Influence of Copper and Metallic Alloys on the Oxidation Reaction of Commercial Biodiesel in Mixture with Natural Antioxidant

Applications of an electronic nose in the prediction of oxidative stability of stored biodiesel derived from soybean and waste cooking oil

“…The lower oxidative stability, higher acidity and lower iodine values obtained for biodiesel stored in carbon steel flasks suggest that the contact of the fuel with the metal surface accelerates the oxidation rate. This may be explained by the formation of free radicals induced by the presence of metal ions throughout the storage [43] , [44] . According to the induction times obtained, 93% of the WCO- and SBO-samples in storage would be unsuitable for use according to ASTM standards.…”

“…According to the induction times obtained, 93% of the WCO- and SBO-samples in storage would be unsuitable for use according to ASTM standards. Therefore, the addition of antioxidants is essential in maintaining the properties of B100 fuel (pure biodiesel) even for short-term storage [43] . The results presented herein showed that high temperature and long storage time increased the acidity and reduced the iodine value and oxidation stability of samples stored in similar types of container, thus reinforcing earlier findings that temperature and storage time contribute to the degradation and, consequently, alteration of the physicochemical properties of biodiesel [45] .…”

The Effect of Fe3+, Fe2+, Co2+ e Cr3+ Ions in the Oxidative Stability and Kinetics of biodiesel Oxidation Reaction With and Without the Addition of Rosemary Extract

“…Since biodiesel has unsaturated methyl esters in its composition, it is exposed to the oxidation process that can be accelerated in the presence of some transition metallic cations. 12 Spacino, K. R. et al…”

“…The increase of the reaction rate is determined by a complex mixture of factors: the metal and the type of complexes that form (inner or outer sphere), presence of chelating or complexing agent, the redox potential of the metal and its complexes, solvents and availability of oxygen or preformed hydroperoxides. 12 Studies regarding catalysts activity in the biodiesel oxidation reaction have gained importance. Sui and Li (2019) 10 studied the effect of tetraethylenepentamine as an antioxidant in biodiesel with iron, nickel, manganese, copper and cobalt contamination.…”

Mathematical Modeling of the Relative Protection Factor of Synthetic Antioxidants in Commercial Biodiesel

“…5 Pois diferentemente dos combustíveis fósseis que são relativamente inertes, o biodiesel devido à variedade de óleos e gorduras utilizados na sua fabricação, tende a formar radicais livres e degradar-se quando exposto a presença do oxigênio do ar, luz, temperatura, enzimas, íons de elementos metálicos e umidade, tornando difícil garantir sua qualidade, de forma a atender a todos os parâmetros de conformidade obrigatórios para a sua comercialização. [6][7][8][9] Como a reação em cadeia, da autooxidação do biodiesel B100, se inicia e se propaga mediante a formação de radicais livres, sua desativação ou remoção, determinaria cedo o fim da auto-oxidação em etapas, antes que os produtos responsáveis pela formação de gomas pudessem formar-se. Então se deduz que os antioxidantes devem ser acionados o mais cedo possível no processo de obtenção do biodiesel.…”