Chitin / cotton linter pulp fiber composite antibacterial film and preparation method thereof

Abstract

The invention discloses a chitin / cotton linter pulp fiber composite antibacterial film and a preparation method thereof. The preparation method comprises the following steps: extraction of chitin, dissolution of chitin, dissolution of cotton linter pulp cellulose, preparation of a blended solution, film formation and post-treatment. The extraction of the chitin comprises the following steps: sequentially carrying out deproteinization, desalination, decoloration and crushing on shrimp shell powder to obtain powdery chitin; the dissolution of the chitin comprises the step of dissolving the extracted chitin in an aqueous solution containing 15-25wt% of potassium hydroxide and 3-6wt% of urea to obtain a chitin solution. According to the composite antibacterial film, cotton linter pulp cellulose is used as a substrate, chitin extracted from shrimp shells through a system process is used as an auxiliary material, potassium hydroxide / urea is used for dissolving the chitin, and the composite film with good transparency, swelling degree, film forming uniformity and antibacterial performance is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, in particular to a chitin / cotton linter pulp fiber composite antibacterial film and a preparation method thereof. BACKGROUND

[0002] Chitin is the second largest renewable resource in nature after fiber, and widely exists in shrimps. Chitin has good chemical stability and good chelation of pollutants, and has antibacterial property; however, chitin film has high brittleness and low elongation at break, and needs to be blended with other materials to effectively improve the mechanical and physical and chemical properties of the film.

[0003] Cellulose has excellent biological compatibility, biodegradability and non-toxicity. Cellulose and chitin are natural high molecular materials with abundant reserves in nature, and have many similarities in structure and function. Compared with conventional filling materials, chitin as a filling material can better improve the surface tension of the film, so that the film has good mixing performance with the fiber matrix, and can also improve the thermodynamic properties of the film. After blending of different substances, a composite substance with better performance than the original single component can be obtained. However, cellulose and chitin have poor solubility in aqueous solution, and chitin is prone to aggregation during film formation, which affects the uniformity of the composite film. Moreover, the source and pretreatment process of chitin are not systematically optimized in the prior art, so that the degree of deacetylation of chitin is unstable, which finally affects the antibacterial performance of the film.

[0004] Therefore, there is no report on a chitin / cotton linter pulp fiber composite antibacterial film with good film uniformity and excellent and stable antibacterial performance. SUMMARY

[0005] Therefore, the present application provides a chitin / cotton linter pulp fiber composite antibacterial film and a preparation method thereof. The composite antibacterial film uses cotton linter pulp cellulose as a substrate, uses chitin extracted from shrimp shells through a systematic process as an auxiliary material, and uses potassium hydroxide / urea to dissolve the chitin, so as to prepare a composite film with good transparency, swelling degree, film uniformity and antibacterial performance.

[0006] In order to achieve the above purpose, the present application realizes the following technical solutions:

[0007] A preparation method of a chitin / cotton linter pulp fiber composite antibacterial film, comprising the following steps:

[0008] S1, extraction of chitin: comprising the following steps in sequence: (1) deproteinization: mixing shrimp shell powder with sodium hydroxide solution with a concentration of 1.8-2.2 mol / L according to a solid-liquid ratio of 1:5-1:10 g / mL, stirring at 65-75℃ for 1.5-2.5 h, then washing with water to neutral, and then drying at 60-70℃ for 60-120 min to obtain deproteinized shrimp shell powder; (2) desalination: mixing the deproteinized shrimp shell powder with hydrochloric acid solution with a concentration of 0.9-1.1 mol / L according to 1:5-1:10 g / mL, heating to 23-27℃, stirring for 25-35 min, then washing with water to neutral, and then drying at 60-70℃ for 60-120 min to obtain desalted shrimp shell powder; (3) bleaching: mixing the desalted shrimp shell powder with hydrogen peroxide solution with a mass volume concentration of 9-11% according to a solid-liquid ratio of 1:6-1:10 g / mL, heating to 55-65℃ in a water bath, stirring for 1.5-2.5 h, then washing with water to neutral, drying at 60-70℃ for 60-120 min, finally crushing to a particle size of 0.1-0.5 mm with a crusher, and then passing through a 60-100 mesh sieve to obtain powdered chitin;

[0009] S2, dissolution of chitin: dissolving the chitin obtained in S1 in potassium hydroxide / urea aqueous solution to obtain a chitin solution; the potassium hydroxide / urea aqueous solution is an aqueous solution containing 15-25 wt% potassium hydroxide and 3-6 wt% urea;

[0010] S3, dissolution of cotton linter pulp cellulose: dissolving cotton linter pulp cellulose in lithium hydroxide / urea aqueous solution to obtain a cotton linter pulp cellulose solution; the lithium hydroxide / urea aqueous solution is an aqueous solution containing 4-5 wt% lithium hydroxide and 14-16 wt% urea.

