Extraction of vanillin using ionic-liquid-based aqueous two-phase systems

Abstract

a b s t r a c tTo explore proper extractive solvents and to design an optimized separation process it is highly imperative to understand the molecular-based phenomena governing the solutes partitioning. Moreover, the development of new techniques for the biomolecules separation and purification, while maintaining their functional characteristics unchanged, is still ongoing. Therefore, in this work, the partition coefficients of vanillin, a compound with well-known organoleptic properties, were determined using improved ionicliquid-based aqueous two-phase systems (ATPS). Three main parameters were evaluated through the vanillin partitioning process: the ionic liquid (IL) cation and anion structure, the temperature of equilibrium and the available concentration of vanillin in the global system. In all systems and conditions tested, vanillin preferentially migrates for the IL-rich phase. In addition, the three studied parameters largely influence the vanillin partitioning. In an attempt to elucidate the thermodynamics of the partitioning process, the standard molar thermodynamic functions of transfer of vanillin were also determined based on the temperature dependence data. These data indicate that the partition of vanillin results from an interplay between enthalpic and entropic contributions where both the IL anion and more complex cations play an essential role. Moreover, viscosities and densities of both aqueous phases were experimentally measured at the mass fraction compositions for which the partition coefficients were determined. The results gathered in this work indicate that IL-based ATPS can be further employed in the extraction and purification of vanillin from different matrices, as confirmed by the large partition coefficients obtained and improved low viscosity systems.

Surface tensions of ionic liquids: Non-regular trend along the number of cyano groups

“…Since then, a large interest on their application has emerged, comprising the application of cyano-based ILs as fluoro-free alternatives in the development of lithium-conducting electrolytes [19,20], and in organic dye-sensitized solar cells [21]. Cyano-based ILs have also been studied as alternative solvents in separation approaches, namely in the extraction of aromatics from aromatic/aliphatic mixtures [22], in the extraction of phenolic compounds from biomass [23], in the selective separation of CO 2 and N 2 (using supported IL membranes) [24], and in the separation and recovery of alcohols from aqueous media [14,25]. For a better design of these processes, the solvation capacity and ability to establish hydrogen bonds with water and ethanol [26,27], the volumetric properties of binary mixtures composed of benzene and cyano-based ILs [28], and thermophysical properties, such as densities, viscosities and refractive index [29] of these CN-based fluids, have been evaluated.…”

Role of tailored surface of activated carbon for adsorption of ionic liquids for environmental remediation

“…Ionic liquids have gained significant attention due to wide range of applications, including catalysis, synthesis (Olivier-Bourbigou et al 2010) and biocatalytic reactions (van Rantwijk and Sheldon 2007), electrochemical (Armand et al 2009), separation processes (Han and Armstrong 2007;Claudio et al 2010), supercapacitors (Xu et al 2010), nanomaterials (Migowski and Dupont 2007) and some processes working at industrial scale (Plechkova and Seddon 2008). The ILs are categorized as green solvents in comparison with the other conventional organic solvents.…”

Distribution of N-Methylimidazole in Ionic Liquids/Organic Solvents Systems

“…It is noteworthy that this phenomenon is most pronounced for the less polar cyclohexane (K mim enhancement of 167%) and less pronounced for the solvent of the highest polarity-BuOAc (K mim enhancement of 12%). The van't Hoff plots ln (K mim ) vs. 1/T exhibit linearity for all systems (see Figure 1a), which indicates that the standard enthalpy of transfer of mim is temperature-independent [23] in the temperature range studied. The calculated ∆ tr G 0 and ∆ tr H 0 values are positive for all systems; consequently, the partition of mim from the IL-phase to the organic phase is a thermodynamically unfavorable and endothermic structure-breaking process.…”

“…The partition coefficient of a species between two immiscible liquid phases can be considered as an important physicochemical parameter from an engineering perspective, since it can be useful in the recovery of compounds by liquid-liquid extraction [23][24][25][26][27][28][29][30][31]. In our present study [32], we introduced an improved apparatus for continuous liquid-liquid extraction to be used as a tool for the purification of halide-based ionic liquids after the quaternization step.…”