Preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper

Abstract

The application provides a preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper. The preparation method of the polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper comprises the following steps: S1. A proper amount of urea is weighed, wrapped with aluminum foil paper, placed in a tube furnace, calcined under nitrogen protection, and a light yellow powder graphite phase carbon nitride is obtained after natural cooling; S2. 500 mg of graphite phase carbon nitride is ultrasonically dispersed in 500 ml of water, then water and potassium persulfate are added, a KOH solution is used to adjust the pH to 12, and after 6 h of stirring in a 85 DEG C water bath, the product is washed with deionized water until neutral, and then freeze-dried to obtain graphite phase carbon nitride nanosheets. The preparation method of the polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has the advantages of simple process, excellent antibacterial performance, green environmental protection, and effective extension of product shelf life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photosensitive antibacterial packaging paper, and particularly relates to a preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper. BACKGROUND

[0002] The food used by people in daily life is contaminated by microorganisms during processing, transportation, storage and sales, which increases economic losses, reduces the safety quality of food and threatens human health. Paper is made of natural plant fibers and is the most ideal packaging material. At present, most paper-based packaging on the market does not have antibacterial properties. In recent years, more and more cases of product contamination caused by microbial attachment to packaging materials have occurred in the logistics and transportation industry. Therefore, it is urgent to develop a truly green and environmentally friendly antibacterial packaging paper.

[0003] Common antibacterial agents include inorganic metal antibacterial agents, organic antibacterial agents, natural antibacterial agents and photocatalytic antibacterial agents. Organic antibacterial agents and inorganic antibacterial agents have harmful substances that can accumulate in animals and soil due to their physical and chemical properties, making it difficult to achieve complete degradation and causing problems such as bacterial resistance, secondary pollution and safety hazards during long-term use. Inorganic photocatalytic materials have the advantages of low cost, significant effect, long effective period and no drug resistance. As a new type of non-metallic photocatalytic material, graphite phase carbon nitride is non-toxic, environmentally friendly and easy to manufacture. Its antibacterial properties are mainly due to the production of active oxygen substances such as superoxide radicals (·O2 - ) and hydroxyl radicals (·OH) during the electron-hole pair reaction, which can damage the cell membrane of bacteria and disrupt cell respiration, thereby having long-term and broad-spectrum antibacterial properties.

[0004] Graphite phase carbon nitride has not been widely used in packaging and transportation, and the loading method and antibacterial properties of graphite phase carbon nitride are key factors affecting its development.

[0005] Therefore, it is necessary to provide a new preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper to solve the above technical problems. SUMMARY

[0006] The technical problem solved by the present application is to provide a preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper, which has the advantages of simple process, excellent antibacterial properties, green environmental protection and effective shelf life extension.

[0007] To solve the above technical problems, the preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper provided by the present application comprises the following steps:

[0008] S1. Take a certain amount of urea, tightly wrap it with aluminum foil paper, and then place it in a tube furnace for calcination under nitrogen protection. After natural cooling, a light yellow powdery graphite phase carbon nitride is obtained;

[0009] S2. Take 500mg of graphite phase carbon nitride, ultrasonically disperse it in 500ml of water, then add water and potassium persulfate, adjust the pH to 12 with KOH solution, stir in a 85℃ water bath for 6h, then wash with deionized water until neutral, and freeze-dry to obtain graphite phase carbon nitride nanosheets;

[0010] S3. Ultrasonically disperse the graphite phase carbon nitride nanosheets in water, add polyvinyl alcohol and glycerol, stir in a 95℃ water bath for 60min, and then cool to prepare a photosensitive antibacterial emulsion;

[0011] S4. Apply the photosensitive antibacterial emulsion prepared in step 3 to the base paper, dry in an oven at 60℃ for 2h to obtain a polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper.

[0012] As a further scheme of the present application, in step S1, the heating rate is 5℃ / min, and the calcination temperature is 550℃.

