Variations and correlations of the flash point, refractive index and density of soybean biodiesel, diesel and their binary and ternary blends with n-butanol

Abstract

In recent years, the use of n-butanol (BU) as a biofuel has received significant interest as a promising option to reduce pollutant emissions when blending it with diesel fuel (DF), biodiesel (BD), and their blends for use in Diesel engines. However, little is known on the behavior of the values of key properties such as Flash Point (FP), Refractive Index (RI), and Density (DE) for these blends. Thus, this study aimed to fill this gap by performing experimental measurements of the FP, RI, and DE for both soybean-based BD and DF, as well as for their binary and ternary blends with BU, covering the full range of composition. Additionally, regression equations were proposed to estimate the FP, RI, and DE of the binary and ternary blends as a function of their composition. The RI and DE values of the binary and ternary blends were accurately fitted by linear regression equations, whereas FP data were fitted to a quadratic equation with excellent agreement. In the DF/BU and BD/BU binary blends, when the percentage of BU added was 10%, the FP decreased from 83ºC to 40ºC and from 168ºC to 48ºC, respectively. Furthermore, considering the simplicity, speed, and minimal sample volume required for RI and DE measurements, a correlation analysis of the blends was proposed to estimate FP values as a function of these two properties. The R2 values exceeded 0.995, showing the accuracy and reliability of these straightforward correlations.