Ion-solvent interaction of 1-decyl-3-methylimidazolium chloride and isopropanol in a quaternary aqueous two phase system for the efficient partitioning of vanillin and L-tryptophan

A novel quaternary aqueous biphasic system (ABS) composed of 1-decyl-3-methylimidazolium chloride ([Dmim]Cl), 2-propanol, and dipotassium hydrogen phosphate (K2HPO4) was determined at 298.15 K, and impact of 2-propanol:[Dmim]Cl mass ratio on the partition of L-tryptophan and vanillin, was investigated systematically. Additionally, the ion-association and solvation behavior of the ionic liquid in a solution of the aqueous-alcoholic mixture was investigated using the electrical conductivity measurement and analyzed with the low-concentration chemical model (lcCM). It is found that ion-association phenomena govern significantly at the top phase, and biomolecules affinity enhanced where it solvated completely by the ionic liquid. The hybrid ion-interaction and solvation model (HIS) coupled with the UNIQUAC model, was implemented to fit liquid-liquid equilibrium (LLE) data and investigate the ion-solvent interaction of ionic and nonionic compounds. The interaction parameter's analysis of the HIS-UNIQUAC model declared the great solvation for the ionic liquid at the bottom phase. At the 2-propanol:[Dmim]Cl mass ratio of 3:1, the highest partition coefficient of vanillin, K = 389.4, was achieved while the highest partitioning of L-tryptophan, K = 66.5, occurs at the 2-propanol: [Dmim]Cl mass ratio of 1:10, respectively. The partition behavior of biomolecules independently describes using the electrostatic and solvation terms of the HIS-UNIQUAC model, and in general, the activity model provided favorable agreement with theoretical concepts and experimental data. (C) 2021 Elsevier B.V. All rights reserved.