Aerogel capable of visualizing adsorbed malodor and preparation method and application thereof

Abstract

The application discloses a kind of aerogel of visualizing adsorbing peculiar smell and preparation method and application, steps: 1) cellulose powder is dissolved in acid solution, heated stirring, obtain cellulose solution;2) cellulose solution is centrifuged, washed with water, freeze-drying and obtain acid-modified cellulose powder;3) cellulose powder and organic amine are dissolved respectively after mixing and obtain hydrogel precursor solution;4) crosslinking agent is added to hydrogel front solution, adjust the pH of solution to neutral, room temperature stationary 2 h, obtain hydrogel;5) after hydrogel washing, immerse in copper salt solution and obtain copper ion doped hydrogel, freeze-drying and obtain the aerogel of adsorbing peculiar smell.The preparation method of the application is prepared aerogel with three-dimensional porous structure and larger specific surface area and porosity, can be adsorbed by physical adsorption and chemical complexation peculiar smell substance, and adsorption range is wide, can adsorb a variety of different types of peculiar smell molecule, and color change occurs after adsorbing acid-alkali peculiar smell.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material technology, specifically relating to a visually adsorbent aerogel, its preparation method, and its application. Background Technology

[0002] As people's living standards continue to improve, the variety of food they purchase is becoming increasingly diverse. However, storing food for extended periods can lead to the growth and reproduction of large numbers of bacteria. These bacteria further decompose the nutrients in the food, producing a large number of compounds containing nitrogen and sulfur elements, which emit a foul odor. Even after discarding rotten food, the foul odor will persist for a long time and cannot be completely removed. The presence of this odor not only causes sensory discomfort and affects the eating experience but also damages the flavor of the food.

[0003] Traditional odor removal methods typically involve adding scented substances to mask unpleasant smells. However, this method only provides a temporary solution; once the effect wears off, the original odor reappears. Furthermore, zeolite, a commonly used adsorbent material, has a high moisture absorption capacity, which may lead to saturation and deactivation. Additionally, zeolite has a relatively narrow adsorption range and cannot effectively adsorb certain types of odors. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a visually absorbent aerogel, its preparation method, and its applications. This is achieved through the following technical solution:

[0005] A method for preparing a visually absorbent odor aerogel, the method comprising the following steps:

[0006] 1) Dissolve cellulose powder in an acid solution, heat and stir to obtain a cellulose solution;

[0007] 2) The cellulose solution obtained in step 1) is repeatedly centrifuged, washed with water, and freeze-dried at -60℃ to obtain acid-modified cellulose powder;

[0008] 3) Dissolve acid-modified cellulose powder and organic amine in water to prepare cellulose powder aqueous solution and organic amine solution, and mix cellulose powder aqueous solution and organic amine solution in a certain proportion to obtain hydrogel precursor solution;

[0009] 4) Add a cross-linking agent to the hydrogel precursor solution, adjust the pH of the solution to neutral, and let it stand at room temperature for 2 h to obtain the hydrogel;

[0010] 5) After washing the hydrogel with water, it is soaked in a copper salt solution to obtain a copper ion-doped hydrogel, which is then freeze-dried at -60℃ to obtain an aerogel that can adsorb odors.

[0011] Copper ion doping makes Cu 2+It forms coordination complexes with odor-causing substances such as ammonia (NH3), trimethylamine ((CH3)3N), methanethiol (CH4S), and hydrogen sulfide (H2S) through chemical reactions.

[0012] Cu 2+ +4NH3→[Cu(NH3)4] 2+ Cu 2+ +(CH3)3N→[CuN(CH3)3] 2+ Cu 2+ +CH4S→CH3S-Cu + +H + Cu 2+ +H₂S→CuS+2H₂ + .

[0013] Further, in step 1), the ratio of cellulose powder to acid solution is 1-5g:50-250mL, the heating temperature is 60-100℃, and the heating time is 3-6h.

[0014] Further, in step 1), the acid solution is a mixed solution of hydrochloric acid and citric acid, wherein the volume ratio of hydrochloric acid to citric acid is 1:9.

[0015] Further, in step 3), the concentration of the cellulose powder aqueous solution is 1%, the concentration of the organic amine solution is 5%, and the cellulose powder aqueous solution and the organic amine solution are mixed in a volume ratio of 1-3:1-3.

[0016] Further, in step 3), the organic amine is at least one of chitosan, carboxymethyl chitosan, and polyethyleneimine.

[0017] Further, in step 4), the crosslinking agent is trifunctional aziridine, and the amount of the crosslinking agent added accounts for 5-10% of the mass of the hydrogel precursor solution.

[0018] Further, in step 5), the copper salt is selected from at least one of copper chloride, copper sulfate, and copper nitrate.

[0019] The above preparation method yields a visual odor-adsorbing aerogel and its application in food odor adsorption.

