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Method for preparing carboxylated nanocellulose by hydrolyzing citric acid under high-pressure condition

A technology of nanocellulose and citric acid aqueous solution, which is applied in the field of green preparation of nanocellulose, can solve problems such as low yield, and achieve the effects of improving yield, low preparation process risk and cost, and high yield

Inactive Publication Date: 2020-04-28
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The present invention mainly aims at the problem of low yield mainly existing in the process of preparing nano-cellulose with organic acids, and provides an environmentally friendly method for preparing carboxylated nano-cellulose by high-pressure assisted hydrolysis of citric acid in one step

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Embodiment 1: Citric acid is hydrolyzed under the condition of high pressure one-step method to prepare carboxylated nanocellulose

[0041] (1) Under the condition that the temperature is 121° C. and the pressure is 0.1 MPa, crush 5 g of absolutely dry bleached bagasse pulp and add it to a citric acid aqueous solution (60 g of citric acid, 40 ml of deionized water) with a concentration of 60 wt % to react for 2 h , to obtain a hydrolyzed suspension;

[0042] (2) The hydrolyzed suspension is vacuum filtered through a G4 sand core funnel to obtain solid fibers and filtrate; the solid fibers are repeatedly added to deionized water and centrifugally washed to neutrality at 4000r / min, and then the filtrate is Rotary steaming was carried out at 70°C and 60r / min to obtain a white citric acid crystalline solid, and the citric acid was recovered, and the obtained citric acid had a mass of 57.3g;

[0043] (3) Dialyze the washed solid fiber with deionized water until the conducti...

Embodiment 2

[0044] Embodiment 2: Citric acid is hydrolyzed under the condition of high pressure one-step method to prepare carboxylated nanocellulose

[0045] (1) Under the condition of 121°C and 0.1MPa, crush 5g of absolute dry bleached bagasse pulp and add it to a 50wt% aqueous solution of citric acid (50g of citric acid, 50ml of deionized water) to react for 4 hours to obtain a hydrolyzed suspension liquid.

[0046] (2) Vacuum filter the hydrolyzed suspension through a G4 sand core funnel to obtain solid fibers and filtrate. Repeatedly add deionized water to the fiber and centrifuge and wash at 4000r / min until neutral. The filtrate is rotated at 70°C and 60r / min to obtain a white citric acid crystalline solid; the quality of the obtained citric acid is 58.1g;

[0047] (3) Dialyze the washed water under the condition of deionized water until the conductivity of the dialysate leaked from the dialysis bag is the same as that of deionized water, take the retention liquid to obtain a cellu...

Embodiment 3

[0048] Embodiment 3: Citric acid is hydrolyzed under the condition of high pressure one-step method to prepare carboxylated nanocellulose

[0049] (1) Under the condition of 121° C. and 0.1 MPa, crush 5 g of absolutely dry bleached bagasse pulp and add it to a citric acid aqueous solution (40 g of citric acid, 60 ml of deionized water) with a concentration of 40 wt % to react for 4 hours to obtain a hydrolyzed suspension liquid.

[0050] (2) Vacuum filter the hydrolyzed suspension through a G4 sand core funnel to obtain solid fibers and filtrate. Repeatedly add deionized water to the fiber and centrifuge and wash at 4000r / min until neutral. The filtrate is rotary evaporated at 70°C and 60r / min to obtain a white citric acid crystalline solid with a mass of 57.4g;

[0051] (3) dialyze under the condition of deionized water after washing, until the conductivity of the dialysate permeated from the dialysis bag is the same as that of deionized water, take the retention liquid to o...

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Abstract

The invention discloses a method for preparing carboxylated nanocellulose by hydrolyzing citric acid under a high-pressure condition. According to the method, a bleached fiber pulp board serves as a base material, citric acid serves as hydrolysate, acid hydrolysis is conducted under high pressure, then cellulose nanocrystals are prepared through centrifugation, and cellulose nanofibrils are prepared from remaining solid fibers through a high-pressure homogenizer. The method is green, non-toxic, short in consumed time and high in yield, and the used citric acid is easy to recycle so that the preparation cost of the nanocellulose is reduced. Besides, the prepared carboxylated cellulose nanocrystals and cellulose nanofibrils have relatively high dispersion stability, excellent specific surface area and relatively high carboxyl content so that more chemical ways are provided for further modification of the nanocellulose. Finally, the prepared nanocellulose has no toxic and harmful substance residues so that the nanocellulose has a wide application prospect in the aspects of food emulsifiers, health care products, skin care products, medical materials and the like.

Description

technical field [0001] The invention belongs to the field of green preparation of nanocellulose, in particular to a method for preparing carboxylated nanocellulose by hydrolyzing citric acid under high pressure conditions. Background technique [0002] Cellulose is the most abundant renewable resource on the earth, and it is also the natural polymer compound with the most abundant reserves in nature. It exists widely in the cell walls of various plants, algae, fungi, etc. With the advantages of regeneration, low cost and easy modification, it is expected to replace petroleum as the main raw material for energy and chemical industry in the future. Nanocellulose refers to cellulose with a diameter of 1 to 100 nm, which can be divided into cellulose nanocrystals and cellulose nanofibrils according to their size and shape. Cellulose nanocrystals are shorter in length and are rod-shaped cellulose with a length of about 100nm-300nm obtained by acid or enzyme hydrolysis of the amo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/04D01F2/24
CPCC08B15/04D01F2/24
Inventor 宋涛祁海松熊海平冯秉权李茂安罗元超岑钰陈功
Owner SOUTH CHINA UNIV OF TECH
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