Kinetics of Essential Oil Extraction of Kaffir Lime Peel Using Microwave Assisted Hydrodistillation

The purpose of this study is to study the kinetics of kaffir lime peel essential oil extraction using microwave assisted hydrodistillation. Extraction was carried out at various powers and the ratios of material to solvent for 1 hour. Soxhlet extraction using n-hexane solvent was also carried out to determine the yield of essential oil. The extraction kinetics was investigated using a mass transfer-controlled approach and expressed by the 1st and 2nd order of reaction rate. The Soxhlet extraction results indicated that the yield of kaffir lime peel essential oil was 5.65% w/w. The higher the microwave power being applied (180, 300, 450, and 600 Watt), the higher the essential oil yielded (2.2; 2.8; 3; and 3.8% w/w), respectively, but at 800 Watt, the yield decreased (3.2% w/w). The smaller the ratio of material to solvent, which means more diluted, the lower the yield of oil were, namely from 4.56; 3.9; and 3.8% w/w, at ratios of material to solvent 1:3, 1:3.5, and 1:4 w/v. Different results were obtained at a ratio of 1:3 (4.56% w/w) which produced a yield greater than the ratio of 1:1.25 (2.88% w/w). Therefore, the optimum conditions for extracting kaffir lime peel essential oil were at 600 Watt and a ratio of material to solvent 1:3 w/w for 56 minutes with a yield of 4.58% and a density of 0.86 g/cm 3 . The kinetics of the 2nd order of homogeneous model better represented results of the experiments with extraction rate constants at 180, 300, 450, 600, and 800 Watt of 14.89; 14.95; 15.53; 21.32; and 19.85 L.g -1 .min -1 . While the extraction rate constants at the material to solvent ratio of 1:2.5; 1:3; 1:3.5; and 1:4 w/v of 17.38; 19.80; 22.09; and 32.31 L.g -1 .min -1 . The extraction capacity was also affected by the power and the ratio of material to solvent, the extraction capacity were 0.0095; 0.0100; 0.0104; 0.0125; and 0.0106 g.L -1 , at 180, 300, 450, 600, and 800 Watt respectively, and 0.0094; 0.0134; 0.0134; and 0.0118 g.L -1 , at material to solvent ratio of 1:2.5; 1:3; 1:3,5; and 1:4 w/v respectively.