[0020] The aerogel prepared by the method of this invention has a three-dimensional porous structure and a large specific surface area and porosity. It can adsorb odor substances through physical adsorption and chemical complexation. The aerogel prepared by this method has a wide adsorption range and can adsorb a variety of different types of odor molecules, including volatile organic compounds, sulfides, nitrides, etc., and will change color after adsorbing acidic and alkaline odors. Attached Figure Description

[0021] Figure 1 The images show the copper-free CTC hydrogels prepared during the preparation process of Examples 1-3 of this invention.

[0022] Figure 2 This is a SEM image of the CTC aerogel in the comparative example of this invention;

[0023] Figure 3 The graph shows the adsorption effect of CTC-Cu aerogel prepared in Example 2 of this invention on NH3 and the CTC aerogel prepared in the comparative example. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution.

[0025] Example 1

[0026] An aerogel material for visually absorbing odors is prepared according to the following steps:

[0027] 1) Dissolve 1 g of cellulose powder (CEL) in a mixed acid solution consisting of hydrochloric acid (6M, 5mL) and citric acid (3M, 45mL), and heat and stir at 60°C for 6 hours;

[0028] 2) The CEL solution obtained in step 1) was repeatedly centrifuged, washed with water, and freeze-dried at -60℃ to obtain acid-modified cellulose powder;

[0029] 3) Dissolve the CEL powder and carboxymethyl chitosan (CMCS) obtained in step 2) in water to obtain a 1% CEL solution and a 5% CMCS solution. Mix the CEL solution and CMCS solution evenly in a 1:1 volume ratio to obtain a hydrogel precursor solution.

[0030] 4) Add 5% (by mass) of a trifunctional aziridine crosslinking agent (TMPTAP) to the hydrogel precursor solution from step 3), adjust the pH of the solution to neutral, and let it stand at room temperature for 2 hours to obtain CTC hydrogel; the prepared hydrogel is shown in the figure. Figure 1 'a' in 'a';

[0031] 5) Wash the hydrogel obtained in step 4) three times with deionized water, and then soak it in copper chloride solution to obtain copper ion-doped hydrogel;

[0032] 6) The hydrogel obtained in step 5) was freeze-dried at -60℃ for 48h to obtain copper ion-doped aerogel (CTC-Cu).

[0033] Example 2

[0034] An aerogel material for visually absorbing odors is prepared according to the following steps:

[0035] 1) Dissolve 3g of cellulose powder (CEL) in a mixed acid solution consisting of hydrochloric acid (6M, 15mL) and citric acid (3M, 135mL), and heat and stir at 80℃ for 4h.

[0036] 2) The CEL solution obtained in step 1) was repeatedly centrifuged, washed with water, and freeze-dried at -60℃ to obtain acid-modified cellulose powder;

[0037] 3) Dissolve the CEL powder and chitosan obtained in step 2) in water and 1% acetic acid solution respectively to obtain 1% CEL solution and 5% chitosan solution. Mix the CEL solution and chitosan solution evenly at a volume ratio of 1:3 to obtain hydrogel precursor solution.

[0038] 4) Add 8% (by mass) of a trifunctional aziridine crosslinking agent (TMPTAP) to the hydrogel precursor solution from step 3), adjust the pH of the solution to neutral, and let it stand at room temperature for 2 hours to obtain CTC hydrogel; the prepared hydrogel is shown in the figure. Figure 1 b in the middle;

[0039] 5) Wash the hydrogel obtained in step 4) three times with deionized water, and then soak it in copper sulfate solution to obtain copper ion-doped hydrogel;

[0040] 6) The hydrogel obtained in step 5) was freeze-dried at -60℃ for 48h to obtain copper ion-doped aerogel (CTC-Cu).

[0041] Example 3

[0042] An aerogel material for visually absorbing odors is prepared according to the following steps:

[0043] 1) Dissolve 5g of cellulose powder (CEL) in a mixed acid solution consisting of hydrochloric acid (6M, 25mL) and citric acid (3M, 225mL), and heat and stir at 100℃ for 3h.

[0044] 2) The CEL solution obtained in step 1) was repeatedly centrifuged, washed with water, and freeze-dried at -60℃ to obtain acid-modified cellulose powder;

[0045] 3) Dissolve the CEL powder and polyethyleneimine obtained in step 2) in water to obtain a 1% CEL solution and a 5% polyethyleneimine solution. Mix the CEL solution and the polyethyleneimine solution evenly at a volume ratio of 3:1 to obtain a hydrogel precursor solution.

