Eco-Friendly Extraction of Thevetia peruviana Oil: A Synergistic Approach of d-Limonene and Ultrasound Activation

The increase in the demand for nonfood applications of vegetable oil within the context of a green economy has made it imperative to explore energy-efficient and environmentally-friendly extraction methods that uphold sustainability. This study compares the efficiency of Soxhlet and ultrasound-assisted extraction (UAE) techniques for extracting Thevetia peruviana oil using hexane and d-limonene as solvents. The findings demonstrate that UAE outperformed Soxhlet extraction, yielding 64.6% compared to 55.6% at 80 °C and a solvent–seed ratio of 20 mL/g. Scanning electron microscopic (SEM) analysis revealed that sonication improved extraction efficiency by increasing the surface area of the pulverized seed. Response surface methodology (RSM) optimization of UAE with hexane resulted in a yield of 72.8% using an extraction time of 45 min, an 80 °C temperature, and a solvent–seed ratio of 15. UAE with d-limonene achieved a yield of 67.2% using a temperature of 80 °C, a solvent–seed ratio of 16, and an extraction time of 49 min. NMR analysis indicated the potential for solvent recycling, while GC-MS analyses show that the oil extract of d-limonene has a similar composition to that of hexane. This study provides insights into the efficiency, quality, and environmental sustainability of T. peruviana oil extraction using d-limonene and ultrasound techniques.