Análise cinética e termodinâmica do processo de extração de óleo de soja com n-hexano

Abstract

The soybean is one of basic food of consumption in Brazil and the world. It’s used in the production of protein base foods, flours and oils. The constituent oil of seeds represents about 20% of the seed’s mass and it is obtained from the extraction liquid-solid process. For the extraction, it is necessary the use of a solvent with certain characteristics that give good rates of the oil removal from the seed. In this work, it was done the evaluation of the kinetics and thermodynamics involved on extraction of soybean oil with the use of n-hexane as solvent. The study offers parameters that involves the mass transfer process, measuring its efficiency on different temperatures (66, 68 and 70 ºC). The extraction process was lead in batch mode with Soxhlet extractor, using a kinetic model of two steps, washing and intern diffusion, to describe the phenomenon. Parameters like mass transfer constant, activation energy and enthalpy variation were availed. As results, the study provided a relation between the increase of the soybean oil in function of time with the rise of temperature. The process shows spontaneity in every availed temperature of operation through the measured Gibbs free energy values. Therefore, the internal diffusion of solvent has been indicated as the limiting step of the extraction solid-liquid process.