Graphene oxide and cellulose composite aroma-adding gel as well as preparation method and application thereof

Abstract

The invention discloses graphene oxide and cellulose composite aroma-adding gel as well as a preparation method and application thereof, and belongs to the technical field of nano materials and perfume slow release. The preparation method comprises the following steps: selecting northern bleached softwood kraft pulp as a cellulose source, preparing nano-cellulose through TEMPO-mediated oxidation reaction, performing in-situ perfuming in the nano-cellulose, and compounding with graphene oxide (GO) to prepare the composite perfuming gel with a high specific surface area and a porous structure. Through an in-situ perfuming method, the perfume is emulsified and dispersed in the nanocellulose suspension before the aerogel is formed, and through combination with an optimized freeze-drying process, uniform anchoring of perfume molecules in three-dimensional pores is realized, the problems of non-uniform distribution and volatilization of the perfume in a traditional method are solved, and efficient adsorption and slow release of the perfume are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of graphene oxide cellulose composite perfuming aerogel and its preparation method and application, belong to nanometer material and perfume slow-release technical field. BACKGROUND

[0002] Perfume has a close relationship with people's life, has the functions of disinfection, sterilization, environmental improvement and comfort, and is widely used in the fields of cigarettes, food, cosmetics and other fields with large amount, but its volatile and oxidizable characteristics result in short lingering time and difficult to control release rate. Therefore, the slow-release and controlled-release technology of perfume is one of the important fields of international and domestic research, and is also one of the difficulties of international research. Slow-release technology is a substance control release technology, which makes the target substance slowly or controllably release in the release medium by processing the target substance or relying on the special properties of auxiliary materials. Slow-release technology is widely used in the field of cigarette flavor and perfume, and by slow-release treatment of flavor in cigarette filter, the purpose of controlling release time during smoking and locking flavor during storage can be achieved. Traditional flavor slow-release materials usually use physical adsorption or surface modification method, but these methods have the problems of low flavor loading, uneven release and other problems.

[0003] Aerogel refers to a kind of nanoscale porous solid material formed by replacing the liquid phase in the gel with gas through sol method and certain drying method, which has many types, such as silicon, carbon, sulfur, metal oxide, metal, etc. Aerogel has the characteristics of ultra-low density, high porosity, nanoscale pore, high specific surface area, low thermal conductivity, high temperature resistance and stable chemical properties, which makes it have broad application prospects in the fields of aerospace, building energy saving, chemical industry, electronic and electrical industry, biological medicine and other fields. Due to the excellent properties of aerogel, some researchers use aerogel materials to adsorb perfume to achieve the slow-release effect of perfume, but the existing aerogel materials often have problems such as volume shrinkage and insufficient mechanical properties during perfume adsorption, which limits its popularization in practical application.

[0004] Graphene oxide (GO) as a kind of two-dimensional material with high specific surface area and rich functional groups has potential in the field of adsorption, but it has the problems of poor mechanical properties and high production cost when used alone. Cellulose is a natural polymer with the largest reserves in the world, non-toxic, renewable and degradable. As the third generation of aerogel after inorganic aerogel and synthetic aerogel, cellulose aerogel has the advantages of both green renewable cellulose material and porous aerogel material, and is a rational modification material of graphene oxide. However, the preparation of traditional graphene oxide / cellulose aerogel usually adopts simple blending method, and its density is >50 mg / cm 3, porosity <95%, and rely on post-adsorption of the loaded perfume during perfume release, which is inefficient. Therefore, it is of great practical significance to develop a composite material with high perfume adsorption capacity, stable structure and simple preparation process. SUMMARY

[0005] The first object of the present application is to provide a preparation method of graphene oxide cellulose composite perfumed aerogel, and to provide a preparation method of perfumed aerogel different from the prior art and simple in preparation.

[0006] The second object of the present application is to provide a graphene oxide cellulose composite perfumed aerogel to solve the problem of low perfume adsorption rate of the material for perfume release in the prior art.

