Effect of Isolation Techniques on the Structural and Thermal Properties of Nanocellulose: A Comparative Approach

Abstract

Abstract

Biocompatible materials have attracted considerable interest for the development of bioactive formulations. In this study, nanocellulose was isolated from banana (Musa acuminata) rachis using three different approaches viz. acid hydrolysis (AH), TEMPO-mediated oxidation (T-cellulose) and ionic liquid treatment (I-cellulose). In acid hydrolysis, the strong acids selectively break the amorphous regions of cellulose by cleaving β-(1→4)-glycosidic bonds, leaving behind highly crystalline nanoscale cellulose particles (nanocellulose). TEMPO mediated process oxidizes surface -OH group into carboxylate groups, while ionic liquid method promotes the fiber swelling and fragmentation. The prepared nanocellulose (NC) was characterised with FTIR spectroscopy, which confirms the presence of cellulose functional groups along with the added carboxylate groups in both samples. XRD analysis revealed well-defined diffraction peaks for TEMPO-treated cellulose, characteristic of a semi-crystalline structure, whereas ionic liquid-treated cellulose exhibited a broader diffraction peak, consistent with a predominantly amorphous structure. SEM and TEM images indicating extended, high-aspect-ratio fibrils in TEMPO cellulose and shorter, uniform fibrils in ionic cellulose, both celluloses forming dense and interconnected structure. TGA and DTA exhibited a three-step decomposition pattern for all samples, with TEMPO-treated cellulose possessing the highest thermal stability.