Preparation method of nano-cellulose

Abstract

The invention discloses a preparation method of nano-cellulose, comprising the following steps of: firstly, swelling the raw material cellulose by aqueous alkali, soaking for a while, centrifugally separating out cellulose, and washing by deionized water till the filter liquor is neutral; dispersing the separated cellulose in water, adding sodium bromide, 2, 2, 6, 6-tetramethyl piperidine-1-oxide and sodium hypochlorite solution, carrying out an oxidation reaction under sonic oscillation, centrifugally separating after reaction, and carrying out freeze drying treatment on suspension liquid to obtain the nano-cellulose powder. Compared with the prior art, the preparation method is incompact in cellulose structure, can enlarge the unit cell distance, and can improve the reaction accessibility after the raw material cellulose is pretreated, so that the oxidation reaction efficiency can be improved, and the product yield can be obviously improved; the oxidation reaction conditions are mild, and are easy to control, and the product quality can not be influenced due to the fact that only a small quantity of sodium chloride and minute quantity of oxidizing agent are mixed in a reaction system after the reaction; and the sonic oscillation is adopted in the process of reaction, so that the oxidation reaction speed can be accelerated, and the reaction time can be obviously shortened.

Description

technical field [0001] The invention relates to a preparation method of nano-cellulose, which belongs to the technical field of nano-materials. Background technique [0002] As a natural polymer nanomaterial, nanocellulose has the advantages of cheap, easy to obtain, renewable, biocompatible, simple preparation, chemical or physical modification, etc. It is used in polymer composite reinforcement materials, template materials, biological Molecular immobilization, optical materials and other aspects have a wide range of applications. [0003] The preparation method of nanocellulose is usually the hydrolysis method of concentrated sulfuric acid. The concentrated acid hydrolyzes the crystalline and amorphous regions of cellulose to separate nanocellulose with high purity and complete crystallinity. Although the method is simple to operate and the reaction conditions are easy to control, there are problems such as complicated post-treatment process, high requirements on product...

AI Technical Summary

Problems solved by technology

Although the method is simple to operate and the reaction conditions are easy to control, there are problems such as complex post-treatment process, high requirements for production equipment, and difficult handling of reaction acid.

For example, CN101509209A discloses a preparation method of rod-shaped nanocellulose, which uses concentrated sulfuric acid with a concentration of 50%-65% to hydrolyze the cellulose raw material. The hydrolysis acid solution is difficult to handle, and the post-treatment process of the product is complicated and difficult to operate.

[0004] One of the ways to oxidize cellulose is: use N-oxygen compounds as cellulose oxidation catalysts to treat cellulose raw materials in the presence of sodium bromide and sodium hypochlorite, and can introduce carboxyl groups into cellulose macromolecules. During the reaction, the N-oxygen compound, sodium bromide and sodium hypochlorite react toge...