Preparation method of nanocellulose film precipitated by applying water solution

Abstract

The invention discloses a preparation method of a nanocellulose film precipitated by applying a water solution. The preparation method comprises the following steps: dissolving cellulose with concentration of 10-40g / L into a mixed solution of sodium hydroxide, urea and water at minus 15-minus 8 DEG C; after heating the cellulose solution to the room temperature, dropwise adding water to the cellulose solution to precipitate cellulose to obtain nanocellulose colloid dispersion liquid; filter-pressing the nanocellulose colloid dispersion liquid to obtain the nanocellulose film, wherein the mixed solution contains 5-10% of sodium hydroxide, 10-15% of urea and the balance of water by mass percent, and the volume ratio of water to the cellulose solution is (1-3):1. The method overcomes the defects of difficulty in acid waste liquor recovery, high preparation cost, high preparation energy consumption, heavy environmental pollution and the like in the existing preparation method of nanocellulose and the film thereof, and has the advantages of simplicity and high efficiency in operation, solvent reusability, environment friendliness and low energy consumption.

Description

technical field [0001] The invention relates to cellulose, in particular to a nano-cellulose, in particular to a method for preparing a nano-cellulose film precipitated by an aqueous solution, and belongs to the field of material processing. Background technique [0002] With the rapid development of human society and the irrational use of fossil energy, the problems of energy shortage and environmental pollution are becoming more and more serious, and people are paying more and more attention to the research of cellulose, an inexhaustible and renewable resource. Compared with ordinary cellulose, nanocellulose has broad application prospects in the fields of nano fine chemical industry, nano medicine, nano food, nano composite materials and new energy because of its particularity in aggregated structure and physical properties. [0003] The current preparation methods of nanocellulose include: (1) Preparation of nanocellulose by acid method, that is, using inorganic acid or ...

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Problems solved by technology

[0003] The current preparation methods of nanocellulose include: (1) Preparation of nanocellulose by acid method, that is, using inorganic acid or organic acid as a catalyst to provide high-concentration hydrogen ions into the amorphous region of cellulose to break hydrogen bonds and hydrolyze it to generate glucose At the same time, the cellulose chain is cracked to a certain extent, resulting in a decrease in the degree of cellulose polymerization, thereby obtaining nanocellulose. In 1947, Nickerson and Habrle used hydrochloric acid and sulfuric acid to hydrolyze wood and cotton wool to prepare nanocellulose colloidal dispersion. However, this method requires the use of strong acid, which requires high reaction equipment, and will produce acid waste liquid, which is difficult to recycle and process; (2) enzymatic hydrolysis to prepare nanocellulose, that is, using cellulase to selectively enzymatically decompose amorphous Cellulose leaves some cellulose crystals. This method can improve the quality and purity of nanocellulose without using chemicals, but has the defects of low yield and high cost; (3) TEMPO oxidation method to prepare nanocellulose, That is, TEMPO is used to catalyze oxidation to prepare nanocellulose. TEMPO acts as a catalyst to promote the selective oxidation of primary hydroxyl groups on cellulose C6 to oxidize it into polyglucuronic acid, which makes the surface of the filaments negatively charged. Electrostatic repulsion is generated to obtain a stable nanocellulose colloidal dispersion, and TEMPO is expensive in this method

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