[0011] S4, preparation of a blended solution: mixing the chitin solution prepared in S2 and the cotton linter pulp cellulose solution prepared in S3 according to a dry mass ratio of chitin to cotton linter pulp cellulose of 1:5-1:1, stirring at 5-10℃ for 10-20 min to obtain a blended solution;

[0012] S5, film formation and post-treatment: pouring the blended solution prepared in S4 onto a film forming plate to lay a film, then placing it in a 3-8 wt% sodium sulfate coagulation bath for solidification and regeneration, then washing with water, and then drying at a temperature of 30-60℃ for 6-12 h to obtain a chitin / cotton linter pulp cellulose composite antibacterial film.

[0013] Specifically, the dissolving of the chitin in S2 is specifically: freezing at -20 to -30℃ for 4 to 8 hours, then thawing at room temperature and mechanical stirring at 600 to 1000 rpm for 1 to 3 hours, and then repeating the freezing-thawing step for 1 to 3 times; the dissolving of the cotton linter pulp cellulose in S3 is specifically: freezing at -15 to -25℃ for 6 to 10 hours, then thawing at room temperature and mechanical stirring at 600 to 1000 rpm for 1 to 3 hours.

[0014] Specifically, in S2, the mixed weight ratio of chitin to potassium hydroxide / urea aqueous solution in the chitin solution is 2 to 10:100; in S3, the mixed weight ratio of cotton linter pulp cellulose to lithium hydroxide / urea aqueous solution in the cotton linter pulp cellulose solution is 2 to 10:100.

[0015] Specifically, the potassium hydroxide / urea aqueous solution is an aqueous solution containing 20wt% potassium hydroxide and 4wt% urea, and the lithium hydroxide / urea aqueous solution is an aqueous solution containing 4.6wt% lithium hydroxide and 15wt% urea.

[0016] Specifically, the stirring speed in step (1) of S1 is 600 to 1000 rpm, the stirring speed in step (2) of S1 is 600 to 1000 rpm, and the stirring speed in step (3) of S1 is 600 to 1000 rpm.

[0017] Specifically, the shrimp shell is the shell of Penaeus vannamei, and the water for washing is distilled water, and the film forming plate is an acrylic plate.

[0018] The application also provides a chitin / cotton linter pulp fiber composite antibacterial film prepared by the above method.

[0019] Compared with the prior art, the application has the following advantages:

[0020] 1. The chitin is dissolved by potassium hydroxide / urea aqueous solution, which significantly improves the solubility and stability of the chitin solution, and can obtain a more uniform and transparent solution, and reduces the molecular chain breakage, which is conducive to forming a more uniform blending film and stable film forming performance.

[0021] 2. The shrimp shell is used as the raw material, and through the step-by-step deproteinization-desalination-decolorization process, and accurate control of the reaction temperature, time and reagent concentration, high-quality chitin with a deacetylation degree of ≥80% can be stably obtained, which solves the problem of raw material quality fluctuation. The high deacetylation degree means more free amino groups, which not only enhances the antibacterial activity of the composite antibacterial film, especially increases the inhibition zone diameter of Staphylococcus aureus and Escherichia coli, but also improves the compatibility with cotton linter pulp cellulose.

