Cinética e estudo da difusão durante o processo de secagem de folhas de Terramicina (Alternanthera brasiliana (L.) Kuntze)

Abstract

Terramycin is a plant found in several regions of Brazil, highly valued for its applications in popular medicine. Research has corroborated its pharmacological actions, including anti- inflammatory, analgesic and antiviral properties. Therefore, the objective of this work was to evaluate the kinetics and diffusivity during the drying process of terramycin leaves. Terramycin leaves were harvested with an initial water content of approximately 4.30 b.s. and subjected to drying under different controlled temperature conditions (40, 50, 60 and 70 °C) and drying air speeds (0.4 and 0.8 m s-1) in an experimental fixed-bed dryer until reaching a content of water of approximately 0.12 b.s. Eight mathematical models constantly used to represent the drying of agricultural products were adjusted to the experimental data. Based on the results obtained, Midilli's mathematical model was selected to represent the drying kinetics for thin-layer terramycin sheets. The reduction in drying time due to the increase in drying air speed is more pronounced at lower temperatures. Values of the effective diffusion coefficient increase with increasing temperature and drying air speed. The activation energy values for liquid diffusion were 80.9120 and 77.7422 kJ mol-1, for drying air velocities of 0.4 and 0.8 m s-1 respectively for the temperature range studied. (40 to 70 °C).