Scale Up & Optimization of the Liquid Carbon Dioxide Extraction of Orange Oil with Dry Ice

Essential oils have numerous chemical and therapeutic applications. Some oil extraction methods, including steam distillation, require a large energy input. An alternative technique with a lower energy demand is the extraction of oils using supercritical liquid carbon dioxide (CO2), which extracts essential oils with minimal environmental impact. While this often requires large-scale equipment, recent academic studies have established a simple procedure that uses liquid CO2 from dry ice to extract orange oil. The following study aimed to improve upon that method, introducing a 50-mL extraction vessel for larger botanical masses and proposing a pressure release outlet as a safety feature. An optimal process was developed and a total yield of 5.71% was obtained from a 7.5-g sample of orange zest. Changes in pressure and temperature were determined to not significantly affect oil yield. Analysis of oils using GC-MS determined that the primary component of the oil was D-limonene. The rate of sublimation of dry ice was measured and used to design a pressure release outlet. The goal of future work will be to improve the extraction process and the sublimation process, and the results of this study could inspire an interactive activity for students to learn thermodynamics and heat transfer