Insights on biodiesel blends with alkanol solvents

Abstract

Thermophysical properties of mixtures of fatty acid esters with alkanols were measured in the whole composition range as a function of temperature for understanding features of biodiesel blends. Excess and mixing properties calculated from experimental measurements allowed to quantify and analyze the intermolecular forces in the considered systems. Likewise, molecular modelling studies using quantum chemistry and classical molecular dynamics simulations led to a detailed characterization of these systems at the nanoscopic level. The nature of hydrogen bonding in these liquid mixtures was particularly analyzed from macroscopic properties and theoretical modelling results. The reported experimental and computational study allowed to infer the relationships between the intermolecular forces and additional microscopic features and the mixtures macroscopic properties, which are relevant for the development and characterization of biodiesels. The non-ideality behavior of the studied systems shows relevant changes in hydrogen bonding structuring upon mixing, with the fatty acid esters largely disrupting the alcohols self-association, although ester – alcohol hydrogen bonding is developed, this type of interactions is remarkably weaker than those for alcohols. Therefore, the studied biodiesel blends macroscopic properties may be tuned and controlled through the amount of alcohols in the mixtures and rooted on its effect on hydrogen bonding.