CN-122011219-A - Method for preparing nanocellulose through fluid shear induction

Abstract

The invention discloses a method for preparing nanocellulose by fluid shear induction, which belongs to the technical field of biomass resource high-value utilization and nanomaterial preparation, the method takes bagasse pith parenchyma cells as raw materials, cellulose is obtained by sieving, delignification and hemicellulose removal treatment, after the N, N-Dimethylacetamide (DMAC) system containing quaternary ammonium salt ionic liquid is dissolved, the rapid and controllable regeneration of cellulose is realized in low-concentration urea aqueous solution by a microfluidic double-channel fluid shearing technology, and the regenerated nanocellulose is prepared. Compared with the traditional regeneration method, the method has the advantages of less consumption of the regeneration liquid, low energy consumption, simple process, uniform product structure, controllable size and the like, and is suitable for large-scale production and multi-field application.

Inventors

• ZHANG HENG
• SHAO WANYI
• GAO XIN

Assignees

• 昆明理工大学

Dates

Publication Date

20260512

Application Date

20260311

Claims (4)

1. 1. A method for preparing nanocellulose by fluid shear induction, characterized by the steps of: (1) Adding crushed and sieved bagasse pith parenchyma cell powder into deionized water, adding sodium chlorite and citric acid to the reaction system until the concentration of chlorine dioxide is 6-10 g/L, then reacting at 60-90 ℃ for 5-7 hours, washing a reaction product with water until the reaction product is neutral, drying, adding an absolute ethyl alcohol solution containing diisopropylethylamine with the mass concentration of 4-6% into the dried product, reacting at 50-80 ℃ for 2-6 hours, washing and drying to obtain the bagasse pith parenchyma cell cellulose; (2) Adding bagasse pith parenchyma cell cellulose into N, N-dimethylacetamide, adding quaternary ammonium salt type ionic liquid triethyl octyl ammonium chloride, uniformly mixing, and treating for 1.5-4.5 hours under the stirring condition of 100-110 ℃ and 300-600 r/min to fully swell and dissolve cellulose, and cooling the dissolution liquid to 2-6 ℃ and storing overnight; (3) Diluting the solution in the step (2) by using N, N-dimethylacetamide until the mass content of cellulose is 0.2% -2%, respectively injecting the diluted solution and urea aqueous solution into different channels of a microfluidic chip in a microinjection pump, controlling the two-phase flow rate ratio of the diluted solution to the urea aqueous solution to be 1:1-1:100, generating high-strength fluid shear force by regulating and controlling the two-phase flow rate difference, and inducing cellulose molecules to synchronously perform in-situ regeneration and nanocrystallization in the dynamic flow process under the room temperature condition; (4) And collecting the regenerated suspension, washing, and freeze-drying to obtain the nanocellulose.
2. 2. The method for preparing nanocellulose by fluid shear induction of claim 1, wherein in the step (2), the feed liquid ratio g of the bagasse pith parenchyma cell cellulose to the N, N-dimethylacetamide is 2% -6% of mL, and the volume ratio of the triethyloctylammonium chloride to the N, N-dimethylacetamide is 5% -15%.
3. 3. The method for preparing nanocellulose by fluid shear induction of claim 1, wherein the concentration of urea in urea aqueous solution is 0.5-5 mol/L.
4. 4. The nanocellulose prepared by the method for preparing nanocellulose by fluid shear induction as claimed in any one of claims 1 to 3, wherein the nanocellulose has a diameter of 30 to 80nm, a length of 0.8 to 4.5 μm and a crystallinity of 60 to 70%.

Description

Method for preparing nanocellulose through fluid shear induction Technical Field The invention belongs to the technical field of high-value utilization of biomass resources and preparation of nano materials, and particularly relates to a method for preparing nanocellulose by shearing induction regeneration of microfluidic fluid by taking bagasse pith parenchyma cells as a raw material. Background Cellulose, which is a natural polysaccharide with the widest distribution and the most abundant reserves in the nature, has the excellent characteristics of reproducibility, biodegradability, good biocompatibility and the like, is a sustainable polymer material with great development potential, and has become one of the important research points in the fields of chemistry, chemical engineering and material science in recent years. The basic structural unit of cellulose is D-glucopyranose, and is connected through beta-1, 4 glycosidic bond to form linear polymer chain, which has wide polymerization degree range, wide molecular weight distribution and generally higher crystallinity. The cellulose molecular chain is rich in hydroxyl groups, and is easy to form intramolecular and intermolecular hydrogen bond networks, and the structural characteristics endow the cellulose with good mechanical properties, and meanwhile, the cellulose has poor solubility in conventional aqueous phase and organic solvent, so that the processing and high-value utilization of the cellulose are greatly limited. Therefore, developing efficient and green cellulose dissolution and nanocrystallization technology is a key research direction for promoting the development of cellulose-based materials. The cellulose nanofiber is used as a representative material obtained by nanocrystallization of cellulose, not only remains the biodegradability and environmental friendliness of the cellulose, but also has the characteristics of high specific surface area, high strength, high crystallinity and excellent optical, electrical and magnetic properties of the nanomaterial, and has wide application prospects in various fields of composite materials, biological medicines, energy storage, environmental management and the like. At present, the preparation method of the cellulose nanofiber mainly comprises two major types of chemical mechanical methods and biological methods. The chemical mechanical method generally adopts chemical reagents such as strong acid, strong oxidant and the like to pretreat cellulose, and then adopts high-energy consumption mechanical means such as high-pressure homogenization, ball milling and the like to realize the nanocrystallization splitting of the fiber. Although the method can prepare the nanofiber with better performance, corrosive chemicals are often used in the process, a large amount of waste water and waste liquid are generated, the environmental pollution pressure is high, and the subsequent treatment and reagent recovery are difficult. In addition, equipment such as high-pressure homogenization is high in energy consumption, easy to block and difficult to continuously produce, so that the large-scale application of the equipment is restricted. The biological method mainly relies on microorganisms (such as acetobacter xylinum) to synthesize bacterial cellulose, and the obtained product has high purity and excellent mechanical properties, but has the problems of harsh culture conditions, long production period, low yield, high cost and the like, and is difficult to meet the requirement of large-scale industrial production. Therefore, the development of the cellulose nanocrystallization preparation method which is simple in process, mild in condition, environment-friendly, continuous in operation and controllable in cost has important significance in pushing the cellulose nanomaterial from a laboratory to practical application. In recent years, a fluid dynamics regulation and control method based on a microfluidic technology is paid attention to, and can realize controllable forming and structure regulation and control of materials on a microscopic scale by accurately controlling a fluid interface and a shear field, so that a new technical idea is provided for green and continuous preparation of cellulose nanofibers. Disclosure of Invention The existing nanocellulose preparation technology has the problems of complex process, high energy consumption, poor environmental protection, difficult structure regulation and control and the like, so that the large-scale production and high-end application of the nanocellulose are severely restricted. Therefore, the invention provides a method for preparing nanocellulose based on the regeneration of the sugarcane marrow parenchyma cells by microfluidic fluid shear induction, which can generate controllable fluid shear force by regulating and controlling the flow velocity difference of two-phase flow in a microfluidic chip in a microinjection pump, realize the in-situ regeneration and