Separation of Cellulose Nanocrystals from Bromelia (Neoglaziovia variegate) Fibers Using Ionic Liquids Based on Hydrogen Sulfate Anion

Abstract

Due to the environmental appeal that has grown in recent years, the use of agricultural wastes and plant fibers to develop new biodegradable materials is increasing quickly. In this context, nanocomposites reinforced with cellulose nanocrystals (CNCs) obtained from Bromelia (Neoglaziovia variegate) fibers have stood out as promising materials. Despite CNCs used to be separated from a cellulosic matrix in a good way with inorganic acids, the use of acidic ionic liquids (IL) has been arising as a safer and greener approach. Several authors have proposed the aprotic IL [BMIM][HSO4] as an excellent alternative media to CNCs separation, and in previous work, we have proven that the cheaper protic IL [2-HEA][HSO4] is valid for the same purpose. In this work, CNCs were separated from cellulose previously extracted from bromelia through the processing with H2SO4, [BMIM][HSO4], and [2-HEA][HSO4]. A variety of techniques, like thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), electrophoretic light scattering (ELS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to CNCs characterization. The rod-like and spherical nanoparticles showed good thermal stability, and this could allow their incorporation into a polymeric matrix. Nanoparticles isolated with protic ionic liquid showed more excellent crystallinity when compared with nanoparticles with aprotic ionic liquid.