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Nano cellulose prepared through catalyzing formic acid to hydrolyze by using metal salt and preparation method of nano cellulose

A technology of nanocellulose and metal salt, which is applied in the field of natural polymer material preparation, can solve the problems of unrecyclable catalyst, low reaction efficiency and environmental pollution.

Inactive Publication Date: 2019-02-12
DONGGUAN UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these methods often have disadvantages such as harsh enzymatic hydrolysis conditions, low reaction efficiency and long reaction time.
[0005] In summary, the existing methods for preparing nanocellulose mainly have problems such as non-recyclable catalyst, long reaction time, environmental pollution, high energy consumption, or low product yield.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0114] Weigh 3 g of dry bleached eucalyptus pulp and 0.45 g of anhydrous tin chloride into a 250 mL round bottom flask, add 100 mL of 60% (w / w) formic acid aqueous solution, and stir magnetically at 55° C. for 5 h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was transferred into a centrifuge tube and centrifuged at 8000 rpm for 5 min. The supernatant obtained after centrifugation, that is, the hydrolyzate, can be directly returned to prepare the next batch of nanocellulose. The precipitate obtained after centrifugation and the precipitated colloid are centrifuged and washed with distilled water until neutral, and the precipitate after centrifugation is the prepared product, which is freeze-dried to obtain nanocellulose crystals. The yield of nanocellulose obtained in the present embodiment is 85% (relative to the original dry bleached eucalyptus pulp), and the crystallinity is increased to 92% o...

Embodiment 2

[0116] Weigh 2 g of dry bleached eucalyptus pulp and 0.4 g of anhydrous silver nitrate into a 250 mL round bottom flask, add 100 mL of 60% (w / w) formic acid aqueous solution, and stir magnetically at 55° C. for 5 h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was moved into a centrifuge tube and centrifuged at 5000 rpm for 10 min. The hydrolyzate can be directly reused to prepare the next batch of nanocellulose. The precipitated jelly is centrifuged and washed with distilled water until neutral, and the centrifuged product is freeze-dried to obtain nanocellulose crystals. The yield of nanocellulose produced in this example is 82% (relative to the original dry bleached eucalyptus pulp), and the crystallinity is increased from 65% of the original slurry (Pulp) to 93% of nanocellulose (CNC).

Embodiment 3

[0118] Weigh 3 g of absolute dry corn cob cellulose and 0.6 g of nickel nitrate into a 250 mL round bottom flask, add 100 mL of 50% (w / w) formic acid solution, and magnetically stir at 55° C. for 5 h. After the reaction, the flask was quickly placed in a cold water bath to cool to room temperature, and then the reaction mixture was moved into a centrifuge tube and centrifuged at 5000 rpm for 15 min. The hydrolyzate can be directly reused to prepare the next batch of nanocellulose. The precipitated jelly is centrifuged and washed with distilled water until neutral, and the centrifuged product is freeze-dried to obtain nanocellulose crystals. The yield of nanocellulose prepared in this example was 92% (relative to the original dry corn cob cellulose), and the crystallinity increased from 59% of the original slurry to 95% of nanocellulose (CNC). Example 4

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Abstract

The invention discloses a nano cellulose prepared through catalyzing formic acid to hydrolyze by using metal salt and a preparation method of the nano cellulose, relating to the field of natural macromolecule material preparation. The preparation method mainly comprises the following steps: (1) adding the raw materials of the cellulose into a formic acid solution, adding the metal salt to serve asa catalyst, heating, stirring and hydrolyzing to obtain the nano cellulose; (2) separating the nano cellulose from hydrolysate through centrifugal sedimentation, centrifuging and washing precipitatednano cellulose a plurality of times by using water, then carrying out freeze drying or spray drying to obtain a nano cellulose crystal; and (3) recycling the hydrolysate separated out in the step (2), then reducing pressure, distilling and recycling the formic acid, and then adding water, alkali and acid successively in solid residue to cooperate with centrifugal sedimentation to recycle the metal salt. The preparation method has high hydrolysis efficiency and high nano cellulose yield, the used formic acid and metal salt are easy to recycle, and the cost is saved, thereby meeting the requirements on green sustainable production.

Description

technical field [0001] The invention relates to the field of preparation of natural polymer materials, in particular to a nanocellulose and a preparation method thereof. Background technique [0002] In recent years, the preparation and application of nanocellulose have been extensively studied. Due to its special nanostructure and properties, such as nanoscale, high specific surface area, high aspect ratio, low density, superior strength properties, etc., nanocellulose is widely used in nanomaterials, such as aerogels, biomedical materials, Packaging materials, optoelectronic materials and various nanocomposites, etc. [0003] The most commonly used method for preparing nanocellulose is inorganic acid hydrolysis, such as sulfuric acid, hydrochloric acid, nitric acid, hydrobromic acid, phosphoric acid and their mixed acid hydrolysis. Among them, the sulfuric acid hydrolysis method has been the most widely studied. Although the obtained nanocellulose has good dispersion in ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/02
CPCC08B15/02
Inventor 李豫珍王璞琳
Owner DONGGUAN UNIV OF TECH