Optimization of sugarcane pretreatments aiming promising substrates to obtain crystalline nanocellulose

• Grant number: 16/22570-1
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2017
• Effective date (End): November 30, 2018
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Camila Alves de Rezende
• Grantee: Bruna dos Santos Botelho
• Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Sugarcane bagasse is a biomass available in large quantities in Brazil (around 200 million tons/year), being produced as a residue of ethanol and sugar production. Currently, this biomass has been underutilized, but new ideas for its use have emerged, such as the production of second generation ethanol, whiskers and cellulose nanofibers for the preparation of polymer composite materials with improved mechanical properties. For whiskers production, it is necessary to apply pretreatment steps to convert the in natura biomass to a substrate rich in crystalline cellulose, which can then be hydrolyzed for the isolation of the whiskers. There are many possible strategies and experimental conditions that can be used as pretreatments and they depend on the type of biomass. Thus, the objective of this project is to optimize methodologies of acid and alkali sequential pretreatments in sugarcane bagasse, aiming to obtain pulps rich in crystalline cellulose, which can be used in the future for the preparation of whiskers. In the acid step, sulfuric acid (H2SO4) will be used as the main reagent and, in the basic step, sodium hydroxide (NaOH). The optimization of the pre-treatments aims to decrease the concentration of reagents, the temperature and the reaction time and increase the solid/liquid ratio. The solids obtained after each step will have their compositional characterization determined by high performance liquid chromatography (HPLC) and UV-VIS spectroscopy, which will determine the enrichment of the sample in terms of the cellulose content. The crystallinity of the samples will be evaluated by X-ray diffractometry (XRD), with minimum crystallinity indexes of 60% being required for the success of the later stages of hydrolysis and isolation of the whiskers. The best experimental condition determined will be applied to prepare whiskers by acid hydrolysis and these nanoparticles will be characterized by transmission electronic microscopy. This final stage of hydrolysis will not be optimized, previously established conditions of our group will be used and this will be important to validate the conclusions about the efficiency and optimization of the pre-treatments. Finally, it is expected that the results obtained with the optimization of the pretreatments contribute effectively with the other projects that are being done in the group. (AU)