Extraction of cellulose nanofibrils from amylase-treated cassava bagasse using high-pressure homogenization

Cassava bagasse (CB) is one of the largest yielding agricultural residues in Thailand. Thus, utilization of CB in cellulose extraction with amylase-assisted pretreatment was carried out in this research. Amylase pretreatment was used for starch removal, followed by bleaching with sodium chloride. Subsequently, cellulose nanofibrils (CNFs) were prepared using high-pressure homogenization. The chemical composition of the fibers at different stages showed an increase in the α-cellulose content from 19.27 ± 0.36 to 50.45 ± 0.46%. In contrast, the starch content clearly decreased from 61.60 ± 0.38 to 7.20 ± 0.42%. Scanning electron microscopy demonstrated a smooth surface on the bleached fibers due to the removal of non-cellulosic compounds. Atomic force microscopy and transmission electron microscopy confirmed that the diameter of the CNFs was in the range 15–30 nm after high-pressure homogenization at 15,000 psi for 30 passages. Moreover, the crystallinity and thermal stability were evaluated using X-ray diffraction and thermogravimetric analysis, respectively. The crystallinity of the CNFs was 63.40 ± 0.48%; whereas the temperature of maximum decomposition of the CNFs was 325 °C. Therefore, the CNFs prepared from amylase-treated CB using high-pressure homogenization could be applied as a reinforced matrix in material research.