Photocatalytic porous aerogel with ethylene degradation performance and preparation method and application thereof

Abstract

This invention discloses a photoactivated porous aerogel with ethylene degradation properties, its preparation method, and its applications. The preparation method includes: mixing a gelatin solution and a resin solution for a first crosslinking reaction, followed by adding a polythioctic acid solution for a second crosslinking reaction to obtain a gelatin-resin / polythioctic acid solution; adding a silver source to the gelatin-resin / polythioctic acid solution and mixing thoroughly, then subjecting the mixture to static degassing, gradient cooling, freeze-curing, and freeze-drying to obtain a gelatin-resin / polythioctic acid / silver ion composite aerogel precursor; and subjecting the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor to a catalytic in-situ reduction reaction to obtain a photoactivated porous aerogel with ethylene degradation properties. The photoactivated porous aerogel prepared by this invention has a three-dimensional porous network structure, exhibits sensitive photoresponse, strong surface hydrophobicity, excellent UV blocking performance, good thermal stability, and also possesses high encapsulation efficiency and excellent biocompatibility.

Description

Technical Field

[0001] This invention belongs to the technical field of fruit and vegetable storage and preservation materials, specifically relating to a photoactivated porous aerogel with ethylene degradation properties, its preparation method, and its application. Background Technology

[0002] Postharvest ripening and senescence of fruits and vegetables are induced by ethylene, a key factor leading to quality decline and postharvest losses. To control ethylene release, the industry has developed various technologies, including physical adsorbents, chemical scavengers, low-temperature inhibition, and catalytic degradation. However, existing technologies often struggle to simultaneously achieve high adsorption capacity, sustained catalytic efficiency, and long-term stability, particularly in achieving efficient synergy between "static adsorption" and "dynamic catalytic degradation" of ethylene. Physical adsorbents are easily saturated and cannot decompose ethylene, chemical scavengers are rapidly consumed and prone to failure, while traditional photocatalytic systems generally suffer from low catalytic activity, slow response, and insufficient contact with ethylene gas, making it difficult to achieve sustained and efficient ethylene control in real storage environments. Against this backdrop, developing a smart material capable of simultaneously achieving efficient ethylene capture and immediate photocatalytic degradation has become a crucial issue for overcoming postharvest preservation technology bottlenecks and driving the industry towards green and efficient development.

[0003] In recent years, photocatalytic degradation of ethylene has been considered a highly promising green preservation strategy. The core technology lies in developing functional materials that combine high adsorption and high catalytic activity. An ideal photocatalytic ethylene removal material should possess a highly developed porous structure to efficiently enrich ethylene molecules, while simultaneously loading a photocatalyst that can efficiently utilize light energy. This enables immediate degradation of adsorbed ethylene and in-situ regeneration of the material, forming a continuous "adsorption-catalysis" synergistic cycle. However, existing material systems generally suffer from problems such as separation of adsorption sites and catalytically active sites, high interfacial mass transfer resistance, high recombination rates of photogenerated carriers, and insufficient catalytic stability, making it difficult to achieve sustained and efficient ethylene removal in practical applications.

[0004] To overcome these limitations, researchers have attempted to enhance material properties by constructing porous supports to load photocatalysts. Bio-based aerogels, due to their wide availability, biodegradability, tunable structure, and high specific surface area, are considered ideal adsorption supports and functional matrices. However, conventional aerogels often have limited functionality and struggle to achieve uniform, stable loading and efficient interfacial coupling of photocatalysts. Meanwhile, silver-based nanomaterials have attracted widespread attention due to their strong visible light responsiveness, high photocatalytic activity, and excellent antibacterial properties, but their tendency to aggregate and poor stability limit their practical applications. Summary of the Invention

[0005] The main objective of this invention is to provide a photoactivated porous aerogel with ethylene degradation properties, its preparation method, and its application, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] This invention provides a method for preparing a photoactivated porous aerogel with ethylene degradation properties, comprising:

[0008] A gelatin solution and a resin solution were mixed to carry out a first cross-linking reaction, and then a polythioctic acid solution was added to carry out a second cross-linking reaction to obtain a gelatin-resin / polythioctic acid solution.

[0009] A silver source was added to the gelatin-resin / polythioctic acid solution and mixed thoroughly. Then, the mixture was subjected to static degassing, gradient cooling, freeze curing, and freeze drying to obtain a gelatin-resin / polythioctic acid / silver ion composite aerogel precursor.

[0010] Furthermore, the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor is subjected to a catalytic in-situ reduction reaction to obtain a gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with an Ag / Ag2S heterostructure, namely a photoactivated porous aerogel with ethylene degradation properties.

[0011] The present invention also provides a photoactivated porous aerogel with ethylene degradation properties prepared by the aforementioned preparation method. The photoactivated porous aerogel has a three-dimensional porous network structure and Ag / Ag2S heterojunctions are uniformly dispersed in the photoactivated porous aerogel.

[0012] This invention also provides the application of the aforementioned photoactivated porous aerogel with ethylene degradation properties in the storage and preservation of fruits and vegetables.

[0013] This invention also provides a method for preserving fruits and vegetables, comprising: placing the fruits or vegetables in a storage box provided with the aforementioned photoactivated porous aerogel with ethylene degradation properties and sealing and storing them.

[0014] The storage environment is characterized by an ambient temperature of 20-25°C and a relative humidity of 70-80%.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) The preparation method provided by the present invention has the advantages of mild process conditions, low energy consumption, simple operation and controllable cost, and is suitable for large-scale preparation;

[0017] (2) The photoactivated porous aerogel prepared by the present invention has a three-dimensional porous network structure, sensitive photoresponse, strong surface hydrophobicity, excellent ultraviolet barrier performance, good thermal stability, and at the same time has high encapsulation rate and excellent biocompatibility.

[0018] (3) The porous framework of the photoactivated porous aerogel prepared in this invention can achieve efficient physical adsorption of ethylene gas, while the Ag / Ag2S heterojunction formed in situ can significantly promote the effective separation of photogenerated electron-hole pairs under light irradiation, thereby dynamically catalyzing the degradation of adsorbed ethylene and realizing the efficient synergistic effect of static adsorption and photocatalytic dynamic degradation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figures 1a-1c The images show scanning electron microscopy, water contact angle, and UV barrier properties of the gelatin-resin and gelatin-resin / polythiooctanoic acid composite aerogels prepared in Example 1 of this invention.

[0021] Figures 2a-2b Fourier transform infrared spectra and X-ray diffraction patterns of the gelatin-resin / polythioctic acid composite aerogel, the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor, and the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel prepared in Comparative Example 1 and Example 1 of this invention.

[0022] Figure 3 Atomic force microscopy and scanning electron microscopy images of gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels with different proportions prepared in Examples 1-5 of the present invention.

