Preparation method and application of gelatin aerogel microspheres

Abstract

The invention relates to the technical field of adsorption material preparation, and discloses a preparation method and application of gelatin aerogel microspheres, the preparation method comprises the following steps: S1, putting gelatin in deionized water to prepare a gelatin solution with the concentration of 5-23%; s2, putting silicone oil into a container, and standing in a low-temperature environment; s3, dropwise adding the gelatin solution into silicone oil in a low-temperature environment, and solidifying in the low-temperature environment to obtain gelatin gel microspheres; s4, the gelatin gel microspheres are taken out, silicone oil on the surfaces of the gelatin gel microspheres is washed away, the gelatin gel microspheres are soaked with deionized water, and swollen gelatin wet gel microspheres are obtained; and S5, drying the gelatin wet gel microspheres to obtain the gelatin aerogel microspheres. The preparation process provided by the invention is simpler, and the prepared gelatin aerogel microspheres have larger specific surface area and higher adsorption efficiency; and the adsorbent is applied to adsorption of essence, spices and organic pollutants and can adsorb more spices.

Description

Technical Field

[0001] The invention relates to the technical field of adsorption material preparation, and in particular to a preparation method of gelatin aerogel microspheres and application thereof. Background Art

[0002] Aerogel is a lightweight solid material with a nanoporous three-dimensional skeleton structure. It is usually prepared from organic, inorganic or organic-inorganic co-precursors through a sol-gel process and a specific drying technology. Due to its excellent properties such as high porosity, low density, and ultra-large specific surface area, it can be used as an ideal adsorption filtration material and sustained-release material. Traditional inorganic aerogels have the problem of low mechanical strength and poor formability, so they are mostly powdery; organic aerogels are prone to environmental pollution during the production process; and carbon aerogels are expensive to prepare. In contrast, biomass-based aerogels not only retain many of the characteristics of aerogels, but also have outstanding advantages such as good biocompatibility, rich functional groups, low cost, and green recyclability.

[0003] Gelatin is a protein macromolecular compound formed by connecting multiple amino acids through amino and carboxyl groups, and is mainly derived from animal skin tissue and connective tissue. Its unique protein tissue structure and good biocompatibility give it excellent biological properties. In the field of aerogels, gelatin is often used as a composite reinforcement for aerogels with low mechanical strength, while related research on pure gelatin aerogels is relatively scarce; at the same time, compared with commonly used powder aerogels, aerogel microspheres have excellent properties such as large specific surface area, high adsorption efficiency, and easy recycling, and have broad application prospects.

[0004] The patent scheme with publication number CN114870816A discloses a biomass aerogel microsphere and its preparation method and application. A mixed solution of gelatin, chitosan and acetic acid solution is dripped into an alkaline solution, and the particle size of the microsphere is controlled by controlling the dripping rate to obtain microspheres with uniform particle size and containing a large number of amino groups. Composite microspheres are obtained by cross-linking reaction, and then caffeic acid is grafted and modified onto the surface of the composite microspheres by amidation reaction to further enrich the types and number of functional groups on the surface of the composite microspheres, and then freeze-dried to obtain biomass aerogel microspheres. The aerogel microspheres prepared by the aerogel microsphere preparation method are used in the textile printing and dyeing industry. The preparation process also requires chemical cross-linking reaction, and the process is relatively complicated. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method of gelatin aerogel microspheres and applications thereof. The preparation process is simpler, and the prepared gelatin aerogel microspheres have a larger specific surface area and a higher adsorption efficiency; they can be used to adsorb more flavors, fragrances and organic pollutants.