[0046] 4) Add 10% (by mass) of a trifunctional aziridine crosslinking agent (TMPTAP) to the hydrogel precursor solution from step 3), adjust the pH of the solution to neutral, and let it stand at room temperature for 2 hours to obtain the CTC hydrogel; the prepared hydrogel is shown in the figure. Figure 1 c in the middle;

[0047] 5) Wash the hydrogel obtained in step 4) three times with deionized water, and then soak it in copper nitrate solution to obtain copper ion-doped hydrogel;

[0048] 6) The hydrogel obtained in step 5) was freeze-dried at -60℃ for 48h to obtain copper ion-doped aerogel (CTC-Cu).

[0049] Comparative Example

[0050] The comparative example follows the same steps as Example 2, except that copper doping was not performed. The specific steps are as follows:

[0051] 1) Dissolve 3g of cellulose powder (CEL) in a mixed acid solution consisting of hydrochloric acid (6M, 15mL) and citric acid (3M, 135mL), and heat and stir at 80℃ for 4h.

[0052] 2) The CEL solution obtained in step 1) was repeatedly centrifuged, washed with water, and freeze-dried at -60℃ to obtain acid-modified cellulose powder;

[0053] 3) Dissolve the CEL powder and chitosan obtained in step 2) in water and 1% acetic acid solution respectively to obtain 1% CEL solution and 5% chitosan solution. Mix the CEL solution and chitosan solution evenly at a volume ratio of 1:3 to obtain hydrogel precursor solution.

[0054] 4) Add 8% (by mass) of trifunctional aziridine crosslinking agent (TMPTAP) to the hydrogel precursor solution in step 3), adjust the pH of the solution to neutral, and let it stand at room temperature for 2 h to obtain CTC hydrogel.

[0055] 5) The hydrogel obtained in step 4) was washed three times with deionized water and freeze-dried at -60℃ for 48 h to obtain copper-free CTC aerogel, the morphology of which is shown in the figure. Figure 2 As shown in Figure a, the CTC aerogel prepared by this method has a porous structure. A cross-sectional SEM image of the CTC aerogel is shown below. Figure 2 As shown in b, the aerogel exhibits a 3D multi-walled perforated cell structure, which may be due to the different forces that hinder ice crystal growth in the CTC hydrogel, resulting in different growth rates and sizes inside and outside the ice crystals.

[0056] Verification Example

[0057] The copper-doped aerogel (CTC-Cu) prepared in Example 2 and the CTC aerogel prepared in the comparative example were placed in polytetrafluoroethylene gas bags and sealed. Ammonia gas was introduced at 150 ppm, and the gas concentration inside the gas bags was measured at regular intervals using a gas detection tube. The removal rate of NH3 by the aerogel is as follows: Figure 3As shown, due to its porous structure, CTC aerogel can adsorb a small amount of NH3. Compared with pure CTC aerogel, CTC-Cu aerogel adsorbs a large amount of NH3 through physical adsorption and complexation, exhibiting a significant NH3 removal efficiency.

Claims

1. A method of preparing a visualizing adsorbent malodor gas gel, characterized by, The method comprises the following steps: 1) dissolving cellulose powder in an acid solution, heating and stirring to obtain a cellulose solution; 2) repeatedly centrifuging, washing with water and freeze-drying at -60℃ the cellulose solution obtained in step 1) to obtain acid-modified cellulose powder; 3) dissolving the acid-modified cellulose powder and an organic amine separately to obtain a cellulose powder aqueous solution with a concentration of 1% and an organic amine solution with a concentration of 5%, mixing the cellulose powder aqueous solution and the organic amine solution at a volume ratio of 1-3:1-3 to obtain a hydrogel precursor solution; the organic amine is at least one of chitosan, carboxymethyl chitosan and polyethyleneimine; 4) adding a crosslinking agent to the hydrogel precursor solution, adjusting the pH of the solution to neutral, standing at room temperature for 2 h to obtain a hydrogel; the crosslinking agent is a trifunctional aziridine, and the amount of the crosslinking agent added accounts for 5-10% of the mass of the hydrogel precursor solution; 5) washing the hydrogel, immersing it in a copper salt solution to obtain a copper ion-doped hydrogel, and freeze-drying at -60℃ to obtain an odor-absorbing aerogel.

2. The method of claim 1, wherein the visualizing the adsorbing malodor aerosol gel is characterized by In step 1), the ratio of cellulose powder to acid solution is 1-5 g:50-250 mL, the heating temperature is 60-100℃, and the heating time is 3-6 h.

3. The method of claim 1, wherein the visualizing adsorbing malodor aerosol gel is prepared by In step 1), the acid solution is a mixed solution of hydrochloric acid and citric acid, wherein the volume ratio of hydrochloric acid to citric acid is 1:

9.

4. The method of claim 1, wherein the visualizing the adsorbing malodor aerosol gel is characterized by In step 5), the copper salt is at least one of copper chloride, copper sulfate and copper nitrate.

5. The odor-absorbing aerogel prepared by the method of any one of claims 1-4.

6. The use of the odor-absorbing aerogel of claim 5 in food odor absorption.

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