[0013] As a further scheme of the present application, in step S2, the graphite phase carbon nitride used is a block-like layered porous structure with a diameter of 1.5-3μm, and in step S2, the potassium persulfate added is 5.6g.

[0014] As a further scheme of the present application, in step S3, the prepared photosensitive antibacterial emulsion has a graphite phase carbon nitride nanosheet mass fraction of 0.5%-0.9%, a polyvinyl alcohol mass fraction of 6%, and a glycerol mass fraction of 1.5%.

[0015] As a further scheme of the present application, in step S3, the graphite phase carbon nitride nanosheets used have a diameter of 90-320nm and a thickness of 5-10nm, and in step S3, the polyvinyl alcohol has an alcoholysis degree of 87.0-89.0%.

[0016] As a further scheme of the present application, in step S4, the base paper includes food packaging kraft paper, oil-proof paper, and fresh-keeping water-absorbing paper, and in step S4, the coating thickness of the photosensitive antibacterial emulsion is 30μm.

[0017] Compared with the related art, the preparation method of the polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper provided by the present application has the following beneficial effects:

[0018] 1. The present application uses the non-metal photocatalytic material graphite phase carbon nitride as an antibacterial agent, which has the characteristics of green environmental protection, non-toxicity and non-pollution, can produce reactive oxygen species under visible light, and can effectively and widely resist bacteria for a long time;

[0019] 2. This invention uses urea as a precursor to prepare graphitic carbon nitride by thermal polymerization. The process is simple, the cost is low, and it can realize the large-scale production of graphitic carbon nitride.

[0020] 3. This invention uses polyvinyl alcohol as a film-forming agent to uniformly disperse graphite phase carbon nitride nanosheets into an emulsion. After coating the paper surface, it can obtain excellent antibacterial properties and also enhance the physical properties of the paper.

[0021] 4. This invention uses paper as the base material and the coating solution is green and pollution-free, making it a truly biodegradable and environmentally friendly food packaging material. The process is simple, and the antibacterial effect is significant. It can effectively inhibit the growth and reproduction of food pathogens and has potential commercial value in the packaging of fresh meat, fruits and vegetables, and other products.

[0022] 5. This invention uses a thermal oxidation exfoliation method to exfoliate sheet-like porous blocky graphitic carbon nitride into nanosheets, which increases the specific surface area of ​​the material, promotes the separation of electron-hole pairs, and thus enhances the photocatalytic antibacterial properties of graphitic carbon nitride. Attached Figure Description

[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram illustrating the antibacterial rate of the polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper of the present invention. Detailed Implementation

[0025] A method for preparing a polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper includes the following steps:

[0026] S1. Weigh an appropriate amount of urea, wrap it tightly in aluminum foil, place it in a tube furnace, calcine it under nitrogen protection, and after natural cooling, obtain a light yellow powdery graphitic carbon nitride.

[0027] S2. Take 500 mg of graphitic carbon nitride and ultrasonically disperse it in 500 ml of water. Then add water and potassium persulfate, adjust the pH to 12 with KOH solution, stir in an 85℃ water bath for 6 h, wash with deionized water until neutral, and freeze dry to obtain graphitic carbon nitride nanosheets.

[0028] S3. Graphite-phase carbon nitride nanosheets were ultrasonically dispersed in water, polyvinyl alcohol and glycerol were added, and the mixture was stirred in a water bath at 95°C for 60 min. After cooling, a photosensitive antibacterial emulsion was obtained.

[0029] S4. The photosensitive antibacterial emulsion prepared in step 3 is coated onto the base paper and dried in an oven at 60°C for 2 hours to obtain polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper.

[0030] The temperature rising rate in the step S1 is 5℃ / min, and the calcination temperature is 550℃.

[0031] In the step S2, the graphite phase carbon nitride used is in a bulk lamellar porous structure with a diameter of 1.5-3μm, and the potassium persulfate added in the step S2 is 5.6g.

