Cellulose nanocrystals from blueberry pruning residues isolated by ionic liquids and TEMPO-oxidation combined with mechanical disintegration
Claudia Marcela Pacheco Pinilla, Cecilia Bustos, Guillermo Reyes
Abstract
In the last years, Chile has increased the production of blueberries; consequently, a large number of lignocellulosic residues derived from the harvesting and pruning are being generated. These residues are commonly burned, therefore increasing CO2 emissions. This study focuses on the extraction of two added-value products from blueberry pruning residues (BPRs), cellulose nanocrystals (CNC-IL) isolated using ionic liquid (IL) 1-ethyl-3-methylimidazolium [emim][Cl], and carboxylated nanocellulose (TOCNC), isolated with (2,2,6,6-tetramethylpiperidine-1-yl) oxyl or TEMPO reagent combined with a mechanical disintegration process. These products were characterized by zeta potential (ζ), FTIR, XRD, TGA, AFM, and conductometric titration. Results show oval-shaped CNC-IL particles with lengths of 46.1 ± 9.3 nm; meanwhile, TOCNC were rod-like shaped particles, with lengths of 120.3 ± 30.6 nm. These BPRs showed a promising potential to produce cellulose nanocrystals (CNCs) with different surface properties, opening a new alternative for the production of cellulose nanomaterials (CNMs) with promising applications in colloidal formulations, coatings, among others.