Avaliação de diferentes tecnologias na extração do Óleo do Pinhão-manso (Jatropha curcas L)

Abstract

This work had as goal the available of the composition of the oil of physic nut (Jatropha curcas L), a seed with high oil content, considered a promising raw material for biodiesel production. It was firstly investigated conventional techniques of extraction such cold pressing, hydrodistillation and the extraction with organic solvents as hexane and ethanol. All these methods were analyzed according to the efficiency of extraction of oil, defined as the ratio between the extracted mass of oil and the initial mass of seed. The best results were obtained using ethanol as solvent, reaching the highest yield (46.4%). The extraction time varied in two and four hours and the comparison between them indicated that the results didn t presented relevant differences. So, the lowest time of extraction is economically more favorable. The oil has been characterized in accordance with the indices of acid, iodine, viscosity, refractive, and peroxides. The analyses were performed based on the standard American Oil Chemical Society. The oil of the physic nut, analyzed by gas chromatography, indicated an unsaturated oil profile with the presence of higher concentrations of oleic and linoleic fatty acids. The palmitic, palmitoleic and linolenic acids were detected in lower concentrations. In order to compare the results using the conventional technology, supercritical CO2 was used for the extraction of oil varying the temperature (40, 60 and 80ºC) and pressure (100, 150 and 200bar). The best condition was obtained at 40ºC and 200bar with the yield of 1.86%. In all conditions, it was observed that the time necessary to extract the oil was 240 minutes. The extraction curves were modeled using two masstransfer mathematical models, one being the empirical model used by ESQUIVEL et al. (1999) and the other proposed by CHRASTIL (1982), which involves the solubility of compounds in supercritical CO2. The validation of the models was based on the experimental results of oil extraction. The deviations of the empirical model ranging from 3.4 to 7.9% and the CHRASTIL (1982) model ranging from 18 to 35%, respectively.