[0022] 3、The solvent used in the application, lithium hydroxide, urea, etc., can be recycled, and the environmental pollution is small. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The transparency trend chart of the chitin / cotton linter pulp fiber composite antibacterial film with different proportions of the third to seventh embodiments and comparative example 1 of the application;

[0024] Figure 2 The moisture content trend chart of the chitin / cotton linter pulp fiber composite antibacterial film with different proportions of the third to seventh embodiments and comparative example 1 of the application;

[0025] Figure 3 The swelling degree trend chart of the chitin / cotton linter pulp fiber composite antibacterial film with different proportions of the third to seventh embodiments and comparative example 1 of the application;

[0026] Figure 4 The scanning electron microscope chart of the chitin / cotton linter pulp fiber composite antibacterial film with different proportions of comparative example 1, example 4 and example 3 of the application: (a) cotton linter pulp fiber film, i.e. the dry weight mass ratio of chitin to cotton linter pulp cellulose is 0:1; (b) the dry weight mass ratio of chitin to cotton linter pulp cellulose is 1:2; (c) the dry weight mass ratio of chitin to cotton linter pulp cellulose is 1:1. DETAILED DESCRIPTION

[0027] The exemplary embodiments disclosed herein will now be described in more detail, in order to enable a full and complete disclosure of the present application to those skilled in the art. Although the exemplary embodiments of the present application are shown and described, it is to be understood that the present application is not to be limited to the embodiments disclosed herein.

[0028] Example 1

[0029] A preparation method of a chitin / cotton linter pulp fiber composite antibacterial film, comprising the following steps:

[0030] S1, extraction of chitin: (1) deproteinization: 10 g of dry shrimp shell powder from South America was weighed, 50 mL of 1.8 mol / L sodium hydroxide solution was added, and heating and stirring were carried out at 65°C and 1000 rpm for 2.5 h, then distilled water was washed until neutral, and then dried at 60°C for 120 min to obtain deproteinized shrimp shell powder; (2) desalination: 10 g of deproteinized shrimp shell powder was weighed, 50 mL of 0.9 mol / L hydrochloric acid solution was added, and heating was carried out to 23°C, stirring was carried out at 1000 rpm for 35 min, then distilled water was washed until neutral, and then dried at 60°C for 120 min to obtain desalted shrimp shell powder; (3) decolorization: 10 g of desalted shrimp shell powder was weighed, 60 mL of 9% hydrogen peroxide solution was added, and heating was carried out in a water bath to 55°C, then stirring was carried out at 1000 rpm for 1.5 h, then distilled water was washed until neutral, and then dried at 60°C for 120 min, finally, the powder was crushed to a particle size of 0.5 mm with a crusher, and then passed through a 60-mesh sieve to obtain chitin powder, which was stored in a desiccator for use.

[0031] S2, dissolution of chitin: 2 g of chitin powder obtained in step S1 was taken, 100 g of an aqueous solution containing 15 wt% potassium hydroxide and containing 6 wt% urea was added, frozen at -30°C for 6 h, then thawed at room temperature and 600 rpm for 3 h, and then the above freezing-thawing cycle was repeated 3 times to obtain a chitin solution with a mass fraction of 2 wt%.

[0032] S3, dissolution of cotton linter pulp cellulose: 2 g of cotton linter pulp cellulose was taken, 100 g of an aqueous solution containing 4 wt% lithium hydroxide and containing 16 wt% urea was added, frozen at -25°C for 10 h, then thawed at room temperature and 600 rpm for 3 h to obtain a cotton linter pulp cellulose solution with a mass fraction of 2 wt%.

[0033] S4, preparation of a blended solution: the chitin solution obtained in step S2 and the cotton linter pulp cellulose solution obtained in step S3 were mixed in a dry weight mass ratio of chitin to cotton linter pulp cellulose of 1:5 (i.e. 25 g of chitin solution + 125 g of cellulose solution), stirred at 10°C for 20 min to obtain a blended solution.

[0034] S5, film formation and post-treatment: the blended solution prepared in S4 was poured onto a plexiglass plate to form a film, then placed in a 3% sodium sulfate coagulation bath for solidification and regeneration, then washed with distilled water, and dried in a 30°C drying oven for 12 h to obtain a chitin / cotton linter pulp cellulose composite antibacterial film.

