A method for preparing a Ni-doped modified UiO-66-NH2 / chitosan / polyvinyl alcohol composite food preservation film
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG AGRICULTURAL UNIVERSITY
- Filing Date
- 2026-03-06
- Publication Date
- 2026-06-19
Smart Images
Figure CN122234429A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of photocatalytic materials and preservation materials, specifically to a method for preparing a Ni-doped modified UiO-66-NH2 composite preservation film with chitosan / polyvinyl alcohol. Background Technology
[0002] Fruits remain physiologically active after harvest and are highly susceptible to microbial contamination and spoilage during transportation and storage, resulting in significant economic losses. Developing efficient and safe antibacterial packaging materials is crucial for extending the shelf life of fruits. Chitosan (CS) and polyvinyl alcohol (PVA) are commonly used basic materials for preparing biodegradable preservation films. Chitosan possesses excellent film-forming properties, biocompatibility, and natural antibacterial activity, while polyvinyl alcohol exhibits high mechanical strength and good chemical stability. Blending the two can form a composite film with complementary properties. However, the antibacterial effect of traditional CS / PVA composite films mainly relies on the passive contact inhibition of chitosan itself, lacking an active and efficient bactericidal mechanism. Its effectiveness in killing suspended bacteria in the packaging environment and bacteria attached to the film surface is limited, making it difficult to meet increasingly stringent preservation requirements.
[0003] Photocatalytic sterilization technology has received widespread attention in the food packaging field in recent years. Its mechanism of action involves the excitation of the photocatalyst under light irradiation, generating photogenerated electrons and holes. These photogenerated charge carriers further react with water and oxygen to produce highly oxidizing reactive oxygen species (ROS), including hydroxyl radicals (·OH) and superoxide anions (·O2). - ) and singlet oxygen ( 1 Photocatalysts (such as O2) can disrupt the structure of microbial cells and cause leakage of cell contents, thereby achieving a broad-spectrum and highly efficient bactericidal effect. However, photocatalysts generally face the problem of easy recombination between photogenerated electrons and holes in practical applications, so improving the photogenerated carrier separation efficiency of photocatalysts is very important.
[0004] Metal-organic frameworks (MOFs) exhibit unique advantages in photocatalysis due to their large specific surface area, abundant active sites, and tunable band structure. Among them, UiO-66-NH2 not only possesses excellent water and chemical stability, but its amino functional groups can also extend the visible light response range, making it a very promising photocatalytic material. Introducing UiO-66-NH2 into a CS / PVA matrix is expected to endow the composite membrane with photocatalytic reactive oxygen species (ROS) bactericidal function. However, pure UiO-66-NH2 still suffers from a high recombination rate of photogenerated carriers, which limits its ROS yield and actual bactericidal effect.
[0005] Transition metal ion doping is an effective means to suppress photogenerated carrier recombination and improve photocatalytic efficiency. Nickel (Ni), as a transition metal element, can introduce defects into the semiconductor lattice through doping, effectively capturing photogenerated electrons and promoting the separation and migration of electron-hole pairs, thereby improving the generation efficiency of reactive oxygen species. Currently, there are no reports on the use of Ni-doped UiO-66-NH2 as a photocatalytic functional filler in CS / PVA matrices to achieve active sterilization using its highly efficient photogenerated oxygen. Summary of the Invention
[0006] This invention addresses the issues of high photogenerated carrier recombination efficiency in UiO-66-NH2 and limited bactericidal effect in chitosan / polyvinyl alcohol composite films by providing a method for preparing a Ni-doped modified UiO-66-NH2 / chitosan / polyvinyl alcohol composite preservation film. The prepared composite film exhibits good visible light response, higher photogenerated carrier separation efficiency, and sustainable antibacterial activity, showing broad application prospects in fruit and vegetable preservation, photocatalytic sterilization, and other fields.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a Ni-doped modified UiO-66-NH2 / chitosan / polyvinyl alcohol composite food preservation film, comprising the following steps: Step S1: Prepare Ni / UiO-66-NH2 by hydrothermal method.
[0008] Step S2: Mix chitosan and polyvinyl alcohol solution to obtain a blend. Add Ni / UiO-66-NH2 prepared in (1) to the blend, stir thoroughly, and defoam by ultrasonication to obtain a film-forming solution. Pour the film-forming solution evenly into a mold. Dry to obtain a composite food preservation film.
