Novel phase diagrams of aqueous two-phase systems based on tetrahydrofuran plus carbohydrates plus water: Equilibrium data and partitioning experiments

This work addresses the partitioning of diuron, a herbicide heavily employed in agriculture, using the aqueous two-phase system formed by tetrahydrofuran and carbohydrates. Phase diagrams using tetrahydrofuran (THF) and six monosaccharides, two disaccharides and three commercial sugars at 298.15 K and 0.1 MPa were constructed. The equilibrium phases were further characterized by determining the density and viscosity at 283.15-333.15 K and 0.1 MPa. Finally, the diuron extraction was assessed by the partition coefficient (K-DIU) and recovery in the top-phase (R-T). The number of equatorial hydroxyl groups present in the carbohydrates' structures is the driving force for the phase separation; disaccharides are stronger inducers of the ATPS formation than monosaccharides. The differences in the density and viscosity of the phases allowed an easy phase separation. In all cases, the diuron partitions preferentially to the THF-rich phase with K-DIU ranging from 1.23 (commercial glucose) to 16.19 (pure glucose) and recovery between 49.45% (commercial glucose) and 92.70% (pure glucose), demonstrating the applicability in the partition of diuron. (C) 2016 Elsevier B.V. All rights reserved.