Partially acetylated cellulose nanofibrils from Agave tequilana bagasse and Pickering stabilization

Abstract

Partially acetylated cellulose nanofibrils were obtained from the major residual stream associated with tequila production. The morphology and high cellulose content of the bagasse of Agave tequilana greatly facilitated deconstruction of such underutilized biomass. Mild chemical acetylation of the starting material afforded cellulose nanofibrils bearing surface ester groups, making the system less hydrophilic and plasticized. The acetylated nanofiber were characterized for morphology (atomic force microscopy), electrostatic charge (electrophoretic mobility), degree of substitution (DS) (titration) and main chemical features (infrared spectroscopy). Aqueous suspensions of the partially acetylated nanofibers (0.5% concentration) were mixed with a non-polar organic solvent (toluene) to obtain emulsions that were stable for at least 43 days. Cellulose nanofibrils of given DSs (different wettability) formed emulsions with different droplet size, thereby producing emulsion with different properties and stability. The cellulose nanofibrils with smaller sizes and higher contact angle (81°) generated small droplets (10–60 µm) while the cellulose nanofibrils with larger sizes and smaller water contact angle (40°) generated larger droplets (20–80 µm). Agave Bagasse CNF offers a great potential as Pickering emulsion stabilizers, which can be considered in the food, cosmetic and pharmaceutical fields.