Density of aqueous choline chloride-based ionic liquids analogues

Abstract

Ionic liquids analogues known as Deep Eutectic Solvents (DESs) are increasingly realized in many chemical and industrial applications. The physical and chemical characteristics of these fluids are affected considerably by their moisture content. This study focuses on the evaluation and prediction of the density of choline chloride-based DES aqueous mixtures. The study involved six well known DESs with water mole fraction ranging between 0 and 1 within the temperature range (298.15–353.15K). Since, the density of pure DESs is more than that of water, the resulting aqueous mixtures density trends were similar. The Jouyban-Acree mixture density correlation was adopted for each DES mixture separately with very good prediction accuracy. In addition, an alternative modified model was suggested. This model is capable of predicting all DES mixtures density data based on their corresponding critical properties. Negative excess molar volume suggests formation of stronger H-bond and a more extensive H-bond network within the mixture. This is enhanced by the packing effect created by difference between the molecular structures of the DES and water. The aqueous DES solutions density model presented in this work may assist in evaluating the effect of moisture content on this important physical property. This will further help in adopting proper chemical equipment design considerations and relevant process modeling and simulation calculations.