Preparation and characterization of cellulose nanocrystals from rice straw

• Published in: Carbohydrate polymers Vol. 87; no. 1; pp. 564 - 573
• Main Authors: Lu, Ping, Hsieh, You-Lo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 04-01-2012; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; cellulose; Cellulose and derivatives; Cellulose nanocrystals (CNCs); crystallites; Exact sciences and technology; Food industries; freeze drying; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; mixing; nanocrystals; Natural polymers; Physicochemistry of polymers; Rice straw; Self-assembly; sulfuric acid; Sulfuric acid hydrolysis; Ultra-fine fibers; Use and upgrading of agricultural and food by-products. Biotechnology; Use of agricultural and forest wastes. Biomass use, bioconversion; Self-assembly; Ultra-fine fibers; Cellulose nanocrystals (CNCs); Rice straw; Sulfuric acid hydrolysis; Self assembly; Freeze drying; Cellulose; Chemical degradation; Fibrillar structure; Experimental study; Rice by product; Dimension spectrum; Hydrolysis; Morphology; Physical separation; Surface area; Nanocrystal; Macroporosity
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2011.08.022

► Successful isolation of pure cellulose from rice straw by an effective three-step process. ► Derivation of cellulose nanocrystals (CNCs) from sulfuric acid hydrolysis of rice straw-derived cellulose. ► Detailed characterization of rice straw-derived CNCs. ► Self-assembly of rice straw-derived CNCs into ultra-fine fibers after freeze–drying diluted CNCs suspension. ► High stability of self-assembled CNC ultra-fine fibers in aqueous media.
Pure cellulose have been isolated from rice straw at 36% yield and hydrolyzed (64% H2SO4, 8.75mL/g, 45°C) for 30 and 45min to cellulose nanocrystals (CNCs), i.e., CNC30 and CNC45, respectively. CNC45 was smaller (11.2nm wide, 5.06nm thick and 117nm long) than CNC30 (30.7nm wide, 5.95nm thick and 270nm long). Freeze–drying of diluted CNC suspensions showed both assembled into long fibrous structures: ultra-fine fibers (∼400nm wide) from CNC45 and 1–2μm wide broad ribbons interspersed with CNC clusters from CNC30. The self-assembled fibers from CNC30 and CNC45 were more highly crystalline (86.0% and 91.2%, respectively) and contained larger crystallites (7.36nm and 8.33nm, respectively) than rice straw cellulose (61.8%, 4.42nm). These self-assembled fibers had essentially nonporous or macroporous structures with the CNCs well aligned along the fiber axis. Furthermore, the self-assembled ultra-fine fibers showed extraordinary structural stability, withstanding vigorous shaking and prolong stirring in water.