[0032] In the step S3, the prepared photosensitive antibacterial emulsion has a graphite phase carbon nitride nanosheet mass fraction of 0.5%-0.9%, a polyvinyl alcohol mass fraction of 6%, and a glycerol mass fraction of 1.5%.

[0033] In the step S3, the graphite phase carbon nitride nanosheet used has a diameter of 90-320nm and a thickness of 5-10nm, and the alcoholysis degree of the polyvinyl alcohol in the step S3 is 87.0-89.0%.

[0034] In the step S4, the base paper includes food packaging kraft paper, oil-proof paper, and fresh-keeping water-absorbing paper, and the coating thickness of the photosensitive antibacterial emulsion in the step S4 is 30μm.

[0035] In the step S1, urea is used as a precursor, the process for preparing the graphite phase carbon nitride by thermal polymerization is simple and low in cost, and the graphite phase carbon nitride can be produced on a large scale.

[0036] In the step S4, polyvinyl alcohol is used as a film-forming agent, the graphite phase carbon nitride nanosheet is uniformly dispersed in the emulsion, and after being coated on the surface of the paper, excellent antibacterial performance can be obtained, and the physical properties of the paper can be enhanced.

[0037] In the step S2, the graphite phase carbon nitride is used as an antibacterial agent of a metal-free photocatalytic material, has the characteristics of green environmental protection, non-toxicity, and no pollution, can produce reactive oxygen substances under visible light, improve the antibacterial performance, and has long-term and effective broad-spectrum antibacterial effect.

[0038] Embodiment 1 is a preparation method of a polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper, which comprises the following steps:

[0039] (1) Under room temperature conditions, 0.1% mass fraction of graphite phase carbon nitride nanosheet is ultrasonically dispersed in deionized water, 6% mass fraction of polyvinyl alcohol is added after 30min, and stirring is continuously performed to make the polyvinyl alcohol fully dispersed in water;

[0040] (2) Then, water bath stirring is performed at 95℃ for 60min to make the polyvinyl alcohol fully dissolved, and an antibacterial coating emulsion is obtained after natural cooling to room temperature;

[0041] (3). The polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper is prepared according to the above step S4, wherein the paper coating thickness is 30 μm, the air oven drying is performed at 60 ℃ for 2 h, and the antibacterial rate is 99.9%. Figure 1 .

[0042] The preparation method of the polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper described in the embodiment 1 has the following advantages:

[0043] The graphite phase carbon nitride nanosheet has excellent photocatalytic performance and antibacterial performance, and the photosensitive antibacterial paper with good antibacterial effect is prepared.

[0044] The graphite phase carbon nitride nanosheet is fully dispersed in deionized water by the ultrasonic dispersion method, and the dispersibility and antibacterial effect of the nanosheet are improved.

[0045] The polyvinyl alcohol is added into the graphite phase carbon nitride nanosheet dispersion liquid to prepare an antibacterial coating emulsion, and then the antibacterial coating emulsion is coated on the surface of the paper to form a uniform antibacterial coating.

[0046] The coating thickness is 30 μm, which can ensure the antibacterial effect while not affecting the use performance and printing performance of the paper.

[0047] The air oven drying is performed at 60 ℃ for 2 h, which can effectively promote the solidification of the coating and the improvement of the antibacterial performance.

[0048] The obtained polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper has a high antibacterial rate, which can meet the antibacterial requirements of various application scenarios.

[0049] Embodiment 2, a preparation method of a polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper, comprising the following steps:

[0050] (1). Under room temperature conditions, 0.3% mass fraction of graphite phase carbon nitride nanosheet is ultrasonically dispersed in deionized water, 6% mass fraction of polyvinyl alcohol is added after 30 min, and the polyvinyl alcohol is fully dispersed in water by constant stirring;

[0051] (2). Then, the water bath stirring is performed at 95 ℃ for 60 min to make the polyvinyl alcohol fully dissolved, and the antibacterial coating emulsion is obtained after natural cooling to room temperature;

[0052] (4). The polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper is prepared according to the above step S4, wherein the paper coating thickness is 30 μm, the air oven drying is performed at 60 ℃ for 2 h, and the antibacterial rate is 99.9%. Figure 1 .

