The insight into the separation of erucic acid,palmitic acid, and nervous acid in Acer truncatum seed oil from solid-liquid phase equilibrium and eutecticbehaviors

Acer truncatum seed oil, extracted from the samaras of the yuanbaofeng (A. truncatum Bunge) tree, is rich in oleic acid, palmitic acid (PA), erucic acid (EA), and nervonic acid (NA). The melt crystallization is a crucial way to isolate NA. In this present study, the solid-liquid equilibrium of erucic acid/palmitic acid (EA- +PA), erucic acid/nervonic acid (EA-NA), and nervonic acid/palmitic acid (NA-PA) binary systems was investigated by differential scanning calorimetry. The solid-liquid phase diagrams of binary systems were constructed by thermodynamic analysis and model simulations, which illustrated the influence of molecular interaction on the melting point change of binary systems. The solid-liquid phase and the enthalpy change diagrams together demonstrated eutectic phenomenon. The eutectic behavior appeared in the EA-NA and EA-PA binary systems at the EA concentration more than 50% and 70%, respectively. Additionally, the FTIR spectra of PA, EA, NA, and various binary systems were characterized, which found that there was no chemical interaction between the binary components. Based on the calculation of the enthalpy, onset melting temperature, and peak temperature in the melting stage, the melting Gibbs free energy of binary systems during phase transformation was predicted. These findings provided a fresh light for the separation of NA from A. truncatum seed oil, hence providing theoretical instruction for the separation of fatty acids in plant oil.