[0009] Optionally, in step S1, the hydrothermal method for preparing Ni / UiO-66-NH2 is as follows: ZrCl4 and 2-aminoterephthalic acid are dissolved in 40 mL of DMF solution, respectively. Then, a certain amount of acetic acid and Ni(NO3)2·6H2O are added to the above solution, and the mixture is sonicated for 30 min. The resulting solution is transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 120 °C for 24 h. After natural cooling and centrifugation, the solution is washed and dried to obtain Ni / UiO-66-NH2.
[0010] Optionally, in step S2, the concentration of the chitosan solution is 2.5%; the concentration of the polyvinyl alcohol solution is 5%, and the volume ratio of the chitosan solution to the polyvinyl alcohol solution is 1:1.
[0011] Optionally, in step S2, the amount of Ni / UiO-66-NH2 added is 1-10% of the total mass of chitosan and polyvinyl alcohol in the blend.
[0012] In a second aspect, the present invention provides a Ni-doped modified UiO-66-NH2 composite food preservation film prepared by the above preparation method and chitosan / polyvinyl alcohol.
[0013] A third aspect of the present invention provides the application of the above-described composite preservation film in the preservation of fruits and vegetables.
[0014] Optionally, in the above applications, the fruit or vegetable is Shine Muscat.
[0015] A fourth aspect of the present invention provides a method for preserving fruits and vegetables using the above-mentioned composite preservation film, comprising the following steps: Fruits and vegetables to be preserved are placed in an open preservation box. A Ni-doped UiO-66-NH2 composite preservation film is used to cover the opening of the preservation box and then sealed. The preservation box is then stored under visible irradiation.
[0016] Compared to the original materials, the present invention has the following advantages: The composite preservation film prepared by this invention improves the separation and transport efficiency of photogenerated carriers and enhances the photocatalytic activity of the material due to Ni-doped UiO-66-NH2. Adding Ni / UiO-66-NH2 to the CS / PVA composite film enhances the film's mechanical properties, giving it good flexibility. The addition of Ni / UiO-66-NH2 also enhances the film's visible light response and antibacterial activity. Attached Figure Description
[0017] Figure 1 XRD pattern of Example 1 Figure 2 SEM images of Example 3; in the image, a is the SEM image of the membrane surface and b is the SEM image of the membrane cross section.
[0018] Figure 3 Mechanical properties of plastic wrap prepared by different methods; In the figure, CS / PVA is the plastic wrap prepared by Comparative Example 1 of the present invention; NNU-1 is the composite plastic wrap prepared by Example 2 of the present invention; NNU-5 is the plastic wrap prepared by Example 3 of the present invention; NNU-10 is the plastic wrap prepared by Example 4 of the present invention.
[0019] Figure 4Images of Sunshine Roses preserved using different treatment methods; in the images, control represents treatment 1 in the application example, without covering with plastic wrap; PE represents treatment 2 in the application example, covered with commercially available PE film; CS / PVA represents treatment 3 in the application example; NNU-1 is the composite plastic wrap prepared in Example 2 of the present invention; NNU-5 is the plastic wrap prepared in Example 3 of the present invention; NNU-10 is the plastic wrap prepared in Example 4 of the present invention.
[0020] Figure 5 The antibacterial effect of Staphylococcus aureus under both light and dark conditions is shown in the figure. "Light" represents visible light irradiation, and "dark" represents darkness. In the figure, "control" indicates no membrane material is added; "CS / PVA" represents the preservation film prepared in Comparative Example 1 of this invention added to the bacterial solution; "NNU-1" represents the composite preservation film prepared in Example 2 of this invention added to the bacterial solution; "NNU-5" represents the preservation film prepared in Example 3 of this invention added to the bacterial solution; and "NNU-10" represents the preservation film prepared in Example 4 of this invention added to the bacterial solution.
[0021] Figure 6 The figure shows the antibacterial effect of Escherichia coli under both light and dark conditions; where "light" represents visible light irradiation and "dark" represents darkness. In the figure, "control" represents no membrane material added; "CS / PVA" represents the preservation film prepared in Comparative Example 1 of this invention added to the bacterial solution; "NNU-1" represents the composite preservation film prepared in Example 2 of this invention added to the bacterial solution; "NNU-5" represents the preservation film prepared in Example 3 of this invention added to the bacterial solution; and "NNU-10" represents the preservation film prepared in Example 4 of this invention added to the bacterial solution. Detailed Implementation
[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0023] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.
