阅读说明：本技术 一种具有抗菌性的纳米纤维素的制备方法 (Preparation method of antibacterial nanocellulose ) 是由 李营战 陈心怡 唐峰 余厚咏 于 2020-12-18 设计创作，主要内容包括：本发明提出了一种具有抗菌性的纳米纤维素的制备方法。本方法利用过氧化氢热氧化处理技术,将天然生物质中的木质素、半纤维素果胶等杂质除去的同时,将纤维素分子束中无定形β-d-葡萄糖环之间的1→4糖苷键断裂,制备直径在纳米范围内的纳米纤维素。同时,将纤维素中的部分羟基氧化成羧基。由于纤维素表面具有大量功能性基团,生物质含有的抗菌成分会通过分子间作用力、氢键或共价键方式,接枝到纳米纤维素的表面,赋予其抗菌性能。该方法制备的纳米纤维素不但具有优异的抗菌性能和良好的有机溶剂分散稳定性；且制备流程简单,绿色无污染,成本低且利于工业化。该材料在抗菌复合材料领域中有广阔的应用前景。(The invention provides a preparation method of antibacterial nanocellulose. The method utilizes a hydrogen peroxide thermal oxidation treatment technology to remove impurities such as lignin, hemicellulose pectin and the like in natural biomass, and simultaneously breaks 1 → 4 glycosidic bonds between amorphous beta-d-glucose rings in cellulose molecular bundles to prepare the nano cellulose with the diameter in a nano range. At the same time, part of the hydroxyl groups in the cellulose are oxidized to carboxyl groups. Because the surface of the cellulose has a large number of functional groups, the antibacterial components contained in the biomass can be grafted to the surface of the nanocellulose in the modes of intermolecular force, hydrogen bonds or covalent bonds, and the antibacterial performance is endowed. The nano-cellulose prepared by the method not only has excellent antibacterial performance and good dispersion stability of the organic solvent; and the preparation process is simple, green, pollution-free, low in cost and beneficial to industrialization. The material has wide application prospect in the field of antibacterial composite materials.)

1. A preparation method of antibacterial nanocellulose is characterized by comprising the following steps:

1) cleaning natural fiber containing antibacterial ingredients, placing the natural fiber in an oven at a proper temperature for drying treatment for a period of time, and performing proper mechanical treatment to obtain solid fiber;

2) adding hydrogen peroxide solution with proper concentration into the solid fiber obtained in the step 1) according to a proper solid-liquid ratio, sealing and placing a beaker filled with cellulose and hydrogen peroxide solution with a proper solid-liquid ratio, placing the beaker in a water bath, heating and stirring for a period of time, placing the beaker in a low-temperature ultrasonic cleaning instrument, and performing ultrasonic treatment for a proper time to obtain the nano-cellulose.

2. The method for preparing nanocellulose having antibacterial activity according to claim 1, characterized in that: the natural fiber containing the antibacterial ingredients in the step 1) is one of pine cone, pine needle, pine wood, pine bark, towel gourd, industrial hemp, flax, jute, apocynum venetum and bamboo; the proper temperature is 50-90 ℃; the period of time is 5-12 h.

3. The method for preparing nanocellulose having antibacterial activity according to claim 1, characterized in that: the proper concentration of the hydrogen peroxide in the step 2) is 10-30%; the appropriate solid-to-liquid ratio is 1: 50-1: 160.

4. the method for preparing nanocellulose having antibacterial activity according to claim 1, characterized in that: the proper temperature of the water bath kettle in the step 2) is 50-90 ℃; the period of time is 5-8 h.

5. The method for preparing nanocellulose having antibacterial activity according to claim 1, characterized in that: the low temperature of the ultrasonic cleaning instrument in the step 2) is-5-20 ℃.

6. The method for preparing nanocellulose having antibacterial activity according to claim 1, characterized in that: the appropriate time for the ultrasound in the step 2) is 25-45 min.

Technical Field

The invention relates to a preparation method of nanocellulose, in particular to a preparation method of antibacterial nanocellulose, and belongs to the field of preparation of high polymer materials.

Background

Coronavirus which is outbreaked in large scale in 2019 year end becomes one of epidemic diseases with the highest fatality rate in human history. Direct transmission, aerosol transmission and contact transmission are the main transmission routes of new coronary pneumonia, and the antibiosis becomes a hot topic during epidemic situations. Because of the advantages of high specific surface area, biocompatibility, biodegradability and the like of the nano-cellulose, the nano-cellulose is widely used in the fields of wound dressing, antibacterial spray, packaging materials, drug carriers and the like by being combined with antibacterial materials.

At present, most of antibacterial nanocellulose is synthesized by toxic heavy metal ions, and the preparation process is complicated. An article published by Jatoi Abdul Wahab in Materials Science and Engineering: C, A comparative study on synthesis of AgNPs on cellulose nanofibers by thermal treatment and DMF for antibacterial activities (Materials Science and Engineering: C, 2019, 98: 1179. sup. 1195.) describes the use of nanosilver generation on cellulose nanofibers in the antibacterial field. However, the high cost, high exposure and potential risks of human safety and health of nano silver limit the application of nano silver in the field of antibacterial spraying.