[0006] The present invention solves the above technical problems by the following technical means: In a first aspect, the present invention discloses a method for preparing gelatin aerogel microspheres, comprising the following steps: S1. Place gelatin in deionized water to prepare a gelatin solution with a concentration of 5%-23%; S2. Put silicone oil in a container and place it in a low temperature environment; S3, adding the gelatin solution dropwise into the silicone oil in a low temperature environment, and solidifying it in a low temperature environment to obtain gelatin gel microspheres; S4, taking out the gelatin gel microspheres, washing off the silicone oil on the surface, and soaking them in deionized water to obtain swollen gelatin wet gel microspheres; S5. Drying the wet gelatin microspheres to obtain gelatin aerogel microspheres.

[0007] Furthermore, when preparing the gelatin solution in step S1, the gelatin is placed in deionized water and stirred in a water bath at a temperature of 35-50°C.

[0008] Furthermore, in step S2, the depth of the silicone oil in the container is 5-8 cm, and the standing time is 10-30 min.

[0009] Furthermore, in step S3, when the gelatin solution is added drop by drop into the silicone oil in the low temperature environment, a syringe is used for the addition, and the syringe is kept perpendicular to the surface of the silicone oil during the addition.

[0010] Furthermore, in step S3, when the gelatin solution is added dropwise by the syringe, the outlet of the syringe is 2-3 cm away from the surface of the silicone oil, and the outlet size of the syringe is 1.5-3.0 mm.

[0011] Furthermore, the low temperature environment in steps S2 and S3 is 2-6°C, and the solidification time is 10-25 minutes.

[0012] Furthermore, when washing away the silicone oil on the surface in step S4, n-hexane is used to wash away the silicone oil on the surface of the gelatin gel microspheres; and the immersion time in deionized water is 24-60 hours.

[0013] Furthermore, the drying of the wet gelatin microspheres in step S5 is performed by vacuum freeze drying.

[0014] Furthermore, the freezing temperature of the vacuum freeze drying is -35°C to -55°C, the freezing time is 2.5-3.5 hours, and the freeze drying time is 10-24 hours.

[0015] In a second aspect, the present invention further discloses an application of the gelatin aerogel microspheres as described above, wherein the application is application in the adsorption of flavors, fragrances and organic pollutants.

[0016] Beneficial effects of the present invention: 1. The gelatin aerogel microspheres prepared by the method of the present invention have a large specific surface area and are easy to recycle. The diameter is 2-5 mm, the density is 0.116 g / cm3-0.290 g / cm3, and the porosity is 86.83%-93.64%. In terms of fragrance adsorption application, compared with the known activated carbon adsorption of ethyl acetate of 881.0 mg / g in 24 hours, the gelatin aerogel microspheres obtained by the present invention have an adsorption capacity of ethyl acetate of up to 3881.27 mg / g in 24 hours; the 1 hour retention rate under open conditions at room temperature is 52.47%, the 2 hour retention rate is 36.59%, and the 3 hour retention rate is 24.47%. It has excellent adsorption and sustained release characteristics and has important application value in the field of adsorption and sustained release of flavors and fragrances and in the field of oil removal and decontamination.

[0017] 2. The preparation process of the gelatin aerogel microspheres of the present invention adopts a dripping method, which no longer requires a cross-linking reaction. The entire preparation process is simple and has the potential for mass production and promotion. The macroscopic morphology of gelatin aerogel is spherical, and the microsphere forming process is a physical gelation process. It uses the principle that oil and water are immiscible and the protein molecular chain of gelatin changes from an irregular coil to a helical conformation at low temperature, and the three helices are entangled into cross-linking points to form a gel. There is no chemical reaction, and it is green and convenient.

[0018] 3. The raw material gelatin used in the present invention has a wide range of sources and is green, harmless and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Diameter test diagram of some samples of gelatin aerogel microspheres prepared in Examples 1 to 4; Figure 2 This is an electron microscope scanning image of the gelatin aerogel microspheres prepared in Example 1.

[0020] Figure 3 This is an electron microscope scanning image of the gelatin aerogel microspheres prepared in Example 2.

