Evaluation of the effects of operational parameters in the pretreatment of sugarcane bagasse with diluted sulfuric acid using analysis of variance

ABSTRACT

The pretreatment of lignocellulosic residues has been extensively studied as a method to disrupt the cellulose–hemicelluloses–lignin complex in biomass to access the sugars in their respective components. In this work, we carried out a study using sulfuric acid pretreatment of sugarcane bagasse by varying the following operational parameters: solid loading (10–30% of bagasse relative to the volume of the sulfuric acid solution), sulfuric acid concentration (0.5–2.5% relative to the dry mass of bagasse), reaction time (5–25 min), and temperature (135–195°C). The obtained solids from each pretreatment condition were submitted to enzymatic hydrolysis under the same process conditions: 0.232 g of Celluclast 1.5 L and 0.052 g of Novozym 188 per g of pretreated sugarcane bagasse, 72 h of hydrolysis, and 200 rpm of agitation at 50°C. Using central composite rotational design configuration in the experiments and analysis of variance, the results indicate that the conditions that produced larger quantities of glucose by enzymatic hydrolysis (0.35 g glucose/g pulp) with minimum amounts of degradation products were as follows: 20% solids loading, 15 min of reaction time, 1.5% sulfuric acid, and a minimum temperature of reaction of 170°C.

KEYWORDS:

• Degradation products
• diluted sulfuric acid pretreatment
• enzymatic hydrolysis
• glucose
• sugarcane bagasse
• xylose

Acknowledgments

The authors thank Usina Central Olho d’Agua for the supply of sugarcane bagasse and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil) and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil) for their financial supports.