Cellulose nanocrystals isolated from sugarcane bagasse using the formic/peroxyformic acid process: Structural, chemical, and thermal properties

Abstract

Sugarcane bagasse (SCB) is a renewable biomass source for cellulose extraction. In the pretreatment, SCB is processed to break down the cellulose-lignin-hemicellulose matrix and isolate components. This work proposes a formic/peroxyformic acid process for extracting cellulose nanocrystals (CNCs) from SCB. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and solid-state 13C nuclear magnetic resonance (ss- 13C NMR) were employed to evidence the removal of wax, hemicellulose, and lignin from the raw SCB. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) were used for analyzing crystallinity, morphology, and thermal properties. SEM results showed that after lignin removal, the size of purified cellulose fibrils decreased significantly, and the structure of cellulose microfibers became smoother and more apparent. After acid hydrolysis of bleached cellulose microfibers, XRD analysis showed CNCs had the highest crystallinity (70.8 %). In TEM images, rod-like structures of CNCs were measured to be 23 ± 2.7 nm wide and 610 ± 18 nm long. The eco-friendly formic/peroxyformic acid procedure with a chlorine-free bleaching stage produced a white, cellulose-rich solid powder of CNCs