Integrated process, kinetic, energy, and chemotype evaluation of microwave-assisted hydrodistillation for Eupatorium capillifolium essential oil recovery

Eupatorium capillifolium is an underutilized aromatic biomass that may serve as a non-food source of essential oil. This study assessed microwave-assisted hydrodistillation (MAHD) by integrating extraction performance, nominal-power-based energy estimates, kinetic modelling, GC-MS profiling, and preliminary bioactivity screening. Microwave power (150–450 W) and fresh-biomass loading (100–250 g) were evaluated using quadratic response-surface models and multi-response desirability analysis. The highest-desirability tested condition was 450 W and 250 g biomass, giving an experimental essential-oil yield of 2.95 % (dry basis) and an estimated specific electrical energy consumption of 0.70 kWh g −1 oil. The extraction profile was best described by the pseudo-first-order model (R² = 0.9930). GC-MS library matching tentatively assigned a thymol-type compositional profile dominated by thymol methyl ether, germacrene D, thymyl isobutyrate, and dehydrothymol isobutyrate. Relative to published hydrodistillation data, the MAHD-derived oil showed a different monoterpenoid–sesquiterpenoid distribution. Screening assays showed inhibition zones against Escherichia coli and Staphylococcus aureus and concentration-dependent mortality of adult Aedes aegypti. Because the factorial design was unreplicated, energy use was estimated from nominal microwave power, and GC-MS assignments lacked experimental retention indices, the results define process trends within the investigated domain rather than externally validated performance.