Microcrystalline cellulose is a pure cellulose depolymerization product, particle size 2 (Γ80μπι. From natural cellulose preparations, is odorless crystalline powder products. In the pharmaceutical industry can be used as a pharmaceutical excipient and tablet disintegrating agents; in the food industry can be used as an important functional food base - dietary fiber, is an ideal health food additives; the use of its thixotropic and thickening in the coatings industry as water based paint thickener and emulsifier; set it on cosmetic fillers, thickening and emulsifying effect in one, oily substance has good emulsifying ability; and used as thickening filler in the manufacture of wet leather production, so leather smooth surface, uniform thickness. Thus, microcrystalline cellulose, which uses a wide range of domestic demand for the products will continue to increase. Cellulose nanocrystals not only has the basic structure and properties of microcrystalline cellulose, but also has nano properties of the particles, such as the huge surface area, strong adsorption capacity and high reactivity, so its very broad application prospects. current methods for preparing microcrystalline cellulose, cellulose degradation mainly acid hydrolysis and enzymatic hydrolysis. acid hydrolysis method requires a high concentration of acid, corrosive, high cost; low degradation efficiency of enzymatic hydrolysis, it is difficult to achieve industrial production.
For the above-mentioned problems of the prior art, it is to provide a method for preparing cellulose nanocrystals. The method is simple, low cost, the resulting cellulose nanocrystals prepared uniform size, good performance. Aspect of the present invention is as follows:
Method for preparing cellulose nanocrystals, concrete steps are as follows
(1) the quality of its refined cotton linters into 1 (Γ20 times the water, placed in an ultrasonic generator ultrasonic agitation Γ8 small Time;
(2) to continue to the ultrasonic generator was added to the quality of refined linters mass 58 times O.5mol / L sulfuric acid aqueous solution, and the quality of refined linters quality fly 2 times O. 5mol / L of aqueous hydrochloric acid, maintaining agitation, ultrasound at a temperature of 3 (T60 ° C for 812 hours;
(3) Step (2) The resulting solid product was washed with water until the pH value to 67. Useful technical effect of the invention that
The application first ultrasonic agitation pretreated cellulose, water generated microbubbles under the action of ultrasound, micro-bubble burst instantly generates energy, which can effectively separate the purified linters cracks, the molecule of cellulose in an extended stretch of state easy to be degraded in the subsequent acid hydrolysis process. Purified cotton linters stirring allows more uniform dispersion, no caking. Since cellulose after pretreatment, therefore acid hydrolysis process for concentration of sulfuric acid and hydrochloric acid requirements greatly reduced, while the ultrasonic energy so that small bubbles form a large number of acid in the chemical degradation but also increased the bombardment of cellulose macromolecules physical effects, heating the cellulose macromolecules such increased activity of a group, it is more easily broken down into small molecules, and therefore by the above method can easily degrade cellulose particles 5 10nm nanoscale microcrystalline cellulose.
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