[0023] Figures 4a-4b The UV-Vis diffuse reflectance spectra and corresponding Tauc curves of the gelatin-resin / polythioctic acid composite aerogels and gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels prepared in Comparative Example 1 and Examples 1-5 of this invention are shown.

[0024] Figures 5a-5b The thermal stability diagrams are shown for the gelatin-resin / polythioctic acid composite aerogels and gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels prepared in Comparative Example 1 and Examples 1-5 of the present invention.

[0025] Figure 6The diagram shows the encapsulation efficiency of silver in gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels prepared in different proportions in Examples 1-5 of this invention.

[0026] Figure 7 The graph shows the adsorption capacity of gelatin-resin / polythioctic acid composite aerogels and gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels with different proportions for ethylene gas prepared in Comparative Example 1 and Examples 1-5 of the present invention.

[0027] Figures 8a-8b The graph shows the degradation performance of gelatin-resin / polythioctic acid composite aerogels and gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels with different proportions for ethylene gas prepared in Comparative Example 1 and Examples 1-5 of the present invention.

[0028] Figure 9 The images show the cytotoxicity of the gelatin-resin / polythioic acid composite aerogels and gelatin-resin / polythioic acid / silver nanoparticle composite aerogels prepared in Comparative Example 1 and Examples 1-5 of this invention.

[0029] Figures 10a-10e The images show the application of the gelatin-resin / polythioic acid composite aerogel and the gelatin-resin / polythioic acid / silver nanoparticle composite aerogel prepared in Comparative Example 1 and Example 1 (light-shielded group and light-exposed group) of the present invention in tomato preservation. Detailed Implementation

[0030] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] Specifically, as one aspect of the technical solution of this invention, a method for preparing a photoactivated porous aerogel with ethylene degradation properties includes:

[0032] A gelatin solution and a resin solution were mixed to carry out a first cross-linking reaction, and then a polythioctic acid solution was added to carry out a second cross-linking reaction to obtain a gelatin-resin / polythioctic acid solution.

[0033] A silver source was added to the gelatin-resin / polythioctic acid solution and mixed thoroughly. Then, the mixture was subjected to static degassing, gradient cooling, freeze curing, and freeze drying to obtain a gelatin-resin / polythioctic acid / silver ion composite aerogel precursor.

[0034] Furthermore, the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor is subjected to a catalytic in-situ reduction reaction to obtain a gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with an Ag / Ag2S heterostructure, namely a photoactivated porous aerogel with ethylene degradation properties.

[0035] In some preferred embodiments, the preparation method specifically includes:

[0036] Gelatin and resin were separately dispersed in an aqueous acetic acid solution and then subjected to ultrasonic treatment to form a gelatin solution and a resin solution, respectively.

[0037] The gelatin solution and resin solution are mixed and the pH value is adjusted to 4.0~4.5. The first cross-linking reaction is carried out for 1~2 hours under the conditions of 300-500 rpm and 50~60℃. Then the pH value is adjusted to 7.0~8.0 to obtain a gelatin-resin mixed solution.

[0038] Furthermore, polythioctic acid is pre-dissolved in anhydrous ethanol, and then water is added to fully dissolve it to form a polythioctic acid solution. This solution is then mixed with a gelatin-resin mixed solution and subjected to a second crosslinking reaction for 2-3 hours at a speed of 400-600 rpm and a temperature of 40-50°C to obtain a gelatin-resin / polythioctic acid solution.

[0039] Furthermore, the volume concentration of the acetic acid aqueous solution is 1-2%.

[0040] Furthermore, the mass-to-volume ratio of the gelatin to the acetic acid aqueous solution is 1g:10mL to 1g:30mL.

[0041] Furthermore, the mass-to-volume ratio of the resin to the aqueous acetic acid solution is 1g:10mL to 1g:30mL.

[0042] Furthermore, the volume ratio of the gelatin solution to the resin solution is 1:1 to 1:1.5.

[0043] Furthermore, the mass-to-volume ratio of the polythioctic acid to anhydrous ethanol is 0.5~1.5g:5~10mL.

[0044] Furthermore, the mass-to-volume ratio of the polythiooctanoic acid to water is 1g:50mL to 1g:200mL.

[0045] Furthermore, the volume ratio of the polythioctic acid solution to the gelatin-resin mixture is 1:1 to 1:1.2.

[0046] In some preferred embodiments, the preparation method specifically includes: adding a silver source to the gelatin-resin / polythioctic acid solution and stirring for 2-3 hours at a speed of 400-600 rpm and a temperature of 40-50°C; then allowing the obtained solution to stand at room temperature to degas; subsequently, gradient cooling to form a hydrogel network; and then freeze-curing and freeze-drying to obtain a gelatin-resin / polythioctic acid / silver ion composite aerogel precursor.

[0047] Furthermore, the ratio of the gelatin-resin / polythioctic acid solution to the silver source is 180~220mL:0.2~2.5g.

[0048] Furthermore, the molar ratio of polythioctic acid to silver source in the gelatin-resin / polythioctic acid solution is 1:0.25 to 1:3.

[0049] Furthermore, the silver source includes any one or more combinations of silver nitrate, silver acetate, silver sulfate, and silver trifluoroacetate, and is not limited thereto.

[0050] Furthermore, the temperature for static degassing is 20~25℃, and the time is 2~3h.

[0051] Furthermore, the gradient cooling process for forming the hydrogel network is carried out at a temperature of 4-5°C for 8-10 hours.

[0052] Furthermore, the freeze-curing temperature is -25~-20℃, and the time is 10~12h.

[0053] Furthermore, the freeze-drying temperature is -80 to -60°C, and the time is 20 to 24 hours.

[0054] In some preferred embodiments, the preparation method specifically includes: subjecting the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor to a catalytic in-situ reduction reaction under simulated sunlight irradiation to form Ag / Ag2S heterojunctions in situ, thereby obtaining a gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with an Ag / Ag2S heterojunction structure.

[0055] Furthermore, the simulated sunlight irradiation conditions include: T5 LED white light tubes with a power of 15~20W, a light source distance of 30~40cm, and an irradiation duration of 3~5h.

[0056] In some preferred embodiments, the method for preparing the photoactivated porous aerogel with ethylene degradation properties includes:

[0057] (1) Disperse gelatin and resin powder separately in an aqueous acetic acid solution, sonicate to aid dissolution, and after complete dissolution, mix the two in proportion, adjust the pH, and carry out a cross-linking reaction under stirring. After thorough stirring, adjust the pH to an appropriate level to obtain a gelatin-resin mixed solution. Separately, pre-dissolve a certain amount of polythioctic acid powder in a small amount of anhydrous ethanol, and add distilled water to dissolve it completely. Then, add the polythioctic acid solution to the above gelatin-resin mixed solution in proportion, carry out a cross-linking reaction under stirring, and after complete reaction, obtain a gelatin-resin / polythioctic acid mixed solution. Let the two solutions stand at room temperature to degas, then gradually lower the temperature to form a hydrogel network at low temperature, then further freeze-cure, and finally freeze-dry to obtain a gelatin-resin matrix and a gelatin-resin / polythioctic acid composite aerogel matrix.

