Cellulose nanocrystals prepared by TEMPO-mediated oxidation of wild Musa spp. pseudostem



Valorization of agricultural waste to produce value-added products such as nanocellulose is important in bringing sustainable development and reducing our dependence on petroleum-based products which are harmful to our environment. 
Objective: The present work is carried out to investigate the potential of the pseudostems from the wild Musa spp. as a novel sustainable source of cellulose nanocrystals (CNCs).
TEMPO-mediated oxidation and ultrasonication methods were followed for theisolation of CNCs. The CNCs were characterized by various physicochemical parameters such as FTIR, TEM, Zeta potential, degree of oxidation, swelling and water retention value. TGA studies were performed to evaluate the thermal stability and percent crystallinity was determined by XRD spectroscopy. 
The final carboxylated CNC (cCNC) gel contains 5.56%w/w solid CNC exhibiting degree of oxidation of 34.91%. The CNC also showed high water retention value exhibiting ionic sensitivity to NaCl. The zeta potential value was determined to be -50.3 mV indicating the stability of the cCNC the particle size of which was less than 200nm. The percent crystallinity was found to be 66.18% and TGA analysis showed the reduced thermal stability of the cCNCs. 
Carboxylated CNC was successfully isolated from the wild banana pseudostem following TEMPO-oxidation method. Ultrasonication of the cCNC resulted in the formation of cCNCs with mostly spherical shapes and the results from analysis indicate that the wild banana pseudostem could be a potential sustainable source of cellulose nanocrystals.
