Obtención de Etanol Celulósico a Partir de la Variedad de Pasto Pennisetum Clandestinum

Abstract

This research project presents a methodological proposal that uses the grass species Pennisetum Clandestinum as a raw material for the production of cellulosic ethanol. Two different delignification methodologies were implemented in order to determine the most efficient; the one proposed by (Wise Elsberg, 1946) where sodium chlorite and glacial acetic acid are used and the one proposed by (Azzam, 2008) and (Gould, 1983) where an alkaline hydrogen peroxide solution is used, these two authors Although they use the same reaction medium, they propose different optimal conditions, for which numerous laboratory tests were carried out aimed at comparing and determining that the experimental conditions proposed by AM Azzam are more efficient, consequently the pretreatments of partial removal of lignin and hemicelluloses proposed by the latter author and the lignin removal pretreatment proposed by Wise et al. Were evaluated. The products obtained in both processes were subjected to a hemicelluloses removal using 17.5% and 8.3% NaOH solutions and a 10% CH3COOH solution according to NTC Standard 697. Subsequently, they underwent a hydrolysis process consisting of a modification of the methodology proposed by Chen (1998) that uses ZnCl2 as a solvent and catalyst for hydrolysis in the presence of 0.5 M HCl, numerous experimental tests were carried out to determine the most optimal hydrolysis conditions, obtaining a maximum conversion yield of 27.6% reducing sugars after 18 hours for the samples pretreated with the methodology proposed by AM Azzam, and 23.29% after 20 hours for the samples pretreated with the methodology proposed by Wise et al. The yield percentage of the conversion of cellulose to reducing sugars in the hydrolysates was monitored using the Miller colorimetric method or 3,5-Dinitrosalicylic acid (DNS) taking aliquots of 0.5 ml every certain time interval to be read at 490nm, the The rest of the hydrolyzate was fermented according to the methodology proposed by (Hossain, Golam, & Narayan Sahu, 2014) and (Manasa, Narasimhulu, & Paramjeet) and the obtained fermentation product was distilled to obtain the ethanol that was qualitatively characterized by a oxidation test of primary alcohols with a solution of K2Cr2O7 and H2SO4. In addition, a characterization was made of the grass species Pennisetum Clandestinum, where an ash content of 5.85%, humidity 7.72%, lignin 10.72%, holocellulose (hemicellulose + cellulose) 69.10%, hemicellulose 39.82% and cellulose 29.28% were determined. .