Kinetic studies on extraction of essential oil from sandalwood (Santalum album) by microwave air-hydrodistillation method

Abstract

Essential oil from sandalwood is commonly obtained by conventional extraction methods which requires great energy, significant amount of solvents, and quite a long process time. Therefore, the use of new ‘green method’ for extracting essential oil with minimum/low energy, solvents, and time needs to be considered. One extraction method that has been successfully developed is microwave hydrodistillation method. This research employs a method developed from microwave hydrodistillation, that is microwave air-hydrodistillation for optimizing the extraction of essential oil. The purpose of this study was to examine the effect of the presence and absence of additional air flow to the microwavehydrodistillation method. The material used in this study includes sandalwood powder. The extractions by microwave hydrodistillation and microwave air-hydrodistillation methods were done on the power of 600W; the ratio of the raw material to be extracted and the solvent was 0.05gmL−1 and the extraction time was 120min. In the extraction by microwave air-hydrodistillation, the rates of air flow used were 0.1, 0.5, 1.5, 3.0, and 5.0L/min. The results of the research show that the extraction of sandalwood oil by microwave air-hydrodistillation is faster and produces higher yields compared to the extraction by microwave hydrodistillation method. Based on kinetics modeling that has been done, it can be said that the second-order kinetic model more can represent well the experimental results of sandalwood oil extraction by microwave hydrodistillation and microwave air-hydrodistillation methods when compared with the first-order kinetic model. The testing of the physical properties of the sandalwood oil indicates that essential oil obtained by microwave hydrodistillation and microwave air-hydrodistillation has the same quality (refractive index and specific gravity). Further, the testing of the chemical properties of the sandalwood oil shows that essential oil obtained by microwave air-hydrodistillation has better quality (flavor) compared to the oil obtained by microwave hydrodistillation.