[0035] Example 2

[0036] A method for preparing a chitin / cotton linter pulp cellulose composite antibacterial film:

[0037] S1, extraction of chitin: (1) deproteinization: 10 g of dry shrimp shell powder from South America was weighed, 80 mL of 2.2 mol / L sodium hydroxide solution was added, and the mixture was heated and stirred at 75°C and 600 rpm for 1.5 h. Then, the mixture was washed with distilled water until neutral, and then dried at 70°C for 60 min to obtain deproteinized shrimp shell powder; (2) desalination: 10 g of deproteinized shrimp shell powder was weighed, 80 mL of 1.1 mol / L hydrochloric acid solution was added, and the mixture was heated to 27°C, stirred at 600 rpm for 25 min, washed with distilled water until neutral, and then dried at 70°C for 60 min to obtain desalted shrimp shell powder; (3) decolorization: 10 g of desalted shrimp shell powder was weighed, 80 mL of 11% hydrogen peroxide solution was added, and the mixture was heated to 65°C in a water bath, stirred at 600 rpm for 2.5 h, then washed with distilled water until neutral, and then dried at 70°C for 60 min. Finally, the mixture was crushed to a particle size of 0.1 mm with a crusher, and then passed through a 100-mesh sieve to obtain chitin powder, which was stored in a desiccator for later use.

[0038] S2, dissolution of chitin: 5 g of chitin powder obtained in step S1 was taken, 100 g of an aqueous solution containing 25 wt% potassium hydroxide and 3 wt% urea was added, and the mixture was frozen at -25°C for 8 h, then thawed at room temperature with mechanical stirring at 1000 rpm for 1 h, and then the above freezing-thawing cycle was repeated twice to obtain a chitin solution with a mass fraction of 5 wt%.

[0039] S3, dissolution of cotton linter pulp cellulose: 5 g of cotton linter pulp cellulose was taken, 100 g of an aqueous solution containing 5 wt% lithium hydroxide and 14 wt% urea was added, and the mixture was frozen at -18°C for 7 h, then thawed at room temperature with mechanical stirring at 1000 rpm for 1 h to obtain a cotton linter pulp cellulose solution with a mass fraction of 5 wt%.

[0040] S4, preparation of a blended solution: the chitin solution obtained in step S2 and the cotton linter pulp cellulose solution obtained in step S3 were mixed in a dry weight mass ratio of chitin to cotton linter pulp cellulose of 1:2 (i.e. 40 g of chitin solution + 80 g of cellulose solution), and stirred at 6°C for 12 min to obtain a blended solution.

[0041] S5, film formation and post-treatment: the blended solution prepared in S4 was poured onto a plexiglass plate to form a film, and then placed in an 8% sodium sulfate coagulation bath for solidification and regeneration, then washed with distilled water, and dried in a 60°C drying oven for 8 h to obtain a chitin / cotton linter pulp cellulose composite antibacterial film.

[0042] Example 3

[0043] A method for preparing a chitin / cotton linter pulp cellulose composite antibacterial film:

[0044] S1, extraction of chitin: (1) deproteinization: 10 g of dry shrimp shell powder from South America was weighed, 100 mL of 2.0 mol / L sodium hydroxide solution was added, heated and stirred at 70°C and 800 rpm for 2 h, washed with distilled water until neutral, and dried at 65°C for 90 min to obtain deproteinized shrimp shell powder; (2) desalination: 10 g of deproteinized shrimp shell powder was weighed, 100 mL of 1.0 mol / L hydrochloric acid solution was added, heated to 25°C, stirred at 800 rpm for 30 min, washed with distilled water until neutral, and dried at 65°C for 90 min to obtain desalted shrimp shell powder; (3) decolorization: 10 g of desalted shrimp shell powder was weighed, 100 mL of 10% hydrogen peroxide solution was added, heated to 60°C in a water bath, stirred at 800 rpm for 2 h, then washed with distilled water until neutral, dried at 65°C for 90 min, and finally crushed to a particle size of 0.3 mm with a crusher, and then passed through an 80-mesh sieve to obtain chitin powder, which was stored in a desiccator for use.

[0045] S2, dissolution of chitin: 10 g of chitin powder obtained in step S1 was taken, 100 g of an aqueous solution containing 20 wt% potassium hydroxide and 4 wt% urea was added, frozen at -20°C for 4 h, then thawed at room temperature with mechanical stirring at 800 rpm for 2 h, and then the above freezing-thawing cycle was repeated once to obtain a chitin solution with a mass fraction of 10 wt%.

[0046] S3, dissolution of cotton linter pulp cellulose: 10 g of cotton linter pulp cellulose was taken, 100 g of an aqueous solution containing 4.6 wt% lithium hydroxide and 15 wt% urea was added, frozen at -15°C for 6 h, then thawed at room temperature with mechanical stirring at 800 rpm for 2 h to obtain a cotton linter pulp cellulose solution with a mass fraction of 10 wt%.

