Essential oils are volatile chemical compounds, characteristic for its fragrance and frequent antimicrobial and antioxidant activities. Essential oils are extracted from the glandular trichomes of herbs from various extraction methods. Industries give preference to extraction by steam distillation, for its traditional method, simple operation and low cost. The mathematical modeling of this process is an inevitable step for designing industrial plants of essential oil extraction with good operating condition. The model used in this article is based on the diffusion of the oil within the leaf. The discretization procedure of this model is presented through finite differences and its validation by comparing with the analytical solution. Data of profiles yield by extraction time were used to estimate the diffusion coefficient. In order to improve the model empirical equations were applied to describe de diffusion coefficient as a function of the oil concentration and the parameters of these equations were estimated. Using this modification, the model has no longer analytical solution, which justifies the adopted numerical procedure. The model was validated using data from literature.
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