Avaliação da aplicação da argila bentonita como catalisador no processo de pré-tratamento do sabugo de milho.

Abstract

Corn cultivation and processing generates a considerable amount of waste that can cause environmental impacts if not disposed of properly. Among these, we highlight the cob, a lignocellulosic biomass, which can be reused as raw material in the generation of energy and products with high added value. Applying a pretreatment step to this type of material can promote the rupture of the lignin-cellulose-hemicellulose complex, making it suitable for application in bioprocesses. In this context, some catalysts have been studied due to benefits such as possible reuse, easy removal of the reaction medium and generation of less polluting effluents. Thus, the objective of this work was to evaluate the catalytic activity of bentonite clay in the pretreatment process of lignocellulosic biomass, corn cob. Pretreatment tests were conducted in an autoclave at 120 ° C, without catalyst and in the presence of bentonite, fresh and acid-treated. Factorial design 2² with three repetitions at the central point was applied to evaluate the influence of reaction time and catalyst mass on the amount of reducing sugars (RS) present in the reaction medium. Then, the tests were performed on a larger scale, applying the treated clay to the planning conditions that generated the best results in relation to the amount of RS generated. After the extended scale test, the solid product was separated and the pretreatment with the recovered clay repeated to verify the possibility of reuse. The best results were obtained for a time of 180 minutes and clay mass of 5.0 g, with 143.20 mg.mL-1 RS, indicating that acidified bentonite has catalytic activity. By increasing the scale, 118.26 mg.mL-1 RS and the reduction of holocellulosic fraction in the solid product were observed, proving the catalytic activity of the treated clay. Reuse of clay provided slight changes in the AR content of the reaction medium and solid product composition. Thus, it is possible to affirm that the treated clay can be applied as a catalyst in the corn cob pretreatment and that its reuse, under the studied conditions, is not feasible.