Dielectric Relaxation Studies of Ternary Mixture of Dimethyl Phthalate and Heptanol in Benzene Solution in the Microwave Region

Abstract

Abstract The molecular structure and molecular forces in liquids and solutions, in particular, have been investigated by dielectric relaxation studies. The nature and strength of the molecular interactions have been established as the main cause for the chemical behaviour of compounds. The dielectric behaviour of dimethyl phthalate with heptanol in benzene solution has been studied at a microwave frequency of 9.36 GHz at different temperatures 303, 308, and 313 K. Different dielectric quantities such as dielectric constant (ε′), dielectric loss (ε″), static dielectric constant (ε 0), and dielectric constant at optical frequency (ε ∞) have been determined. The relaxation time τ has been calculated by both Higasi’s method and Cole–Cole method. The dielectric relaxation process can be treated as a rate process just like the viscous flow process. The complex system investigated shows the maximum relaxation time values at high temperatures by both Higasi’s method and Cole–Cole method. The molar free energies of activation of dipole moment (ΔF τ) and viscous force (ΔF η) have also been reported. The excess dipole moment is also determined. The excess dipole moment is a qualitative index for the presence of a hydrogen bond in the ternary system. The value of Δμ obtained in our study indicates the presence of hydrogen bonds between the components of the mixture. The system investigated shows that the relaxation time value increases with the increase in the concentration of solute.