A thermodynamic investigation of solute - solvent interactions through volumetric, ultrasonic, dielectric, refractive and excess properties of binary mixtures of Tri-n-butyl phosphate with dichloro, trichloro and tetrachloromethane at 298.15 K

Abstract

This study reports the density (ρ), molar volume(V),ultrasonic velocity (U), dielectric permittivity (ε), refractive index (nD) Kirkwood correlation factor (g/geff) and excess Helmholtz energy (∆AE) of binary mixtures of polar TBP (Tri-n-butyl phosphate) with polar CH2Cl2, CHCl3 and non-polar CCl4 over the entire range of mole fractions at 298.15 K. Several mixing rules have been applied to predict the ultrasonic velocity, dielectric permittivity and refractive index of the binary mixtures. The excess properties (VE, βsE, LfE, ZE, εE, PE and ∆nD) have been calculated in order to throw light on the kinds of molecular interactions existing in the binary systems. The experimentally obtained excess properties are fitted into Redlich-Kister polynomial equation. The negative values of VE and βsE for TBP and CCl4 mixtures resulted from the study may be attributed to dissimilar nature of the constituent molecules. In case of polar – polar TBP + CHCl3/CH2Cl2 mixtures, negative excess Helmholtz energy visualize anti parallel orientation of dipoles in TBP rich region.