Multiphysics Experimental Approaches for Insight into the Hydrogen Bonded Structures of Ethylene Glycol and Glycerol Mixtures toward Green Solvent Technology

Abstract

Alcohols and their mixtures are credited most important polar solvents for advances in pharmaceutical, chemical,biological, thermal, and material technologies. A rigorous study for the characterization of hydrogen bonded heterogeneousintermolecular structures that formed in a mixed solvent based on alcohols containing two and three hydroxyl groupsmolecules is crucial to specific technological and industrial applications. Hence, in this work, the multiphysics experimentalapproaches including the measurements of dielectric, electrical, viscous, acoustic, thermal, and optical properties are appliedand analyzed to confirm the behaviour of hydrogen bonded molecular structures of ethylene glycol (EG; dihydric alcohol)with glycerol (Gl; trihydric alcohol) over the entire concentration range of EG+Gl mixtures at 298.15 K. The static dielectricpermittivity, direct current electrical conductivity, low frequency relaxation time, and refractive index values of the EG+Glmixtures are reported. Additionally, dynamic viscosity, density, ultrasound velocity, adiabatic compressibility,intermolecular free length, acoustic impedance, free volume, Rao’s constant, Wada constant, and viscoacoustic relaxationtime of the EG+Gl mixtures are determined, and also explored their significance to these alcohols molecular interactions.Ultraviolet-visible range absorbance behaviour of the alcohol mixtures is characterized in detail and confirmed theelectronic transitions at higher energy ultraviolet radiations. The detailed analysis of all the experimental results along withthe consideration of excess properties evidenced the formation of heterogeneous intermolecular hydrogen bonded structuresin these Newtonian-type alcohols mixtures. A small to adequate variation in the thermodynamical and other investigatedproperties with the concentration variation showed that the EG+Gl mixture can be optimized as a green solvent according tothe prerequisite properties for huge advances in soft condensed matter technologies.