[0047] S4, preparation of a blended solution: the chitin solution obtained in step S2 and the cotton linter pulp cellulose solution obtained in step S3 were mixed in a dry weight mass ratio of chitin to cotton linter pulp cellulose of 1:1 (i.e. 50 g of chitin solution + 50 g of cellulose solution), stirred at 5°C for 10 min to obtain a blended solution.

[0048] S5, film formation and post-treatment: the blended solution prepared in S4 was poured onto an acrylic plate to form a film, then placed in a 5% sodium sulfate coagulation bath for solidification and regeneration, then washed with distilled water, and dried in a 50°C drying oven for 6 h to obtain a chitin / cotton linter pulp cellulose composite antibacterial film.

[0049] Example 4: the same as example 3, except that the dry weight mass ratio of chitin to cotton linter pulp cellulose was 1:2.

[0050] Example 5: The same as example 3, except that the dry mass ratio of chitin to cotton linter pulp cellulose is 1:3.

[0051] Example 6: The same as example 3, except that the dry mass ratio of chitin to cotton linter pulp cellulose is 1:4.

[0052] Example 7: The same as example 3, except that the dry mass ratio of chitin to cotton linter pulp cellulose is 1:5.

[0053] Comparative Example 1: The same as example 3, except that the dry mass ratio of chitin to cotton linter pulp cellulose is 0:1 (i.e. only cotton linter pulp cellulose).

[0054] A method for preparing an antibacterial film:

[0055] S1, Dissolution of cotton linter pulp cellulose: Take 10 g of cotton linter pulp cellulose, add 100 g of an aqueous solution containing 4.6 wt% lithium hydroxide and 15 wt% urea, freeze at -15°C for 6 h, then thaw at room temperature with mechanical stirring, to obtain a 10 wt% cotton linter pulp cellulose solution.

[0056] S2, Film formation and post-treatment: Pour the cotton linter pulp cellulose solution onto an acrylic plate to form a film, place it in a 5% sodium sulfate coagulation bath for solidification and regeneration, then wash it with distilled water, and dry it in a 50°C drying oven for 6 h to obtain an antibacterial film.

[0057] The above examples and comparative examples were respectively tested for the following properties:

[0058] Determination of the degree of deacetylation of chitin: Weigh 0.20 g of the sample, heat to boiling in distilled water and maintain for 1 h, then filter; centrifuge the precipitate of the washed sample, and dry it for use. Put it into a mechanical stirrer and stir for 1 h. Titrate a standard sodium hydroxide solution (0.1 mol / L) with an excess of HCl solution, record the amount of (0.1 mol / L) consumed at the end point of titration, and calculate the degree of deacetylation of the shrimp shell and chitin.

[0059] Determination of the thickness of the composite antibacterial film: Refer to GB / T1040.1-226 to test the tensile properties of the composite antibacterial film.

[0060] Test of the light transmittance of the composite antibacterial film: Use ultraviolet absorption spectroscopy for testing. Cut the composite antibacterial film into 25 mm x 10 mm film samples of the same size, set the ultraviolet spectrophotometer to 200 nm, 400 nm, 600 nm, and 800 nm wavelengths, take a dry quartz cuvette as the control group, place a film sample on one side of the clean quartz cuvette, and measure the absorbance of the sample and the blank group.

[0061] Microstructure analysis of composite antibacterial films: The surface morphology of the experimental sample films was observed using a Hitachi SU8240 top-of-the-line cold-field scanning electron microscope. Gold was sputtered onto the surface of chitosan / cotton linter pulp composite antibacterial films with different proportions, and the accelerating voltage was set to 10kV for testing.

[0062] Antibacterial performance test of composite antibacterial film: The antibacterial effect of chitosan / cotton linter pulp fiber composite antibacterial films with different ratios against Staphylococcus aureus and Escherichia coli was tested using the agar diffusion method. Composite antibacterial films with different ratios were cut into 18mm diameter discs and sterilized with ultraviolet light for 2 hours. 1×10⁻⁶ samples were collected. 8 100 μL of a CFU / mL suspension of experimental bacteria (Escherichia coli and Staphylococcus aureus) was evenly spread onto an agar plate. Then, sterilized membranes (18 mm in diameter) at different proportions were placed on the surface of the inoculated agar plates, which were then inverted and incubated at 37°C for 24 hours. After incubation, the diameter of the inhibition zone (including the membrane diameter) was measured using a digital caliper.

