Method for sustainably preparing nanometer cellulose

A nanocellulose and cellulose technology, applied in the field of natural polymer material preparation, can solve the problems of water and air pollution, human irritation, explosion danger, etc. Effect

Inactive Publication Date: 2016-11-09
QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Recently, Chinese patent (application number: 201610041840.1) reported that citric acid was used to pre-hydrolyze natural fiber raw materials, and then mechanical post-treatment was used to prepare cellulose nanofibrils, but citric acid has strong irritation to human body, and lemon Acid is flammable, has explosion hazard, and safety is lower; Reported in document Green Chemistry, 2016,18,3835-3843 uses oxalic acid (pKa=1.27), maleic acid (pKa=1.92) and p-toluenesulfonic acid (pKa= -2.8) to prepare the method for nanocellulose, but these several kinds of acidity are still stronger, still have stronger corrosivity to equipment, are big to human body irritation, and p-toluenesulfonic acid easily pollutes water body and atmosphere.

Method used

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  • Method for sustainably preparing nanometer cellulose
  • Method for sustainably preparing nanometer cellulose

Examples

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preparation example Construction

[0045] In the preparation method according to the present invention, the cellulose raw material is reacted with an organic acid to realize hydrolysis and esterification of cellulose, and the organic acid includes: one or more mixtures of malic acid, pyruvic acid, tartaric acid and lactic acid; these acids The pKa values ​​of all are about 3, preferably between 2.49-3.86, are all easily soluble in water, have one or more carboxylic acid groups, are all organic acids with relatively strong acidity, and are safe to the human body and the environment. If the pKa of the acid is too large, the acidity will be insufficient, and the preparation efficiency of nanocellulose will be too low, which is not conducive to realizing industrialization. In addition, these acids are commonly used in the fields of medicine and food industry, and can be obtained through fermentation or widely present in living organisms. They have little toxic and side effects on the human body, and are less corrosi...

Embodiment 1

[0049] Weigh 5g of dry bleached eucalyptus pulp into a 250mL round bottom flask, add 100mL of 80wt% tartaric acid solution, and stir magnetically at 120°C for 5h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was transferred into a centrifuge tube and centrifuged at 8000 rpm for 5 min. The precipitated colloid was centrifugally washed with distilled water to neutrality, and the centrifuged product was diluted to a concentration of 0.2 wt% with distilled water, and then homogenized 6 times at 50 MPa by a high-pressure homogenizer to obtain a viscous product. The yield of cellulose nanofibrils prepared in this example was 71% (relative to the original dry bleached eucalyptus pulp), and the aqueous suspension of cellulose nanofibrils with good dispersibility was left for 24 hours without sedimentation. The transmission electron micrographs (SEM photos) of cellulose nanocrystals and cellulose nanofi...

Embodiment 2

[0051] Weigh 3g of absolute dry furfural residue into a 150mL round bottom flask, add 60mL of 70wt% tartaric acid solution, and stir magnetically at 130°C for 5h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was transferred into a centrifuge tube and centrifuged at 8000 rpm for 8 min. After the precipitated jelly was centrifuged and washed 3 times with distilled water, the residual acid and degradation by-products were removed by dialysis. The obtained product was diluted with distilled water to a concentration of 5 wt%, and the upper layer of cellulose nanocrystal suspension was taken out after standing for 24 hours. The cellulose solid in the lower layer of the suspension was diluted with distilled water to 0.3 wt%, and then homogenized 7 times by a high-pressure homogenizer at 60 MPa to obtain a viscous cellulose nanofibril product. The total yield of nanocellulose obtained in this example ...

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Abstract

The invention discloses a method for sustainably preparing nanometer cellulose in an environment-friendly and economic mode. The preparing method includes the following steps that 1, cellulose raw materials and organic acid are hydrolyzed and esterified; 2, the treated cellulose is prewashed in a centrifugal sedimentation mode, the organic acid is separated to be continuously recycled, washed cellulose suspension liquid is dialyzed, and then reacted acid and accessory substances are removed; 3, the dialyzed suspension liquid is separated to obtain small-particle cellulose nanometer crystals; 4, cellulose solid precipitated on a lower layer of the suspension liquid is treated through a high-pressure homogenizer or an ultrasonication physical machine to obtain colloidal cellulose nanometer fibrils. According to the method, in the preparing process, the modified cellulose raw materials are synchronously hydrolyzed and esterified through relative-safety and environment-friendly food-grade organic acid; compared with inorganic strong acid, the used organic acid is low in corrosion performance, high in boiling point, small in reaction pressure and easy to control and operate, and the cellulose nanometer crystals with the stable quality and the cellulose nanometer fibril products with the stable quality can be obtained at the same time.

Description

technical field [0001] The present invention relates to the field of preparation of natural polymer materials, in particular to a method for preparing novel cellulose nanocrystals and cellulose nanofibrils by combining physical crushing with food-grade organic esterification modification and synchronous hydrolysis of natural cellulose . Background technique [0002] In recent years, people have paid more and more attention to resource and environmental issues, and it has become an inevitable trend to develop and utilize renewable resources to replace traditional fossil resources. Cellulose is the most abundant biopolymer on earth, and it is mainly found in the cell walls of higher plants. Nanocellulose not only has the advantages of cellulose itself, such as wide source of raw materials, non-toxic, water-insoluble, and degradable, but also has various characteristics of nanoparticles, such as nanoscale, high specific surface area, high aspect ratio, low density, etc. At th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/02C08B3/14
CPCC08B3/14C08B15/02
Inventor 刘超李滨牟新东张跃冬于光
Owner QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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