Avaliação da influência de polietilenoglicol (PEG) na hidrólise enzimática de fibra de coco verde pré-tratada com ácido fosfórico

Abstract

Global population growth, the advance of industrialization, the growing scarcity of fossil energy sources and the need for sustainable means of development are some of the main motivations for the search for renewable energy sources. In this context, the biofuels production reusing agroindustrial wastes has been gaining relevance in the energy matrix of Brazil and the world, in which the lignocellulosic biomass is responsable for 50% of total biomass available in the world. Due to high recalcitrance of vegetable lignocellulosic structure, pretreatment techniques to removal lignin and/or hemicellulose are necessary to increase the enzymatic accessibility in the hydrolysis processes, by using cellulases. In addition to pretreatment, for second-generation ethanol production, steps of enzymatic hydrolysis and fermentation are required. Motivated by the search for increasingly efficient processes, this study had a main goal to evaluate the influence of on polyethyleneglycol (PEG) in enzymatic hydrolysis of green coconut husk, with and without pretreatment based on phosphoric acid (H3PO4, 1.0% v/v), aiming to enhance the production of fermentable surgars. Therefore, was evaluated the effect of variation in the average molar mass of PEG over biomass, at the same concentration (150 g/L), used to increase cellulose-enzyme interaction in hydrolysis step, once it reduces the non-productive adsorption of cellulases onto residual lignin. The implications of this were analyzed in terms of release of fermentable sugars, for further cellulosic ethanol production, and by the cellulosic conversion of the different Tests: A (without PEG), B (100% PEG 1500), C (100% PEG 4000), D (75% PEG 1500 / 25% PEG 4000), E (50% PEG 1500 / 50% PEG 4000) and F (25% PEG 1500 / 75% PEG 4000). Since the phosphoric acid pretreatment demonstrated efficiency in removing hemicelulose (82%), the use of PEG was still important for break the cation- interaction of the lignin-cellulose complex to improve the enzymatic process yield, since lignin retention was around 28% in the pretreated biomass. After analyzing the result of hydrolysis with different polymers based on ethyleneglycol solutions, in general terms, increasing the average PEG molar mass, also increases the cellulosic conversion, until the average viscosity increase of the solution became a detrimental factor for the process. For fiber pretreated with H3PO4, the cellulosic conversion has shown higher for the in natura fiber.