Preparation method for nano-microcrystalline cellulose

Abstract

The invention discloses a preparation method for nano-microcrystalline cellulose. The method comprises: preparation and treatment of a nano-microcrystalline cellulose raw material, enzyme treatment, acid hydrolysis and deacidification treatment. The raw material is one of a wood fiber raw material, a non-wood fiber raw material, and a microbial fiber raw material, and the raw material is treated by grinding equipment. The enzyme used for enzyme treatment can be one of or a composition of several of endoglucanase, exoglucanase and beta-glucosidase. Cellulose is added into a slurry system, when reaction of a cellulose-slurry system ends, the solid phase and the liquid phase are separated by a filter screen, and then the solid phase is transferred to an acid hydrolysis reaction kettle to carry out acid hydrolysis treatment and follow-up deacidification treatment. The prepared nano-microcrystalline cellulose has a spherical, ellipsoidal or clavate shape, the particle length is 50nm-500nm, the width is 10nm-30nm, and the particle size distribution is uniform. The acid dose for acid treatment is only 5wt%-40wt%, which is 7.7%-61.5% of that of the traditional method, thus reducing the preparation cost and being beneficial to environmental protection.

Description

[0001] technical field [0002] The invention relates to a preparation method of nano microcrystalline cellulose. Background technique [0003] Cellulose is the most widely sourced and renewable natural polymer material in nature, and is the main chemical component of plant fiber raw materials. Nanocrystalline cellulose (NCC) prepared from natural cellulose is now widely used in food, cosmetics, medicine, plastic and rubber fillers, and synthetic leather production. NCC has many excellent characteristics, such as good mechanical properties (Young's modulus and tensile strength can reach 150Gpa and 250MPa respectively), good biocompatibility, large specific surface area, low density, biodegradable, surface with With the advantages of many highly reactive hydroxyl groups, high crystallinity, and good shape retention, it is expected that NCC will play a greater role in the above application fields, thereby expanding the application fields of cellulose nanocrystals. [0004] I...

AI Technical Summary

Problems solved by technology

[0006] The disadvantages of this method for preparing nanocrystalline cellulose: the acid concentration in the mixed system is too high, which requires high corrosion resistance of the equipment, and hydrochloric acid, nitric acid, etc. are volatile at high concentrations, which affects the airtightness of the equipment. The requirements are also high, and it is difficult to ensure the stability of its concentration under high concentration. The increase of acid concentration makes the preparation process, especially the subsequent acid removal process, more cumbersome. load

[0008] Although the method is simple to prepare, its disadvantages are: a large amount of ultrasonic stirring is used, and the energy consumption is too high, which is not conducive to large-scale preparation; the amount of sulfuric acid and hydrochloric acid used is too large, and the total concentration of the acid reaches 80%, which increases the Subsequent acid removal costs, and increase the environmental load, easy to cause environmental pollution

[0010] The disadvantage of this invention: it is difficult to further hydrolyze lignocellulose into nano-sized microcrystalline cellulose by cellulase, and the cellulose hydrolyzed by cellulase is often entangled in a network and difficult to disperse. Moreover, the preparation cost is high, the preparation conditions are relatively harsh, and the preparation cycle is relatively long, which directly affects the production efficiency and economic benefits of nano-microcrystalline cellulose.

[0012] This method provides a method for preparing shorter cellulose by mechanical method, but its disadvantages: nano-microcrystalline cellulose prepared by physical mechanical grinding method often has uneven particle size, wide distribution, and difficult classification , It is difficult to achieve uniform dispersion in the matrix, high energy consumption, etc., especially for the graft modification of nano-microcrystalline cellulose, the wide distribution of cellulose size will lead to different graft densities and graft chain lengths , which in turn affects the performance of the grafted polymer

[0014] Although this invention can produce relatively uniform microcrystalline cellulose, its disadvantage is that the amount of sulfuric acid is too large, and the concentration of concentrated sulfuric acid has reached 65%, which requires high corrosion resistance of equipment and increases the preparation of microcrystalline cellulose. cost, and the follow-up deacidification is relatively cumbersome. Although some concentrated sulfuric acid can be recycled and reused, some sulfuric acid will still be discharged into the environment, which increases the environmental load, and its production process is relatively complicated, which is not conducive to industrial production