At present, the nano-cellulose is mainly prepared by methods such as strong acid hydrolysis, enzymolysis, alkali hydrolysis and the like. Although nanocellulose (nanocellulose) including Cellulose Nanowires (CNFs), Cellulose Nanocrystals (CNCs) and Regenerated cellulose (Regenerated cellulose) has been successfully prepared by these methods at present. However, the nanocellulose used in these methods has the disadvantages of low preparation yield, poor heat resistance, poor dispersibility of organic solvents and the like, which causes a great deal of environmental pollution and limits the large-scale production thereof. Therefore, it is necessary to develop an environment-friendly method for preparing nanocellulose with good dispersibility in organic solvents.

Therefore, the invention takes natural fiber containing antibacterial components as raw material, removes impurities such as lignin, hemicellulose pectin and the like in natural biomass by a hydrogen peroxide thermal oxidation method, and breaks 1 → 4 glycosidic bonds between amorphous beta-d-glucose rings in cellulose molecular beams to prepare the nano cellulose with the diameter in a nano range. At the same time, part of the hydroxyl groups in the cellulose are oxidized to carboxyl groups. Because the surface of the cellulose has a large number of functional groups, the antibacterial components contained in the biomass can be grafted to the surface of the nanocellulose in the modes of intermolecular force, hydrogen bonds or covalent bonds, and the antibacterial performance is endowed.

Disclosure of Invention

The invention aims to provide a preparation method of antibacterial nanocellulose, which is simple to prepare, green, low in cost and beneficial to industrialization.

The invention takes natural fiber containing antibacterial ingredients as raw materials, and prepares the antibacterial nanocellulose by removing impurities and attacking a cellulose non-qualitative area.

A preparation method of antibacterial nanocellulose comprises the following specific steps:

1) cleaning natural fiber containing antibacterial ingredients, placing the natural fiber in an oven at a proper temperature for drying treatment for a period of time, and performing proper mechanical treatment to obtain solid fiber;

2) adding hydrogen peroxide solution with proper concentration into the solid fiber obtained in the step 1) according to a proper solid-liquid ratio, sealing and placing a beaker filled with cellulose and hydrogen peroxide solution with a proper solid-liquid ratio, placing the beaker in a water bath, heating and stirring for a period of time, placing the beaker in a low-temperature ultrasonic cleaning instrument, and performing ultrasonic treatment for a proper time to obtain the nano-cellulose.

The natural fiber containing the antibacterial ingredients in the step 1) is one or more of pine cone, pine needle, pine wood, pine bark, towel gourd, industrial hemp, flax, jute, apocynum venetum and bamboo; the proper temperature is 50-90 ℃; the period of time is 5-12 h.

The proper concentration of the hydrogen peroxide in the step 2) is 10-30%; the appropriate solid-to-liquid ratio is 1: 50-1: 160.

the proper temperature of the water bath kettle in the step 2) is 50-90 ℃; the period of time is 5-8 h.

The low temperature of the ultrasonic cleaning instrument in the step 2) is-5-20 ℃.

The appropriate time for the ultrasound in the step 2) is 25-45 min.

The morphology of the antibacterial nanocellulose obtained by the method comprises cellulose nanocrystals (cellulose nanocrystals) and cellulose nanowires (cellulose nanofibers).

Observing the morphology of the nano-cellulose obtained by the method by using a field emission scanning electron microscope (FF-SEM); analyzing its chemical structure using fourier infrared spectroscopy (FTIR); staphylococcus aureus was used to test its antibacterial ability, with the following results:

(1) the field emission scanning electron microscope (FF-SEM) test shows that the antibacterial nano-cellulose is in a long strip shape and the surface is accompanied with coarse solid particles, and the test is shown in attached figures 1 and 2.

(2) Fourier infrared spectroscopy (FTIR) tests show that the antibacterial nanocellulose is successfully introduced with bacteriostatic substances and other impurities are removed, and see figure 2.

(3) The antibacterial nanocellulose has excellent bacteriostatic ability, see figure 3.

The antibacterial nanocellulose prepared by the method has excellent antibacterial ability, and has wide application prospect in the field of antibacterial materials.

The invention has the beneficial effects that:

according to the invention, the antibacterial nanocellulose is prepared from the natural fibers containing antibacterial substances, no organic solvent is introduced in the preparation process, the antibacterial components in the natural biomass are utilized, no antibacterial agent is required to be added, the preparation process is green and environment-friendly, and the defects of complicated preparation and high pollution of the antibacterial nanocellulose can be effectively overcome; and the prepared product is completely natural, and has the characteristics of safety, harmlessness, good biocompatibility and the like.