[0024] The test materials used in the embodiments of this invention are all conventional test materials in the art and can be purchased through commercial channels. Experimental methods without specified detailed conditions are performed according to conventional test methods or the supplier's recommended operating instructions.
[0025] Example 1: Preparation of Ni-doped modified UiO-66-NH2 233 mg ZrCl4 and 181 mg 2-aminoterephthalic acid were dissolved separately in 40 mL DMF solution. Then, 1.7 mL of acetic acid and 145.40 mg of Ni(NO3)2·6H2O were added to the above solutions, and the mixture was sonicated for 30 min. The resulting solution was transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 120 °C for 24 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. Finally, the sample was centrifuged three times with DMF and ethanol, respectively. After drying at 60 °C for 8 h, the Ni / UiO-66-NH2 catalyst was obtained, denoted as NNU.
[0026] The XRD pattern of the prepared NNU is shown below. Figure 1 As shown.
[0027] Example 2: Preparation of Ni-doped modified UiO-66-NH2 composite food preservation film with chitosan / polyvinyl alcohol First, weigh 1 g of PVA and add it to 20 mL of deionized water, dissolving it completely in a 95 ℃ oil bath to obtain a PVA aqueous solution. Then, weigh 0.5 g of CS and add it to 20 mL of 2.5% acetic acid solution, dissolving it completely in a 60 ℃ oil bath to obtain a CS solution. Next, mix the CS solution with the PVA solution and stir at room temperature for 12 h. Add 15 mg of NNU to the CS / PVA solution, naming it NNU-1. Pour the film-forming solution into a mold and dry it in a 50 ℃ oven for 4 h to finally obtain the composite film.
[0028] Example 3: Preparation of Ni-doped modified UiO-66-NH2 composite food preservation film with chitosan / polyvinyl alcohol First, weigh 1 g of PVA and add it to 20 mL of deionized water, dissolving it completely in a 95 °C oil bath to obtain a PVA aqueous solution. Then, weigh 0.5 g of CS and add it to 20 mL of 2.5% acetic acid solution, dissolving it completely in a 60 °C oil bath to obtain a CS solution. Next, mix the CS solution with the PVA solution and stir at room temperature for 12 h. Add 75 mg of NNU to the CS / PVA solution, naming it NNU-5. Pour the film-forming solution into a mold and dry it in a 50 °C oven for 4 h to finally obtain the composite film.
[0029] Example 4: Preparation of Ni-doped modified UiO-66-NH2 composite food preservation film with chitosan / polyvinyl alcohol First, weigh 1 g of PVA and add it to 20 mL of deionized water, dissolving it completely in a 95 °C oil bath to obtain a PVA aqueous solution. Then, weigh 0.5 g of CS and add it to 20 mL of 2.5% acetic acid solution, dissolving it completely in a 60 °C oil bath to obtain a CS solution. Next, mix the CS solution with the PVA solution and stir at room temperature for 12 h. Add 150 mg of NNU to the CS / PVA solution, naming it NNU-10. Pour the film-forming solution into a mold and dry it in a 50 °C oven for 4 h to finally obtain the composite film.
[0030] Comparative Example 1: First, weigh 1 g of PVA and add it to 20 mL of deionized water. Dissolve the PVA in a 95 °C oil bath to obtain an aqueous PVA solution. Then, weigh 0.5 g of CS and add it to 20 mL of 2.5% acetic acid solution. Dissolve the CS in a 60 °C oil bath to obtain a CS solution. Next, mix the CS solution and PVA solution and stir at room temperature for 12 h. Pour the film-forming solution into a mold and dry it in a 50 °C oven for 4 h to obtain a CS / PVA film.
[0031] Scanning electron microscopy was performed on the composite preservation film prepared in Example 2 and the CS / PVA preservation film prepared in Comparative Example 1. The results are as follows: Figure 1 As shown in the figure, the CS / PVA food preservation film has a smooth surface and a tight cross-section; the Ni / UiO-66-NH2 in the composite food preservation film is uniformly distributed and does not affect the integrity of the film.
