Deep Eutectic Phase Research Articles

Selective Extraction of Antioxidants by Formation of a Deep Eutectic Mixture through Mechanical Mixing

Extraction of active compounds from natural materials is commonly used to produce a diverse range of ingredients, nutrients, drugs, flavors, and fragrances. While solvent-based approaches are standard for these extraction procedures, large solvent volumes, greenhouse gas emission (due to atmospheric release of volatile organic compounds), and large energy requirements are significant issues. Here, we describe a novel process wherein a mechanical action is applied to a solid-state mixture comprising a quaternary ammonium salt and a biological material containing active molecules to form a deep eutectic mixture. It is first shown that eutectic mixtures can be formed for a wide range of naturally occurring compounds. Selective extraction of these compounds from natural products is then demonstrated using rosemary leaves with three different quaternary ammonium salts. The eutectic mixture formed is purified by liquid/liquid extraction using an oily phase to concentrate the active constituents in the deep eutectic phase. The resulting natural extracts are shown to exhibit high antioxidant activities, which were measured using the conjugated autoxidizable triene (CAT) and the oxygen radical absorbance capacity (ORAC) assays.

Liquid-Liquid Extraction of Furfural from Water by Hydrophobic Deep Eutectic Solvents: Improvement of Density Function Theory Modeling with Experimental Validations.

This study outlines the methodology to model hydrophobic deep eutectic solvent (HDES) interactions to obtain computational results that accurately represent experimental results of furfural removal from water. Computational prediction with high accuracy of HDES behavior could elucidate hydrogen bond interaction in HDES. COSMOtherm modeling and experimental evaluation demonstrated that both decanoic and dodecanoic acid-based HDES can remove furfural from water even at very low concentrations of 0.1 mol %. The modeling methodology considered salts as independent cations, which were paired with the hydrogen bond donor (HBD) species. These resulted in computational predictions of liquid–liquid equilibrium (LLE) between tetra n-alkyl ammonium bromide salt-based HDES with >95% accuracy of experimental results. The COSMOtherm modeling methodology strengthens the understanding of HDES by considering intermolecular forces that affect electron density (σ) of the HDES components to determine the LLE of the HDES-aqueous system. This results in a deep eutectic phase that has a positive sigma potential (potentials, μ(σ), up to 0.1 kcal/mol Å2) at charge densities associated with hydrogen bonding (±0.0084 e/Å2). Though n-alkyl ammonium salts ranging from tetramethyl- to tetraoctylammonium bromide were considered in the computational model, only pentyl- and longer alkyl chains displayed hydrophobic behavior with less than 1% salt loss to the aqueous phase. However, there was still significant water uptake in the eutectic phase (final phase composition containing greater than 60 mol and 12% by mass) for the hydrophobic DES.