Density, Excess Volumes, and Partial Volumes of Binary Mixtures of Soybean Biodiesel + Diesel and Soybean Biodiesel + n-Hexadecane at Different Temperatures and Atmospheric Pressure

Abstract

Densities, ρ, of binary mixtures of diesel + soybean biodiesel and n-hexadecane + soybean biodiesel have been measured as a function of the composition at different temperatures (293.15, 313.15, 333.15, 353.15, and 373.15) K and atmospheric pressure, over the entire composition range, using an Anton Paar SVM 3000 oscillating U-tube densimeter. The excess molar volume, VE, and excess partial molar volume, V̅E, of the binary mixtures were calculated from the density data. These data have been correlated using the Redlich−Kister type function in terms of mass fraction (w), with a maximum standard deviation of 0.152 cm3·mol−1. The excess volumes are positive for the soybean biodiesel + diesel system. The values of the excess volume for the system soybean biodiesel + n-hexadecane are also positive and an inversion of sign in VE is observed at higher molar fractions of soybean biodiesel (around x1 = 0.60 to 0.80). The excess partial volume at infinite dilution has been also calculated.