Method for making BC bacterial cellulose membrane clearer by using epoxypropane

Abstract

The invention discloses a method for making a BC bacterial cellulose membrane clearer by using epoxypropane, and relates to the technical field of biological material modification. The method comprises the following steps: S1, preparation of a BC bacterial cellulose membrane; S2, epoxypropane treatment; and S3, post-treatment. According to the method, the light transmittance of the BC bacterial cellulose membrane treated by the method can reach 85% or above (the wavelength range of 400-800 nm) and is improved by 50% or above compared with that of an untreated membrane, the use requirement of an optical material can be met, the treated membrane still keeps high tensile strength (larger than or equal to 80 MPa) and elongation at break (larger than or equal to 10%), meanwhile, the biocompatibility is good, and the BC bacterial cellulose membrane is suitable for being used in the field of optical materials. The method can be applied to the fields of medical treatment, food packaging and the like, the corn straw is used as a raw material, a low-cost epoxypropane treatment process is combined, the overall production cost is reduced, and the method has a good industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of biomaterial modification, and in particular to a method for making BC bacterial cellulose membrane clearer by utilizing propylene oxide. Background Art

[0002] Bacterial cellulose (BC) is a natural nanocellulose material synthesized by microbial fermentation. It has high purity, high crystallinity, good biocompatibility and mechanical properties, and has broad application prospects in the fields of food, medicine, biomaterials, etc. The preparation of BC bacterial cellulose membrane using corn straw as raw material can not only achieve high-value utilization of agricultural waste, but also reduce production costs, which is in line with the concept of green and sustainable development.

[0003] However, corn straw-based BC bacterial cellulose membranes prepared using existing technologies suffer from low transparency, primarily due to residual pigments, impurities, and disordered accumulation of cellulose fibers within the membrane. This limits their application in areas requiring high transparency, such as optical devices and high-end packaging materials.

[0004] At present, although traditional methods such as physical grinding and chemical bleaching can improve the transparency of the membrane to a certain extent, they have defects such as complex operation, easy destruction of cellulose structure, and introduction of secondary pollution.

[0005] The specific defects are as follows:

[0006] Transparency issues caused by the BC membrane's own structure: The bacterial cellulose membrane is composed of nanofibers interwoven into a network structure. The large number of pores between the fibers causes strong light scattering, resulting in low transparency of the BC membrane. This limits its application in fields with high transparency requirements, such as electronic displays and optical instruments.

[0007] Impact of raw materials: When corn straw is used as raw material to prepare BC film, impurities such as lignin and hemicellulose may remain. The presence of these impurities will affect the optical properties of the BC film, reduce the transparency of the film, and may form an uneven structure within the film, further increasing light scattering and absorption;

[0008] Disadvantages of existing modification methods: Traditional methods for improving BC membrane transparency may have problems such as complex processes, high costs, the use of toxic and hazardous chemical reagents, or adverse effects on other membrane properties. For example, some physical methods may not be able to deeply change the internal structure of the membrane, and chemical methods may introduce impurities or damage the membrane's biocompatibility.

[0009] In response to the above problems, the inventors proposed a method of using propylene oxide to make BC bacterial cellulose membrane clearer to solve the above problems. Summary of the Invention

[0010] In order to solve the above problems, the present invention aims to provide a method for making BC bacterial cellulose membrane clearer by using propylene oxide.

[0011] To solve the above technical problems, the present invention adopts the following technical solution: a method for making BC bacterial cellulose membrane clearer by using propylene oxide, comprising the following steps:

[0012] S1. Preparation of BC bacterial cellulose membrane

[0013] After crushing corn stalks, alkali treatment is used to remove impurities such as lignin and hemicellulose to obtain pure cellulose raw materials; the pretreated cellulose raw materials are mixed with fermentation medium, inoculated with bacteria, and then fermented to obtain BC bacterial cellulose wet film; the wet film is washed with water and other treatments to obtain BC bacterial cellulose dry film;

[0014] S2, propylene oxide treatment

[0015] The BC bacterial cellulose dry film prepared in S1 is immersed in a mixed solution of propylene oxide and an organic solvent and treated in the mixed solution;

[0016] S3, post-processing

[0017] The treated BC bacterial cellulose membrane was repeatedly rinsed with deionized water several times to remove residual propylene oxide and solvent; the membrane was placed in a vacuum drying oven and dried to constant weight to obtain a BC bacterial cellulose membrane with high transparency.

[0018] Preferably, in S1, the inoculated bacteria include Acetobacter xylinum, the fermentation temperature is 25-30°C, the pH is 5-7, and the fermentation time is 3-7 days.

[0019] Preferably, in S2, the organic solvent is any one of ethanol and acetone, the volume ratio of propylene oxide to the organic solvent is 1:1-1:3, the temperature of the treatment in the mixed solution is 30-50°C, the stirring rate of the treatment is 100-200rpm, the treatment time is 1-3h, and the solid-liquid ratio of the BC bacterial cellulose dry film to the mixed solution is 1:10-1:20 (g / mL).