[0058] (2) Take the gelatin-resin / polythioctic acid mixed solution obtained in step (1), add silver nitrate powder of different proportions, stir to make the silver ions uniformly loaded, stir thoroughly, let the solution stand at room temperature to degas, then cool down in a gradient, first form a hydrogel network at low temperature, then freeze solidify, and finally freeze dry to obtain gelatin-resin / polythioctic acid / silver ion composite aerogel precursors with different silver ion proportions.

[0059] (3) The aerogel precursor obtained in step (2) is subjected to photocatalytic in-situ reduction reaction under certain conditions, simulating sunlight irradiation, so that silver ions are reduced and partially converted into silver element, forming a uniformly dispersed Ag / Ag2S heterostructure, and finally obtaining gelatin-resin / polythioctic acid / silver nanoparticle composite aerogels with different silver loading.

[0060] Preferably, in step (1), the gelatin and resin powder are dispersed in an aqueous acetic acid solution and solubilized by ultrasound. The mass of the gelatin and resin powder is 2-3g, the concentration of the aqueous acetic acid solution is 1-2% (v / v), the volume is 40-60mL, the mass-to-volume ratio (g / mL) of the gelatin and resin powder to the aqueous acetic acid solution is 1:10-1:30, and the ultrasound duration is 0.5-1h.

[0061] Preferably, after the gelatin solution and resin solution are fully dissolved in step (1), they are mixed in proportion, the pH is adjusted, and a cross-linking reaction is carried out under stirring. The mixing ratio of gelatin solution and resin solution is 1:1 to 1:1.5, the pH value after mixing is 4.0 to 4.5, the stirring speed is 300 to 500 rpm, the temperature is 50 to 60°C, and the duration is 1 to 2 hours.

[0062] Preferably, after thorough stirring in step (1), the solution is adjusted to an appropriate pH, and the pH of the gelatin-resin mixture should be adjusted to 7.0~8.0.

[0063] Preferably, in step (1), a certain amount of polythioctic acid powder is pre-dissolved in a small amount of anhydrous ethanol and then dissolved in distilled water. The mass of the polythioctic acid powder is 0.5~1.5g, the volume of the anhydrous ethanol is 5~10mL, the volume of the distilled water is 90~95mL, and the mass-volume ratio (g / mL) of the polythioctic acid powder to the distilled water is 1:50~1:200.

[0064] Preferably, in step (1), the polythioctic acid solution is added to the gelatin-resin mixture in proportion, and a crosslinking reaction is carried out under stirring. The mixing ratio of polythioctic acid solution and gelatin-resin mixture is 1:1 to 1:1.2, the stirring speed is 400 to 600 rpm, the temperature is 40 to 50°C, and the duration is 2 to 3 hours.

[0065] Preferably, after the complete reaction described in step (1), the two solutions are allowed to stand at room temperature to degas, followed by a gradient cooling process to form a hydrogel network at low temperature, then further freeze-cured, and finally freeze-dried to obtain a gelatin-resin matrix and a gelatin-resin / polythioctic acid composite aerogel matrix. The temperature for standing degassing is 20~25℃ for 2~3h, the temperature for forming the hydrogel network is 4~5℃ for 8~10h, the temperature for freeze-curing is -25~-20℃ for 10~12h, and the temperature for freeze-drying is -80~-60℃ for 20~24h.

[0066] Preferably, in step (2), the gelatin-resin / polythioctic acid mixed solution obtained in step (1) is taken, and silver nitrate powder of different proportions is added. The silver ions are uniformly loaded by stirring. The volume of the gelatin-resin / polythioctic acid mixed solution is 180~220mL, the mass of silver nitrate powder is 0.2~2.5g, the molar ratio of polythioctic acid added to silver nitrate powder in the gelatin-resin / polythioctic acid mixed solution is 1:0.25~1:3, the stirring speed is 400~600rpm, the temperature is 40~50℃, and the time is 2~3h.

[0067] Preferably, after thorough stirring in step (2), the solution is allowed to stand at room temperature to degas, followed by gradient cooling to form a hydrogel network at low temperature, then further freeze-cured, and finally freeze-dried to obtain gelatin-resin / polythioctic acid / silver ion composite aerogel precursors with different silver ion ratios. The temperature for standing degassing is 20~25℃ for 2~3h, the temperature for forming the hydrogel network is 4~5℃ for 8~10h, the temperature for freeze-curing is -25~-20℃ for 10~12h, and the temperature for freeze-drying is -80~-60℃ for 20~24h.

[0068] As a preferred embodiment, in step (3), the aerogel precursor obtained in step (2) is subjected to photocatalytic in-situ reduction reaction under certain conditions, simulating sunlight irradiation, so that silver ions are reduced and partially converted into elemental silver, forming a uniformly dispersed Ag / Ag2S heterostructure, and finally obtaining gelatin-resin / polythioctic acid@silver nanoparticle composite aerogels with different silver loadings. The irradiation conditions are: using a T5 LED white light tube simulating sunlight, with a power of 15~20W, a light source distance of 30~40cm, and an irradiation time of 3~5h.

[0069] Another aspect of the present invention provides a photoactivated porous aerogel with ethylene degradation properties prepared by the aforementioned preparation method, wherein the photoactivated porous aerogel has a three-dimensional porous network structure and Ag / Ag2S heterojunctions are uniformly dispersed in the photoactivated porous aerogel.

[0070] Another aspect of the present invention provides the application of the aforementioned photoactivated porous aerogel with ethylene degradation properties in the storage and preservation of fruits and vegetables.

[0071] Another aspect of the present invention provides a method for preserving fruits and vegetables, comprising: placing the fruits or vegetables in a storage box provided with the aforementioned photoactivated porous aerogel having ethylene degradation properties and sealing and storing them.

[0072] The storage environment is characterized by an ambient temperature of 20-25°C and a relative humidity of 70-80%.

[0073] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0074] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0075] Example 1

[0076] This embodiment provides a method for preparing a photoactivated porous aerogel with high ethylene degradation performance, specifically including the following steps:

[0077] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution, sonicate for 1h to aid dissolution, and after complete dissolution, mix the two in a volume ratio of 1:1, adjust the pH to 4.2, and carry out cross-linking reaction under stirring at 500rpm, 60℃ and for 1h. After thorough stirring, adjust the pH to 7.5 to obtain a gelatin-resin mixed solution; Separately, predissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol, add 90mL of distilled water to fully dissolve to obtain a polythioctic acid solution, and then mix the polythioctic acid solution in a 1:1 ratio. A 1:1 ratio was added to the above gelatin-resin mixture, and a cross-linking reaction was carried out under stirring at 600 rpm, 45°C, and 3 h. After the reaction was complete, a gelatin-resin / polythioctic acid mixed solution was obtained. The gelatin-resin mixed solution and the gelatin-resin / polythioctic acid mixed solution were allowed to stand at 25°C for 3 h to degas, and then the temperature was gradually reduced. First, the mixture was placed at 4°C for 8 h to form a hydrogel network, and then placed at -20°C for 12 h for further freeze-curing. Finally, the mixture was freeze-dried at -60°C for 24 h to obtain the gelatin-resin and gelatin-resin / polythioctic acid composite aerogel matrix.

