Impact of the bleaching process on the production of nanocellulose from eucalyptus

Abstract The growing demand for sustainable materials has increased interest in nanocellulose derived from renewable resources. This study investigated the influence of different bleaching sequences on the production and characteristics of nanocellulose from Eucalyptus urograndis pulp. Three bleaching sequences, D 0 ( E + P ) D 1 P 2 , A HT DP 2 , and A HT E HT DP 1 , were evaluated using an industrially bleached pulp as reference. Nanocellulose was produced by sulfuric acid hydrolysis at 63 % (v/v), 55 °C, and 30 or 40 min, followed by centrifugation, dialysis, and ultrasonication. Increasing the hydrolysis time from 30 to 40 min consistently reduced the hydrodynamic diameter and polydispersity index, while the different bleaching conditions showed a similar response. FEG-SEM revealed nanometric structures with average widths of 32–41 nm and lengths of 293–353 nm, with yields close to 80 %. XRD, FTIR, and TG/DTG analyses showed similar crystalline, chemical, and overall thermal characteristics among the samples. Overall, under the conditions investigated, hydrolysis time showed a more consistent influence on hydrodynamic size distribution than the bleaching sequence, while the evaluated bleaching sequences resulted in nanocellulose with comparable morphological and structural characteristics.