[0021] Figure 4 This is an electron microscope scanning image of the gelatin aerogel microspheres prepared in Example 4. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to embodiments: Example 1

[0023] This embodiment is a method for preparing 5% concentration gelatin aerogel microspheres, comprising the following steps: S1. Mix 0.5264 g gelatin with 10 ml deionized water in a beaker, then place the beaker in a water bath and stir at 35°C and 20 r / min until the gelatin is completely dissolved to obtain a 5% gelatin solution, and keep it warm at this temperature for later use.

[0024] S2. Pour silicone oil to a depth of 8 cm into a beaker and place it at 2°C for 30 minutes in a refrigerator. S3. Use a syringe (needle diameter of 1.5 mm) to absorb the gelatin solution stored at a constant temperature in step S1 and drip it into the refrigerated silicone oil. During this process, ensure that the syringe needle is perpendicular to the silicone oil surface, the vertical distance is controlled at 2 cm, and the syringe drips the solution into the silicone oil every 0.5 seconds, and the solidification time is 25 minutes; the gelatin solution is spherical in the silicone oil, and the microspheres sink to the bottom of the beaker in the silicone oil, slowly gelling in the process to form spherical gelatin gel.

[0025] S4. Take out the microspheres in the silicone oil in step S3, wash them with n-hexane three times to wash away the excess silicone oil on the surface of the microspheres, then wash the microspheres with a large amount of deionized water and soak them in deionized water for 24 hours to obtain gelatin wet gel microspheres with a concentration of 5%.

[0026] S5. The wet gelatin microspheres obtained in step S4 are subjected to vacuum freeze drying treatment; the samples are frozen at a cold trap temperature of -45°C for 3 hours, and then the samples are taken out and placed in a material bin for vacuum drying for 24 hours to obtain gelatin aerogel microspheres. Example 2

[0027] This embodiment is a method for preparing 14% concentration gelatin aerogel microspheres, comprising the following steps: S1. Mix 1.628 g of gelatin with 10 ml of deionized water in a beaker, then place the beaker in a water bath and stir at 40°C and 20 r / min until the gelatin is completely dissolved to obtain a 14% gelatin solution. Keep the solution warm at this temperature for later use.

[0028] S2. Pour silicone oil to a depth of 7 cm into a beaker and place it at 4°C for 25 minutes in a refrigerator. S3. Use a syringe (needle diameter of 2.0 mm) to absorb the gelatin solution stored at a constant temperature in step S1 and drip it into the refrigerated silicone oil. During this process, ensure that the syringe needle is perpendicular to the silicone oil surface, the vertical distance is controlled at 2.5 cm, and the syringe drips the solution into the silicone oil every 0.5 seconds, and the solidification time is 20 minutes; the gelatin solution is spherical in the silicone oil, and the microspheres sink to the bottom of the beaker in the silicone oil, slowly gelling in the process to form spherical gelatin gel.

[0029] S4. Take out the microspheres in the silicone oil in step S3, wash them with n-hexane three times to remove the excess silicone oil on the surface of the microspheres, then wash the microspheres with a large amount of deionized water and soak them in deionized water for 48 hours to obtain gelatin wet gel microspheres with a concentration of 14%.

[0030] S5. The wet gelatin microspheres obtained in step S4 are subjected to vacuum freeze drying treatment; the samples are frozen at a cold trap temperature of -45°C for 3.0 hours, and then the samples are taken out and placed in a material bin for vacuum drying for 24 hours to obtain gelatin aerogel microspheres. Example 3

[0031] This embodiment is a method for preparing gelatin aerogel microspheres with a concentration of 16.7%, comprising the following steps: S1. Mix 2 g of gelatin with 10 ml of deionized water in a beaker, then place the beaker in a water bath and stir at 45°C and 20 r / min until the gelatin is completely dissolved to obtain a 16.7% gelatin solution. Keep the solution warm at this temperature for later use.