[0078] (2) Take 200 mL of the gelatin-resin / polythioctic acid mixed solution obtained in step (1), add 0.82 g of silver nitrate powder (i.e., the molar ratio of polythioctic acid to silver ions is 1:1), stir at 600 rpm, 45°C for 3 h to uniformly load silver ions, and after thorough stirring, let the solution stand at 25°C for 3 h to degas, then gradually lower the temperature, first place at 4°C for 8 h to form a hydrogel network, then place at -20°C for 12 h for further freeze-curing, and finally freeze-dry at -60°C for 24 h to obtain the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor.

[0079] (3) The aerogel precursor obtained in step (2) was subjected to photocatalytic in-situ reduction under simulated sunlight using a T5 LED white light tube (power 16W, light source distance 35cm, irradiation time 4h). This reduced silver ions and partially converted them into elemental silver, forming a uniformly dispersed Ag / Ag2S heterojunction structure. Finally, the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with a molar ratio of 1:1 to polythioctic acid and silver ions, as described in Example 1, was obtained. Finally, in the tomato preservation experiment, the aerogel was divided into a light-shielded group and a light-illuminated group. The light-illuminated group was still subjected to simulated sunlight using a T5 LED white light tube (power 16W, light source distance 35cm).

[0080] (4) In an orchard in Anhui Province, China, fresh green-ripe tomatoes were carefully selected to ensure that the selected fruits were similar in shape, size, color, and ripeness, and had no obvious visual defects or diseases. After harvesting, the fruits were quickly transported to the laboratory for further processing. In the laboratory, the fruits were first thoroughly washed with distilled water and air-dried. Then, aerogel material with a radius of 3 cm and a height of 1 cm was attached to the bottom of the lid of a plastic box of uniform size and specifications. The aerogel material from Comparative Example 1 and Example 1 (divided into a light-protected group and a light-exposed group) was attached to the bottom of the plastic box lid, and a plastic box without aerogel material was used as a control group. The fruits were then divided into 4 groups and sealed in four types of plastic boxes. Each group had 20 boxes, and each box contained 8 tomatoes. After treatment, the boxes were stored in an incubator at 25°C and 75% relative humidity. Samples were collected regularly on days 0, 1, 3, 5, 7, and 9, and various parameters such as red-green value, flesh firmness, weight loss, and total soluble solids content were measured and optical photographs were taken. Each group had three replicates, and all operations were performed at room temperature.

[0081] Figures 1a-1c The images show scanning electron microscopy (SEM) images, water contact angles, and UV barrier properties of the gelatin-resin, gelatin-resin / polythioic acid (PoTOC) composite aerogels, and gelatin-resin / PoTOC / silver nanoparticle composite aerogels prepared in Example 1. Figure 1a As shown in the figure, the microstructure reveals that pure gelatin-resin aerogel exhibits porous characteristics, but the pore distribution shows some inhomogeneity, and the pore size also exhibits local differences. However, after crosslinking modification with polythioctic acid, the resulting gelatin-resin / polythioctic acid composite aerogel displays a more continuous, dense, and uniformly distributed three-dimensional porous network structure, indicating that the introduction of polythioctic acid significantly optimizes the pore structure of the aerogel. Furthermore, based on this, the cross-section of the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel exhibits a rougher morphology, but it still maintains a continuous and uniform porous network with good structural integrity. Regarding surface wettability, the modification with polythioctic acid significantly enhances the hydrophobicity of the aerogel. Figure 1b As shown in the figure, water contact angle tests revealed that the water contact angles of both gelatin-resin / polythioic acid composite aerogel and gelatin-resin / polythioic acid / silver nanoparticle composite aerogel were significantly improved compared to pure gelatin-resin aerogel, demonstrating that their surfaces transitioned from hydrophilic to hydrophobic. This is beneficial for the structural stability and functional maintenance of the material in humid environments. Figure 1cAs shown, in terms of UV blocking performance, gelatin-resin / polythioic acid composite aerogel and gelatin-resin / polythioic acid / silver nanoparticle composite aerogel exhibit excellent shielding effects in the UV-A, UV-B, and UV-C bands. This is mainly attributed to the rich aromatic structure in the polythioic acid molecule and the introduced Ag / Ag2S heterojunction, which can effectively absorb ultraviolet light, thereby significantly improving the material's ability to block ultraviolet radiation and helping to delay the quality deterioration of photosensitive fruits and vegetables.

[0082] Figures 2a-2b Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns of the gelatin-resin / polythioic acid (PoTOC) composite aerogel, the gelatin-resin / PoTOC / silver ion composite aerogel precursor, and the gelatin-resin / PoTOC / silver nanoparticle composite aerogel prepared in Comparative Example 1 and Example 1; Figure 2a As shown in the Fourier transform infrared spectroscopy analysis, compared with the material in Comparative Example 1, the characteristic absorption peaks of the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel in Example 1 exhibit a systematic shift and change. Specifically, the absorption peak attributed to the amide I band (-C=O stretching vibration) shifted from 1646 cm⁻¹. -1 Moved to 1638 cm -1 The amide II band (-NH bending vibration) is 1572 cm⁻¹ -1 Migrating to 1562 cm -1 The vibrational peak of the -CS bond is at 645 cm⁻¹. -1 Significant displacement to 618 cm -1 Meanwhile, located at 521 cm -1 The characteristic peaks belonging to -SS- were significantly weakened. These spectral changes confirm that silver ions have been successfully loaded onto the aerogel matrix through chemical action and may be further partially reduced to elemental silver under photocatalytic conditions. Furthermore, as... Figure 2bAs shown, the three materials exhibit distinctly different crystal structure characteristics in their X-ray diffraction patterns. Comparative Example 1 shows typical amorphous diffuse diffraction peaks, indicating that its matrix is ​​mainly amorphous. In Example 1, the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor, while maintaining the amorphous diffuse background, shows a series of clear diffraction peaks belonging to the Ag2S crystal phase, indicating that silver ions react with the disulfide bonds in polythioctic acid to form Ag2S and are stably loaded. The diffraction pattern of the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel in Example 1 further evolved: the intensity of the original Ag2S characteristic peaks was relatively weakened, while characteristic diffraction peaks belonging to the face-centered cubic structure of metallic silver (111), (200), and (311) crystal planes appeared at 2θ of approximately 38.1°, 44.3°, and 77.4°. This result directly proves that, under simulated sunlight irradiation, the loaded silver ions are reduced in situ to metallic silver nanoparticles, successfully constructing an Ag / Ag₂S heterostructure composite system. In summary, the infrared and X-ray diffraction results corroborate each other, systematically elucidating the step-by-step transformation process from silver ion loading and Ag₂S intermediate formation to the final photocatalytic reduction to silver nanoparticles, providing ample spectroscopic and structural evidence for the successful construction of Ag / Ag₂S heterostructures in the material.

