Comparative screening of organic solvents, ionic liquids, and their binary mixtures for vitamin E extraction from deodorizer distillate

Abstract

Although it is well known that solvent is one of the most important decision variables in liquid-liquid extraction processes, many previous studies focused on a specific class of solvents while neglecting alternatives. This work presents a comparative screening of two types of most extensively studied solvents, i.e., organic solvents (OS) and ionic liquids (ILs), as well as their binary systems for the extraction of vitamin E from methylated oil deodorizer distillates (modelled as a mixture of α-tocopherol and methyllinoleate). For this practically relevant task, the ternary liquid-liquid equilibria (LLE) of {OS or IL + α-tocopherol + methyllinoleate} are first calculated by use of the COnductor-like Screening Model for Real Solvents (COSMO-RS), after which the physical and environmental, health, and safety (EHS) properties of solvents are assessed to identify the top-ranked OS and ILs. To intensify the separation performance, binary solvent systems are also explored, where one of the pre-selected ILs is taken as the first solvent for α-tocopherol and an OS is screened as the second solvent for methyllinoleate. Then, the IL-OS combinations are investigated regarding their binary immiscibility and ranked with respect to the LLE performance in the quaternary system {IL + α-tocopherol + methyllinoleate + OS}. By comparing the extraction distribution coefficient and the selectivity of the top-ranked OS, ILs and IL-OS systems, the notable intensified performance of binary solvent system is proven.