Thermal analysis of the evaporation of compounds used in aromatherapy using thermogravimetry

Thermogravimetric analysis is often used to evaluate the evaporation phenomenon of several substances. The present study was designed to characterize the vaporization characteristics of three essential oils; lemon oil, lavender oil and cinnamon oil and their several components. All three oils represent multi-component systems, whereas their main components represent single component systems. Linalyl acetate was used as the calibration compound and the coefficient of vaporization was obtained as 7×107 (SI system). The order of reaction was first determined for each of the compounds under study. Vapor pressure curves were then plotted using Langmuir and Antoine equations for the compounds, which represent single component systems, undergoing zero-order non-activated evaporation processes. The vapor pressure curves obtained were statistically quantified along with the calculations for the Antoine constants using SPSS version 10.0 software. The energies of activation for cinnamon oil, lemon oil and lavender oil were found to be 45.10, 33.2 and 33.9 kJ/mol, respectively.