[0083] Figure 3 Atomic force microscopy and scanning electron microscopy images of the gelatin-resin / polythioic acid / silver nanoparticle composite aerogels prepared in different proportions in Examples 1-5. Figure 3As shown in the three-dimensional surface morphology, the surface pore structure and distribution of the aerogel exhibit significant differences with varying silver ion addition ratios. At a moderate silver ion addition level (e.g., Example 1), the aerogel surface displays a uniform porous structure with relatively uniform pore size and a more ordered distribution, with regular surface undulations, indicating that an ideal coordination equilibrium is achieved between the polymer network and silver ions under these conditions. As the silver ion addition ratio changes towards low (e.g., Examples 2 and 3) or high (e.g., Examples 4 and 5), the surface pore structure shows a systematic evolution: under low load, the pores tend to increase but fail to maintain good uniformity; while under high load, the pores shrink significantly, and the uniformity of distribution also decreases markedly, indicating that excessive silver ions may interfere with the orderly cross-linking and pore formation of the gel network. Simultaneously, scanning electron microscopy results of the aerogel cross-section further confirm the above-mentioned variation patterns. At a moderate silver loading ratio (e.g., Example 1), the aerogel cross-section exhibits a more continuous and uniform porous network with good structural integrity. As the silver loading deviates from the optimal ratio, the cross-sectional pores gradually exhibit a trend of discrete distribution, localized densification, or decreased connectivity. Example 1 consistently demonstrates the best structural uniformity and silver nanoparticle dispersion. This indicates that the addition ratio in Example 1 not only facilitates the formation of a stable porous framework but also achieves uniform anchoring of the active component in the matrix and interfacial compatibility. In summary, a moderate loading ratio (Example 1) establishes an optimal balance between polymer crosslinking density, metal ion coordination, and pore structure, thereby constructing a functional material system with both uniform porous morphology and a good dispersion interface, laying the structural foundation for achieving efficient adsorption-catalysis synergistic performance.

[0084] Figures 4a-4b This document presents the UV-Vis diffuse reflectance spectra and corresponding Tauc curves of the gelatin-resin / polythioic acid composite aerogels prepared in Comparative Examples 1 and Examples 1-5, and gelatin-resin / polythioic acid / silver nanoparticle composite aerogels with different proportions. UV-Vis absorption spectra of the aerogel materials were obtained using a UV-Vis spectrophotometer, and corresponding Tauc curves were plotted to determine the band gap (reflecting the photoresponse capability) of each aerogel material. Figures 4a-4bAs shown in the spectral analysis, the introduction of silver ions significantly alters the optical properties of the aerogel. Compared to Comparative Example 1 (band gap of approximately 3.25 eV), all Examples 1-5 loaded with silver nanoparticles exhibit a significant reduction in band gap, ranging from 3.03 eV to 3.15 eV. This indicates that the loading of silver nanoparticles effectively enhances the material's photoresponse capability and expands its visible light absorption range. Notably, in Example 1 with a moderate silver loading, the aerogel exhibits the smallest band gap (approximately 3.03 eV), indicating that the Ag / Ag₂S heterojunction is most fully formed under these conditions, resulting in the highest photogenerated carrier separation efficiency and thus endowing the material with optimal photocatalytic activity potential. This improvement in optical performance provides an important electronic structure basis for achieving efficient adsorption-photocatalytic degradation synergy of ethylene.

[0085] Figures 5a-5b The thermal stability diagrams are shown for the gelatin-resin / polythioic acid composite aerogels prepared in Comparative Example 1 and Examples 1-5, and for gelatin-resin / polythioic acid / silver nanoparticle composite aerogels with different proportions. Figures 5a-5b As shown, the loading of silver nanoparticles significantly enhances the thermal stability of the aerogel material, reflecting its thermal decomposition behavior. Compared to Comparative Example 1 (without silver loading), all silver-containing samples (Examples 1-5) exhibited a slower mass loss trend during heating, and their maximum thermal degradation temperature shifted significantly towards higher temperatures. In particular, Example 1, with a moderate silver loading, demonstrated the best thermal stability. Its initial decomposition phase was delayed, its overall thermal weight loss rate was the lowest, and its maximum thermal degradation temperature significantly increased from 259.35℃ in Comparative Example 1 to 293.71℃, an increase of over 34℃. This indicates that at this loading ratio, a stable interfacial interaction was formed between the silver nanoparticles and the polymer matrix, effectively suppressing the thermal motion of molecular chain segments and enhancing the thermal stability of the aerogel network.

[0086] Figure 6 The graph shows the encapsulation efficiency of silver in the gelatin-resin / polythioic acid / silver nanoparticle composite aerogels prepared in different proportions in Examples 1-5. Figure 6As shown, the proportion of silver ions added has a significant impact on the silver loading efficiency in the aerogel. With increasing silver ion content, the encapsulation efficiency exhibits a non-linear trend of first increasing and then decreasing, with the specific values ​​as follows: Example 1 (95.27%), Example 2 (72.36%), Example 3 (87.33%), Example 4 (66.19%), and Example 5 (45.08%). Among these, the aerogel achieved its peak silver encapsulation efficiency at a moderate silver loading ratio (Example 1), indicating that the effective loading sites in the polymer network and silver ions reached the optimal ratio under this condition, achieving efficient fixation and utilization of silver. This result further illustrates that the silver loading ratio not only affects the structure and properties of the material but also directly determines the loading efficiency of the active component. The moderate addition amount (Example 1) maximized the stable loading of silver nanoparticles while maintaining the integrity of the aerogel's porous structure, laying an important foundation for the material's subsequent photocatalytic activity and long-term stability.