[0053] The preparation method of the polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper has the following advantages:

[0054] By adjusting the mass fraction of graphitic carbon nitride nanosheets (0.3%) and polyvinyl alcohol (6%), the antibacterial effect and coating performance of antibacterial paper can be improved.

[0055] During the same preparation process, the coating thickness is kept at 30μm, which can ensure the antibacterial effect without affecting the paper's performance and printability.

[0056] Drying in a 60℃ forced-air oven for 2 hours can effectively promote the curing of the coating and improve its antibacterial properties.

[0057] The resulting polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has a high antibacterial rate and can meet the antibacterial needs of various application scenarios.

[0058] The antibacterial paper prepared by this method has the advantages of low cost, simple operation, and good antibacterial effect.

[0059] Example 3, a method for preparing a polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper, comprising the following steps:

[0060] (1). At room temperature, 0.5% by mass of graphite phase carbon nitride nanosheets were ultrasonically dispersed in deionized water. After 30 min, 6% by mass of polyvinyl alcohol was added and stirred continuously to ensure that the polyvinyl alcohol was fully dispersed in the water.

[0061] (2). Then, stir in a water bath at 95°C for 60 minutes to fully dissolve the polyvinyl alcohol. After naturally cooling to room temperature, an antibacterial coating emulsion is obtained.

[0062] (3) Polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper was prepared according to step 4 above, wherein the paper coating thickness was 30 μm, and it was dried in a forced-air oven at 60℃ for 2 h. Its antibacterial rate is shown in the figure. Figure 1 .

[0063] The method for preparing the polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has the following advantages:

[0064] By adjusting the mass fraction of graphitic carbon nitride nanosheets (0.5%) and polyvinyl alcohol (6%), the antibacterial effect and coating performance of antibacterial paper can be improved.

[0065] During the same preparation process, the coating thickness is kept at 30μm, which can ensure the antibacterial effect without affecting the paper's performance and printability.

[0066] Drying in a 60℃ forced-air oven for 2 hours can effectively promote the curing of the coating and improve its antibacterial properties.

[0067] The obtained polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has high antibacterial rate, which can meet the antibacterial needs of various application scenarios.

[0068] It should be noted that the mass fraction in this method may be adjusted according to specific application scenarios and needs in order to obtain the best antibacterial effect and coating performance.

[0069] Example 4, a preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper, comprising the following steps:

[0070] (1). Under room temperature conditions, 0.7% mass fraction of graphite phase carbon nitride nanosheet is ultrasonically dispersed in deionized water, 6% mass fraction of polyvinyl alcohol is added after 30 min, and constant stirring is carried out to make the polyvinyl alcohol fully dispersed in water;

[0071] (2). Then water bath stirring at 95℃ for 60 min to make the polyvinyl alcohol fully dissolved, and the antibacterial coating emulsion is obtained after natural cooling to room temperature;

[0072] (3). According to the above step 4, polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper is prepared, wherein the paper coating thickness is 30μm, 60℃ air oven drying for 2h, and the antibacterial rate is seen Figure 1

[0073] The preparation method of the polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has the following advantages:

[0074] By adjusting the mass fraction of graphite phase carbon nitride nanosheet (0.7%) and the mass fraction of polyvinyl alcohol (6%), the antibacterial effect and coating performance of the antibacterial paper can be improved.

[0075] In the preparation process of the same step, the coating thickness is kept at 30μm, which can ensure the antibacterial effect while not affecting the use performance and printing performance of the paper.

