Mathematical modelling of essential oil supercritical carbon dioxide extraction from chamomile flowers

Abstract

This study investigates the supercritical extraction process of essential oil from chamomile flowers. Essential oils of chamomile are used extensively for medicinal purposes. Many different chamomile products have been developed, the most popular of which is herbal tea. In this study, a mathematical model is formulated that describes the governing mass transfer phenomena in a solid–fluid environment under supercritical conditions using carbon dioxide. The concept of quasi-one-dimensional flow is applied to reduce the number of spatial dimensions. The flow of carbon dioxide is assumed to be uniform across any cross-section, although the area available for the fluid phase can vary along the extractor. The physical properties of the solvent are estimated based on the Peng–Robinson equation of state. Model parameters, including the partition factor, internal diffusion coefficient, and decaying factor, were determined through maximum likelihood estimation based on experimental data assuming normally distributed errors. The model parameters were combined to obtain a set of correlations. The generalized process model is capable of reproducing the dataset with satisfactory accuracy.