COSMO-RS-Based Screening of Antisolvents for the Separation of Sugars from Ionic Liquids: Experimental and Molecular Dynamic Simulations

The use of ionic liquids (ILs) in the biorefinery process has been increasing for the past few decades. In biorefinery, the separation process with respect to sugars needs to be evaluated for an efficient process design. Therefore, the present work aims to investigate the separation of sugars and ILs by means of a precipitation process using an antisolvent method. For this purpose, both theoretical and experimental studies were conducted. Initially, the conductor-like screening model for real solvents model was employed to screen the suitable antisolvents for the separation of sugars from the ILs. From the screening study, dichloromethane (DCM) and 1,2-dichloroethane were found to be the better antisolvents for the separation process. With the selected antisolvents, precipitation experiments were conducted for the mixtures involving four different sugars and three ILs at different experimental conditions. The process variables such as different antisolvents, sugars, ILs, antisolvent-IL molar ratios, and temperatures were examined in terms of their effect on sugar removal and IL recovery. DCM was found to be the most suitable antisolvent in this study with 90-99% of sugar removal and 80-98% of IL recovery. Further, molecular dynamics simulations were adopted to understand the structural properties of carbohydrates with ILs and antisolvents via interaction energies, hydrogen bonding, and coordination numbers. It was observed that the interaction energy between the sugars and IL plays a critical role in the removal of sugar. Higher the interaction energy between the sugars and IL, lower is the sugar removal.