[0063] Table 1. Results of chitin degree of deacetylation test in Examples 1-7

[0064] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Degree of deacetylation / % 82.0 82.1 82.4 82.3 82.2 82.1 81.9

[0065] Table 2. Test results of various properties of the composite antibacterial film in Examples 1-7 and Comparative Example 1.

[0066]

[0067]

[0068] Table 1 shows the results of the chitin deacetylation degree test in Examples 1-7. The results show that the chitin deacetylation degree prepared in Examples 1-7 is ≥80%, which is beneficial for subsequent preparation of high-performance composite antibacterial films.

[0069] In Table 2, Examples 3 to 7 and Comparative Example 1 show the antibacterial effect of chitin / cotton pulp fiber composite antibacterial films with different proportions on E. coli and S. aureus. According to the analysis of the health industry standard WS / T 650-2019, the data clearly shows that the antibacterial effect is positively correlated with the content of chitin. With the increase of the proportion of chitin in the composite film, the diameters of the inhibition zones for E. coli and S. aureus continue to increase; on the contrary, when the proportion of cotton pulp cellulose increases, the inhibition zone decreases accordingly. This shows that cotton pulp fiber mainly serves as a base material, and its antibacterial property is weak, while chitin is the key active ingredient that plays an antibacterial function. The composite film shows broad-spectrum antibacterial ability to both gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus), and with the increase of the proportion of chitin, the inhibition effect on S. aureus gradually increases to be slightly better than that on E. coli. In summary, increasing the proportion of chitin can effectively enhance the antibacterial performance of the composite film.

[0070] Figures 1 to 4 The transparency, moisture content, swelling degree and microstructure of the chitin / cotton pulp fiber composite antibacterial film with different proportions are shown respectively: Figure 1 It shows that with the increase of the content of chitin, the transparency of the antibacterial film generally increases first and then decreases. When the dry weight mass ratio of chitin to cotton pulp cellulose is 1:5, the transparency of the film is the best, which may be related to the difference in internal structure density and thickness of the film; Figure 2 It shows that with the increase of the content of chitin, the moisture content of the composite antibacterial film also increases, which may be due to the strong hygroscopicity of chitin, leading to the increase of the moisture content of the composite antibacterial film; Figure 3 It shows that with the increase of the content of chitin (0%-50%), the swelling degree of the composite antibacterial film gradually increases. Since chitin is prone to phase separation in the blending system, the increase of the swelling degree of the composite antibacterial film slows down when the content of chitin increases from 25% (i.e. the dry weight mass ratio of chitin to cotton pulp cellulose is 1:3); Figure 4 The surface of the cotton pulp fiber is very flat Figure 4 -a), after adding a certain amount of chitin (chitin content is 0-33%), the compatibility of cotton pulp fiber and chitin is good, and the surface is still flat Figure 4 -b), however, with the further increase of the content of chitin (chitin content is 33%-50%), the surface of the blended film is rough and uneven, and obvious phase separation structure Figure 4 -c) can be seen, indicating that the compatibility between the two decreases, which may be related to the strong hydrogen bonding between the molecular chains of chitin, leading to the aggregation of chitin itself.

[0071] In summary, the above results show that within the process parameters and ratio ranges claimed in the present application, composite films with good transparency, swelling and significant antibacterial properties can be prepared. With the increase of chitin ratio, the antibacterial property is enhanced, but the transparency is decreased, and at a higher ratio, the swelling degree may increase slowly due to phase separation. In practical applications, appropriate ratios can be selected according to needs.

[0072] The above description is merely preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, which should be encompassed within the protection scope of the present application.