[0032] S2. Pour silicone oil to a depth of 6 cm into a beaker and place it at 4°C for 20 minutes in a refrigerator. S3. Use a syringe (needle diameter of 2.5 mm) to absorb the gelatin solution stored at a constant temperature in step S1 and drip it into the refrigerated silicone oil. During this process, ensure that the syringe needle is perpendicular to the silicone oil surface, the vertical distance is controlled at 2.5 cm, and the syringe drips the solution into the silicone oil every 0.5 seconds, and the solidification time is 20 minutes; the gelatin solution is spherical in the silicone oil, and the microspheres sink to the bottom of the beaker in the silicone oil, slowly gelling in the process to form spherical gelatin gel.

[0033] S4. Take out the microspheres in the silicone oil in step S3, wash them with n-hexane three times to remove the excess silicone oil on the surface of the microspheres, then wash the microspheres with a large amount of deionized water and soak them in deionized water for 48 hours to obtain gelatin wet gel microspheres with a concentration of 16.7%.

[0034] S5. The wet gelatin microspheres obtained in step S4 are subjected to vacuum freeze drying treatment; the samples are frozen at a cold trap temperature of -45°C for 3.0 hours, and then the samples are taken out and placed in a material bin for vacuum drying for 24 hours to obtain gelatin aerogel microspheres. Example 4

[0035] This embodiment is a method for preparing 23% concentration gelatin aerogel microspheres, comprising the following steps: S1. Mix 3g gelatin with 10ml deionized water in a beaker, then place the beaker in a water bath and stir at 50°C and 20r / min until the gelatin is completely dissolved to obtain a 23% gelatin solution. Keep the solution warm at this temperature for later use.

[0036] S2. Pour silicone oil to a depth of 5 cm into the beaker, place it at 6°C, and refrigerate it for 10 minutes; S3. Use a syringe (needle diameter of 3.0 mm) to absorb the gelatin solution stored at a constant temperature in step S1 and drip it into the refrigerated silicone oil. During this process, ensure that the syringe needle is perpendicular to the silicone oil surface, the vertical distance is controlled at 3.0 cm, and the syringe drips the solution into the silicone oil every 0.5 seconds, and the solidification time is 10 minutes; the gelatin solution is spherical in the silicone oil, and the microspheres sink to the bottom of the beaker in the silicone oil, slowly gelling in the process to form spherical gelatin gel.

[0037] S4. Take out the microspheres in the silicone oil in step S3, wash them with n-hexane three times to wash away the excess silicone oil on the surface of the microspheres, then wash the microspheres with a large amount of deionized water and soak them in deionized water for 60 hours, thereby obtaining gelatin wet gel microspheres with a concentration of 23%.

[0038] S5. The wet gelatin microspheres obtained in step S4 are subjected to vacuum freeze drying treatment; the samples are frozen at a cold trap temperature of -45°C for 3 hours, and then the samples are taken out and placed in a material bin for vacuum drying for 24 hours to obtain gelatin aerogel microspheres.

[0039] like Figure 1 As shown in the figure, some samples of gelatin aerogel microspheres prepared in Examples 1 to 4 are shown in Figure 1 As shown, it is determined that their diameters are about 2-5 mm; through density and porosity tests, their density is 0.116 g / cm3-0.290 g / cm3, and their porosity is 86.83%-93.64%.

[0040] The gelatin aerogel microspheres prepared in Examples 1 to 4 were subjected to an adsorption test of ethyl acetate, and the specific method was as follows: 1. Take the gelatin aerogel microspheres obtained in the embodiment with a mass of m1, put them into a container, pour in an appropriate amount of ethyl acetate, seal the container, and perform constant temperature static adsorption in a 35°C oven. After adsorption for 24 hours, take out the gelatin aerogel microspheres and wipe off the excess ethyl acetate on the surface, weigh the mass of the gelatin aerogel microspheres after adsorption m2; and calculate the adsorption amount α of ethyl acetate adsorbed by the gelatin aerogel microspheres using formula (1).

[0041] (1) 2. Carry out adsorption experiment according to step 1, m1=0.0219g, m2=0.1069g, adsorption amount α is 3881.27mg / g.

