Kinetic modeling for microwave-assisted green extraction: Effects of power on citronella oil from Cymbopogon nardus leaf

Cymbopogon nardus, known as a native plant to the subtropical and tropical areas, is widely cultivated and utilized for food flavoring and pharmaceutical purposes. Microwave-assisted hydrodistillation (MHD) was preferred as a greener method to extract essential oils. Kinetics of essential oil extraction from Cymbopogon nardus leaves were observed under different values of microwave irradiation power at atmospheric pressure. This method facilitated a high yield of citronella oil (3.68%–3.79%) at reduced time. Kinetic investigation of citronella oil extraction process was simulated using mathematic formulation such as pseudo-first and pseudo-second-order models. Results indicated that the studied models provided moderate fit for the experimental data, whereas the latter of the two kinetic models demonstrated better general fit, especially at low power levels. Moreover, GC-MS analysis of the citronella oil showed that the main compounds identified were geraniol and methyl isoeugenol. Other active compounds such as citronellal and β-citronellol were also present in considerable amount. These results suggested that the MHD method could be a prominent alternative to obtain essential oils in higher yields and deliver valuable chemical constituents upon shorter extraction time, compared to its conventional alternatives.