[0007] The third object of the present application is to provide an application of graphene oxide cellulose composite perfumed aerogel in cigarette perfuming, and to provide a perfumed material with high perfume adsorption rate for cigarette perfuming.

[0008] In order to achieve the above-mentioned objects, the technical scheme adopted by the preparation method of graphene oxide cellulose composite perfumed aerogel in the present application is as follows:

[0009] The preparation method of graphene oxide cellulose composite perfumed aerogel comprises the following steps:

[0010] (1) Using northern bleached softwood kraft pulp as raw material, a nanocellulose suspension is prepared by 2,2,6,6-tetramethylpiperidine oxide mediated oxidation reaction;

[0011] (2) mixing and emulsifying the perfume to be perfumed with the nanocellulose suspension to obtain in-situ perfumed nanocellulose solution;

[0012] (3) mixing the in-situ perfumed nanocellulose solution with graphene oxide solution, freeze-drying, to obtain graphene oxide cellulose composite perfumed aerogel.

[0013] The beneficial effects of the above technical scheme are that the preparation method of graphene oxide cellulose composite perfumed aerogel is an open-ended invention. By comparison, the present application selects northern bleached softwood kraft pulp as the source of cellulose, prepares nanocellulose by 2,2,6,6-tetramethylpiperidine oxide (TEMPO) mediated oxidation reaction, and performs in-situ perfuming on the nanocellulose, and then composites with graphene oxide (GO) to prepare a composite perfumed aerogel with high specific surface area and porous structure. Specifically, the present application optimizes the mass ratio of in-situ perfumed nanocellulose solution to GO, which significantly improves the mechanical properties and adsorption capacity of the aerogel.

[0014] Further, the application realizes uniform anchoring of perfume molecules in three-dimensional pores by in-situ perfuming method, i.e. emulsifying and dispersing the perfume in the nanocellulose suspension before aerogel formation, combined with optimized freeze-drying process, solves the problems of uneven distribution and volatilization in traditional methods, and realizes efficient adsorption and slow release of the perfume. Moreover, the preparation method of the application is simple and easy to scale up.

[0015] As a further improvement, the oxidation reaction in step (1) comprises swelling the northern bleached softwood kraft pulp in water, and adding 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO for the oxidation reaction.

[0016] As a further improvement, the mass ratio of the 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO is (0.01-0.03):0.1:(0.2-1.5).

[0017] Preferably, the mass ratio of the 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO is (0.016-0.03):0.1:(1.24-1.5); further preferably, the mass ratio of the 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO is 0.016:0.1:1.24.

[0018] As a further improvement, the oxidation reaction is reacted at room temperature for 4-8h.

[0019] Preferably, the oxidation reaction is reacted at room temperature for 4-6h; further preferably, the oxidation reaction is reacted at room temperature for 4.

[0020] Specifically, the room temperature is 25℃±5℃.

[0021] As a further improvement, the mass ratio of the perfume to be perfumed to the solid in the nanocellulose suspension in step (2) is (0.5-2):1.

[0022] Preferably, the mass ratio of the perfume to be perfumed to the solid in the nanocellulose suspension in step (2) is (1-2):1; further preferably, the mass ratio of the perfume to be perfumed to the solid in the nanocellulose suspension in step (2) is 1:1.

[0023] As a further improvement, the mass ratio of the in-situ perfumed nanocellulose solution to the solid in the graphene oxide solution in step (3) is (20-5):1.

[0024] As a further improvement, the freeze-drying in step (3) is freeze-dried at a temperature of -80 to -5℃ for 12-24h, and then vacuum freeze-dried for 24-48h.

[0025] Preferably, the freeze-drying in step (3) is freeze-drying for 12-16 hours at a temperature of -80 to -5℃, followed by vacuum freeze-drying for 32-48 hours; further preferably, the freeze-drying in step (3) is freeze-drying for 12 hours at a temperature of -80 to -50℃, followed by vacuum freeze-drying for 48 hours.

