Extraction of cellulose nanowhiskers from natural fibers and agricultural byproducts

Abstract

In this work the feasibility of extracting cellulose from cotton, sisal and flax fibers, corn stover and rice husk by means of usual chemical procedures such as acid hydrolysis, chlorination, alkaline extraction, and bleaching was analyzed. Cellulose nanowhiskers from these sources, and from commercial cellulose, were produced by the acid hydrolysis of the obtained celluloses. The final products were characterized by means of Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Atomic Force Microscopy (AFM). The chemical procedure used to obtain cellulose nanowhiskers was effective in all cases but differences on the thermal stability, chemical composition, crystallinity and morphology were found due to the dissimilar nature of the different sources. Thus, this work demonstrates that the morphology and physical properties of cellulose nanowhiskers synthesized by the same conditions are strongly dependent on their source.

Revalorization of rice husk waste as a source of cellulose and silica

“…Procedure I was based on our previous studies [6,11]. Procedure II was proposed as an alternative of procedure I changing the treatments sequences looking for the concurrently extraction of high purity cellulose and silica.…”

“…The most commercially exploited natural resource containing cellulose is wood [1] but cellulose is the main component of several other well employed natural fibers such as banana, coconut husk fibers, cotton, flax, hemp, jute, sisal fibers, and waste such as rice husk [2][3][4][5][6]. Cellulose in these natural resources is embedded in non-cellulosic matrix mainly formed by hemicellulose and lignin.…”

“…In this work, however, the extraction of silica was not reported in any step of the procedure. Recently, we proposed a new strategy based on chemical treatments reported in the literature that allows the separation of silica and cellulose simultaneously from rice husk [6,11]. Silica can be isolated by a combination of alkaline treatments followed by precipitation with acid (mainly hydrochloric acid, HCl) [6].…”

“…Recently, we proposed a new strategy based on chemical treatments reported in the literature that allows the separation of silica and cellulose simultaneously from rice husk [6,11]. Silica can be isolated by a combination of alkaline treatments followed by precipitation with acid (mainly hydrochloric acid, HCl) [6]. After that cellulose was isolated from organic residue by means of a multistep procedure consisting of alkali and bleaching treatment steps.…”

“…The aim of this work is to analyze different sequences of the chemical treatments studied in previous works [6,11,15] in order to concurrently extract cellulose and silica from rice husk using alkali and bleaching treatments. Then, the chemical and physical characteristics of the cellulose obtained will be compared with that of previous studies.…”