Produção de etanol combustível primeira e segunda geração a partir de vagens de algaroba (prosopis juliflora (sw.) Dc.).

Abstract

The mesquite pod stands out for the large amount of carbohydrates and polysaccharides present in its constitution. Due to this characteristic, the objective of this work is the production of first and second generation ethanol using mesquite pods (Prosopis juliflora SW DC) as raw material. The project was developed in the Food Engineering laboratory - LEA of the Technology and Natural Resources Center - CTRN of the Federal University of Campina Grande - UFCG. Mature pods were used, purchased from producers in the city of Sumé, in the Cariri region of Paraíba. The extraction of carbohydrates from the mesquite pod was carried out through hydration and subsequent pressing, where the broth obtained had the pH adjusted to 4.3 and the ° Brix corrected for 20, 18 and 16 and subjected to fermentation with different types of yeast (Fresh yeast, Granulated yeast and FLNF CA-11), at a concentration of 25 gL-1. The alcoholic fermentation was carried out in a batch system, where the cell concentration (biomass), soluble solids concentration (° Brix), ethanol concentration (° GL) and pH were evaluated at 2 hour intervals during a 20h period. process. The fermentate was distilled and called first generation ethanol. The pressing residue (polysaccharides) was dried in an oven with forced air circulation at 1.5ms-1 until constant mass at different temperatures (50, 60.70 and 80 ° C). The dry residue selected was the one submitted to a temperature that best preserved its constituents and reached the best break point (fragmentation), consequently facilitating the hydrolysis process. Then the following analyzes were performed: lignin, cellulose and hemicellulose. After the analyzes, the material was crushed and submitted to acid hydrolysis in different concentrations (1; 3 and 5 Mol L-1) of sulfuric acid and different temperatures (100, 120 and 140 ° C), the carbohydrates obtained in this step were fermented with the yeast LNF CA-11 and later distilled to obtain second generation ethanol. Therefore, the yeast LNF CA 11 is the most suitable for fermenting broth and dry mesquite residue to obtain first and second generation bioethanol, in compliance with current legislation. And the drying data adapted to the tested models, the best fit being the Cavalcanti mata model, allowing the determination of the material's thermo-physical properties.