[0026] As a further improvement, the perfume to be perfumed in step (2) is methyl dihydrojasmonate.

[0027] In order to achieve the above-mentioned purpose, the technical scheme of the graphene oxide cellulose composite perfumed aerogel in the application is:

[0028] A graphene oxide cellulose composite perfumed aerogel prepared by the above preparation method.

[0029] The beneficial effects of the above technical scheme are that the graphene oxide cellulose composite perfumed aerogel provided by the application has a high specific surface area and a porous structure, can efficiently load perfume, and realizes uniform release of perfume, solving the problems of low perfume loading and uneven release in traditional physical adsorption methods.

[0030] Further, the graphene oxide cellulose composite perfumed aerogel prepared by the application has excellent mechanical properties and adsorption properties, and can effectively solve the problems of volume shrinkage, low adsorption capacity, and uneven release in the process of traditional aerogel material adsorbing perfume.

[0031] In order to achieve the above-mentioned purpose, the technical scheme of the graphene oxide cellulose composite perfumed aerogel in the application is:

[0032] The application of a graphene oxide cellulose composite perfumed aerogel in cigarette perfuming.

[0033] The beneficial effects of the above technical scheme are that the application sets a temperature environment of 60℃ to simulate the temperature change in the process of cigarette combustion, tests the slow-release performance of the graphene oxide cellulose composite perfumed aerogel to perfume, and the results show that the composite perfumed aerogel can realize precise release of perfume under high-temperature conditions, meeting the temperature-controlled perfume release requirement during cigarette combustion. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 SEM of NBSK, NCNF, NCA, and NCA-F in Example 1 of the application (wherein (a) is northern bleached softwood kraft pulp, (b) is nanocellulose, (c) is nanocellulose aerogel, and (d) is nanocellulose aerogel with in-situ added methyl dihydrojasmonate);

[0035] Figure 2 SEM of graphene oxide cellulose composite perfumed aerogels in Examples 1-4 of the present application (wherein (a) is graphene oxide, (b) is graphene oxide aerogel, (c)-(f) are graphene oxide cellulose composite perfumed aerogels of Examples 4-1, respectively);

[0036] Figure 3 Three-dimensional effect and three-dimensional pore distribution of NCA aerogel in Example 1 of the present application (wherein (a) is three-dimensional effect, (b) is three-dimensional pore distribution);

[0037] Figure 4 Release curve of graphene oxide cellulose composite perfumed aerogels in Examples 1-4 at 60℃ for MD perfume in Example 5 of the present application. DETAILED DESCRIPTION

[0038] Taking perfume methyl dihydrojasmonate (MD) as an example, in the prior art, the adsorption amount of physical adsorption material (such as activated carbon) for MD perfume is generally less than 100 mg / g, and the release fluctuation (±30%) is caused by uneven pore size distribution. The traditional GO / cellulose aerogel is prepared by simple blending method, and the density is >50 mg / cm 3 , the porosity is <95%, and the perfume is loaded by post-adsorption, which is low in efficiency. Based on this, the present application provides a graphene oxide cellulose composite perfumed aerogel and a preparation method thereof.

[0039] The present application realizes high adsorption amount (592.01 mg / g), low density (20.58 mg / cm 3 ) and stable release (60℃ release rate 13.86%±0.5%) by optimizing NBSK pulp, in-situ perfuming process and raw material dosage ratio, and solves the above technical bottlenecks.

[0040] The present application will be further described in detail below in conjunction with specific examples. Unless otherwise specified, the equipment and reagents used in each example, experimental example and comparative example can be obtained from commercial channels.

