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Method for preparing CNC (cellulose nanocrystal) by inorganic molten salt-trace acid co-promoted system

A nanocrystal and cellulose technology, applied in the field of cellulose, can solve the problems of high production and environmental protection costs, equipment corrosion, etc., and achieve the effects of simple operation, low equipment corrosion, and easy preparation

Inactive Publication Date: 2019-08-30
DALIAN POLYTECHNIC UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention aims to solve the problems of corrosion of equipment caused by strong acid, high cost of preparation and environmental protection in the preparation process of cellulose nanocrystals (CNC), so as to speed up the industrialized production process of CNC

Method used

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  • Method for preparing CNC (cellulose nanocrystal) by inorganic molten salt-trace acid co-promoted system
  • Method for preparing CNC (cellulose nanocrystal) by inorganic molten salt-trace acid co-promoted system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Accurately prepare 100 g of LiBr-HCl co-promoter system containing 35% LiBr and 0.1M hydrochloric acid content. Accurately weigh 5g of microcrystalline cellulose with a solid-to-liquid ratio of 1:20, add it to the LiBr-HCl co-promoting system, raise the temperature to 70°C, and keep stirring for 12 hours to obtain a homogeneous system, then perform desalting and dialysis to obtain cellulose nano The aqueous crystal solution is freeze-dried to obtain cellulose nanocrystals. The yield of cellulose nanocrystals prepared by this method is 57%, and the crystallinity is 87%. by scanning electron microscope figure 1 It can be seen from observation that the cellulose nanocrystals prepared by this method are in the shape of short rods. by transmission electron microscopy figure 2 It can be seen from observation that the average length of the cellulose nanocrystals prepared by this method is 143nm, and the average diameter is 10nm.

Embodiment 2

[0024] Accurately prepare 200g of LiCl-H containing 60% LiCl and 0.01M sulfuric acid 2 SO 4 co-promotion system. Accurately weigh 1g of absorbent cotton, the solid-to-liquid ratio is 1:200, and add it to LiCl-H 2 SO 4 In the co-promoting system, the temperature was raised to 85° C., and a homogeneous system was obtained after continuous stirring for 8 hours, and then desalting and dialysis were performed to obtain an aqueous solution of cellulose nanocrystals, which was freeze-dried to obtain cellulose nanocrystals. The yield of the cellulose nano crystals prepared by this method is 64%, the crystallinity is 82%, the average length is 131nm, the average diameter is 13nm, and it is in the shape of a short rod.

Embodiment 3

[0026] Accurately prepare 100g containing 55% CaCl 2 and formic acid content of 4M CaCl 2 -Formic acid co-promoting system. Accurately weigh 1g of pulp, the solid-to-liquid ratio is 1:100, add to CaCl 2 -In the formic acid co-promoting system, the temperature was raised to 110° C., and a homogeneous system was obtained after continuous stirring for 7 hours, and then desalted and dialysis was performed to obtain an aqueous solution of cellulose nanocrystals, which was freeze-dried to obtain cellulose nanocrystals. The yield of the cellulose nano crystals prepared by this method is 61%, the crystallinity is 79%, the average length is 137nm, the average diameter is 15nm, and it is in the shape of a short rod.

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Abstract

The invention discloses a method for preparing a CNC (cellulose nanocrystal) by an inorganic molten salt-trace acid co-promoted system. The method comprises the steps as follows: a raw material containing cellulose is added to the inorganic molten salt-trace acid co-promoted system, the temperature is increased to 50-130 DEG C, continuous stirring is performed for 0.5-72 h, a uniform system is obtained, then, desalination dialysis is performed, a CNC aqueous solution is obtained, the CNC is obtained after freeze-drying, and inorganic molten salt removed from desalination dialysis is reused continuously. The method has the advantages that the inorganic molten salt-trace acid co-promoted system has the advantages of being environmentally friendly, cheap in price, easy to prepare, small in use amount of formic acid, and the inorganic molten salt can be recovered and recycled. The reaction condition is relatively mild, equipment corrosion is small, the operation is convenient, and the product yield is high. The prepared CNC is higher in yield, adopts a short rod structure, has excellent mechanical strength and has broad application prospects in the fields of nanocomposites and the like.

Description

technical field [0001] The invention belongs to the technical field of cellulose, and in particular relates to a method for preparing cellulose nanocrystals by using an inorganic molten salt-slight acid co-promoting system. Background technique [0002] Cellulose is the most abundant renewable natural resource on earth, with an annual output of about 180 billion tons. In recent years, the extraction of nanocellulose from various cellulose raw materials has become a research hotspot at home and abroad. Cellulose nanocrystals (CNC) are chemically or mechanically decomposed cellulose raw materials into products with nano-sized structures. The obtained cellulose nanocrystals not only have the inherent characteristics of natural cellulose, but also have low density, high specific surface area, Excellent characteristics such as high aspect ratio, biodegradability, and high strength. Therefore, cellulose nanocrystals have broad application prospects in the fields of biomedicine, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/02
CPCC08B15/02
Inventor 韩颖邢新月王兴孙广卫李尧胡美茜屈桂洋
Owner DALIAN POLYTECHNIC UNIVERSITY
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