Novel natural deep eutectic solvent-based supramolecular solvents designed for extracting phytochemicals from pigeon pea leaves and its scale-up and recovery process

In this study, a novel green natural deep eutectic solvent-based supramolecular solvent/equilibrium solution (NADES-SUPRAS/EqS) system was designed. The microstructure and formation processes were characterized, revealing the formation and extraction mechanism of this novel solvent. In combination with vortex-assisted extraction, NADES-SUPRAS/EqS was used to efficiently extract and enrich representative active ingredients of different polarities in Cajanus cajan (Linn.) Millsp leaves. The influencing factors, including auxiliary extraction methods, the type of NADES, the proportion of NADES and ethanol for synthesis, the solid-to-liquid ratio, and the vortex time, were then adjusted utilizing single-factor optimization and response surface methodology. Under ideal extraction parameters, the extraction rates obtained were higher than other conventional organic solvents and had an excellent enrichment effect with only 90 s of vortex-shaking. Ultimately, an integrated multi-stage counter-current extraction and recovery unit was developed, capable of reducing costs and easily recovering solvents and target compounds, exploring the possibility of large-scale applications in the industry. A complete set of extraction, isolation, and recovery from plant material to chemical components offers a new perspective for the development of a high-value industry for plant secondary metabolites.