Pré-tratamento do bagaço de cana-de-açúcar aplicando sais alcalinos.

Abstract

One of the main sources of renewable energy in Brazil is biomass, with lignocellulose being the primary component of plant biomass, mainly composed of cellulose, hemicellulose, and lignin. The cultivation and processing of various crops, such as sugarcane, generate a considerable amount of waste that can cause environmental impacts if not properly disposed of. A significant portion of this waste can be reused as raw material for energy production and for obtaining high value added products. Applyi ng a pretreatment step to this type of material allows for the breakdown of the lignin cellulose hemicellulose complex, making it suitable for bioprocess applications. In this context, some catalysts have been studied due to their benefits, such as the gen eration of less corrosive and non polluting effluents. Thus, the main objective of this project was to evaluate the delignification of sugarcane bagasse after the application of a pretreatment using alkaline salts. The lignocellulosic biomass was dried, mi lled, and subjected to processes to determine lignin content and reducing sugars, with these steps performed both before and after pretreatment. The catalytic tests were carried out in an autoclave at 120°C, in the absence and presence of each salt, specif ically sodium carbonate and sodium phosphate. The conditions were defined through a 2² factorial design with three central point repetitions to evaluate the influence of salt mass and reaction time on the amount of lignin and reducing sugars (RS) present i n the solid residue and in the reaction medium, respectively. For the design using sodium carbonate, the interaction between salt and time was statistically significant for lignin removal; however, the isolated factors were not statistically significant. U sing this salt, it was possible to remove up to 61% of the lignin mass from the untreated material. This result was achieved by applying 10 g of salt for 45 minutes. The treatment using sodium phosphate did not show statistically significant values for eit her reducing sugar release or lignin removal. The maximum lignin removal achieved was 42%, using 10 g of salt for 15 minutes. The alkaline pretreatment proposed in the objectives was successfully completed following the methodology outlined in this work, s tatistically confirming the role of alkaline salts in the lignin removal process from sugarcane bagasse.