Enzymatic hydrolysis of several pith fractions from sugarcane bagasse obtained by two different methods of particulate separation

The growing interest on renewable energy sources worldwide has made ethanol appear as one of the most appealing form of alternative fuels. In Brazil ethanol is produced from the fermentation of sugarcane juice, the so-called “first generation ethanol, and one of its main by-products is bagasse. In order to increase productivity, it is possible to obtain fermentable sugars from the hydrolysis of this lignocellulosic material, and the ethanol obtained through this method is called “second generation ethanol”. The sugarcane bagasse is mainly composed of two fractions: fiber (rich in fibrovascular tissue) and pith (rich in parenchyma tissue). Differences in structure, composition and morphology between these fractions show that pith is more easily hydrolyzed than the fiber, thus some effort has been made in order to efficiently separate them. This separation can allow that each fraction be treated differently to obtain a wide variety of products. This work aims to separate the pith from the bagasse, obtaining the most pure sample possible, and analyze its performance on dilute acid pretreatment, alkaline delignification and enzymatic hydrolysis. Two separation methods were studied: sieving and pneumatic classification, and the samples obtained were analyzed for theirs composition, morphology, structure and the ratio of pith/fiber. The fraction obtained from pneumatic classification presented high pith content, high porosity and the best performance both in pre-treatment and enzymatic hydrolysis, and its delignification yielded up to 96% cellulose conversion on hydrolysis.