Isolation and characterization of nanofibers from agricultural residues – Wheat straw and soy hulls

• Published in: Bioresource technology 2008-04, Vol.99 (6), p.1664-1671
• Main Authors: Alemdar, Ayse, Sain, Mohini
• Format: Article
• Language: English
• Subjects: Agriculture - instrumentation; Agriculture - methods; Agronomy. Soil science and plant productions; Biocompatible Materials - chemistry; Biological and medical sciences; Biotechnology - instrumentation; Biotechnology - methods; Cellulose - chemistry; Cellulose nanofiber; Crystallization; Food industries; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Glycine max - chemistry; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanofiber characteristics; Nanoparticles - chemistry; Nanotechnology - methods; Natural fibers; Soy hulls; Soybean Proteins - chemistry; Spectroscopy, Fourier Transform Infrared - methods; Temperature; Triticum - chemistry; Triticum aestivum; Use and upgrading of agricultural and food by-products. Biotechnology; Use of agricultural and forest wastes. Biomass use, bioconversion; Wheat straw; X-Ray Diffraction
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2007.04.029

Cellulose nanofibers were extracted from the agricultural residues, wheat straw and soy hulls, by a chemi-mechanical technique to examine their potential for use as reinforcement fibers in biocomposite applications. The structure of the cellulose nanofibers was investigated by transmission electron microscopy. The wheat straw nanofibers were determined to have diameters in the range of 10–80 nm and lengths of a few thousand nanometers. By comparison, the soy hull nanofibers had diameter 20–120 nm and shorter lengths than the wheat straw nanofibers. Chemical characterization of the wheat straw nanofibers confirmed that the cellulose content was increased from 43% to 84% by an applied alkali and acid treatment. FT-IR spectroscopic analysis of both fibers demonstrated that this chemical treatment also led to partial removal of hemicelluloses and lignin from the structure of the fibers. PXRD results revealed that this resulted in improved crystallinity of the fibers. After mechanical treatments of cryocrushing, disintegration and defibrillation, the thermal properties of the nanofibers were studied by the TGA technique and found to increase dramatically. The degradation temperature of both nanofiber types reached beyond 290 °C. This value is reasonably promising for the use of these nanofibers in reinforced-polymer manufacturing.