[0041] I. A specific embodiment of the graphene oxide cellulose composite perfumed aerogel and the preparation method thereof of the present application:

[0042] Example 1

[0043] The present embodiment prepares nanocellulose (NCNF) from northern bleached softwood kraft pulp (NBSK) through TEMPO-mediated oxidation reaction, mixes and emulsifies with perfume, freeze-dries to obtain in-situ perfumed nanocellulose aerogel (NCA-F), then disperses and mixes with graphene oxide (GO) solution, secondary freeze-dries to form the final graphene oxide / cellulose (GO / NCF-F) composite perfumed aerogel, the specific implementation operation is as follows:

[0044] 1. Preparation of NCNF suspension

[0045] Firstly, 1 g of northern bleached softwood kraft pulp (NBSK) is cut into uniform block-shaped objects, put into 50 mL of deionized water and stirred to swell for 3 hours to ensure that the fiber molecular chains in the wood pulp are as much as possible to be disentangled. Then, 0.016 g of TEMPO, 0.1 g of NaBr and 1.24 g of NaClO are sequentially added to the aqueous solution of NBSK, and 1M NaOH solution is continuously added during the reaction to maintain the pH value at 10±0.2. The reaction mixture is stirred at a speed of 300 r / min at room temperature for 4 hours, and 10 mL of ethanol is added to terminate the reaction after the reaction is completed. The precipitate is obtained by centrifugation, and the product is washed thoroughly with deionized water, and then treated by a high-pressure homogenizer at a speed of 15000 r / min for 5 minutes to obtain a NCNF suspension with a mass concentration of 1.5%, which is stored in a 4°C refrigerator for subsequent use.

[0046] 2. In-situ perfuming

[0047] The perfume dihydrojasmone (MD) is accurately weighed, mixed with the NCNF suspension prepared in step 1 at a mass ratio of dihydrojasmone (MD) to solid content of 1:1, and emulsified by a high-pressure homogenizer to obtain an in-situ perfumed nanocellulose solution.

[0048] 3. Preparation of graphene oxide / cellulose (GO / NCF-F) composite perfumed aerogel

[0049] 100 mg of GO powder is dispersed in 10 mL of deionized water and ultrasonicated for 1 h to obtain a GO solution of 10 mg / mL; the in-situ perfumed nanocellulose solution prepared in step 2 is mixed with the solid content of the graphene oxide (GO) solution at a mass ratio of 5:1, ultrasonically dispersed and stirred at high speed for 30 min; the mixed solution is poured into a mold and placed in a-80°C refrigerator for 12 hours, and then vacuum freeze-dried for 48 h to obtain a GO / NCF-F composite perfumed aerogel, which is hereinafter referred to as GO / NCF-F-5.

[0050] Example 2

[0051] The graphene oxide cellulose (GO / NCF-F) composite fragrant aerogel of the present example is only different from that of example 2 in that the solid content in the in-situ fragrant nanocellulose solution and the graphene oxide (GO) solution is mixed at a mass ratio of 10:1 in step 3, and the rest is the same, which will not be repeated here, and is hereinafter referred to as GO / NCF-F-10.

[0052] Example 3

[0053] The graphene oxide cellulose (GO / NCF-F) composite fragrant aerogel of the present example is only different from that of example 2 in that the solid content in the in-situ fragrant nanocellulose solution and the graphene oxide (GO) solution is mixed at a mass ratio of 15:1 in step 3, and the rest is the same, which will not be repeated here, and is hereinafter referred to as GO / NCF-F-15.

[0054] Example 4

[0055] The graphene oxide cellulose (GO / NCF-F) composite fragrant aerogel of the present example is only different from that of example 2 in that the solid content in the in-situ fragrant nanocellulose solution and the graphene oxide (GO) solution is mixed at a mass ratio of 20:1 in step 3, and the rest is the same, which will not be repeated here, and is hereinafter referred to as GO / NCF-F-20.

