Comparative Analysis of Bio-based and Conventional Solvent Extraction Efficiency in Essential Oil Production

Thesis Abstract

The efficiency of solvent extraction methods significantly influences the yield, quality, and sustainability of essential oil production, yet comparative assessments between bio-based and conventional solvents remain limited within current scientific literature. This study aims to critically evaluate the extraction efficiency of bio-based solvents—specifically ethanol and vegetable oil mixtures—against traditional chemical solvents such as hexane and diethyl ether, with a focus on optimizing yield and preserving bioactive components in essential oils derived from Mentha spicata and Lavandula angustifolia. The research objectives include quantifying extraction yields, analyzing volatile compound profiles, and assessing environmental and economic impacts associated with each solvent type. Employing a quantitative research design, the study adopts a cross-sectional experimental approach, involving the collection of plant samples from cultivated fields in the Mediterranean region, with a total sample size of 60 plants per species divided equally for extraction trials. The population encompasses mature, healthy plants with standardized harvesting procedures to eliminate variability attributable to plant maturity or health status. A stratified random sampling technique ensures representative sampling across different growth stages and field locations. Data collection involves performing extraction procedures under controlled laboratory conditions, utilizing a Soxhlet apparatus for conventional solvents and optimized ultrasonic-assisted extraction (UAE) for bio-based solvents. Yield measurements are obtained gravimetrically, while chemical composition is characterized through Gas Chromatography-Mass Spectrometry (GC-MS). To evaluate the efficiency and quality of extracts, the study employs moisture analysis methods, Total Phenolic Content (TPC) assays, and Fourier-transform infrared spectroscopy (FTIR). Environmental and economic assessments are conducted through life cycle analysis (LCA) and cost-benefit analysis, respectively. Data analysis begins with descriptive statistics to summarize extraction yields and chemical profiles. Inferential statistics involve applying Analysis of Variance (ANOVA) to compare means across solvent types, followed by post hoc tests for pairwise comparisons. Regression analysis assesses correlations between extraction parameters and oil quality indices. The study is grounded in the Sustainable Extraction Theory and Green Chemistry Principles, providing a theoretical framework that emphasizes eco-friendly processes and pollutant reduction. The reliability of laboratory instruments is verified through calibration standards, and validity is ensured via validation against established reference materials. Expected findings suggest that bio-based solvents, particularly ethanol mixtures, achieve comparable extraction yields and preserve higher concentrations of key bioactive compounds than conventional solvents, with additional benefits in reduced environmental impact and lower toxicity. The study anticipates statistically significant differences (p < 0.05) favoring bio-based solvents in terms of sustainability metrics, while chemical analyses reveal notable differences in volatile compound profiles. The findings are expected to confirm that bio-based solvents serve as environmentally sustainable alternatives without compromising oil quality, thus advancing the principles of green extraction technologies. This research contributes to the existing body of knowledge by providing comprehensive, empirically validated data on sustainable solvent alternatives in essential oil production, filling gaps related to economic feasibility and environmental implications. The study recommends adopting bio-based solvents for scalable industrial applications, promoting further research into solvent mixtures and process optimization, and developing standardized protocols for environmentally friendly essential oil extraction. Ultimately, the findings aim to inform industry practices, policymaking, and future academic inquiry toward sustainable and efficient natural product extraction methods.