Nanofibrillated Cellulose Extracted by Enzymatic Hydrolysis Followed by Mechanical Fibrillation

Abstract

In a comparison with certain one-step processes, enzymatic hydrolysis followed by mechanical defibrillation may avoid the use of nonrenewable resources, mitigate the generation of toxic effluents, and reduce the energy consumption related to a single mechanical process. In the present study, bleached and unbleached hardwood pulps were employed as raw materials for producing nanofibrillated cellulose (CNF) using a two-step process, in which a cellulase enzyme was inoculated to act as a pretreatment for a subsequent grinding process. The obtained CNF reached high crystallinity indexes (above 70%) and high thermal stability (degradation onset temperatures around 200°C). Increases in enzyme concentration yielded decreases in diameter and increases in both thermal stability and crystallinity index. These findings indicated that the enzymatic hydrolysis used as a pretreatment to a further grinding process can allow the production of valuable CNF-based products.

Keywords

• nanocellulose
• biological pretreatment
• cellulase
• eucalyptus