Processamento de resíduos da extração de azeite de oliva usando hidrólise subcrítica

Abstract

Oil is the main raw material currently used for fuel production. Petroleum is a non-renewable source of energy and causes considerable quantities of pollutants into the atmosphere, such as carbon dioxide and sulphur dioxide, resulting from fuel burning. Therefore, plant biomass is used to replace the use of fossil fuels due to their ability to produce fuels in a sustainable way. Plant biomass is abundant and present in different forms in nature, such as bark, seeds and straws, among others. One example is the olive oil extraction bagasse. Some processes need to be applied for the use of biomasses in the production of second-generation ethanol. One of the steps that can be used in this process comprises the application of subcritical water hydrolysis. Therefore, the aim of this study was to evaluate experimental processing conditions using subcritical water hydrolysis in order to dissociate cellulose and hemicellulose into reducing sugars, such as glucose and xylose, which can be fermented for ethanol production. In such case, temperature and water/biomass ratio were studied in a laboratory-scale equipment using fresh (untreated) samples. The results suggest that the best hydrolysis condition, among those evaluated in this study, to be applied in order to obtain the largest amount of reducing sugars is the pressure of 20 MPa, temperature of 220ºC and water/biomass ratio of 5 g of water/g bagasse. Hydrolysis technology with subcritical water is a promising pretreatment procedure, environmentally suitable by using sustainable solvents, and can be used as a process of converting lignocellulosic residues from olive oil extraction bagasse as one of the steps for biofuel production.