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This work studies the partition of phenolic compounds, namely caffeic acid, syringic acid, vanillic acid, ferulic acid, and vanillin, in aqueous two-phase systems (ATPSs) formed by acetonitrile and deep eutectic solvents (DESs) based on choline chloride ([Ch]Cl) and carbohydrates (sucrose, d-glucose, d-mannose, arabinose, and d-xylose). The binodal curves built at 25 °C and 0.1 MPa using DES were compared with ATPS composed of [Ch]Cl and the same carbohydrates. The ability to form ATPS depends on the number and kind of hydroxyl groups in DES's hydrogen-bond donor compound (carbohydrates). ATPS based on DES showed biphasic regions larger than the systems based on [Ch]Cl and carbohydrates alone due to the larger hydrophilicity of DES. The ATPS were used to study the partition of the phenolic compounds. For all the systems, the biomolecules preferentially partitioned to the acetonitrile-rich phase (K > 1), and the best recovery in the top phase ranged between 53.36% (caffeic acid) and 90.09% (vanillin). According to the remarkable results, DES-based ATPS can selectively separate ferulic acid and vanillin for the top phase and syringic, caffeic, and vanillic acids for the bottom phase, achieving a selectivity higher than two. [ABSTRACT FROM AUTHOR]

Abstract Novel aqueous two-phase systems (ATPS) formed by water, acetonitrile and maltodextrin with different dextrose equivalent values (DE) are here described and characterized. The respective ternary phase diagrams were determined at 298.15 K. It was found that ATPS formed by maltodextrin and acetonitrile require lower amounts of phase forming-components to undergo liquid-liquid demixing than similar systems formed by mono- and disaccharides. To evaluate the ability of these systems as extraction strategies, experiments with vanillin were carried out. Conditions such as DE and concentration of maltodextrin, concentration of acetonitrile, and temperature were evaluated. In all the investigated systems, vanillin partitions preferentially to the top phase – acetonitrile-rich phase - with a partition coefficient (K van) ≫ 1. The best conditions for vanillin partitioning to this phase were obtained using maltodextrin DE 16.5–19.5 at 35 wt% + acetonitrile at 35 wt% + water at 30 wt%, at 308.15 K, for which K van and recovery in top phase (R T) was 12.4 and 91.8 %, respectively. The temperature has no statistical influence in the vanillin partitioning. According to the data gathered at different temperatures, it was found that the vanillin partitioning process is spontaneous, endothermic and governed by entropic forces. Finally, the density and viscosity of the studied aqueous two-phase system (ATPS) coexisting phases were determined, showing significant differences in viscosity and density between the phases, which is highly beneficial for phase separation and scaled-up applications. Highlights • Acetonitrile and maltodextrin are able to form aqueous two-phase system. • The best separation conditions studied lead to a K van of 12.4 and R T of 9138. • Vanillin partition is spontaneous, endothermic and governed by entropic forces. • Differences in viscosity and density between the phases are benefic for separation. [ABSTRACT FROM AUTHOR]