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Method for preparing carboxylated nanocellulose by hydrolyzing citric acid under microwave 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 increasing yield, reducing finished products, and high yield

Inactive Publication Date: 2020-04-17
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 one-step method of microwave-assisted hydrolysis of citric acid

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] Example 1 Preparation of carboxylated nanocellulose by hydrolysis of citric acid under microwave conditions in one step

[0045] (1) Under the condition that the temperature is 100° C. and the microwave frequency is 2450 MHz, crush 5 g of absolute-dry bleached bagasse pulp and add it to a citric acid aqueous solution (80 g of citric acid, 20 ml of deionized water) with a concentration of 80 wt % to react for 2 h , to obtain a hydrolyzed suspension;

[0046] (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; then the filtrate is Rotary steaming was carried out under the conditions of 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 78.1g;

[0047] (3) The solid fiber after washing is dialyzed under the co...

Embodiment 2

[0048] Example 2: One-step method of hydrolysis of citric acid under microwave conditions to prepare carboxylated nanocellulose

[0049] (1) Under the condition that the temperature is 80° C. and the microwave frequency is 2450 MHz, crush 5 g of absolutely dry bleached bagasse pulp and add it to a citric acid aqueous solution (70 g of citric acid, 30 ml of deionized water) with a concentration of 70 wt % to react for 2 h , to obtain a hydrolyzed suspension;

[0050] (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 under the conditions of 70°C and 60r / min to obtain a white citric acid crystalline solid, and the citric acid was recovered, and the quality of the obtained citric acid was 76.7g;

[0051] (3) The solid fiber after washing is dialyzed u...

Embodiment 3

[0052] Example 3: One-step method of hydrolysis of citric acid under microwave conditions to prepare carboxylated nanocellulose

[0053] (1) Under the condition that the temperature is 100° C. and the microwave frequency is 2000 MHz, 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.

[0054] (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. The citric acid was recovered and the quality of the obtained citric acid was 76.3g;

[0055] (3) The solid fiber after washing is dialyzed under the condition of dei...

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Abstract

The invention discloses a method for preparing carboxylated nanocellulose by hydrolyzing citric acid under a microwave condition. The method comprises the following steps: adding a bleached fiber pulpboard into a citric acid solution, hydrolyzing under a microwave condition, preparing cellulose nanocrystals through centrifugation, and preparing cellulose nanofibrils from residual long fibers through a high-pressure homogenizer. The method is green, non-toxic, short in consumed time, low in power consumption and relatively high in yield, and the used citric acid is easy to recycle, so that thepreparation cost of the nanocellulose is reduced, and engineering preparation of the nanocellulose is facilitated. Besides, the prepared 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 nanocellulose. Finally, the prepared nanocellulose has no residues of toxic and harmful substances, and has a wide application prospect in the aspect of functional materials taking cellulose as a substrate, especially in the aspectof materials related to human health.

Description

technical field [0001] The invention belongs to the field of green preparation of nano-cellulose, in particular to a method for preparing carboxylated nano-cellulose by hydrolyzing citric acid under microwave 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 amorp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/04
CPCC08B15/04
Inventor 宋涛祁海松罗元超廖思煌杨喆熊海平岑钰陈功
Owner SOUTH CHINA UNIV OF TECH
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