Mass balance evaluation of different detoxification methods for the sugarcane bagasse hemicellulose hydrolysate

The production of second-generation (2G) ethanol, obtained from plant biomass, still presents technological challenges to become competitive to that obtained from sugarcane juice, the so-called first generation (1G) ethanol. Pretreatment is an important step in the conversion of lignocellulosic substrates to ethanol. The pretreatment using dilute sulfuric acid (acid hydrolysis) is the most widely used for having high efficiency in the separating process of cell wall components resulting in the generation of fermentable sugars and also compounds that are inhibitory to the fermenting microorganism. In the present study, the acid hydrolysate of sugarcane bagasse was subjected to two different detoxification methods (adsorption and flocculation) analyzing each pH change steps through mass balance. Treatment with active charcoal (CaO to pH 7.0, H₃PO₄ to pH 2.5 and adsorption on activated charcoal (1%m/v), 100rpm for 30min at 60°C) and treatment with biopolymer (CaO to pH 8.0, Acqualpol WW biopolymer (15%v/v), 200rpm for 15min at 25°C) were experimented. Analysis of sugars, acetic acid, total phenolic compounds, total volume and quantification of solid residues were performed before and after different treatments. Treatment with calcium oxide followed by active charcoal was the most efficient detoxification method, which resulted in 91% reduction in total phenolics with 6% sugar loss, 30% volume loss and 0.93 less of solid residues when compared to biopolymer treatment. Treatment with biopolymer resulted in decrease 244% acetic acid but the sugar and volume loss (20% and 62%, respectively) were more when compared to calcium hydroxide treatment. Acknowledgments: CAPES, CNPq, FAPESP.