[0042] 3. Carry out adsorption experiment according to step 1, weigh the mass of gelatin aerogel microspheres after adsorbing ethyl acetate as m2, place the gelatin aerogel microspheres after adsorbing ethyl acetate under open conditions at room temperature, and let the ethyl acetate evaporate naturally; weigh the mass of gelatin aerogel microspheres after volatilization for 1 hour as m3; weigh the mass of gelatin aerogel microspheres after volatilization for 2 hours as m4; weigh the mass of gelatin aerogel microspheres after volatilization for 3 hours as m5; and use formula (2) to calculate the fragrance retention rate β of gelatin aerogel at different volatilization times.

[0043] ,x=3,4,5 (2) 4. Carry out the fragrance volatilization test experiment according to step 3, m3=0.0665g, m4=0.0530g, m5=0.0427g, and calculate according to formula (2) that the 1h retention rate β is 52.47%, the 2h retention rate β is 36.59%, and the 3h retention rate β is 24.47%.

[0044] The electron microscope scanning of the gelatin aerogel microspheres in Example 1 is as follows: Figure 2 As shown, the electron microscope scanning of the gelatin aerogel microspheres in Example 2 is as follows Figure 3 The electron microscope scanning of the gelatin aerogel microspheres in Example 4 is as follows: Figure 4 As shown. Figure 2-Figure 4 It can be seen that the gelatin aerogel microspheres prepared by the present invention have a well-developed pore structure, high porosity, large specific surface area, and good adsorption rate.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The techniques, shapes, and structural parts not described in detail in the present invention are all known technologies.

Claims

1. A method for preparing gelatin aerogel microspheres, characterized in that: The following steps are involved: S1. Place gelatin in deionized water to prepare a gelatin solution with a concentration of 5%-23%; S2. Put silicone oil in a container and place it in a low temperature environment; S3, adding the gelatin solution dropwise into the silicone oil in a low temperature environment, and solidifying it in a low temperature environment to obtain gelatin gel microspheres; S4, taking out the gelatin gel microspheres, washing off the silicone oil on the surface, and soaking them in deionized water to obtain swollen gelatin wet gel microspheres; S5. Drying the wet gelatin microspheres to obtain gelatin aerogel microspheres.

2. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: When preparing the gelatin solution in step S1, gelatin is placed in deionized water and stirred in a water bath at a temperature of 35-50°C.

3. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: In the step S2, the depth of the silicone oil in the container is 5-8 cm, and the standing time is 10-30 min.

4. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: In the step S3, when the gelatin solution is added drop by drop into the silicone oil in the low temperature environment, a syringe is used for the addition, and the syringe is kept perpendicular to the surface of the silicone oil during the addition.

5. The method for preparing gelatin aerogel microspheres according to claim 4, characterized in that: In step S3, when the gelatin solution is added dropwise by the syringe, the outlet of the syringe is 2-3 cm away from the surface of the silicone oil, and the outlet size of the syringe is 1.5-3.0 mm.

6. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: The low temperature environment in steps S2 and S3 is 2-6° C., and the solidification time is 10-25 minutes.

7. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: When washing away the silicone oil on the surface in step S4, n-hexane is used to wash away the silicone oil on the surface of the gelatin gel microspheres; the soaking time in deionized water is 24-60 hours.

8. The method for preparing gelatin aerogel microspheres according to claim 1, characterized in that: The drying of the wet gelatin microspheres in step S5 is performed by vacuum freeze drying.

9. The method for preparing gelatin aerogel microspheres according to claim 8, characterized in that: The freezing temperature of the vacuum freeze drying is -35°C to -55°C; the freezing time is 2.5-3.5 hours; and the freeze drying time is 10-24 hours.

10. An application of gelatin aerogel microspheres as claimed in any one of claims 1 to 9, characterized in that: The application is the application in adsorbing flavors, fragrances and organic pollutants.

Images