Kinetic modeling and optimization of musk willow (Salix aegyptiaca L.) essential oil extraction process of using ultrasound assisted hydrodistillation

The aim of the present research was modeling and optimizing the ultrasound-assisted hydrodistillation (USHD) of essential oil extraction process and comparing the effects of hydrodistillation (HD) and USHD techniques on the musk willow (Salix aegyptiaca L.) essential oil. Sonication time (15-45 min), ultrasound power level (100-500 W) and water to plant ratio (3-10 (v/w)) were varied in order to maximize S. aegyptiaca L.essential oil yield, total phenolic content (TPC) and IC50. The effect of sonication time and sound power levels on the essential oil yield, TPC and IC50 was significant at the 5% level. Although increasing water to plant ratio parameter significantly resulted in a higher yield (p<0.05), however, this parameter no significant effect the TPC and IC50 (p>0.05). The optimum parameters were sonication time of 39 min, sound power levels of 189 w, and water to plant ratio of 6.8 V/W. Under optimum conditions, both USHD and HD methods were used for essential oil extraction. USHD showed a significantly higher amount of extraction yield (0.108±0.009% (v/w)) compared to the HD (0.081±0.01% (v/w)) (p<0.05). Compared to the HD extraction, the USHD resulted in a shorter extraction time, less energy consumption, higher antioxidant properties and a higher extraction yield. Physical properties of OAHD and HD essential oils were not significantly different (p>0.05). Among the four kinetics models, the sigmoid model was shown to be the best one. This model can be used for modeling the kinetics of essential oil extraction by both HD and USHD.