(6gr) Eco Friendly Strategies for Nanocellulose Production Using a Non Commercial Enzymatic Cocktail

Teaching Interests: Sustainable Engineering, Nanotechnology

Replacing non-renewable fossil sources by lignocellulosic biomass as raw material for the production of fuels and chemicals is the driving force for the development of sustainable biorefineries. However, the costs associated with the biomass processing still constitute the main economic barriers to biofuels and bioproducts competitiveness. A promising strategy to improve the biorefinery profitability is the production of enzymes on-site and high added-value co-products, such as nanocelullose, which can be obtained from the residual solid fraction of the cellulose saccharification process. These nanomaterials present excellent mechanical properties, good biocompatibility, tailorable surface chemistry, and interesting optical properties. Due to these distinguished properties, nanocellulose has attracted interest for several applications in food packaging, biomedicine, as mechanical reinforcement of matrices, among many others. The current industrial process to obtain nanocellulose employs acid hydrolysis, but the development of more environmentally-friendly strategies such as via enzymatic hydrolysis is highly desirable. In this context, the present work focused on producing home-made enzymatic cocktails and applying them to obtain nanocellulose. Firstly, cellulolytic enzymes were produced by Aspergillus niger cultivated under solid-state fermentation using wheat bran as solid substrate. Then, two strategies were evaluated to obtain nanocellulose: enzymatic hydrolysis of bleached kraft eucalyptus pulp (BKEP) followed or not by a sonication step. The BKEP fibers were pretreated in a ball mill prior to enzymatic hydrolysis. The reactions were carried out in Erlenmeyer flasks containing 50 mL of home-made enzymatic cocktail (fungal fermentation broth) and 2 % (w/v) of solids loading for 96 h and the glucose concentration and cellulose conversion were determined during the reaction. Scanning electron microscope was used to analyze the initial pulp fibers and the nanocellulose material from both strategies (enzymatic treatment and enzymatic combined with mechanic treatment) were characterized by Field Emission Scanning Electron Microscopy, showing that it was possible to obtain nanocellulose using a non-commercial enzymatic cocktail and the combination with mechanical treatment contributed to improve the dispersion of the nanocelullosic material.