The evaluation of RSM optimization and kinetics modeling of essential oil extraction from Citrus hystrix leaves using microwave-assisted hydrodistillation

Abstract

This study explores the optimization and kinetic modeling of microwave-assisted hydrodistillation for essential oil extraction from
Citrus hystrix
leaves. There are three primary parameters of the microwave-assisted hydrodistillation method that were evaluated for their impact: power of microwave, feed to solvent (F/S) ratio, and time of extraction. The optimization extraction was analyzed by response surface methodology (RSM) using Box-Behnken design (BBD) and face-centered central composite design (FCCCD) models, and the quadratic model was the best fit to represent the experimental data. The optimum condition predicted using BBD was at 630 W, a F/S ratio of 0.35, and 135.788 min with a yield prediction of 1.367%. Whereas, the analysis using FCCCD was at 630 W, a F/S ratio of 0.35, and 150 min with a yield prediction of 1.426%. Kinetics modeling was carried out to determine the constant rate of extraction and maximum capacity of extraction, and the best suitable model was the first-order model. The values of
R
2
and RSME were 0.9745 and 0.0556, respectively. FTIR analysis indicates that the essential oil extract has similarity (93.69%) with the citronellal compounds. GC–MS analysis was carried out to identify citronellal and citronellol compounds, whose contents were 70.39% and 14.33%, respectively. SEM analysis indicated the morphological structure of leaves damaged after extraction using microwave-assisted hydrodistillation. This damaged structure of leaves shows that the process of extraction destroys the cell wall structure of
Citrus hystrix
leaves. This study contributes valuable insight for improving and scaling up microwave-assisted hydrodistillation of essential oils from
Citrus hystrix
leaves.