Effect of process variables on heating profiles and extraction mechanisms during hydrodistillation of eucalyptus essential oil

The effect of different process variables, such as solid/liquid ratio (1: 1, 1: 3, or 1: 5 g/ml) and stirring speeds (0, 200, or 400 rpm), was studied on the extraction mechanisms of eucalyptus essential oil obtained by hydrodistillation (HD). Different performance parameters such as obtained yield, energy requirements, and environmental impact were compared to those obtained by steam distillation (SD). Two different mathematical models were used to describe the process behavior. The obtained results indicate that the system with a solid/liquid ratio of 1:5 g/ml using a stirring speed of 400 rpm yielded maximum for HD (1.19% ± 0.01%). The environmental impact expressed as Ecopoints (EI99) ranged between 50.87 ± 13.18 and 78.17 ± 13.82 mPT/g essential oil (EO) for systems with steam injection, whereas for HD took values between 16.9 ± 0.3 and 19.24 ± 1.4 mPT/g EO at optimal operating conditions. The model parameters allowed us to identify that large amounts of steam at lower heating velocities induce a high accumulation of EO in the aqueous layer (vapor-liquid equilibrium at the interface), favoring the extraction process.