[0076] 60℃ air oven drying for 2h can effectively promote the curing of the coating and the improvement of the antibacterial performance.

[0077] The obtained polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper has high antibacterial rate, which can meet the antibacterial needs of various application scenarios.

[0078] It should be noted that the mass fraction in this method may be adjusted according to specific application scenarios and needs in order to obtain the best antibacterial effect and coating performance.

[0079] Example 5, a preparation method of polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper, comprising the following steps:

[0080] (1). Under room temperature, 0.9% mass fraction of graphite phase carbon nitride nanosheets is ultrasonically dispersed in deionized water, 6% mass fraction of polyvinyl alcohol is added after 30 minutes, and constant stirring is carried out to make the polyvinyl alcohol fully dispersed in water;

[0081] (2). Then, under water bath stirring at 95℃ for 60 minutes, the polyvinyl alcohol is fully dissolved, and the antibacterial coating emulsion is obtained after natural cooling to room temperature;

[0082] (3). The polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper is prepared according to the above step 4, wherein the paper coating thickness is 30μm, 2h drying in a 60℃ air oven, and the antibacterial rate is seen in Figure 1 .

[0083] The preparation method of the polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper has the following advantages:

[0084] By adjusting the mass fraction of graphite phase carbon nitride nanosheets (0.9%) and the mass fraction of polyvinyl alcohol (6%), the antibacterial effect and coating performance of the antibacterial paper can be improved.

[0085] In the preparation process of the same step, the coating thickness is kept at 30μm, which can ensure the antibacterial effect while not affecting the use performance and printing performance of the paper.

[0086] 2h drying in a 60℃ air oven can effectively promote the solidification of the coating and improve the antibacterial performance.

[0087] The obtained polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper has a high antibacterial rate, which can meet the antibacterial needs of various application scenarios.

[0088] It should be noted that the mass fraction in this method may be adjusted according to specific application scenarios and needs in order to obtain the best antibacterial effect and coating performance.

[0089] Select the polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper in the above examples 1-5, and calculate the number of colony growth after 48h culture by plate counting method, and the antibacterial rate is seen in Figure 1 . From Figure 1 the data, it can be seen that the antibacterial paper coated with different proportions of graphite phase carbon nitride nanosheets shows antibacterial effect on Escherichia coli and Staphylococcus aureus, and the antibacterial rate increases with the increase of the amount of graphite phase carbon nitride nanosheets, but when the mass fraction of graphite phase carbon nitride nanosheets is 0.7%, the antibacterial effect can reach 99%.

[0090] Graphite phase carbon nitride nanosheets have good antibacterial performance, and can be coated on polyvinyl alcohol paper to prepare paper with antibacterial function.

[0091] The benefits of this antibacterial paper include:

[0092] According to the data, Figure 1 The antibacterial paper coated with different proportions of graphitic carbon nitride nanosheets showed antibacterial effects on both E. coli and S. aureus, and the antibacterial rate increased with the increase of the amount of graphitic carbon nitride nanosheets. When the mass fraction of graphitic carbon nitride nanosheets was 0.7%, the antibacterial effect reached 99%. This antibacterial performance can effectively inhibit the growth of bacteria and reduce the risk of cross infection.

[0093] Antibacterial paper can be applied in medical, food packaging, daily necessities and other fields. In the medical field, antibacterial paper can be used to prepare oral care products, medical dressings, etc., to effectively prevent infection. In the field of food packaging, antibacterial paper can be used to package fresh food to extend the shelf life of food. In the field of daily necessities, antibacterial paper can be used to prepare antibacterial wipes, antibacterial paper towels, etc., to provide a more sanitary use experience.

[0094] Polyvinyl alcohol paper is a degradable material, which has better environmental performance compared with traditional plastic paper. The addition of graphitic carbon nitride nanosheets can provide antibacterial function, reducing the dependence on traditional antibacterial agents, thereby reducing the impact on the environment.

