Destoxificação de hidrolisados lignocelulósico visando à obtenção de etanol 2G

Abstract

The sugarcane bagasse has a high content of lignocellulosic material, which enables the study for the production of second-generation ethanol, requiring the application of a pretreatment that promotes the rupture of the fiber, to make accessible sugars for fermentation. There are several pretreatments aimed at the break and in the search for the most productive one, it is applied severe conditions of temperature and pressure. This promotes the formation of undesirable products in the bioethanol production process, requiring detoxification step for removal of inhibitors. In this study, we used the detoxifying step for two pretreatments, hydrothermal and acid. The methodology raised the pH of the hydrolysates resulting from the acid pretreatment to 7.0 with calcium oxide and then decay to pH 4.0 with phosphoric acid. The hydrolysates of the hydrothermal pretreatment had its pH reduced to 4.0 by addition of phosphoric acid, both pretreated were subjected to adsorption on activated carbon (1% w /v , 100 rpm , 30 minutes at 50 ° C), conditions chosen after design 22 after triplicate with the center point. The evaluation of the efficacy of these procedures was made as to the removal of toxic compounds depending on the fermentation yield with the yeast Saccharomyces cerevisiae, hydrolysates with and without detoxification, assessing the amount of released sugars for conversion into second-generation ethanol. According to the results , the change of pH combined with activated carbon adsorption led to higher fermentation yields in both pretreated 38.51% acid and hydrothermal 44.85% hydrolyzed , when compared to the yield of samples not detoxified , these results may be associated with interference of lignin in the pulp, which can form condensation products able to interfere with the detoxification. However the best results were found in the hydrolysate hydrothermally pretreated with 87.94% efficiency and fermentation alcohol content of 7.41%, compared to the pre-treated hydrolysate with acid and 5.11% 75.05% respectively.