CO₂-triggered switchable hydrophilicity solvent as a recyclable extractant for ultrasonic-assisted extraction of...

In this study, CO₂-triggered switchable hydrophilicity solvents (SHSs) based on different amines and water were employed in the ultrasonic-assisted extraction of Polygonatum sibiricum polysaccharides (PSPs). When CO₂ was pumped into the amine, the solution became hydrophilic and could be used as an extractant for PSPs extraction. When CO₂ was removed, the solution switched hydrophobicity, with the extractants being separated from the extract and further recycled and reused. The factors affecting the solid-liquid extraction of PSPs were studied. The maximum extraction yield of 399.2 mg/g was obtained at a solid-liquid ratio of 1:20, extraction time of 60 min, extraction temperature of 50 °C, and ultrasonic power of 500 W. SHSs could be recovered and reused with 88.4% recovery after the fifth cycle. The molecular weights and monosaccharide compositions of PSPs were also determined. This study provides a new strategy for sustainable extraction of plant polysaccharides and other bioactive ingredients.