Modeling the kinetics of essential oil hydrodistillation from plant materials

Abstract

The present work deals with the modeling of the kinetics of essential oils extraction from plant materials by water and steam distillation. The experimental data were obtained by studying the hydrodistillation kinetics of essential oil from juniper berries. The literature data on the kinetics of essential oils hydrodistillation from different plant materials were also included into the modeling. A physical model based on simultaneous washing and diffusion of essential oil from plant materials were developed to describe the kinetics of essential oils hydrodistillation, and two other simpler models were derived from this physical model assuming either instantaneous washing followed by diffusion or diffusion with no washing (i.e., first-order kinetics). The main goal was to compare these models and suggest the optimum ones for water and steam distillation and for different plant materials. All three models described well the experimental kinetic data on water distillation irrespective of the type of distillation equipment and its scale, the type of plant materials and the operational conditions. The most applicable model is the one involving simultaneous washing and diffusion of the essential oil. However, this model was generally inapplicable for steam distillation of essential oils, except for juniper berries. For this hydrodistillation technique, the pseudo first-order model was shown to be the best one. In a few cases, a variation of the essential oil yield with time was observed to be sigmoidal and was modeled by the Boltzmann sigmoid function.

Rad se bavi modelovanjem kinetike ekstrakcije etarskog ulja iz biljnih materijala primenom destilacija vodom i vodenom parom. Eksperimentalni podaci dobijeni su proučavanjem kinetike hidrodestilacije etarskog ulja ploda kleke. Literaturni podaci o kinetici hidrodestilacije etarskog ulja iz različitih biljnih materijala su, takođe, uključeni u modelovanje. Za opisivanje kinetike hidrodestilacije etarskog ulja razvijen je fizički model koji je zasnovan na istovremenom ispiranju i difuziji etarskog ulja iz biljnog materijala. Iz ovog modela izvedena su dva prostija modela od kojih je prvi zasnovan na trenutnom ispiranju praćenim difuzijom a drugi na difuziji bez ispiranja (tj.na kinetici prvog reda). Glavni cilj je bio poređenje ovih modela i predlaganje optimalnog za destilacije vodom i vodenom parom I za različite biljne materijale. Sva tri modela opisuju dobro eksperimentalne kinetičke podatke u slučaju destilacije vodom nezavisno od tipa destilatora i njegove veličine, tipa biljnog materijala i procesnih uslova, ali je najbolji model koji uključuje istovremeno ispiranje i difuziju etarskog ulja. Ovaj model je, međutim, neprimenljiv za vodeno-parnu destilaciju etarskog ulja, izuzev za etarsko ulje ploda kleke. Za ovu destilaciju etarskog ulja najbolji je kinetički model pseudo-prvog reda. U slučaju nekoliko biljnih materijala, promena prinosa etarskog ulja sa vremenom je sigmoidna, pa je modelovana Bolcmanovom sigmoidnom funkcijom.