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Method for preparing cellulose nanocrystals by combining biological enzymolysis and mechanical shearing

A technology of mechanical shearing and combined preparation, which is applied in the fields of fiber raw material processing, textiles and papermaking, etc., can solve the problems of low operating safety, high equipment requirements, and complicated preparation process, so as to improve operational safety and reliability, mechanical Good strength and high degree of crystallization

Active Publication Date: 2013-05-15
CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, strong acid hydrolysis is a very intense chemical reaction, and strong acid itself can corrode the reaction vessel, which requires high equipment; strong acid spillage can also corrode the clothes and skin of the operator during the operation, and the operation safety is not high
At the same time, the hydrolyzed material needs to be neutralized with alkali to neutralize the unreacted residual acid, and then repeatedly washed to neutrality, and the obtained washing waste liquid also needs to be further recycled, which increases the production cost
Generally speaking, the traditional preparation method not only has high requirements on equipment, low degree of operation safety, and complicated preparation process, but also is accompanied by the discharge of a large number of chemical pollutants during the production process, and the production cost is high.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Step 1: Fully mix the bleached pulp fiber with deionized water and adjust it into a suspended solution with a solid mass number of 1.5%. The liquid is first dispersed under high-speed stirring conditions for 0.5h, and then repeatedly sheared in the ultrafine colloid mill 5 times, the rotation speed of the grinding disc is 2500rpm, and the distance between the grinding discs is ~0.1mm.

[0022] Step 2: adding a certain amount of endoglucanase to the initially sheared fiber mixture solution for hydrolysis treatment. The amount of enzyme added is 5 FPU per gram of dry fiber, the reaction temperature is 48-50°C, the reaction conditions are weakly acidic pH=5.5-6.0, and the reaction time is 18 hours. The enzymatic hydrolysis reaction was completed in a constant temperature (setting temperature: 50°C) shaker with a rotation speed of 180 rpm.

[0023] Step 3: The enzymatically hydrolyzed fiber solution is first frozen at 10°C for 0.5h, and then heated at 90°C for 0.5h to inhi...

Embodiment 2

[0026] Step 1: Fully mix the bleached pulp fiber with deionized water to adjust it into a suspended solution with a solid mass number of 2.0%. The liquid is first dispersed under high-speed stirring conditions for 0.5h, and then repeatedly sheared in the ultrafine colloid mill 4 times, the rotation speed of the grinding disc is 2500rpm, and the distance between the grinding discs is -0.2mm.

[0027] Step 2: adding a certain amount of endoglucanase to the initially sheared fiber mixture solution for hydrolysis treatment. The amount of enzyme added is 8 FPU per gram of dry fiber, the reaction temperature is 48-50°C, the reaction conditions are weakly acidic pH=5.5-6.0, and the reaction time is 20 hours. The enzymatic hydrolysis reaction was completed in a constant temperature (setting temperature: 50°C) shaker with a rotation speed of 200 rpm.

[0028] Step 3: The enzymatically hydrolyzed fiber solution is first frozen at 10°C for 0.5h, and then heated at 90°C for 0.5h to inhib...

Embodiment 3

[0031] Step 1: Fully mix the bleached pulp fiber with deionized water to adjust it into a suspended solution with a solid mass number of 2.0%. The liquid is first dispersed under high-speed stirring conditions for 0.5h, and then repeatedly sheared in the ultrafine colloid mill 5 times, the rotation speed of the grinding disc is 3000rpm, and the distance between the grinding discs is -0.2mm.

[0032] Step 2: adding a certain amount of endoglucanase to the initially sheared fiber mixture solution for hydrolysis treatment. The amount of enzyme added is 10 FPU per gram of dry fiber, the reaction temperature is 48-50°C, the reaction conditions are weakly acidic pH=5.5-6.0, and the reaction time is 24 hours. The enzymatic hydrolysis reaction was completed in a constant temperature (set temperature 50°C) shaker with a rotation speed of 200 rpm.

[0033] Step 3: The enzymatically hydrolyzed fiber solution is first frozen at 10°C for 0.5h, and then heated at 90°C for 0.5h to inhibit a...

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Abstract

The invention relates to a method for preparing cellulose nanocrystals by combining biological enzymolysis and mechanical shearing. The method comprises the following steps of: preliminarily hydrolyzing or dismantling fiber or damaging 1,4-beta-D glucoside bonds in a cellulose amorphous region by using endoglucanase firstly, and then carrying out high-speed high-pressure mechanical shearing to obtain the cellulose nanocrystals. According to method disclosed by the invention, the operation safety and reliability are improved without the traditional strong acid hydrolysis; and meanwhile, the diameter and the length-diameter ratio of the cellulose nanocrystals can be adjusted by adjusting the enzymolysis and mechanical shearing degrees. The cellulose nanocrystals obtained by using the method are good in mechanical strength, good in crystallinity, moderate in length-diameter ratio and strong in light transmissivity, and; no acid radical ion is adsorbed onto the surfaces of the cellulose nanocrystals; and the cellulose nanocrystals are expected to be applied to the field of materials, such as polymerization enhancement, filtration, environmental friendliness and biomedical application instead of the traditional cellulose nanocrystals.

Description

technical field [0001] The invention relates to a method for preparing plant-based cellulose nanocrystals, in particular to a method for preparing cellulose nanocrystals by combining biological enzymolysis and mechanical shearing. Background technique [0002] At present, plant-based cellulose nanocrystals are widely used in the fields of reinforced polymer composite materials, biomedical materials, biopharmaceuticals, and environmental protection materials. Since its main component is cellulose crystals, it has excellent mechanical properties, with a theoretical elastic modulus as high as 150GPa. The cellulose molecules in the crystal region of the plant-based cellulose nanocrystals are well-arranged, so the thermal stability is better. The diameter of cellulose nanocrystals is usually between 20-50nm, the length is about 100-300nm, the aspect ratio is small, and it is easy to be evenly distributed in the polymer matrix. Based on the above reasons, this plant-based cellul...

Claims

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Application Information

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IPC IPC(8): D21C5/00
Inventor 卿彦吴义强
Owner CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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