[0032] Application example: The preservation of Sunshine Roses was carried out using the preservation film prepared in Example 3 and the preservation film prepared in Comparative Example 1, with commercially available PE film and no preservation film covering as controls, as detailed below: Sunshine roses in essentially the same condition were selected as the experimental subjects and randomly divided into 4 treatments, among which: Treatment 1: Rinse five Sunshine Roses that are basically in the same condition with deionized water, then let them air dry. Place them in an open airtight container without covering them with plastic wrap and expose them to visible light indoors for 9 days. Record the condition of the Sunshine Roses during storage.
[0033] Process 2: Rinse five Shine Roses in basically the same condition with deionized water, then let them air dry. Place them in an open food storage container, cover the opening of the container with commercially available PE plastic wrap and seal it. Place the container indoors under visible light for 9 days and record the condition of the Shine Roses during storage.
[0034] Treatment 3: Five Sunshine Roses in basically the same condition were rinsed with deionized water, then air-dried. They were placed in an open food storage container, and the opening of the container was covered with the food storage film prepared in Comparative Example 1 and sealed. The container was then placed in visible light indoors for 9 days, and the condition of the Sunshine Roses during storage was recorded.
[0035] Process 4: Rinse five Sunshine Roses in basically the same condition with deionized water, then air dry them, place them in an open food storage box, cover the opening of the food storage box with the food storage film prepared in Example 3 and seal it, place it in indoor visible light for 9 days, and record the condition of the Sunshine Roses during storage.
[0036] Processing 1-4 photos of Sunshine Roses preserved for 9 days, as shown Figure 2 As shown.
[0037] The results showed that the preservation time of treatment 1 and treatment 2 was 3 days, the preservation time of CS / PVA was 5 days, and the preservation time of composite preservation film could reach 9 days.
[0038] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a Ni-doped modified UiO-66-NH2 composite food preservation film with chitosan / polyvinyl alcohol, characterized in that, Includes the following steps: Step S1: Prepare Ni / UiO-66-NH2 by hydrothermal method. Step S2: Mix chitosan and polyvinyl alcohol solution to obtain a blend. Add Ni / UiO-66-NH2 prepared in (1) to the blend, stir thoroughly, and defoam by ultrasonication to obtain a film-forming solution. Pour the film-forming solution evenly into a mold. Dry to obtain a composite food preservation film.
2. The preparation method according to claim 1, characterized in that, In step S1, the hydrothermal method for preparing Ni / UiO-66-NH2 is as follows: ZrCl4 and 2-aminoterephthalic acid are dissolved in 40 mL of DMF solution, respectively. Then, a certain amount of acetic acid and Ni(NO3)2·6H2O are added to the above solution, and the mixture is sonicated for 30 min. The resulting solution is transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 120 °C for 24 h. After natural cooling and centrifugation, the solution is washed and dried to obtain Ni / UiO-66-NH2.
3. The preparation method according to claim 1, characterized in that, In step S2, the concentration of the chitosan solution is 2.5%; the concentration of the polyvinyl alcohol solution is 5%, and the volume ratio of the chitosan solution to the polyvinyl alcohol solution is 1:
1.
4. The preparation method according to claim 1, characterized in that, In step S2, the amount of Ni / UiO-66-NH2 added is 1-10% of the total mass of chitosan and polyvinyl alcohol in the blend.
5. A Ni-doped modified UiO-66-NH2 composite food preservation film made by the preparation method according to any one of claims 1-4.
6. The application of the Ni-doped modified UiO-66-NH2 and chitosan / polyvinyl alcohol composite preservation film as described in claim 5 in the preservation of fruits and vegetables.
7. The application according to claim 6, characterized in that, The fruit and vegetable in question is Shine Muscat.
8. A method for preserving fruits and vegetables using the Ni-doped modified UiO-66-NH2 and chitosan / polyvinyl alcohol composite preservative film as described in claim 7, comprising the following steps: The fruits and vegetables to be preserved are placed in an open preservation box, and the opening of the preservation box is covered and sealed with the Ni-doped modified UiO-66-NH2 and chitosan / polyvinyl alcohol composite preservation film as described in claim 7. Then, the preservation is carried out under visible light irradiation.