Optimization of solvent-free microwave assisted extraction of essential oil from Cinnamomum camphora leaves

Essential oils extraction from Cinnamomum camphora leaves was performed using the solvent-free microwave assisted extraction (SFME) method and the optimal conditions were determined. Response surface methodology combined with a Box-Behnken design was used to determine the optimal operational conditions, which were found to be as follows: moisture content of 60%, microwave irradiation time of 23 min and microwave irradiation power of 580 W. A second order kinetic model was used for the extraction processes, and the obtained C. camphora essential oils were analyzed by GC-MS analysis. SFME performed better than conventional hydrodistillation with regard to extraction efficiency (3.51 ± 0.12% in 23 min versus 3.35 ± 0.10% in 240 min), initiate extraction rate (3.3772 versus 0.1868), extraction rate constant (0.3002 versus 0.0152), extraction capacity (3.67% versus 3.51%), oxygenated compound content (83.93% versus 74.81%), energy consumption (0.22 kW h versus 4 kW h), and environmental impact (177.87 g CO2 versus 3200 g CO2). These results demonstrated that the SFME process is an efficient, time- and energy- saving and eco-friendly method, that shows great potential as a preferable alternative protocol to traditional method of extraction of essential oil from C. camphora leaves and other plant matrices.