[0087] Figure 7 The graph shows the adsorption capacity of ethylene gas for the gelatin-resin / polythioic acid composite aerogels prepared in Comparative Example 1 and Examples 1-5, and for gelatin-resin / polythioic acid / silver nanoparticle composite aerogels with different proportions. Figure 7 As shown, the introduction of silver nanoparticles significantly enhances the adsorption capacity of the aerogel material for ethylene. Compared with unloaded silver, Example 1 (ethylene adsorption capacity 40.28 cm⁻¹) 3 Compared to (g), all samples loaded with silver nanoparticles exhibited enhanced adsorption performance (ethylene adsorption capacity of 46.42-62.65 cm⁻¹). 3 / g). Notably, in Example 1 with a moderate silver loading, the material exhibited optimal ethylene adsorption performance, reaching an adsorption capacity of 62.65 cm⁻¹. 3 / g, an increase of approximately 55.5% compared to Comparative Example 1. This significant enhancement is attributed to the uniform dispersion of silver nanoparticles at this loading ratio and their synergistic effect with the porous structure of the aerogel: on the one hand, the loading of silver nanoparticles optimizes the electronic structure and adsorption site distribution on the material surface; on the other hand, the uniform porous network formed at a moderate loading ratio provides more efficient diffusion channels and enrichment interfaces for ethylene molecules. This result further demonstrates that by controlling the loading ratio of silver nanoparticles, the gas adsorption performance of the composite aerogel can be effectively optimized. The moderate loading ratio (Example 1) shows the most outstanding performance in improving the ethylene adsorption capacity, laying an important foundation for its subsequent realization of the adsorption-photocatalytic synergistic degradation of ethylene.

[0088] Figures 8a-8b The graph shows the degradation performance of ethylene gas by gelatin-resin / polythioic acid composite aerogels prepared in Comparative Example 1 and Examples 1-5, and gelatin-resin / polythioic acid / silver nanoparticle composite aerogels with different proportions. Figures 8a-8b As shown, the loading of silver nanoparticles significantly enhanced the material's catalytic degradation ability for ethylene. Under light-shielded conditions, all silver-containing samples exhibited superior degradation performance compared to Comparative Example 1. Among them, Example 1, with a moderate silver loading ratio, demonstrated the most outstanding degradation performance, achieving an ethylene degradation rate of 59.55% after 24 hours, far exceeding the 12.31% of Comparative Example 1. Furthermore, under simulated sunlight irradiation, the photocatalytic effect further enhanced the material's degradation performance. The degradation rate of Comparative Example 1 only slightly increased to 13.61% under illumination, while the degradation rate of Example 1 significantly increased to 95.21%, indicating that the Ag / Ag₂S heterojunction can effectively promote the separation and migration of photogenerated carriers under illumination, thereby greatly enhancing the photocatalytic degradation efficiency of ethylene. This comparative result fully demonstrates that the introduction of silver nanoparticles not only provides additional catalytic active sites but, more importantly, synergistically constructs a highly efficient photocatalytic system with the polythioctic acid-modified aerogel matrix. Under a moderate loading ratio (Example 1), the material exhibits optimal ethylene degradation performance under both light-shielded and light-illuminated conditions, achieving efficient synergy between static adsorption and photocatalytic dynamic degradation, providing an important basis for the development of efficient and stable ethylene removal materials.

[0089] Figure 9 Cytotoxicity graphs are shown for the gelatin-resin / polythioic acid composite aerogels prepared in Comparative Examples 1 and Examples 1-5, and for gelatin-resin / polythioic acid / silver nanoparticle composite aerogels with different ratios. Figure 9 As shown, the introduction of silver nanoparticles has a certain impact on the cell compatibility of the material. Compared with Comparative Example 1 without silver loading, the cell viability of the sample groups loaded with silver nanoparticles decreased to varying degrees, but the cell viability of all examples remained above 80%, meeting the conventional safety standards for cell compatibility of biomaterials. In Example 1 (92.06%), with a moderate silver loading, although the cell viability was slightly lower than that of Comparative Example 1 (98.20%), it remained at a high level, indicating that the dispersion and release behavior of silver nanoparticles in the aerogel were effectively regulated under these conditions, without causing significant cytotoxic reactions. These results demonstrate that by optimizing the loading ratio and composite method of silver nanoparticles, functional modification can be achieved while maintaining good biocompatibility of the material. Example 1 achieved a good balance between cell compatibility and functionality, providing a safety basis for its application in food contact materials and related biological fields.

[0090] Figures 10a-10eThis image shows the application of gelatin-resin / polythioic acid composite aerogel and gelatin-resin / polythioic acid / silver nanoparticle composite aerogel prepared in Comparative Example 1 and Example 1 (shadow group and light group) in tomato preservation. The results show that, under simulated sunlight irradiation, the aerogel in Example 1 (light group) exhibited the best preservation performance. Compared with the control group, it had the most significant effect on maintaining the post-harvest quality of tomatoes. It can effectively delay the ripening of fruits (…). The increase in total soluble solids content was slowed down, the decrease in pulp firmness was slowed down, and the weight loss rate during storage was significantly reduced. In contrast, although Comparative Example 1 and Example 1 (light-shielded group) also had a certain preservation effect, their effect was significantly weaker than that of Example 1 (light-illuminated group) under light conditions. This performance difference fully highlights the core role of the photoactivation mechanism in this aerogel system: under simulated sunlight irradiation, the uniformly distributed Ag / Ag2S heterojunctions in the aerogel are excited, generating photogenerated electrons (electrons). - ) and holes (h) + This heterojunction structure effectively promotes the separation of electron-hole pairs and inhibits their recombination, thereby significantly improving photocatalytic efficiency. Photogenerated holes possess strong oxidizing properties and can directly or through the generation of reactive oxygen species (such as ·OH) to oxidize and degrade adsorbed ethylene molecules; simultaneously, photogenerated electrons can also participate in reduction reactions, jointly achieving efficient and continuous catalytic conversion of ethylene. The above photocatalytic process, combined with the physical adsorption and enrichment effect of the aerogel's three-dimensional porous network, constitutes a synergistic cycle of "adsorption-photocatalytic degradation": its porous network efficiently captures and concentrates ethylene, increasing its local concentration near the active sites; the heterojunction continuously degrades the adsorbed ethylene under light irradiation, regenerating the adsorption sites, thus achieving efficient synergy and cyclical effects of static adsorption and dynamic catalytic degradation. The above results comprehensively demonstrate that the gelatin-resin / polythioctic acid@silver nanoparticle composite aerogel prepared in Example 1 of this invention can effectively maintain the post-harvest quality of tomatoes and extend their shelf life under light conditions, showing its application potential as a new generation of intelligent, non-contact green fruit and vegetable preservation material.

[0091] Comparative Example 1

[0092] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution and sonicate for 1h to aid dissolution. After complete dissolution, mix the two in a 1:1 ratio, adjust the pH to 4.2, and carry out the cross-linking reaction under stirring at 500rpm, 60℃, and 1h. After thorough stirring, adjust the pH to 7.5. Separately, pre-dissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol and add 90mL of distilled water to dissolve it completely. Then add the polythioctic acid solution to the above gelatin-resin mixture in a 1:1 ratio and carry out the cross-linking reaction under stirring at 600rpm, 45℃, and 3h. After the reaction was complete, the solution was allowed to stand at 25°C for 3 hours to degas, and then the temperature was gradually reduced. First, it was placed at 4°C for 8 hours to form a hydrogel network, then placed at -20°C for 12 hours for further freeze-curing, and finally freeze-dried at -60°C for 24 hours to obtain the gelatin-resin / polythioctic acid composite aerogel matrix in Comparative Example 1.

