Análise dos parâmetros fermentativos para a produção de etanol 2g a partir de hidrolisado de coco

Abstract

In recent decades, Brazil has made great progress in fuel ethanol production using sugarcane sucrose as raw material, is the world’s second-largest producer of ethanol. However, in terms of water, food, and environmental safety, this production can be optimized by replacing the food raw material with agricultural waste, giving rise to the second generation of fuel: 2G ethanol. Among these biomasses, the coconut husk is a potential raw material for the production of lignocellulosic hydrolysates due to its high percentage of holocellulose (~44.5%), which can be converted into fermentable sugar. In this way, the present work aimed to contribute to the diversification of the raw materials used for ethanol production by analyzing the fermentative parameters of coconut hydrolysate to produce 2G ethanol. Therefore, the coconut husk was submitted to an alkaline pretreatment with calcium hydroxide (20% w/w). Then, the enzymes Ctec2 (2% v/w) and Htec2 (0.5% v/w) were used for hydrolysis. The conversion efficiency of polymers into monomers was 19.33% of cellulose in glucose and 7.30% of hemicellulose in xylose. The presence of the inhibitors acetic acid and formic acid was also observed. In the fermentation assays, the strain Wickerhamomyces sp. UFFS-CE-3.1.2 and the industrial yeast Saccharomyces cerevisiae PE-2 were employed. The best conditions of this process were defined through an experimental design, analyzing the biomass production (g L−1) and the consumed TRS percentage, being established the pH 7 and temperature of 40 ºC. As a result, the yeast UFFS-CE-3.1.2 showed the highest biomass production and the highest TRS consumption, but it did not produce ethanol. In contrast, the industrial strain fermented the sugars, showing an ethanol yield of 0,24 gethanol gsugar −1 . Therefore, coconut husk can be promising biomass for the production of 2G ethanol, and its necessary to optimize the process of pretreatment and hydrolysis processes to increase sugar concentration and reduce inhibitors in the hydrolysate.