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

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0020] Example 1:

[0021] Step 1: Fully mix bleached pulp fibers with deionized water, and adjust to a suspended solution with a solid mass of 1.5%. The liquid is first dispersed under high-speed stirring for 0.5h, and then repeatedly sheared in an ultra-fine colloid mill. 5 times, the grinding disc speed is 2500rpm, and the grinding disc spacing is ~0.1mm.

[0022] Step 2: Add a certain amount of endoglucanase to the preliminarily sheared fiber mixed solution for hydrolysis treatment. The amount of enzyme added was 5 FPU per gram of dry fiber, the reaction temperature was 48~50°C, the reaction conditions were weakly acidic pH=5.5~6.0, and the reaction time was 18h. The enzymatic hydrolysis reaction was completed in a constant temperature (set temperature of 50 °C) shaker, and the shaker speed was 180 rpm.

[0023] Step 3: The enzymatically hydrolyzed fiber solution was first frozen at 10°C for 0.5h, and then heated at 90°C for 0.5h to inhibit the elimination of enzyme acti...

Example Embodiment

[0025] Example 2:

[0026] Step 1: Fully mix bleached pulp fibers with deionized water, and adjust to a suspended solution with a solid mass of 2.0%. The liquid is first dispersed under high-speed stirring for 0.5 hours, and then repeatedly sheared in an ultra-fine colloid mill. 4 times, the grinding disc speed is 2500rpm, and the grinding disc spacing is -0.2mm.

[0027] Step 2: Add a certain amount of endoglucanase to the preliminarily sheared fiber mixed solution for hydrolysis treatment. The amount of enzyme added was 8 FPU per gram of dry fiber, the reaction temperature was 48~50°C, the reaction conditions were weakly acidic pH=5.5~6.0, and the reaction time was 20h. The enzymatic hydrolysis reaction was completed in a constant temperature (set temperature of 50 °C) shaker, and the shaker speed was 200 rpm.

[0028] Step 3: The enzymatically hydrolyzed fiber solution was first frozen at 10°C for 0.5h, and then heated at 90°C for 0.5h to inhibit the elimination of enzyme...

Example Embodiment

[0030] Example 3:

[0031] Step 1: Fully mix bleached pulp fibers with deionized water, and adjust to a suspended solution with a solid mass of 2.0%. The liquid is first dispersed under high-speed stirring for 0.5 hours, and then repeatedly sheared in an ultra-fine colloid mill. 5 times, the grinding disc speed is 3000rpm, and the grinding disc spacing is -0.2mm.

[0032] Step 2: Add a certain amount of endoglucanase to the preliminarily sheared fiber mixed solution for hydrolysis treatment. The amount of enzyme added was 10 FPU per gram of dry fiber, the reaction temperature was 48~50°C, the reaction conditions were weakly acidic pH=5.5~6.0, and the reaction time was 24h. The enzymatic hydrolysis reaction was completed in a constant temperature (set temperature of 50°C) shaker, and the shaker speed was 200rpm.

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

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PUM

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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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