[0056] Characterization of aerogel:

[0057] The graphene oxide cellulose (GO / NCF-F) composite fragrant aerogel prepared in examples 1-4 and the in-situ fragrant nanocellulose aerogel (NCA-F, which is prepared by freezing the in-situ fragrant nanocellulose solution prepared in example 1 in a refrigerator at -50°C for 12 hours, and then vacuum freeze-drying for 48h) were subjected to various characterization tests, including SEM, CT and other tests to verify the surface morphology. The specific results are shown in Figures 1 to 3

[0058] As can be seen from Figure 1 , after fiber oxidation and high-pressure homogenization treatment, the originally thick and strong NBSK raw pulp with a diameter of 30-40 μm is successfully prepared into nanodiameter NCNF. The NCA aerogel prepared from NCNF has a compact honeycomb structure, with many fine cellulose fibers interwoven to form numerous pores, forming a rich and open three-dimensional network structure. The in-situ fragrant NCA-F aerogel mainly presents a smooth lamellar shape, with many fine fibers between the layers, but almost no connection.

[0059] As can be seen from Figure 2 ​It is evident that the GOA-F (GOA-F composite scented aerogel, which differs from Example 2 only in that the solids in the in-situ scented nanocellulose solution and graphene oxide (GO) solution are mixed at a mass ratio of 0:1 in step 3; the rest is the same and will not be repeated here; hereinafter referred to as GOA-F), has a disordered and irregular layer arrangement, resulting in a fragile aerogel structure that is easily compressed and collapsed. When one-dimensional fibrous NCNF is combined with two-dimensional sheet-like GO, the prepared graphene oxide cellulose composite scented aerogel exhibits a tight interfacial bond. With the increase of GO content, the orderliness of the internal pores of the composite aerogel gradually increases, and the structure transforms into a regular network morphology.

[0060] Depend on Figure 3 As can be seen, the NCA aerogel samples are in good condition, with no obvious structural damage or defects. Cellulose is evenly distributed within the aerogel, exhibiting excellent dispersibility. The aerogel contains a large number of dense and uniform pores, which not only endow the NCA aerogel with high porosity but also provide it with excellent adsorption capacity and stability.

[0061] II. Specific embodiments of the application of the graphene oxide cellulose composite flavoring aerogel of the present invention in cigarette flavoring:

[0062] Example 5

[0063] This embodiment tested the adsorption effect and release at 60°C of the graphene oxide cellulose (GO / NCF-F) composite aroma gels prepared in Examples 1-4. The specific implementation procedures are as follows:

[0064] The adsorption capacity of the flavored aerogel was determined using the UV standard calibration curve method. Initially, a certain mass of dried and flavored nanocellulose-based aerogel material was weighed and 10 mL of ethanol was added. The mixture was then heated and stirred at 60 °C for 1 h, followed by ultrasonic treatment for 1 h to ensure complete extraction of the fragrance from the aerogel. Afterward, insoluble substances in the solution were removed by centrifugation. The absorbance of the resulting solution was then measured using a spectrophotometer. Finally, the amount of fragrance was determined according to the standard calibration curve, and the adsorption capacity of the flavored aerogel was calculated using formula (1):

[0065]

[0066] In the formula, Ce is the equilibrium concentration of the aroma (μL / mL), m is the mass of the adsorbent (g), V is the volume of ethanol (mL), and ρ is the aroma density (g / cm³). 3 ).

[0067] Based on the actual application scenario, the fragrance release behavior of aerogel at 60℃ was tested. Within 30 minutes, one perfumed aerogel was taken out every 5 minutes, and its fragrance was extracted with ethanol. Then the absorbance of the supernatant was determined by spectrophotometer. The cumulative release rate of the perfumed aerogel was calculated by formula (2):

[0068]

[0069] Wherein C0is the initial equilibrium concentration of fragrance, C e is the equilibrium concentration of fragrance at time t minutes.

[0070] The specific results are shown in Figure 4 and Table 1.

