Emerging green routes to nanocellulose

Nanocellulose is an exceptional biomaterial whose industrial applications in widely different sectors and technologies so far have been limited by the high cost of its multi‐step extraction routes. Extraction methods of cellulose nanocrystals or nanofibers, indeed, generally involve the energy‐intensive mechanical treatment of wood pulp, treatment with concentrated H2SO4 to obtain cellulose nanocrystals or chemical oxidation followed by mechanical fibrillation of the partly oxidized fibers. In the last decade (2011–2021) a number of green routes to cellulose nanofibers and nanocrystals have been developed. This study provides a critical outlook of said emerging new green routes to this versatile and safe bionanomaterial that, once sustainably produced, preferably from low cost cellulosic biowaste, will become ubiquitous in a number of different industrial products. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.