Efficient recovery of chlorogenic acid and rutin from Ficus erecta leaves using liquid carbon dioxide-ethanol–water extraction with and without ultrasonic irradiation

Chlorogenic acid (CGA) and rutin are bioactive phenolic compounds with antioxidant and anti-inflammatory properties and are valuable for functional food applications. This study investigated their extraction from Ficus erecta leaves using a green solvent system composed of liquid CO₂, ethanol, and water at 298.15 K and 8.0 MPa, with and without ultrasonic irradiation. Extraction yields were evaluated by systematically varying solvent composition. Under optimized conditions (EtOH:H₂O = 1:1), liquid CO₂ extraction significantly increased CGA yield to 25.5 mg g^-1 and rutin to 14.5 mg g^-1 compared with conventional aqueous-ethanol extraction. Ultrasound further enhanced CGA recovery (31.6 mg g^-1, p < 0.001), whereas rutin showed no significant improvement, indicating a solubility-controlled plateau under the selected solvent conditions. Hansen solubility parameter modeling reproduced extraction trends with deviations generally below 25%, indicating that solvent-solute affinity governs extraction yield once mass-transfer resistance is minimized. The results demonstrate compound-specific ultrasound effects: CGA extraction remains partially diffusion-limited, while rutin recovery is primarily dictated by equilibrium solubility in the CO₂-ethanol-water system. These findings provide a thermodynamically supported framework for solvent-composition-driven optimization of green high-pressure extraction processes.