain N-CNF aerogel. 3) Modification of N-CNF aerogel: The obtained N-CNF aerogel was reacted with terephthalaldehyde solution at 150℃ for 2 h to obtain modified N-CNF aerogel. 4) Preparation of COF-300@N-CNF: Tetra(4-aminophenyl)methane and terephthalaldehyde were first dissolved in dioxane, then pyromellitic methylaldehyde was added, followed by acetic acid solution. The mixture was sonicated for 20 minutes to obtain a clear solution. The clear solution was then transferred to a hydrothermal reactor, and the modified N-CNF aerogel was also added to the hydrothermal reactor for reaction. The reaction was carried out at 120°C for 3 days. Finally, after the aerogel cooled naturally, it was washed with dioxane and ethanol and dried under vacuum to obtain COF-300@N-CNF composite aerogel.

2. The method for preparing the composite aerogel material for VOCs adsorption according to claim 1, characterized in that, In step 1), the weight ratio of water to nanocellulose is 150~250:

1.

3. The method for preparing the composite aerogel material for VOCs adsorption according to claim 1, characterized in that, Step 2) involves preparing N-CNF aerogel by freezing the obtained N-CNF suspension in a refrigerator for 24 hours, then placing it in a freeze dryer for 24 hours, and finally drying the sample in a drying oven at 90°C for 1-3 hours to obtain N-CNF aerogel.

4. The method for preparing the composite aerogel material for VOCs adsorption according to claim 1, characterized in that, The 1 mL dioxane solution in step 4) contains 5-20 mg of terephthalaldehyde.

5. The method for preparing the composite aerogel material for VOCs adsorption according to claim 1, characterized in that, In step 4), the mass ratio of tetra(4-aminophenyl)methane to terephthalaldehyde is 1:0.8~1.5, and the volume ratio of dioxane:trimethylammonium oxychloride:3M acetic acid solution is 3~6:0.6~1:

1.

6. The method for preparing the composite aerogel material for VOCs adsorption according to claim 1, characterized in that, In step 4), the clear solution of tetra(4-aminophenyl)methane and terephthalaldehyde obtained by ultrasound is slowly added to a hydrothermal reactor, and the modified N-CNF aerogel is placed horizontally, with the liquid level of the clear solution higher than that of the modified N-CNF aerogel. After the aerogel cools naturally, it is washed three times with dioxane and ethanol, and then vacuum dried at 80°C for 12 hours to obtain COF-300@N-CNF composite aerogel.

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