Improving the production of nanofibrillated cellulose from bamboo pulp by the combined cellulase and refining treatment

Abstract

AbstractBACKGROUNDNanofibrillated cellulose (NFC) has shown great potential for wide applications in various fields and industries such as food, coatings, daily chemicals, superabsorbent high‐strength materials, and other high‐value products. Bamboo, with a chemical composition and fibre properties comparable to wood, is considered as an ideal nonwood material for the production of high‐quality NFC. However, the normally used two‐step process [TEMPO‐mediated oxidation and high‐pressure homogenization (HPH)] not only requires high amounts of energy, but also results in high heterogeneity of the resultant nanocellulose products.RESULTSIn this study, we proposed a sequential treatment method combining cellulase treatment followed by mechanical refining to improve the process for NFC production from bleached bamboo kraft pulp. The results showed that cellulase treatment using an enzyme dosage of 7 U g−1 cellulose followed by mechanical refining for 5000 revolutions increased the content of carboxyl group in treated pulp from 0.46 to 0.90 mmol g−1cellulose following TEMPO‐mediated oxidation. The effect of cellulase treatment and mechanical refining on the fibre properties was investigated in terms of freeness, fibre length, water retention value, pore volume and other fibrillation characteristics, such as the diameter of the NFC fibrils. Finally, we also found that, using the above‐proposed process, ca. 85 g high‐quality NFC could be produced from 100 g bleached bamboo pulp.CONCLUSIONSThis study demonstrated that the combination of cellulase treatment and mechanical refining is a promising strategy to produce high‐quality NFC with short fibril diameter while increasing NFC yield and reducing energy consumption during HPH. © 2019 Society of Chemical Industry