Nanocellulose, a promising raw material: Improving the scalability of TEMPO-mediated oxidation

Abstract

Nanocellulose is a promising raw material due to its distinctive properties, including renewable origin, biodegradability, lightweight, and high mechanical strength. It has a very high potential to enhance products in a broad spectrum of applications. However, the production of highly fibrillated cellulose nanofibrils (CNFs) remains costly due to the high energy and chemical consumption. TEMPO-mediated oxidation (TMO) is the most widely accepted pretreatment for CNF production due to its high efficiency and selectivity. However, challenges associated with scaling up this process are limiting their implementation, as high catalysts and oxidant doses, extended reaction times, and large reaction volumes. Several strategies have been developed with the aim of enhancing the CNF production and optimizing the overall process. These strategies include real-time monitoring of the reaction parameters, optimizing pulp concentration, reusing the reaction medium, and using different reactor configurations such as kneaders and twin-screw extruders. These advancements are reviewed to show the significant and critical progress carried out in the last decade toward achieving more efficient and sustainable nanocellulose production.