Dielectric relaxation study of binary mixture of sulfolane and N,N-dimethylformamide in benzene solution using microwave absorption data

Abstract

The dielectric constant (ɛ′) and dielectric loss (ɛ″) for dilute solutions of the binary mixture of different molar concentrations of sulfolane and DMF in benzene solution has been measured at 9.885 GHz and different temperatures (25, 30, 35, 40°C) by using standard microwave techniques. Following the single frequency concentration variational method, the dielectric relaxation time (τ) and dipole moment (μ) have been calculated. It is found that dielectric relaxation process can be treated as the rate process, just like the viscous flow. The presence of solute-solute molecular associations in benzene solution has been proposed. Energy parameters (ΔH _ɛ, ΔF _ɛ, ΔS _ɛ) for dielectric relaxation process of binary mixture at 50% mole fraction in benzene at 25, 30, 35, and 40°C have been calculated and compared with the corresponding energy parameters (ΔH _η, ΔF _η, ΔS _η) for the viscous flow.