Physicochemical and acoustic characterization of binary mixtures of tetraalkylammonium bromide: PEG based DES and water

Abstract

In modern green chemistry, Deep eutectic solvents (DESs) have gain appreciable recognition as an analogues of ionic liquids (ILs) due to inexpensive and easy to handle preparation method. DESs exhibit similar physiochemical properties to ILs and considered as a suitable alternative to volatile organic solvents. In present study, DESs were formulated by complexing HBA: Tetraethylammonium bromide and Tetrapropylammonium bromide and HBD: Polyethylene glycol of average molecular weight (200/400/600) in 1:2 M ratio. The densities (ρ), speeds of sound (u) of pure DESs and their binary mixtures with H2O were collected as a function of DES concentration and temperature. The excess molar properties: VmE and Ks,mE were calculated using these data and fitted to the Redlich-Kister equation to estimate standard deviation between the experimental and calculated values of excess molar properties. The trends of variation in calculated values of VmE and Ks,mE were interpreted in light of temperature and DES: H2O interactions occurring within the binary mixtures. The PFPT (Prigogine-Flory-Patterson Theory) and ERAS (Extended Real Associated Solution Model) were applied to evaluate the validity of theories to predict VmE for presently studied binary mixtures.