Claims

1. A method for preparing a chitosan / cotton linter pulp fiber composite antibacterial membrane, characterized in that: Includes the following steps: S1. Extraction of chitin: including the following steps in sequence: (1) Deproteinization: mix shrimp shell powder with sodium hydroxide solution with a concentration of 1.8-2.2 mol / L at a solid-liquid ratio of 1:5-1:10 g / mL, stir at 65-75℃ for 1.5-2.5 h, wash with water until neutral, and then dry at 60-70℃ for 60-120 min to obtain deproteinized shrimp shell powder; (2) Desalting: mix deproteinized shrimp shell powder with hydrochloric acid solution with a concentration of 0.9-1.1 mol / L at a ratio of 1:5-1:10 g / mL, and heat in a water bath to 23-27℃. After stirring for 25-35 minutes, wash with water until neutral, and then dry at 60-70°C for 60-120 minutes to obtain desalted shrimp shell powder; (3) Decolorization: Mix the desalted shrimp shell powder with hydrogen peroxide solution with a mass volume concentration of 9-11% at a solid-liquid ratio of 1:6-1:10 g / mL, heat in a water bath to 55-65°C, stir for 1.5-2.5 hours, then wash with water until neutral, dry at 60-70°C for 60-120 minutes, and finally crush with a pulverizer to a particle size of 0.1-0.5 mm, and then pass through a 60-100 mesh sieve to obtain powdered chitin; S2. Dissolution of chitin: The chitin obtained in S1 is dissolved in a potassium hydroxide / urea aqueous solution to obtain a chitin solution; the potassium hydroxide / urea aqueous solution is an aqueous solution containing 15-25 wt% potassium hydroxide and 3-6 wt% urea. S3. Dissolution of cotton linter pulp cellulose: Dissolve cotton linter pulp cellulose in a lithium hydroxide / urea aqueous solution to obtain a cotton linter pulp cellulose solution; the lithium hydroxide / urea aqueous solution is an aqueous solution containing 4-5 wt% lithium hydroxide and 14-16 wt% urea; S4. Preparation of the blend solution: The chitin solution obtained in S2 and the cotton linter pulp cellulose solution obtained in S3 are mixed at a dry weight ratio of 1:5 to 1:1 and stirred at 5 to 10°C for 10 to 20 minutes to obtain the blend solution. S5. Film Formation and Post-treatment: The blended solution prepared in S4 is poured onto a film-forming plate to form a film. Then, it is placed in a 3-8 wt% sodium sulfate coagulation bath for curing and regeneration. After washing with water, it is dried at 30-60℃ for 6-12 hours to obtain a chitin / cotton linter pulp cellulose composite antibacterial film.

2. The method for preparing the chitosan / cotton linter pulp fiber composite antibacterial membrane according to claim 1, characterized in that: The chitin in S2 is dissolved by freezing at -20 to -30°C for 4 to 8 hours, then thawing by mechanical stirring at room temperature and 600 to 1000 rpm for 1 to 3 hours, and then repeating the freezing-thawing steps 1 to 3 times. The specific method for dissolving the cotton linter pulp cellulose described in S3 is as follows: freezing at -15 to -25°C for 6 to 10 hours, followed by mechanical stirring at room temperature and a speed of 600 to 1000 rpm for 1 to 3 hours to thaw.

3. The method for preparing the chitosan / cotton linter pulp fiber composite antibacterial membrane according to claim 1, characterized in that: In S2, the mixing weight ratio of chitin to potassium hydroxide / urea aqueous solution is 2-10:100; in S3, the mixing weight ratio of cotton linter pulp cellulose to lithium hydroxide / urea aqueous solution is 2-10:

100.

4. The method for preparing the chitosan / cotton linter pulp fiber composite antibacterial membrane according to claim 1, characterized in that: The potassium hydroxide / urea aqueous solution is an aqueous solution containing 20 wt% potassium hydroxide and 4 wt% urea, and the lithium hydroxide / urea aqueous solution is an aqueous solution containing 4.6 wt% lithium hydroxide and 15 wt% urea.

5. The method for preparing the chitosan / cotton linter pulp fiber composite antibacterial membrane according to claim 1, characterized in that: The stirring speed in step (1) of S1 is 600-1000 rpm, the stirring speed in step (2) of S1 is 600-1000 rpm, and the stirring speed in step (3) of S1 is 600-1000 rpm.

6. The method for preparing the chitosan / cotton linter pulp fiber composite antibacterial membrane according to claim 1, characterized in that: The shrimp shells are those of whiteleg shrimp, the water used for washing is distilled water, and the film-forming plate is an acrylic plate.

7. A chitosan / cotton linter pulp fiber composite antibacterial film, characterized in that: The antibacterial membrane was prepared using the method described in any one of claims 1 to 6, which is a chitin / cotton linter pulp fiber composite.

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