[0095] In addition to the benefits mentioned above, the polyvinyl alcohol / graphitic carbon nitride nanosheet photosensitive antibacterial paper has the following benefits:

[0096] Graphitic carbon nitride nanosheets have long-lasting antibacterial properties and can form an antibacterial layer on the surface of the paper, continuously inhibiting the growth of bacteria, thereby achieving long-acting antibacterial effect. Compared with traditional antibacterial agents, graphitic carbon nitride nanosheets have more persistent antibacterial effect and are not easily washed or worn off.

[0097] Graphitic carbon nitride nanosheets have low toxicity and good biocompatibility, and are safe to the human body and the environment. Therefore, the use of polyvinyl alcohol / graphitic carbon nitride nanosheet photosensitive antibacterial paper will not harm human health and will not pollute the environment.

[0098] By adjusting the amount of graphitic carbon nitride nanosheets, the antibacterial performance of the antibacterial paper can be flexibly controlled. According to the experimental results, when the mass fraction of graphitic carbon nitride nanosheets is 0.7%, the antibacterial effect reaches 99%. This adjustability allows antibacterial paper to produce products with different antibacterial properties according to different needs.

[0099] While the embodiments of the application have been described and illustrated, it is to be understood that modifications and changes can be devised by those skilled in the art, which do not depart from the spirit and principles of the application, and that the scope of the present application is not to be limited to the embodiments set forth herein. Any and all modifications, changes, substitutions, and variations which fall within the spirit and principles of the application are to be considered as falling within the scope of the application as defined in the appended claims and equivalents thereof.

[0100] The above description is only preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent substitutions or changes according to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for preparing a polyvinyl alcohol-graphite-phase carbon nitride nanosheet photosensitive antibacterial paper, characterized in that, Includes the following steps: S1. Weigh an appropriate amount of urea, wrap it tightly in aluminum foil, place it in a tube furnace, calcine it under nitrogen protection, and after natural cooling, obtain a light yellow powdery graphitic carbon nitride. S2. Take 500 mg of graphitic carbon nitride and ultrasonically disperse it in 500 ml of water. Then add water and potassium persulfate, adjust the pH to 12 with KOH solution, stir in an 85℃ water bath for 6 h, wash with deionized water until neutral, and freeze dry to obtain graphitic carbon nitride nanosheets. S3. Graphite-phase carbon nitride nanosheets were ultrasonically dispersed in water, polyvinyl alcohol and glycerol were added, and the mixture was stirred in a water bath at 95°C for 60 min. After cooling, a photosensitive antibacterial emulsion was obtained. S4. The photosensitive antibacterial emulsion prepared in step S3 is coated onto the base paper and dried in an oven at 60°C for 2 hours to obtain polyvinyl alcohol / graphite phase carbon nitride nanosheet photosensitive antibacterial paper. In step S1, the heating rate is 5℃ / min and the calcination temperature is 550℃; In step S2, the graphitic carbon nitride used has a blocky, sheet-like porous structure with a diameter of 1.5–3 μm, and the amount of potassium persulfate added in step S2 is 5.6 g. In step S3, the prepared photosensitive antibacterial emulsion has a graphite phase carbon nitride nanosheet mass fraction of 0.5% to 0.9%, a polyvinyl alcohol mass fraction of 6%, and a glycerol mass fraction of 1.5%. In step S3, the graphite phase carbon nitride nanosheets used have a diameter of 90-320 nm and a thickness of 5-10 nm. In step S3, the degree of alcoholysis of the polyvinyl alcohol is 87.0-89.0%.

2. The method for preparing polyvinyl alcohol graphite phase carbon nitride nanosheet photosensitive antibacterial paper according to claim 1, characterized in that: In step S4, the base paper includes kraft paper for food packaging, greaseproof paper, and absorbent paper for freshness preservation. In step S4, the coating thickness of the photosensitive antibacterial emulsion is 30 μm.

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