Redução da acidez do óleo de soja residual por meio de adsorção para a produção de biodiesel

Abstract

Biodiesel is a renewable energy source obtained from the natural triglycerides, that can be derivative from vegetable oils or animal fat. It is considered a great alternative as a replacement of traditional fossil fuels, since it is non-toxic, biodegradable and favorable for the environment. It is manufactured through the transesterification of vegetable oils and animal fat, with methanol in the presence of an adequate catalyst. In the face of the growing search for the reutilization of materials used in the production of biofuels, the use of residual soy oil has gained great focus, once its use presents advantages both in the environmental and economic standpoints. However, it presents heightened levels of free fatty acids in its composition, resulting in high acidity, which provokes a reduction in the output and quality of biodiesel manufactured from this material. With that in mind, the objective of the present work was to study one of the ways of pre-treatment of this input, evaluating the reduction of its rate of acidity through the adsorption tests, with subsequent comparison of the utilization of two distinct adsorbent: activated charcoal and hydrochar. The study began through the synthesis of hydrochar, which was manufactured using mate residues, with hydrothermal carbonization (CHT) to 180°C. The adsorbents were characterized by analyzing the physisorption of N2 (BET/BJH), where the activated charcoal presented a greater superficial area when compared to the hydrochar. However, for the tests of kinetic adsorption, it was determined the balance time, it being of 150 min. The kinetic model that best described both adsorbents was the pseudo-first sequence, where the activated charcoal obtained a determination coefficient (R2) of 0,9668, meanwhile the hydrochar was of 0,9931. In comparison, the employment of the hydrochar resulted in a proper reduction of the acidity rate of the residual soy oil. However, the use of activated charcoal resulted in a greater reduction during the tests, of 88,84%. For comparison, the use of hydrochar resulted in a good reduction in the acid level of residual soy oil. However, the use of activated showed the greatest reduction during the tests, of 88,84%.