Rational Screening of Deep Eutectic Solvents for the Direct Extraction of α-Tocopherol from Deodorized Distillates

As traditional methods for retrieving natural vitamin E suffer from harsh operating conditions and poor process performance, seeking more energy-efficient and sustainable alternative approaches is highly desirable. In this work, deep eutectic solvents (DESs) as a class of emerging media are particularly proposed for the extraction of vitamin E (modeled by α-tocopherol) from deodorized distillates under mild operating conditions. To select DESs suitable for this task, a rational screening method is presented which covers the thermodynamic evaluation of individual components and component combinations, the assessment of environment, health, and safety (EHS) impacts of components, and the eutectic behavior estimation of component combinations. Based on experimentally reported DESs from the literature, individual components as well as random combinations of potential hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are successively prescreened by COSMO-RS predicted thermodynamic properties. Five EHS-related properties of HBDs are assessed by VEGA. The formation of eutectics and the corresponding operating window of different HBA–HBD combinations are estimated by COSMO-RS solid–liquid equilibria prediction. Experiments are finally performed with the top-ranked DESs, which well validates the reliability of the screening method and identifies tetrabutylphosphonium chloride–ethanolamine (2:1) as a suitable DES for the α-tocopherol extraction.