Top-Down Production of Nanocellulose from Environmentally Friendly Processes

EHMAN, N.; VALLEJOS M.E.; AREA, M.C.

Handbook of Green and Sustainable Nanotechnology

Springer Nature Switzerland AG

Lugar: Basel; Año: 2023; p. 185 - 202

Theproduction of nanometric size particles from lignocellulosic pulp or waste andother cellulose biomass involves top-down techniques. The first stage is thefractionation of biomass, which is the first opportunity to apply moreenvironmentally friendly methods. Subcritical water or supercritical CO2 aresimple methods to extract hemicelluloses and extractives. A recently developedprocess involves lignin removal by chemical treatment with gamma-valerolactoneto obtain a highly purified cellulosic fraction, avoiding subsequent bleachingstages and facilitating the nanofibrillation process. The most studied greenmethods for nanocellulose production are the enzymatic pretreatment of cellulosicfibers and alternative oxidant methods. Deep eutectic solvents are moreefficient than traditional ones or one-pot oxidative hydrolysis to obtainnanocrystalline sizes that minimize wastewater generation. This chapter coversthe most environmentally friendly processes and reagents that have beenreported for nanocellulose production, including the fractionation of the rawmaterial. Reported properties of nanocellulose produced by green solventspretreatments are similar to those obtained by traditional chemical reagentssuch as TEMPO-oxidation. Then, the future of nanocellulose production fromenvironmentally friendly processes is promising.