title: An ultrasonic-accelerated oxidation method for determining the oxidative stability of biodiesel.
abstract: Biodiesel is considered an alternative energy because it is produced from fats and vegetable oils by means of transesterification. Furthermore, it consists of fatty acid alkyl esters (FAAS) which have a great influence on biodiesel fuel properties and in the storage lifetime of biodiesel itself. The biodiesel storage stability is directly related to the oxidative stability parameter (Induction Time - IT) which is determined by means of the Rancimat® method. This method uses condutimetric monitoring and induces the degradation of FAAS by heating the sample at a constant temperature. The European Committee for Standardization established a standard (EN 14214) to determine the oxidative stability of biodiesel, which requires it to reach a minimum induction period of 6h as tested by Rancimat® method at 110°C. In this research, we aimed at developing a fast and simple alternative method to determine the induction time (IT) based on the FAAS ultrasonic-accelerated oxidation. The sonodegradation of biodiesel samples was induced by means of an ultrasonic homogenizer fitted with an immersible horn at 480Watts of power and 20 duty cycles. The UV-Vis spectrometry was used to monitor the FAAS sonodegradation by measuring the absorbance at 270nm every 2. Biodiesel samples from different feedstock were studied in this work. In all cases, IT was established as the inflection point of the absorbance versus time curve. The induction time values of all biodiesel samples determined using the proposed method was in accordance with those measured through the Rancimat® reference method by showing a R(2)=0.998.
authors.affiliation: FIA Laboratory, Analytical Chemistry Section, Universidad Nacional Del sur, Av. Alem 1253, B8000CPB Bahía Blanca, Buenos Aires, Argentina.
authors.forename: Francisco D
authors.initials: FD
authors.lastname: Avila Orozco
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Sousa
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Domini
authors.forename: Mario Cesar
authors.initials: MC
authors.lastname: Ugulino Araujo
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Fernández Band
mesh_terms: D056804:Biofuels / Q000032:analysis* / Q000528:radiation effects / Q000592:standards; D004951:Esterification; D005230:Fatty Acids, Nonesterified / Q000737:chemistry* / Q000528:radiation effects / Q000592:standards; D019220:High-Energy Shock Waves; D010084:Oxidation-Reduction; D010938:Plant Oils / Q000737:chemistry* / Q000528:radiation effects / Q000592:standards; D013010:Sonication
chemical_list: D056804:Biofuels; D005230:Fatty Acids, Nonesterified; D010938:Plant Oils