A method for preparing cellulose nanofibers

Abstract

The invention discloses a method for preparing cellulose nanofiber dispersion liquid, which comprises the following steps: dispersing a cellulose raw material in a drainage buffer solution system with a pH value of 4-5, and adding laccase and TEMPO so as to prepare a laccase-TEMPO oxidation system; continuously pumping oxygen into a reaction system so as to carry out oxidation reaction for 24-130 hours; after the reaction is completed, carrying out centrifugal filtration on the obtained object so as to obtain supernatant for repeated use; cleaning an obtained precipitate (i.e. water-insoluble oxidized cellulose) to be neutral by using deionized water; and adding deionized water, stirring the obtained mixture so as to obtain an oxidized cellulose water suspension, carrying out homogenation and ultrasonic treatment, and centrifugalizing the obtained object so as to obtain supernatant, i.e. oxidized cellulose nanofiber dispersion liquid. According to the invention, the oxidation efficiency is guaranteed, and the pollution caused by halogen elements to the environment is avoided; and the reaction system can be repeatedly used, so that the utilization rate of the oxidation system is improved, the oxidation effect is uniform, the yield of cellulose nanofibers is increased, and high-length-to-diameter-ratio nanofibers can be obtained.

Description

technical field [0001] The invention relates to the technical field of preparation methods of cellulose nanofibers, in particular to a method for selectively oxidizing cellulose using a selective oxidation system combined with mechanical treatment to prepare a cellulose nanofiber dispersion, and can further be made of cellulose nanofibers The dispersion is used to prepare nanofiber films, gels and other materials. Background technique [0002] Cellulose is the most abundant renewable organic substance on earth and is the main product of plant photosynthesis, which converts light energy into chemical energy. The amount of cellulose produced worldwide is huge, of which 89% of natural cellulose resources are degraded and consumed by various microorganisms in nature, and finally converted into carbon dioxide and water. Although this is an important carbon cycle in nature, it is undoubtedly a huge waste of resources from an economic point of view. [0003] Cellulose is found ma...

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Problems solved by technology

[0008] 2. Small size effect

[0012] Although there are many preparation methods for nanocellulose, there are also many limitations: the chemical method needs to be hydrolyzed with strong acid, which requires high requirements for reaction equipment, and it is difficult to recover and treat the residue after the reaction; the biological method to prepare bacterial cellulose is complicated, time-consuming and expensive , the price is expensive; the preparation of microfibrillated nanocellulose by physical method requires special equipment and high pressure, the energy consumption is relatively high, and the particle size distribution of the prepared nanocellulose is wide; the molecular weight of artificially synthesized cellulose is small; the electrospinning preparation of fine Large fiber cross-section and wide cross-sectional distribution

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