[0093] Example 2

[0094] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution and sonicate for 1h to aid dissolution. After complete dissolution, mix the two in a 1:1 ratio, adjust the pH to 4.2, and carry out the cross-linking reaction under stirring at 500rpm, 60℃, and 1h. After thorough stirring, adjust the pH to 7.5. Separately, pre-dissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol and add 90mL of distilled water to dissolve it completely. Then add the polythioctic acid solution to the above gelatin-resin mixture in a 1:1 ratio and carry out the cross-linking reaction under stirring at 600rpm, 45℃, and 3h. After the reaction was complete, the two solutions were allowed to stand at 25°C for 3 hours to degas, and then the temperature was gradually reduced. First, the solution was placed at 4°C for 8 hours to form a hydrogel network, and then placed at -20°C for 12 hours for further freeze-curing. Finally, the solution was freeze-dried at -60°C for 24 hours to obtain gelatin-resin and gelatin-resin / polythioctic acid composite aerogel matrix.

[0095] (2) Take 200 mL of the mixed solution obtained in step (1), add 0.21 g of silver nitrate powder (i.e., the molar ratio of polythioctic acid to silver ions is 1:0.25), and stir at 600 rpm, 45°C, and for 3 h to uniformly load the silver ions. After thorough stirring, let the solution stand at 25°C for 3 h to degas, then gradually lower the temperature. First, place it at 4°C for 8 h to form a hydrogel network, then place it at -20°C for 12 h for further freeze-curing, and finally freeze-dry at -60°C for 24 h to obtain the gelatin-resin / polythioctic acid@silver ion composite aerogel precursor.

[0096] (3) The aerogel precursor obtained in step (2) was subjected to photocatalytic in-situ reduction reaction under simulated sunlight using a T5 LED white light tube (power of 16W, light source distance of 30-40cm, irradiation time of 3-5h), so that silver ions were reduced and partially converted into silver element, forming a uniformly dispersed Ag / Ag2S heterojunction structure, and finally the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with a molar ratio of polythioctic acid to silver ions of 1:0.25 in Example 2 was obtained.

[0097] Example 3:

[0098] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution and sonicate for 1h to aid dissolution. After complete dissolution, mix the two in a 1:1 ratio, adjust the pH to 4.2, and carry out the cross-linking reaction under stirring at 500rpm, 60℃, and 1h. After thorough stirring, adjust the pH to 7.5. Separately, pre-dissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol and add 90mL of distilled water to dissolve it completely. Then add the polythioctic acid solution to the above gelatin-resin mixture in a 1:1 ratio and carry out the cross-linking reaction under stirring at 600rpm, 45℃, and 3h. After the reaction was complete, the two solutions were allowed to stand at 25°C for 3 hours to degas, and then the temperature was gradually reduced. First, the solution was placed at 4°C for 8 hours to form a hydrogel network, and then placed at -20°C for 12 hours for further freeze-curing. Finally, the solution was freeze-dried at -60°C for 24 hours to obtain gelatin-resin and gelatin-resin / polythioctic acid composite aerogel matrix.

[0099] (2) Take 200 mL of the mixed solution obtained in step (1), add 0.41 g of silver nitrate powder (i.e., the molar ratio of polythioctic acid to silver ions is 1:0.5), and stir at 600 rpm, 45°C, and for 3 h to uniformly load the silver ions. After thorough stirring, let the solution stand at 25°C for 3 h to degas, then gradually lower the temperature. First, place it at 4°C for 8 h to form a hydrogel network, then place it at -20°C for 12 h for further freeze-curing, and finally freeze-dry at -60°C for 24 h to obtain the gelatin-resin / polythioctic acid@silver ion composite aerogel precursor.

[0100] (3) The aerogel precursor obtained in step (2) was subjected to photocatalytic in-situ reduction reaction under simulated sunlight using a T5 LED white light tube (power of 16W, light source distance of 30-40cm, irradiation time of 3-5h), so that silver ions were reduced and partially converted into silver element, forming a uniformly dispersed Ag / Ag2S heterojunction structure, and finally the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with a molar ratio of polythioctic acid to silver ions of 1:0.5 in Example 3 was obtained.

[0101] Example 4

[0102] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution and sonicate for 1h to aid dissolution. After complete dissolution, mix the two in a 1:1 ratio, adjust the pH to 4.2, and carry out the cross-linking reaction under stirring at 500rpm, 60℃, and 1h. After thorough stirring, adjust the pH to 7.5. Separately, pre-dissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol and add 90mL of distilled water to dissolve it completely. Then add the polythioctic acid solution to the above gelatin-resin mixture in a 1:1 ratio and carry out the cross-linking reaction under stirring at 600rpm, 45℃, and 3h. After the reaction was complete, the two solutions were allowed to stand at 25°C for 3 hours to degas, and then the temperature was gradually reduced. First, the solution was placed at 4°C for 8 hours to form a hydrogel network, and then placed at -20°C for 12 hours for further freeze-curing. Finally, the solution was freeze-dried at -60°C for 24 hours to obtain gelatin-resin and gelatin-resin / polythioctic acid composite aerogel matrix.

[0103] (2) Take 200 mL of the mixed solution obtained in step (1), add 1.65 g of silver nitrate powder (i.e., the molar ratio of polythioctic acid to silver ions is 1:2), and stir at 600 rpm, 45 °C for 3 h to uniformly load the silver ions. After thorough stirring, let the solution stand at 25 °C for 3 h to degas, then gradually lower the temperature. First, place it at 4 °C for 8 h to form a hydrogel network, then place it at -20 °C for 12 h for further freeze-curing, and finally freeze-dry at -60 °C for 24 h to obtain the gelatin-resin / polythioctic acid@silver ion composite aerogel precursor.

[0104] (3) The aerogel precursor obtained in step (2) was subjected to photocatalytic in-situ reduction reaction under simulated sunlight using a T5 LED white light tube (power of 16W, light source distance of 30-40cm, irradiation time of 3-5h), so that silver ions were reduced and partially converted into silver element, forming a uniformly dispersed Ag / Ag2S heterojunction structure, and finally the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with a molar ratio of polythioctic acid to silver ions of 1:2 was obtained in Example 4.

