Biodiesel de soja e girassol: Avaliação da estabilidade oxidativa por rancimat e dsc

Abstract

During the last years, it is increasingly common to develop studies about sustainability, which is a constant environmental concern. In this context, finding new renewable fuels and developing those that already exist, leading to substitution of petroleum-derived fuels, can greatly contribute to making a global energy matrix less harmful to the environment. Biodiesel, which comes from several sources of animals and plants, means the renewable one for mineral diesel, which is derived from petroleum and is one of the fuels most used at present, mainly for the transportation of cargo via road modal. This work studied the physicochemical properties of soybean and sunflower biodiesel in accordance with the current norms and resolutions of the National Agency for Petroleum, Natural Gas and Biofuels (Brazil). Most of the properties are within the resolution limits of one point from which the esters produced could be denominated biodiesel. The analysis of oxidative stability is one of the main problems of using such biodiesel in relation to diesel. Therefore, oxidative stability was studied by the techniques of Rancimat and Differential Scanning Calorimetry (DSC). By Rancimat, the oxidative stability of soybean biodiesel was about 5 hours and for sunflower biodiesel was about 2 hours. By DSC, soybean biodiesel showed more stable than sunflower, but with little difference between the DSC’s parameters. When compared the DSC’s analysis before and after Rancimat, the results showed coherence about the effects that an accelerated oxidation, using Rancimat, causes into biodiesel.