In this study, we present a novel green bio-based solvent, star anise oil (SAO), which was employed to develop a two-phase solvent system incorporating both alkaline and acidic solutions for the simultaneous extraction and purification of nuciferine from waste lotus leaf. This integrative approach effectively combines two-phase solvent extraction (TPSE) with back-extraction (BE), resulting in a more streamlined extraction process that requires only vortexing (or stirring) and centrifugation, thus simplifying the overall procedure. It is important to note that this method uses very little solvent (only 2.5 times the volume of SAO relative to the weight of the lotus leaf) and takes just 4 min per extraction. After three such extractions, the recovery rate of nuciferine can reach as high as 96.9%. Unlike volatile solvents such as petroleum ether and ethyl acetate, SAO's high boiling point negates the necessity for nitrogen protection during centrifugation, thereby addressing the Pickering emulsification issues caused by particles. Only two back-extraction operations are needed to recover 96.9% of nunciferine from the TPSE extract, resulting in a nunciferine content of 45.4%. Furthermore, approximately 90% of the SAO can be directly reused for at least five cycles without additional purification. Additionally, 85.0% of the SAO remaining in the TPSE waste can be recovered through hydrodistillation (HD) within 30 min. The excellent performance in biomass and extraction solvent selection, solvent repurposing, and other factors contributed to a Path2Green score of 0.28 for this method, highlighting its suitability for the green recovery of nuciferine from lotus leaf.
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