Aging and stability evaluation of diesel/biodiesel blends stored in amber polyethylene bottles under different humidity conditions

Diesel/biodiesel blends (BX) have great relevance in the market since they cover very important needs of both the economic and environmental sectors in Brazil. However, the increasingly biodiesel introduction in the blend composition can lead to instability problems. Such issues depend on biodiesel quality and type, blends composition, storage material, time and microclimate conditions. The objective of this work is to evaluate the quality performance of diesel/biodiesel blends containing biodiesels produced from pure soybean oil and a mixture of soybean oil/animal fat raw materials, under different storage conditions, at the levels B5, B10, B15, and B20, for six months. The samples were kept stored in two groups of amber polyethylene 1L bottles, under natural aging atmospheric conditions. One group was kept in normal climatic conditions of Belo Horizonte - Brazil (Tropical Wet-Dry Climate). The other under high humidity, in an attempt to simulate fuel storage conditions in the Amazon region (Tropical Moist Climate). Stability parameters monitoring was performed monthly, through analysis of selected physical-chemical properties, such as aspect, water content, acidity index, oxidation stability and total contamination. The results showed that blends with higher biodiesel content (B15 and B20) presented more nonconformities. A reduction in fuel quality was found to occur in the short-term, even for those with antioxidant additives, especially when the biodiesel content, storage temperature, and humidity were high. In general, the study demonstrated that the biofuel should be used judiciously particularly in high humidity storage conditions and alternative viable solutions should be envisage for such regions.