[0105] Example 5

[0106] (1) Disperse 2.5g of gelatin and resin powder separately in 50mL of 1% acetic acid aqueous solution and sonicate for 1h to aid dissolution. After complete dissolution, mix the two in a 1:1 ratio, adjust the pH to 4.2, and carry out the cross-linking reaction under stirring at 500rpm, 60℃, and 1h. After thorough stirring, adjust the pH to 7.5. Separately, pre-dissolve 1.0g of polythioctic acid powder in 10mL of anhydrous ethanol and add 90mL of distilled water to dissolve it completely. Then add the polythioctic acid solution to the above gelatin-resin mixture in a 1:1 ratio and carry out the cross-linking reaction under stirring at 600rpm, 45℃, and 3h. After the reaction was complete, the two solutions were allowed to stand at 25°C for 3 hours to degas, and then the temperature was gradually reduced. First, the solution was placed at 4°C for 8 hours to form a hydrogel network, and then placed at -20°C for 12 hours for further freeze-curing. Finally, the solution was freeze-dried at -60°C for 24 hours to obtain gelatin-resin and gelatin-resin / polythioctic acid composite aerogel matrix.

[0107] (2) Take 200 mL of the mixed solution obtained in step (1), add 2.47 g of silver nitrate powder (i.e., the molar ratio of polythioctic acid to silver ions is 1:3), and stir at 600 rpm, 45°C, and for 3 h to uniformly load the silver ions. After thorough stirring, let the solution stand at 25°C for 3 h to degas, then gradually lower the temperature. First, place it at 4°C for 8 h to form a hydrogel network, then place it at -20°C for 12 h for further freeze-curing, and finally freeze-dry at -60°C for 24 h to obtain the gelatin-resin / polythioctic acid@silver ion composite aerogel precursor.

[0108] (3) The aerogel precursor obtained in step (2) was subjected to photocatalytic in-situ reduction reaction under simulated sunlight using a T5 LED white light tube (power of 16W, light source distance of 30-40cm, irradiation time of 3-5h) to reduce silver ions and partially convert them into silver element, forming a uniformly dispersed Ag / Ag2S heterojunction structure, and finally obtaining the gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with a molar ratio of polythioctic acid to silver ions of 1:3 in Example 5.

[0109] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0110] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for preparing a photoactivated porous aerogel having ethylene degradation performance, characterized by, include: A gelatin solution and a resin solution were mixed to carry out a first cross-linking reaction, and then a polythioctic acid solution was added to carry out a second cross-linking reaction to obtain a gelatin-resin / polythioctic acid solution. A silver source was added to the gelatin-resin / polythioctic acid solution and mixed thoroughly. Then, the mixture was subjected to static degassing, gradient cooling, freeze curing, and freeze drying to obtain a gelatin-resin / polythioctic acid / silver ion composite aerogel precursor. Furthermore, the gelatin-resin / polythioctic acid / silver ion composite aerogel precursor is subjected to a catalytic in-situ reduction reaction to obtain a gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with an Ag / Ag2S heterostructure, namely a photoactivated porous aerogel with ethylene degradation properties.

2. The production method according to claim 1, characterized by, Specifically, it includes: Gelatin and resin were separately dispersed in an aqueous acetic acid solution and then subjected to ultrasonic treatment to form a gelatin solution and a resin solution, respectively. The gelatin solution and resin solution are mixed and the pH value is adjusted to 4.0~4.

5. The first cross-linking reaction is carried out for 1~2 hours under the conditions of 300-500 rpm and 50~60℃. Then the pH value is adjusted to 7.0~8.0 to obtain a gelatin-resin mixed solution. Furthermore, polythioctic acid is pre-dissolved in anhydrous ethanol, and then water is added to fully dissolve it to form a polythioctic acid solution. This solution is then mixed with a gelatin-resin mixed solution and subjected to a second crosslinking reaction for 2-3 hours at a speed of 400-600 rpm and a temperature of 40-50°C to obtain a gelatin-resin / polythioctic acid solution.

3. The method of claim 2, wherein: The volume concentration of the acetic acid aqueous solution is 1-2%; And / or, the mass-to-volume ratio of the gelatin to the aqueous acetic acid solution is 1g:10mL to 1g:30mL; And / or, the mass-to-volume ratio of the resin to the aqueous acetic acid solution is 1g:10mL to 1g:30mL; And / or, the volume ratio of the gelatin solution to the resin solution is 1:1 to 1:1.5; And / or, the mass-to-volume ratio of the polythioctic acid to anhydrous ethanol is 0.5~1.5g:5~10mL; And / or, the mass-to-volume ratio of the polythiooctanoic acid to water is 1g:50mL to 1g:200mL; And / or, the volume ratio of the polythioctic acid solution to the gelatin-resin mixture is 1:1 to 1:1.

2.

4. The production method according to claim 1, characterized by, Specifically, it includes: A silver source was added to the gelatin-resin / polythioctic acid solution and stirred for 2-3 hours at a speed of 400-600 rpm and a temperature of 40-50°C. The resulting solution was then allowed to stand at room temperature to remove bubbles, followed by gradient cooling to form a hydrogel network. The precursor of the gelatin-resin / polythioctic acid / silver ion composite aerogel was obtained by freeze curing and freeze drying.

5. The method of claim 4, wherein: The ratio of the gelatin-resin / polythioctic acid solution to the silver source is 180~220mL:0.2~2.5g; And / or, the molar ratio of polythioctic acid to silver source in the gelatin-resin / polythioctic acid solution is 1:0.25 to 1:3; And / or, the silver source includes any one or more combinations of silver nitrate, silver acetate, silver sulfate, and silver trifluoroacetate; And / or, the temperature for static degassing is 20~25℃, and the time is 2~3h; And / or, the temperature for the gradient cooling to form the hydrogel network is 4~5℃, and the time is 8~10h; And / or, the freeze-curing temperature is -25~-20℃, and the time is 10~12h; And / or, the freeze-drying temperature is -80~-60℃, and the time is 20~24h.

6. The production method according to claim 1, characterized by, Specifically, it includes: The gelatin-resin / polythioctic acid / silver ion composite aerogel precursor was subjected to a catalytic in-situ reduction reaction under simulated sunlight irradiation to form Ag / Ag2S heterojunctions in situ, thereby obtaining a gelatin-resin / polythioctic acid / silver nanoparticle composite aerogel with an Ag / Ag2S heterojunction structure.

7. The method of claim 6, wherein: The simulated sunlight irradiation conditions include: T5 LED white light tubes with a power of 15~20W, a light source distance of 30~40cm, and an irradiation duration of 3~5h.

8. A photoactivated porous aerogel with ethylene degradation properties prepared by the preparation method according to any one of claims 1-7, characterized in that, The photoactivated porous aerogel has a three-dimensional porous network structure, and Ag / Ag2S heterojunctions are uniformly dispersed in the photoactivated porous aerogel.

9. The application of the photoactivated porous aerogel with ethylene degradation properties as described in claim 8 in the storage and preservation of fruits and vegetables.

10. A method for preserving fruits and vegetables, characterized by, include: Fruits or vegetables are placed in a storage box equipped with the photoactivated porous aerogel with ethylene degradation properties as described in claim 8 and then sealed for storage. The storage environment is characterized by a temperature of 20-25°C and a relative humidity of 70-80%.

Images