[0071] Table 1 shows the adsorption amount and release effect of aerogel on MD fragrance in Examples 1-4

[0072]

[0073] From Figure 4 It can be seen that the addition of GO shows a certain degree of inhibition effect on the release of fragrance. In the graphene oxide cellulose composite perfumed aerogel system, the surface functional groups of GO and NCNF respectively delay the release of fragrance molecules through hydrogen bonding, and the maximum release rate is controllable in the range of 9.86%-26.87%.

[0074] From Table 1, it can be seen that the adsorption amount of NCNF composite aerogel containing GO on MD fragrance is higher than that of pure NCA aerogel (317.30mg / g). Moreover, with the increase of the amount of GO added, the adsorption amount of composite aerogel on MD appears a trend of first increasing and then decreasing, and when the mass ratio of NCNF to GO is 10:1, the MD adsorption amount of aerogel is the largest, reaching 592.01mg / g.

[0075] In summary, the preparation method of graphene oxide cellulose (GO / NCF-F) composite perfumed aerogel provided by the present application directly embeds the fragrance into the material inside during the preparation process of aerogel by in-situ perfuming method, which significantly improves the loading capacity and release stability of the fragrance. Moreover, by adjusting the mass ratio of in-situ perfumed nanocellulose aerogel to graphene oxide, the mechanical properties of the aerogel are significantly improved, and it can withstand high pressure without deformation. Moreover, based on the actual application scenario of cigarettes, different temperature gradients are set to simulate the temperature changes during the storage and combustion process of cigarettes, and the temperature response type fragrance release test is carried out on the composite perfumed aerogel. The results also show that the composite perfumed aerogel can accurately release fragrance under high temperature conditions, which meets the temperature-controlled fragrance release requirements during cigarette combustion.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of an oxidized graphene-cellulose composite fragranced aerogel, characterized in that: It comprises the following steps: (1) preparing a nanocellulose suspension by 2,2,6,6-tetramethylpiperidine oxide mediated oxidation reaction with north bleached softwood kraft pulp as raw material; (2) mixing and emulsifying a perfume to be added with the nanocellulose suspension to obtain an in-situ perfumed nanocellulose solution; (3) mixing the in-situ perfumed nanocellulose solution with a graphene oxide solution, freeze-drying to obtain a graphene oxide cellulose composite perfumed aerogel.

2. The process for the preparation of graphene oxide cellulose composite aerogels for perfuming according to claim 1, characterized in that: The oxidation reaction in step (1) comprises swelling the north bleached softwood kraft pulp in water, adding 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO to perform the oxidation reaction.

3. The method for preparing the graphene oxide-cellulose composite aroma gel according to claim 2, characterized in that: The mass ratio of 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO is (0.01-0.03):0.1:(0.2-1.5).

4. Process for the preparation of a graphene oxide-cellulose composite perfumed aerogel according to claim 2 or 3, characterized in that: The oxidation reaction is performed at room temperature for 4-8 hours.

5. The method for preparing the graphene oxide-cellulose composite aroma gel according to claim 1, characterized in that: The mass ratio of the perfume to be added to the solid in the nanocellulose suspension in step (2) is (0.5-2):

1.

6. The method for preparing the graphene oxide-cellulose composite aroma gel according to claim 1, characterized in that: The mass ratio of the in-situ perfumed nanocellulose solution to the solid in the graphene oxide solution in step (3) is (20-5):

1.

7. Process for the preparation of a graphene oxide-cellulose composite perfumed aerogel according to claim 5 or 6, characterized in that: The freeze-drying in step (3) is freeze-drying at a temperature of-80 to-5℃ for 12-24 hours, and then vacuum freeze-drying for 24-48 hours.

8. The method for preparing the graphene oxide-cellulose composite aroma gel according to claim 1, characterized in that: The perfume to be added in step (2) is dihydrojasmone.

9. An oxidized graphene-cellulose composite aerogel, characterized in that: Prepared by the preparation method in any one of claims 1-8.

10. Use of the graphene oxide cellulose composite perfumed aerogel in claim 9 in cigarette perfuming.

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