Acoustic Cavitation as a Novel Approach for Extraction of Oil from Waste Date Seeds

This work deals with the extraction of date seed oil using an acoustic cavitation. The process parameters such as sonication (extraction) time, power dissipation, operating temperature, and solvent to date seed ratio have been optimized on the basis of extracted oil yield. The obtained results have been compared with the frequently used extraction methods (such as maceration and Soxhlet extraction method). The highest extraction efficiency was found at a solvent (hexane) to seed ratio of 5, applied rated power of 30% of 750 W (actual dissipated power is 2.98 W), ultrasound treatment time of 45 min, and at a temperature of 20 °C. It was observed that as ultrasonic power dissipation increases the oil extraction yield also increases and declines with an increase in temperature. These results are attributed to only physical effects of cavitation occuring onto the surface of the date seeds which enhance the permeability of the solvent into the plant tissues due to the formation of cracks, crevices, and microfractures onto seed surfaces. A comparison of field emission scanning electron microscopy (FE-SEM) images of fresh date seed and ultrasonically treated date seed indicated the development of cracks, crevices, and microfractures onto seed surface of date seed which results in the cell walls disruption. However, the cavitation-assisted oil extraction has reduced the environmental impact and lessened the time and energy intensive process as it was performed at room temperature.