Influence of Additives (Isoamyl Laurate or Isoamyl Nonanoate) in the Solid-Liquid Equilibrium of Fatty Acid Ethyl Esters

Solid liquid equilibrium data of binary mixtures of fatty acid ethyl esters present in biodiesel, namely, ethyl laurate, ethyl palmitate, ethyl myristate, ethyl stearate, and ethyl oleate, and fatty esters of branched-chain alcohols used as additives (isoamyl laurate and isoamyl nonanoate) were obtained through differential scanning calorimetry. Most of these systems presented eutectic behavior, except for the system system ethyl laurate + isoamyl laurate, which presented peritectic transition. Equilibrium data were thermodynamically modeled either using two different liquid-phase activity coefficient models or considering that the liquid phase is an ideal mixture. Best correlations were observed for the Flory-Huggins equation, but good agreement between calculated and experimental data was also obtained when using both the ideal and UNIFAC-Dortmund models.