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A kind of preparation method of cellulose nanocrystal

A cellulose and nanocrystal technology, which is applied in the macro-scale preparation of environmental protection and green fields, can solve the problems of large acid consumption, poor heat resistance of cellulose nanocrystals, serious environmental pollution, etc., so as to reduce environmental pollution and enrich the environment. The effect of modifying the way and expanding the scope of application

Active Publication Date: 2019-05-03
QINGDAO UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The preparation of cellulose nanocrystals by acid hydrolysis mostly uses strong acids such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid or mixed acids of several acids, and uses its oxidative properties to remove the amorphous region in the cellulose material to prepare cellulose nanocrystals. For example, the patent number is CN The Chinese invention patents of 101509209B, CN 1171904C, CN 1142185C and CN 102040663B all use the acid hydrolysis method to prepare cellulose nanocrystals. The mass ratio of cellulose to strong acid is 1:14-1:60. The existing acid hydrolysis method prepares cellulose nanocrystals. The technology not only has the problem of serious pollution to the environment due to the large amount of acid consumption, but also has sulfonate groups on the surface of cellulose nanocrystals prepared by sulfuric acid acid hydrolysis, resulting in poor heat resistance of cellulose nanocrystals.
In addition, the existing technology for preparing cellulose nanocrystals also has the disadvantage of low yield (no more than 60%), so the acid hydrolysis method is not suitable for preparing cellulose nanocrystals in large quantities.
The preparation of cellulose nanocrystals with carboxyl groups on the surface by TEMPO oxidation requires the use of various chemical reagents such as Tempo, sodium bromide, and sodium hypochlorite, and TEMPO reagents are expensive. In addition, the process of preparing cellulose nanocrystals by TEMPO oxidation is complicated. The content is strictly dependent on the pH conditions of the reaction system, the process conditions are harsh, and it is not suitable for the macro-preparation of cellulose nanocrystals

Method used

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  • A kind of preparation method of cellulose nanocrystal
  • A kind of preparation method of cellulose nanocrystal
  • A kind of preparation method of cellulose nanocrystal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Break 5g of pulp cellulose into cotton wool with a mixer, add 250mL of 4% sodium hydroxide solution, soak for 24h, filter it with suction and wash until neutral, then disperse the alkali-pretreated cellulose in 300mL Add 2.5g of potassium ferrate and 1mL of malic acid into deionized water, stir at 90°C for 6h, centrifuge the cellulose hydrolyzate at a speed of 8000rpm / min for 10min with a high-speed centrifuge, then wash the precipitate and separate again until the supernatant The liquid becomes cloudy. The obtained cellulose nanocrystal suspension is ultrasonicated to obtain a stable cellulose nanocrystal suspension. The measured average length of the cellulose nanocrystal is about 260 nm, the yield is 60%, and the particle size dispersion index (PDI) is 0.3. The content is 0.5mmol / g.

[0038] The morphology and particle size distribution of the prepared cellulose nanocrystals are as follows: figure 1 and figure 2 , the infrared spectrum of the prepared cellulose n...

Embodiment 2

[0040] The type of raw materials used, the amount and the process flow are the same as in Example 1, except that the amount of potassium ferrate used is 5 g to obtain a stable suspension of cellulose nanocrystals. The average length of the measured cellulose nanocrystals is about 220 nm. The yield was 69%, the PDI was 0.2, and the carboxyl content was 6.5 mmol / g.

Embodiment 3

[0042]The types of raw materials used, the amount and the process flow are the same as in Example 1, except that the amount of potassium ferrate used is 7.5 g to obtain a stable suspension of cellulose nanocrystals, and the average length of the obtained cellulose nanocrystals is about 210 nm. , the yield was 75%, the PDI was 0.2, and the carboxyl content was 9.2mmol / g.

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Abstract

The invention discloses a macroscopic preparation method of a cellulose nanocrystal (CNC), which is green and environment-friendly. Firstly, cellulose is crushed and then is pretreated; afterwards, an oxometallate solution and an organic acid are added, the oxydrolysis is carried out, and the CNC with a carboxyl group on a surface is obtained after centrifugal dialysis treatment. The yield of the preparation method can exceed 70 percent; the length of the made CNC can be adjusted in the range of 195nm to 260nm; the content of the carboxyl group on the surface can reach 50mmol / g; compared with a CNC made by a sulfuric-acid acid hydrolysis method, the CNC made by the macroscopic preparation method provided by the invention is increased by 50 to 100 DEG C in heat resistance; used oxometallate and organic acid are both green reagents and are further a few in use levels; problems that the preparation cost of the CNC is high and further the environmental pollution is easily caused, and the like, at present are solved.

Description

【Technical field】 [0001] The invention belongs to the technical field of nanomaterial preparation, and in particular relates to a green and environment-friendly macro-preparation method of cellulose nanocrystals. 【Background technique】 [0002] Cellulose is the most abundant natural biological material in nature and widely exists in organisms such as green plants and marine animals. By removing the amorphous regions in the cellulose material, nanometer-sized cellulose nanocrystals can be obtained. Cellulose nanocrystals have the characteristics of low density, high strength, and high aspect ratio; in addition, cellulose nanocrystals also have the advantages of high specific surface area, reactive surface, and high crystallinity. The field of preparation of performance composite materials has great application value. [0003] In the prior art, the preparation of cellulose nanocrystals mainly adopts an acid hydrolysis method or a TEMPO reagent oxidation method. The preparat...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08B15/04C08B15/02
CPCC08B15/02C08B15/04
Inventor 张建明周立娟段咏欣王朝露南福春宋翔宇
Owner QINGDAO UNIV OF SCI & TECH
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