[0020] Preferably, in S3, the deionized water is repeatedly rinsed 3-5 times, and the temperature in the vacuum drying oven is 40-60°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, the light transmittance of the BC bacterial cellulose membrane treated by this method can reach more than 85% (400-800nm ​​wavelength range), which is more than 50% higher than that of the untreated membrane, and can meet the requirements for the use of optical materials;

[0023] 2. In the present invention, the treated film still maintains high tensile strength (≥80MPa) and elongation at break (≥10%), and has good biocompatibility, and can be used in medical, food packaging and other fields;

[0024] 3. In the present invention, corn straw is used as raw material and combined with a low-cost propylene oxide treatment process, which reduces the overall production cost and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The present invention is a flow chart of a method for making BC bacterial cellulose membrane clearer by using propylene oxide.

[0027] Figure 2 This is a comparison diagram before and after using propylene oxide on the BC bacterial cellulose membrane of the present invention. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Example 1:

[0030] The present invention provides a method for making BC bacterial cellulose membrane clearer by using propylene oxide, comprising the following steps:

[0031] S1. Preparation of BC bacterial cellulose membrane

[0032] Acetobacter xylinum was inoculated into a culture medium containing 5 g / L glucose, 2.5 g / L yeast extract, 5 g / L peptone, 1.5 g / L citric acid, and 2.5 g / L potassium dihydrogen phosphate, and fermented at 30°C for 6 days to obtain an initial BC film.

[0033] S2. Preprocessing

[0034] After rinsing the BC membrane with deionized water, it was immersed in 0.2 mol / L NaOH solution at 70 °C for 1.5 h and rinsed until neutral;

[0035] S3, propylene oxide treatment

[0036] The BC membrane was immersed in a 50% volume fraction propylene oxide-ethanol mixed solution and stirred at 40°C for 3 h;

[0037] S4. Post-processing

[0038] The BC film was washed with ethanol and deionized water in sequence and dried in vacuum at 45°C. The resulting BC film had a transmittance of 86% and a tensile strength of 120 MPa.

[0039] Example 2:

[0040] The present invention provides a method for making BC bacterial cellulose membrane clearer by using propylene oxide, comprising the following steps:

[0041] S1. Preparation of BC bacterial cellulose membrane

[0042] The BC membrane was obtained by dynamic fermentation at 32℃ for 5 days.

[0043] S2. Preprocessing

[0044] Treat with 0.1 mol / L NaOH solution at 60°C for 1 h;

[0045] S3, propylene oxide treatment

[0046] Use 30% propylene oxide-ethanol solution at 30°C for 4 hours;

[0047] S4. Post-processing

[0048] After natural drying at room temperature, the obtained BC film had a light transmittance of 82% and a tensile strength of 115 MPa.

[0049] The BC film that was not treated with propylene oxide was only pretreated and post-treated. Its transmittance was 48% and its tensile strength was 130 MPa. By comparison, it can be seen that the method of the present invention significantly improves the transparency of the BC film and has little effect on the mechanical properties.

[0050] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for making BC bacterial cellulose membrane clearer by using propylene oxide, characterized in that: The following steps are involved: S1. Preparation of BC bacterial cellulose membrane After crushing corn stalks, alkali treatment is used to remove impurities such as lignin and hemicellulose to obtain pure cellulose raw materials; the pretreated cellulose raw materials are mixed with fermentation medium, inoculated with bacteria, and then fermented to obtain BC bacterial cellulose wet film; the wet film is washed with water and other treatments to obtain BC bacterial cellulose dry film; S2, propylene oxide treatment The BC bacterial cellulose dry film prepared in S1 is immersed in a mixed solution of propylene oxide and an organic solvent and treated in the mixed solution; S3, post-processing The treated BC bacterial cellulose membrane was repeatedly rinsed with deionized water several times to remove residual propylene oxide and solvent; the membrane was placed in a vacuum drying oven and dried to constant weight to obtain a BC bacterial cellulose membrane with high transparency.

2. The method for making BC bacterial cellulose membrane clearer by using propylene oxide according to claim 1, characterized in that: In S1, the inoculated bacteria include Acetobacter xylinum, the fermentation temperature is 25-30°C, the pH is 5-7, and the fermentation time is 3-7 days.

3. The method for making BC bacterial cellulose membrane clearer by using propylene oxide according to claim 1, characterized in that: In S2, the organic solvent is any one of ethanol and acetone, the volume ratio of propylene oxide to the organic solvent is 1:1-1:3, the temperature of the treatment in the mixed solution is 30-50°C, the stirring rate of the treatment is 100-200 rpm, the treatment time is 1-3h, and the solid-liquid ratio of the BC bacterial cellulose dry film to the mixed solution is 1:10-1:20 (g / mL).

4. The method for making BC bacterial cellulose membrane clearer by using propylene oxide according to claim 1, wherein: In S3, the deionized water is rinsed repeatedly for 3-5 times, and the temperature in the vacuum drying oven is 40-60°C.

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